Uma equipe de cientistas da Universidade de Washington e da Universidade de Toronto foram os primeiros a simular nuvens exóticas em 3D na atmosfera de um exoplaneta.
O objeto em questão, é o GJ 1214b, um exoplaneta chamado de mini-Netuno que foi descoberto, seis anos atrás pelos astrônomos no Harvard-Smithsonian Center for Astrophysics.
Também conhecido como Gliese 1214b, esse mundo tem cerca de 2.7 vezes o diâmetro da Terra e uma massa quase 7 vezes maior que a massa do nosso planeta. Ele está localizado a cerca de 52 anos-luz de distância na constelação de Ophiuchus.
O planeta orbita a estrela anã vermelha, GJ 1214, a cada 38 horas, a uma distância de 1.3 milhões de milhas.
De acordo com estudos prévios, o planeta tem uma atmosfera rica em água ou hidrogênio com extensas nuvens.
“Deve existir altas nuvens ou uma névoa orgânica na atmosfera – como nós observamos em Titã. Sua temperatura atmosférica excede o ponto de fusão da água”, disse o Dr. Benjamin Charnay, um dos membros da equipe da Universidade de Washington.
Large scale mass_distribution_in_the_illustris_simulationSérgio Sacani
Observations at low redshifts thus far fail to account for all of the baryons expected in the
Universe according to cosmological constraints. A large fraction of the baryons presumably
resides in a thin and warm–hot medium between the galaxies, where they are difficult to observe
due to their low densities and high temperatures. Cosmological simulations of structure
formation can be used to verify this picture and provide quantitative predictions for the distribution
of mass in different large-scale structure components. Here we study the distribution
of baryons and dark matter at different epochs using data from the Illustris simulation. We
identify regions of different dark matter density with the primary constituents of large-scale
structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift
zero, we find that 49 per cent of the dark matter and 23 per cent of the baryons are within
haloes more massive than the resolution limit of 2 × 108 M⊙. The filaments of the cosmic
web host a further 45 per cent of the dark matter and 46 per cent of the baryons. The remaining
31 per cent of the baryons reside in voids. The majority of these baryons have been transported
there through active galactic nuclei feedback. We note that the feedback model of Illustris
is too strong for heavy haloes, therefore it is likely that we are overestimating this amount.
Categorizing the baryons according to their density and temperature, we find that 17.8 per cent
of them are in a condensed state, 21.6 per cent are present as cold, diffuse gas, and 53.9 per cent
are found in the state of a warm–hot intergalactic medium.
A new universal formula for atoms, planets, and galaxiesIOSR Journals
In this paper a new universal formula about the rotation velocity distribution of atoms, planets, and galaxies is presented. It is based on a new general formula based on the relativistic Schwarzschild/Minkowski metric, where it has been possible to obtain expressions for the rotation velocity - and mass distribution versus the distance to the atomic nucleus, planet system centre, and galactic centre. A mathematical proof of this new formula is also given. This formula is divided into a Keplerian(general relativity)-and a relativistic(special relativity) part. For the atomic-and planet systems the Keplerian distribution is followed, which is also in accordance with observations.
According to the rotation velocity distribution of the galaxies the rotation velocity increases very rapidly from the centre and reaches a plateau which is constant out to a great distance from the centre. This is in accordance with observations and is also in accordance with the main structure of rotation velocity versus distance from different galaxy measurements.
Computer simulations were also performed to establish and verify the rotation velocity distributions in the atomic – planetary- and galaxy system, according to this paper. These computer simulations are in accordance with observations in two and three dimensions. It was also possible to study the matching percentage in these calculations showing a much higher matching percentage between theoretical and observational values by this new formula.
While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology...
Why Does the Atmosphere Rotate? Trajectory of a desorbed moleculeJames Smith
As a step toward understanding why the Earth's atmosphere "rotates" with the Earth, we use using Geometric (Clifford) Algebra to investigate the trajectory of a single molecule that desorbs vertically upward from the Equator, then falls back to Earth without colliding with any other molecules. Sample calculations are presented for a molecule whose vertical velocity is equal to the surface velocity of the Earth at the Equator (463 m/s) and for one with a vertical velocity three times as high. The latter velocity is sufficient for the molecule to reach the Kármán Line (100,000 m). We find that both molecules fall to Earth behind the point from which they desorbed: by 0.25 degrees of latitude for the higher vertical velocity, but by only 0.001 degrees for the lower.
From the workshop "High-Resolution Submillimeter Spectroscopy of the Interste...Lars E. Kristensen
Presentation given at the workshop "High-Resolution Submillimeter Spectroscopy of the Interstellar Medium and Star Forming Regions — From Herschel to ALMA and Beyond" held in Zakopane, Poland, May 2015: https://fox.ncac.torun.pl/export/herschel2alma/?slcn=main
Formation of diamonds in laser-compressed hydrocarbons at planetary interior ...Sérgio Sacani
The effects of hydrocarbon reactions and diamond precipitation
on the internal structure and evolution of icy giant planets
such as Neptune and Uranus have been discussed for more than
three decades1. Inside these celestial bodies, simple hydrocarbons
such as methane, which are highly abundant in the atmospheres2,
are believed to undergo structural transitions3,4 that
release hydrogen from deeper layers and may lead to compact
stratified cores5–7. Indeed, from the surface towards the core,
the isentropes of Uranus and Neptune intersect a temperature–
pressure regime in which methane first transforms into a
mixture of hydrocarbon polymers8, whereas, in deeper layers, a
phase separation into diamond and hydrogen may be possible.
Here we show experimental evidence for this phase separation
process obtained by in situ X-ray diffraction from polystyrene
(C8H8)n samples dynamically compressed to conditions around
150 GPa and 5,000 K; these conditions resemble the environment
around 10,000 km below the surfaces of Neptune and
Uranus9. Our findings demonstrate the necessity of high pressures
for initiating carbon–hydrogen separation3 and imply
that diamond precipitation may require pressures about ten
times as high as previously indicated by static compression
experiments4,8,10. Our results will inform mass–radius relationships
of carbon-bearing exoplanets11, provide constraints for
their internal layer structure and improve evolutionary models
of Uranus and Neptune, in which carbon–hydrogen separation
could influence the convective heat transport7.
Colloquium given at the Caltech star formation group (Feb. 24, 2015) and NASA/JPL (Feb. 26, 2015). The presentation features recent research highlights by myself and collaborators and is intended for a non-expert astronomy audience.
First discovery of_a_magnetic_field_in_a_main_sequence_delta_scuti_star_the_k...Sérgio Sacani
Coralie Neiner do Laboratory for Space Studies and Astrophysics Instrumentation, LESIA (CNRS/Observatoire de Paris/UPMC/Université Paris Diderot) e Patricia Lampens (Royual OIbservatory of Belgium), descobriram a primeira estrela magnética do tipo delta Scuti, através de observações espectropolarimétricas, realizadas com o telescópio CFHT. As estrelas do tipo delta Scuti, são estrelas pulsantes, sendo que algumas delas mostram assinaturas atribuídas para um segundo tipo de pulsação. A descoberta mostra que isso é na verdade a assinatura de um campo magnético. Essa descoberta tem importantes implicações para o entendimento do interior das estrelas.
Dois tipos de estrelas pulsantes existem entre as estrelas com massa entre 1.5 e 2.5 vezes a massa do Sol: as estrelas do tipo delta Scuti e as estrelas do tipo gamma Dor. A teoria nos diz que as estrelas com temperatura entre 6900 e 7400 graus Kelvin podem ter ambos os tipos de pulsação. Essas são então chamadas de estrelas híbridas. Contudo, o satélite Kepler da NASA tem detectado um grande número de estrelas híbridas com temperaturas maiores ou menores do que esse limite pensado anteriormente. A existência dessas estrelas híbridas com temperaturas maiores é algo muito controverso, já que desafia o nosso entendimento sobre as estrelas pulsantes do tipo delta Scuti e gamma Dor.
A rocky planet_transiting_a_nearby_low_mass_starSérgio Sacani
Um exoplaneta rochoso do tamanho da Terra, orbita uma estrela pequena e próxima, poderia ser o mundo mais importante já encontrado além do Sistema Solar, disseram os astrônomos.
O planeta localiza-se na constelação de Vela, no hemisfério sul do céu e é próximo o suficiente para que os telescópios possam observar qualquer atmosfera que ele possua, um procedimento que poderia ajudar a registrar algum tipo de vida, se ela existisse em outros planetas, no futuro.
Denominado de GJ 1132b, o exoplaneta é cerca de 16% maior que a Terra, e está localizado a cerca de 39 anos-luz de distância, o que faz com que ele seja três vezes mais próximo da Terra do que qualquer outro exoplaneta rochoso já descoberto. Nessa distância, espera-se que os telescópios sejam capazes de fazer uma análise química de sua atmosfera, a velocidade dos seus ventos e as cores do pôr-do-Sol, que acontecem no exoplaneta.
Os astrônomos registraram o planeta à medida que ele passava na frente da sua estrela, uma estrela do tipo anã vermelha, com somente um quinto do tamanho do Sol. Apesar de muito mais fria e muito mais apagada que o Sol, o GJ 1132b, tem uma órbita tão próxima da estrela que as suas temperaturas superficiais atingem cerca de 260 graus Celsius.
Essa temperatura, obviamente, é muito alta para reter a água em estado líquido na superfície do exoplaneta, fazendo com que ele seja inóspito para a vida, mas não tão quente para queimar toda uma atmosfera que pode ter se formado no planeta.
Radio continum emission_of_35_edge_on_galaxies_observed_with_the_vlaSérgio Sacani
Usando um dos maiores rádio observatórios do mundo, o Very Large Array do National Radio Astronomy, um grupo de astrônomos descobriram que os halos ao redor dos discos das galáxias espirais são muito mais comuns do que se pensava anteriormente.
A equipe, dirigida pela Dra. Judith Irwin, da Universidade de Queens, em Kingston, ON, Canadá, observou 35 galáxias espirais próximas de lado, de 11 a 137 milhões de anos-luz de distância da Terra.
As galáxias espirais, como a nossa própria Via Láctea ou a famosa Galáxia de Andrômeda, possuem uma vasta maioria de suas estrelas, gás, e poeira num disco plano em rotação com braços espirais. A maior parte da luz e das ondas de rádio observadas com telescópios veem de objetos localizados nesse disco.
“Nós sabíamos antes que alguns halos existiam, mas, usando o poder total do VLA atualizado e o poder total de algumas técnicas de processamento de imagens, nós descobrimos que esses halos são muito mais comuns entre as galáxias espirais do que nós pensávamos antes”, explicou a Dra. Irwin.
Large scale mass_distribution_in_the_illustris_simulationSérgio Sacani
Observations at low redshifts thus far fail to account for all of the baryons expected in the
Universe according to cosmological constraints. A large fraction of the baryons presumably
resides in a thin and warm–hot medium between the galaxies, where they are difficult to observe
due to their low densities and high temperatures. Cosmological simulations of structure
formation can be used to verify this picture and provide quantitative predictions for the distribution
of mass in different large-scale structure components. Here we study the distribution
of baryons and dark matter at different epochs using data from the Illustris simulation. We
identify regions of different dark matter density with the primary constituents of large-scale
structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift
zero, we find that 49 per cent of the dark matter and 23 per cent of the baryons are within
haloes more massive than the resolution limit of 2 × 108 M⊙. The filaments of the cosmic
web host a further 45 per cent of the dark matter and 46 per cent of the baryons. The remaining
31 per cent of the baryons reside in voids. The majority of these baryons have been transported
there through active galactic nuclei feedback. We note that the feedback model of Illustris
is too strong for heavy haloes, therefore it is likely that we are overestimating this amount.
Categorizing the baryons according to their density and temperature, we find that 17.8 per cent
of them are in a condensed state, 21.6 per cent are present as cold, diffuse gas, and 53.9 per cent
are found in the state of a warm–hot intergalactic medium.
A new universal formula for atoms, planets, and galaxiesIOSR Journals
In this paper a new universal formula about the rotation velocity distribution of atoms, planets, and galaxies is presented. It is based on a new general formula based on the relativistic Schwarzschild/Minkowski metric, where it has been possible to obtain expressions for the rotation velocity - and mass distribution versus the distance to the atomic nucleus, planet system centre, and galactic centre. A mathematical proof of this new formula is also given. This formula is divided into a Keplerian(general relativity)-and a relativistic(special relativity) part. For the atomic-and planet systems the Keplerian distribution is followed, which is also in accordance with observations.
According to the rotation velocity distribution of the galaxies the rotation velocity increases very rapidly from the centre and reaches a plateau which is constant out to a great distance from the centre. This is in accordance with observations and is also in accordance with the main structure of rotation velocity versus distance from different galaxy measurements.
Computer simulations were also performed to establish and verify the rotation velocity distributions in the atomic – planetary- and galaxy system, according to this paper. These computer simulations are in accordance with observations in two and three dimensions. It was also possible to study the matching percentage in these calculations showing a much higher matching percentage between theoretical and observational values by this new formula.
While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology...
Why Does the Atmosphere Rotate? Trajectory of a desorbed moleculeJames Smith
As a step toward understanding why the Earth's atmosphere "rotates" with the Earth, we use using Geometric (Clifford) Algebra to investigate the trajectory of a single molecule that desorbs vertically upward from the Equator, then falls back to Earth without colliding with any other molecules. Sample calculations are presented for a molecule whose vertical velocity is equal to the surface velocity of the Earth at the Equator (463 m/s) and for one with a vertical velocity three times as high. The latter velocity is sufficient for the molecule to reach the Kármán Line (100,000 m). We find that both molecules fall to Earth behind the point from which they desorbed: by 0.25 degrees of latitude for the higher vertical velocity, but by only 0.001 degrees for the lower.
From the workshop "High-Resolution Submillimeter Spectroscopy of the Interste...Lars E. Kristensen
Presentation given at the workshop "High-Resolution Submillimeter Spectroscopy of the Interstellar Medium and Star Forming Regions — From Herschel to ALMA and Beyond" held in Zakopane, Poland, May 2015: https://fox.ncac.torun.pl/export/herschel2alma/?slcn=main
Formation of diamonds in laser-compressed hydrocarbons at planetary interior ...Sérgio Sacani
The effects of hydrocarbon reactions and diamond precipitation
on the internal structure and evolution of icy giant planets
such as Neptune and Uranus have been discussed for more than
three decades1. Inside these celestial bodies, simple hydrocarbons
such as methane, which are highly abundant in the atmospheres2,
are believed to undergo structural transitions3,4 that
release hydrogen from deeper layers and may lead to compact
stratified cores5–7. Indeed, from the surface towards the core,
the isentropes of Uranus and Neptune intersect a temperature–
pressure regime in which methane first transforms into a
mixture of hydrocarbon polymers8, whereas, in deeper layers, a
phase separation into diamond and hydrogen may be possible.
Here we show experimental evidence for this phase separation
process obtained by in situ X-ray diffraction from polystyrene
(C8H8)n samples dynamically compressed to conditions around
150 GPa and 5,000 K; these conditions resemble the environment
around 10,000 km below the surfaces of Neptune and
Uranus9. Our findings demonstrate the necessity of high pressures
for initiating carbon–hydrogen separation3 and imply
that diamond precipitation may require pressures about ten
times as high as previously indicated by static compression
experiments4,8,10. Our results will inform mass–radius relationships
of carbon-bearing exoplanets11, provide constraints for
their internal layer structure and improve evolutionary models
of Uranus and Neptune, in which carbon–hydrogen separation
could influence the convective heat transport7.
Colloquium given at the Caltech star formation group (Feb. 24, 2015) and NASA/JPL (Feb. 26, 2015). The presentation features recent research highlights by myself and collaborators and is intended for a non-expert astronomy audience.
First discovery of_a_magnetic_field_in_a_main_sequence_delta_scuti_star_the_k...Sérgio Sacani
Coralie Neiner do Laboratory for Space Studies and Astrophysics Instrumentation, LESIA (CNRS/Observatoire de Paris/UPMC/Université Paris Diderot) e Patricia Lampens (Royual OIbservatory of Belgium), descobriram a primeira estrela magnética do tipo delta Scuti, através de observações espectropolarimétricas, realizadas com o telescópio CFHT. As estrelas do tipo delta Scuti, são estrelas pulsantes, sendo que algumas delas mostram assinaturas atribuídas para um segundo tipo de pulsação. A descoberta mostra que isso é na verdade a assinatura de um campo magnético. Essa descoberta tem importantes implicações para o entendimento do interior das estrelas.
Dois tipos de estrelas pulsantes existem entre as estrelas com massa entre 1.5 e 2.5 vezes a massa do Sol: as estrelas do tipo delta Scuti e as estrelas do tipo gamma Dor. A teoria nos diz que as estrelas com temperatura entre 6900 e 7400 graus Kelvin podem ter ambos os tipos de pulsação. Essas são então chamadas de estrelas híbridas. Contudo, o satélite Kepler da NASA tem detectado um grande número de estrelas híbridas com temperaturas maiores ou menores do que esse limite pensado anteriormente. A existência dessas estrelas híbridas com temperaturas maiores é algo muito controverso, já que desafia o nosso entendimento sobre as estrelas pulsantes do tipo delta Scuti e gamma Dor.
A rocky planet_transiting_a_nearby_low_mass_starSérgio Sacani
Um exoplaneta rochoso do tamanho da Terra, orbita uma estrela pequena e próxima, poderia ser o mundo mais importante já encontrado além do Sistema Solar, disseram os astrônomos.
O planeta localiza-se na constelação de Vela, no hemisfério sul do céu e é próximo o suficiente para que os telescópios possam observar qualquer atmosfera que ele possua, um procedimento que poderia ajudar a registrar algum tipo de vida, se ela existisse em outros planetas, no futuro.
Denominado de GJ 1132b, o exoplaneta é cerca de 16% maior que a Terra, e está localizado a cerca de 39 anos-luz de distância, o que faz com que ele seja três vezes mais próximo da Terra do que qualquer outro exoplaneta rochoso já descoberto. Nessa distância, espera-se que os telescópios sejam capazes de fazer uma análise química de sua atmosfera, a velocidade dos seus ventos e as cores do pôr-do-Sol, que acontecem no exoplaneta.
Os astrônomos registraram o planeta à medida que ele passava na frente da sua estrela, uma estrela do tipo anã vermelha, com somente um quinto do tamanho do Sol. Apesar de muito mais fria e muito mais apagada que o Sol, o GJ 1132b, tem uma órbita tão próxima da estrela que as suas temperaturas superficiais atingem cerca de 260 graus Celsius.
Essa temperatura, obviamente, é muito alta para reter a água em estado líquido na superfície do exoplaneta, fazendo com que ele seja inóspito para a vida, mas não tão quente para queimar toda uma atmosfera que pode ter se formado no planeta.
Radio continum emission_of_35_edge_on_galaxies_observed_with_the_vlaSérgio Sacani
Usando um dos maiores rádio observatórios do mundo, o Very Large Array do National Radio Astronomy, um grupo de astrônomos descobriram que os halos ao redor dos discos das galáxias espirais são muito mais comuns do que se pensava anteriormente.
A equipe, dirigida pela Dra. Judith Irwin, da Universidade de Queens, em Kingston, ON, Canadá, observou 35 galáxias espirais próximas de lado, de 11 a 137 milhões de anos-luz de distância da Terra.
As galáxias espirais, como a nossa própria Via Láctea ou a famosa Galáxia de Andrômeda, possuem uma vasta maioria de suas estrelas, gás, e poeira num disco plano em rotação com braços espirais. A maior parte da luz e das ondas de rádio observadas com telescópios veem de objetos localizados nesse disco.
“Nós sabíamos antes que alguns halos existiam, mas, usando o poder total do VLA atualizado e o poder total de algumas técnicas de processamento de imagens, nós descobrimos que esses halos são muito mais comuns entre as galáxias espirais do que nós pensávamos antes”, explicou a Dra. Irwin.
Astrônomos, usando os dados do Telescópio Espacial de Raios-Gamma Fermi da NASA detectaram pistas de mudanças periódicas no brilho de uma chamada galáxia “ativa”, cujas emissões são alimentadas por um buraco negro gigante. Se confirmada, a descoberta marcaria a primeira emissão cíclica de raios-gamma com anos de duração, já detectada de qualquer galáxia, o que forneceria novas ideias sobre os processos físicos que ocorrem nas proximidades de um buraco negro.
“Observando muitos anos de dados obtidos pelo Large Area Telescope, o LAT, do Fermi, nós identificamos indicações de uma variação com aproximadamente dois anos de comprimento de raios-gamma emitidos pela galáxia conhecida como PG 1553+113”, disse Stefano Ciprini, que coordenou a equipe do Fermi no Centro de Dados Científicos, o ASDC, da Agência Espacial Italiana, em Roma. “Esse sinal é sutil, e dura menos do que 4 ciclos, assim, do mesmo modo que é algo espetacular de se ver é algo que precisa de mais observações”.
Buracos negros supermassivos com uma massa de milhões de vezes a massa do Sol, localizam-se no coração da maioria das galáxias, incluindo a nossa Via Láctea. Em cerca de 1% dessas galáxias, o buraco negro monstruoso, irradia energia equivalente à bilhões de vezes a energia do Sol, emissões que podem variar em escala de tempo de minutos a anos. Os astrônomos se referem a essas como sendo galáxias ativas.
Mais da metade das fontes de raios-gamma observadas pelo LAT do Fermi, são galáxias ativas, chamadas de blazars, como a PG 1553+113. À medida que a matéria cai em direção ao seu buraco negro supermassivo, algumas partículas subatômicas escapam numa velocidade próxima à velocidade da luz em um par de jatos apontados em direções opostas. O que faz um blazar tão brilhante é que um desses jatos de partículas podem estar diretamente apontados para nós.
Supplementary information spectral_evidence_for_hydrated_salts_on_mars_slopesSérgio Sacani
Novas descobertas feitas pela sonda Mars Reconnaissance Orbiter, a MRO, da NASA fornecem FORTES EVIDÊNICAS de que existe água líquida fluindo atualmente na superfície de Marte. Prestem atenção, não foi detectada água em Marte, não foi, o que foram detectadas foram indicações indiretas de que determinadas feições na superfície marciana podem ser causadas por água fluindo atualmente em sua superfície.
Ah, mas por que isso resolve um grande mistério? Pois, depois de muitas análises, do desenvolvimento de novos algoritmos de análise de imagens e de dados espectrométricos os cientistas puderam definir que as marcas escuras encontradas nos taludes de determinadas crateras podem ser causadas por água salgada fluindo na superfície. Essas marcas já foram identificadas há muitos anos, mas agora, com essas novas técnicas foi possível chegar a essa conclusão.
Usando um espectrômetro de imageamento, a bordo da sonda MRO, os pesquisadores detectaram assinaturas de minerais hidratados nos taludes onde misteriosas listras são vistas no Planeta Vermelho. Essas listras escurecidas aparecem como fluxos e refluxos no passar do tempo. Elas se escurecem e parecem fluir pelos íngremes taludes durante as estações mais quentes, e então se apagam nas estações mais frias. Elas aparecem em alguns locais em Marte quando as temperaturas estão acima de -23 graus Celsius, e desaparecem em épocas mais frias.
Estamos nós aqui novamente, nos deparando com mais um erro de interpretação de um artigo científico que transforma uma descoberta feita por cientistas sérios em uma série infindável de posts, textos e tudo mais a respeito de uma estrutura alienígena construída ao redor da estrela KIC 8462852, que não faz sentido nenhum. O intuito desse post é mais uma vez esclarecer todos os pontos dessa descoberta, acompanhado dos artigos e de um vídeo no meu canal onde explico todos os detalhes a respeito de exoplanetas, exocometas, Kepler e a pesquisa séria realizada pelos voluntários do projeto de ciência cidadã, Planet Hunters. Boa leitura.
“Bizarro”. “Interessante”. “Trânsito Gigante”. Essas foram as reações dos voluntários do projeto Planet Hunters quando eles olharam pela primeira vez a curva de luz da estrela parecida com o Sol, outrora normal, KIC 8462852.
Das mais de 150000 estrelas, sob constante observação durante os 4 anos da missão primária do Kepler da NASA, entre 2009 e 2013, essa estrela se destacou devido às inexplicáveis quedas no brilho de sua luz. Enquanto que quase todo mundo aposta em causas naturais para essa queda estranha no brilho da estrela, alguns sugeriram outras possibilidades.
Você lembrará que o observatório orbital Kepler, continuamente monitorou estrelas num campo de visão fixo focado nas constelações de Lyra e Cygnus, na esperança de registrar quedas periódicas no brilho da luz das estrelas, quedas essas geradas por exoplanetas em trânsito. Se uma queda no brilho da luz for observado, mais trânsitos eram observados para confirmar a detecção de um novo exoplaneta.
The neowise discovered_comet_population_and_the_co_co2_production_ratesSérgio Sacani
Após o seu lançamento em 2009, a sonda NEOWISE da NASA já observou 163 cometas durante a missão primária WISE/NEOWISE. Essa amostra do telescópio espacial representa a maior pesquisa infravermelha de cometas já feitas até o momento. Os dados dessa pesquisa estão dando uma nova ideia sobre a poeira, o tamanho dos núcleos do cometa, e a taxa de produção dos gases difíceis de serem observados como dióxido de carbono e monóxido de carbono. Os resultados do censo do NEOWISE dos cometas foram recentemente publicados no Astrophysical Journal.
O monóxido de carbono (CO) e o dióxido de carbono (CO2) são moléculas comuns encontradas no ambiente do início do Sistema Solar, e nos cometas. Na maior parte das circunstâncias, a sublimação do gelo de água provavelmente guia a atividade nos cometas quando eles chegam perto do Sol, mas em distâncias maiores e em temperaturas mais frias, outras moléculas como o CO e o CO2 podem ser os principais guias. O dióxido e o monóxido de carbono são moléculas difíceis de serem detectadas da terra, devido a abundância dessas moléculas na própria atmosfera terrestre que podem obscurecer o sinal. A sonda NEOWISE vaga além da atmosfera da Terra, fazendo essas medidas dos gases emitidos pelos cometas possíveis.
“Essa é a primeira vez que nós observamos essa grande evidência estatística do monóxido de carbono obtida enquanto o gás do cometa é emitido quando ele está mais distante do Sol”, disse James Bauer, vice-principal pesquisador da missão NEOWISE do Laboratório de Propulsão a Jato da NASA em Pasadena, na Califórnia, e autor do artigo. “Emitindo o que é provavelmente monóxido de carbono além de 4 Unidades Astronômicas, ou seja, 600 milhões de quilômetros, isso nos mostra que os cometas podem ter guardado a maior parte dos gases quando eles se formaram, e ficaram ali guardados por bilhões de anos. A maioria dos cometas que nós observamos ativos além das 4 Unidades Astronômicas, são cometas de períodos longos, cometas com períodos orbitais maiores que 200 anos que gastam a maior parte da sua vida além da órbita de Netuno”.
A higher efficiency_of_converting_gas_to_stars_push_galaxies_at_z_1_6_well_ab...Sérgio Sacani
Galáxias formando estrelas em taxas extremas a nove bilhões de anos atrás eram mais eficientes do que a média das galáxias atuais, descobriram os pesquisadores.
A maioria das estrelas acredita-se localizam-se na sequência principal onde quanto maior a massa da galáxia, mais eficiente ela é na formação de novas estrelas. Contudo, de vez em quando uma galáxia apresentará uma explosão de novas estrelas que brilham mais do que o resto. Uma colisão entre duas grandes galáxias é normalmente a causa dessas fases de explosões de formação de estrelas, onde o gás frio que reside nas grandes nuvens moleculares torna-se o combustível para sustentar essas altas taxas de formação de estrelas.
A questão que os astrônomos têm feito é se essas explosões de estrelas no início o universo foram o resultado de se ter um suprimento de gás abundante, ou se as galáxias convertiam o gás de maneira mais eficiente.
Um novo estudo, publicado no Astrophysical Journal Letters de 15 de Outubro, liderado por John Silverman, do Kavli Institute for Physics and Mathematics of the Universe, estudou o conteúdo do gás monóxido de carbono (CO) em sete galáxias de explosão de estrelas muito distantes, quando o universo tinha apenas 4 bilhões de anos de vida. Isso foi possível devido a capacidade do Atacama Large Millimiter/Submillimiter Array (ALMA), localizado no platô no topo da montanha no Chile, que trabalha para detectar as ondas eletromagnéticas no comprimento de onda milimétrico (importante para se estudar o gás molecular) e um nível de sensibilidade que só agora começa a ser explorado pelos astrônomos.
Os pesquisadores descobriram que a quantidade de gás CO emitido já tinha diminuído, mesmo apesar da galáxia continuar a formar estrelas em altas taxas. Essas observações são similares àquelas registradas para as galáxias de explosões de estrelas próximas da Terra atualmente, mas a quantidade da depleção de gás não foi tão rápida quanto se esperava. Isso levou os pesquisadores a concluírem que poderia haver um contínuo aumento na eficiência, dependendo em de quanto acima da taxa de se formar estrelas ela está da sequência principal.
On the theory_and_future_cosmic_planet_formationSérgio Sacani
A Terra chegou cedo para a festa no universo em evolução. De acordo com um novo estudo teórico, quando o nosso Sistema Solar nasceu a 4.6 bilhões de anos atrás, somente 8% dos planetas possivelmente habitáveis que serão formados no universo, existiam. E, a festa não terminaria até quando o Sol queimasse por outros 6 bilhões de anos. A totalidade desses planetas, 92%, não tinham nascido.
Essa conclusão é baseada no acesso dos dados coletados pelo Telescópio Espacial Hubble da NASA e o prolífico caçador de exoplanetas, o Observatório Espacial Kepler.
“Nossa principal motivação foi entender o lugar da Terra no contexto do resto do universo”, disse o autor do estudo Peter Behroozi do Space Telescope Science Institute (STScI), em Baltimore, Maryland, “Comparado a todos os planetas que irão se formar no universo, a Terra, na verdade chegou cedo”.
Olhando distante no espaço e no tempo, o Hubble, tem dado aos astrônomos um verdadeiro “álbum de família”, das observações da galáxia que mostra a história da formação do universo à medida que as galáxias cresciam. Os dados mostram que o universo estava gerando estrelas numa taxa elevada a 10 bilhões de anos atrás, mas a fração do gás hidrogênio e hélio do universo que estava envolvida era muito baixa. Hoje, o nascimento de estrelas está acontecendo numa taxa muito mais lenta do que a muito tempo atrás, mas existe muito gás deixado para trás disponível que o universo continuará gerando estrelas e planetas por muito tempo ainda.
The search for_extraterrestrial_civilizations_with_large_energy_suppliesSérgio Sacani
Estamos nós aqui novamente, nos deparando com mais um erro de interpretação de um artigo científico que transforma uma descoberta feita por cientistas sérios em uma série infindável de posts, textos e tudo mais a respeito de uma estrutura alienígena construída ao redor da estrela KIC 8462852, que não faz sentido nenhum. O intuito desse post é mais uma vez esclarecer todos os pontos dessa descoberta, acompanhado dos artigos e de um vídeo no meu canal onde explico todos os detalhes a respeito de exoplanetas, exocometas, Kepler e a pesquisa séria realizada pelos voluntários do projeto de ciência cidadã, Planet Hunters. Boa leitura.
“Bizarro”. “Interessante”. “Trânsito Gigante”. Essas foram as reações dos voluntários do projeto Planet Hunters quando eles olharam pela primeira vez a curva de luz da estrela parecida com o Sol, outrora normal, KIC 8462852.
Das mais de 150000 estrelas, sob constante observação durante os 4 anos da missão primária do Kepler da NASA, entre 2009 e 2013, essa estrela se destacou devido às inexplicáveis quedas no brilho de sua luz. Enquanto que quase todo mundo aposta em causas naturais para essa queda estranha no brilho da estrela, alguns sugeriram outras possibilidades.
Você lembrará que o observatório orbital Kepler, continuamente monitorou estrelas num campo de visão fixo focado nas constelações de Lyra e Cygnus, na esperança de registrar quedas periódicas no brilho da luz das estrelas, quedas essas geradas por exoplanetas em trânsito. Se uma queda no brilho da luz for observado, mais trânsitos eram observados para confirmar a detecção de um novo exoplaneta.
The vvv survey_reveals_classical_cepheids_tracing_a_young_and_thin_stellar_di...Sérgio Sacani
Com o auxílio do telescópio VISTA instalado no Observatório do Paranal do ESO, astrônomos descobriram uma componente anteriormente desconhecida da Via Láctea. Ao mapear a localização de uma classe de estrelas que variam em brilho chamadas Cefeidas, foi descoberto um disco de estrelas jovens enterradas por trás de espessas nuvens de poeira no bojo central.
O rastreio público do ESO VISTA Variables in the Vía Láctea (VVV) [1] usa o telescópio VISTA instalado no Observatório do Paranal para obter imagens múltiplas em épocas diferentes das regiões centrais da nossa Galáxia nos comprimentos de onda do infravermelho [2]. O rastreio está descobrindo uma enorme quantidade de novos objetos, incluindo estrelas variáveis, aglomerados e estrelas em explosão (eso1101, eso1128, eso1141).
Uma equipe de astrônomos, liderada por Istvan Dékány da Pontificia Universidad Católica de Chile, utilizou dados deste rastreio, obtidos entre 2010 e 2014, para fazer uma descoberta notável — um componente anteriormente desconhecido da Via Láctea, a Galáxia que nos acolhe.
Flaring from the_supermassive_black_hole_in_mrk335_studied_with_swift_and_nustarSérgio Sacani
Os comportamentos estranhos e desconcertantes dos buracos negros tornam-se cada dia menos misteriosos, com as novas observações feitas com as missões Swift e NuSTAR da NASA. Os dois telescópios espaciais registraram um buraco negro supermassivo no meio de uma gigantesca explosão de luz de raio-X, ajudando os astrônomos a tentarem resolver um grande quebra-cabeça: Como os buracos negros supermassivos emitem flares?
Os resultados sugerem que os buracos negros supermassivos emitem flares de raios-X, quando suas coroas circundantes, fontes de partículas extremamente energéticas, são atiradas ou lançadas para fora dos buracos negros.
“Essa é a primeira vez que nós somos capazes de linkar o lançamento da coroa com uma flare”, disse Dan Wilkins, da Universidade de Saint Mary em Halifax, no Canadá e principal autor do artigo que descreve os resultados na revista Monthly Notices of The Royal Astronomical Society. “Isso nos ajudará a entender como os buracos negros supermassivos alimentam alguns dos objetos mais brilhantes do universo”.
Os buracos negros supermassivos não emitem luz por si só, mas eles as vezes são circundados por discos de material quente e brilhante. A gravidade do buraco negro puxa o gás ao redor, aquecendo esse material e fazendo com que ele brilhe com diferentes tipos de luz. Outra fonte da radiação perto do buraco negro é a coroa. As coroas são feitas de partículas altamente energéticas que geram luz de raio-X, mas os detalhes sobre sua aparência, ou como elas se formam, ainda não são claros.
Variability in a_young_lt_transition_planetary_mass_objectSérgio Sacani
Padrões climáticos num misterioso mundo além do nosso Sistema Solar tem sido revelado pela primeira vez, sugere um estudo.
Camadas de nuvens, feitas de poeira quente e gotículas de ferro derretido, foram detectadas num objeto parecido com um planeta descoberto a 75 anos-luz de distância da Terra, dizem os pesquisadores.
As descobertas poderiam melhorar a habilidade dos cientistas de descobrir se condições em planetas distantes seriam capazes de sustentar a vida.
Uma equipe de pesquisadores liderada pela Universidade de Edimburgo, usou um telescópio no Chile para estudar o sistema climático de um mundo distante, conhecido como PSO J318.5-22, que estima-se tenha cerca de 20 milhões de anos de vida.
Os pesquisadores capturaram centenas de imagens infravermelhas do objeto enquanto ele rotacionava em torno do seu próprio eixo num período de 5 horas. Comparando o brilho do PSO J318.5-22, com corpos vizinhos, a equipe descobriu que ele era coberto por múltiplas camadas de nuvens finas e espessas. Essas nuvens causaram as mudanças no brilho do mundo distante enquanto ele executava o seu movimento de rotação, dizem os cientistas.
O telescópio de rastreio VISTA do ESO encontrou uma horda de galáxias massivas anteriormente ocultas por poeira, que existiram quando o Universo era ainda bebê. Ao descobrir e estudar uma grande quantidade deste tipo de galáxias, os astrônomos descobriram, exatamente e pela primeira vez, quando é que tais monstros apareceram pela primeira vez no Universo.
O simples fato de contar o número de galáxias que existem em determinada área do céu permite aos astrônomos testar teorias de formação e evolução galática. No entanto, uma tarefa aparentemente tão fácil torna-se mais difícil quando tentamos contar galáxias cada vez mais distantes e tênues e é mais complicada ainda devido ao fato das galáxias mais brilhantes e fáceis de observar — as mais massivas no Universo — se tornarem mais raras à medida que os astrônomos observam o passado do Universo, enquanto que as galáxias menos brilhantes, mas muito mais numerosas, são ainda mais difíceis de detectar.
Uma equipe de astrônomos liderada por Karina Caputi do Instituto Astronômico Kapteyn da Universidade de Groningen, descobriu muitas galáxias distantes que não tinham sido detectadas anteriormente. A equipe utilizou imagens do rastreioUltraVISTA, um dos seis projetos que usam o VISTA para mapear o céu no infravermelho próximo, e fez um censo das galáxias tênues quando a idade do Universo estava compreendida entre 0,75 e 2,1 bilhões de anos.
Reference Guide To The International Space StationSérgio Sacani
The International Space Station is a unique place – a convergence of science, technology and human innovation that demonstrates new technologies and makes research breakthroughs not possible on Earth.
It is a microgravity laboratory in which an international crew of six people live and work while traveling at a speed of five miles per second, orbiting Earth every 90 minutes.
The space station has been continuously occupied since November 2000. In that time, more than 200 people from 15 countries have visited.
Crew members spend about 35 hours each week conducting research in many disciplines to advance scientific knowledge in Earth, space, physical, and biological sciences for the benefit of people living on our home planet.
The station facilitates the growth of a robust commercial market in low-Earth orbit, operating as a national laboratory for scientific research and facilitating the development of U.S. commercial cargo and commercial crew space transportation capabilities.
More than an acre of solar arrays provide power to the station, and also make it the next brightest object in the night sky after the moon. You don’t even need a telescope to see it zoom over your house. And we’ll even send you a text message or email alert to let you know when (and where) to look up, spot the station, and wave!
First results from_the_hubble_opal_program_jupiter_in_2015Sérgio Sacani
Os cientistas usando o Telescópio Espacial Hubble da NASA/ESA produziram novos mapas de Júpiter, que mostram as contínuas mudanças que ocorrem com a famosa Grande Mancha Vermelha. As imagens também revelam uma rara estrutura em forma de onda na atmosfera do planeta que não tinha sido vista por décadas. A nova imagem é a primeira de uma série de retratos anuais dos planetas externos do Sistema Solar, que nos darão um novo olhar desses mundos remotos, e ajudarão os cientistas a estudarem como eles mudam com o passar do tempo.
Nessa nova imagem de Júpiter, uma grande quantidade de feições foi capturada incluindo ventos, nuvens e tempestades. Os cientistas por trás dessas novas imagens, as obtiveram usando a Wide Field Camera 3 do Hubble, num período de observação de mais de 10 horas e produziram assim dois mapas completos do planeta, a partir das suas observações. Esses mapas fizeram com que fosse possível determinar a velocidade dos ventos em Júpiter, com a finalidade de identificar diferentes fenômenos na sua atmosfera além de traquear as suas feições mais famosas.
As novas imagens confirmam que a grande tempestade que tem existido na superfície de nuvens de Júpiter por no mínimo 300 anos, continua a encolher, mas mesmo que desapareça, ela irá morrer lutando. A tempestade, conhecida como Grande Mancha Vermelha, é vista aqui fazendo seus movimentos em espiral no centro da imagem do planeta. Ela tem diminuído de tamanho de maneira muito rápida de ano em ano. Mas agora, a taxa de encolhimento parece ter reduzido novamente, mesmo apesar da mancha ser cerca de 240 quilômetros menor do que era em 2014.
Dark side of_comet_67_p_churyumov_gerasiemnko_in_august_october_2014Sérgio Sacani
Usando o instrumento Microwave Instrument for Rosetta Orbiter (MIRO), os cientistas estão estudando a região polar sul do cometa no final de sua longa estação de inverno. Os dados sugerem que essas regiões frias e escuras abrigam gelo nas suas primeiras dezenas de centímetros abaixo da superfície em quantidades muito maiores do que as encontradas em outras áreas do cometa.
Desde a sua chegada no Cometa 67P/Churyumov-Gerasimenko, a Rosetta tem pesquisado a superfície e o ambiente desse corpo de forma curiosa. Mas por um longo período de tempo, uma porção do núcleo, as regiões frias e escuras ao redor do polo sul do cometa, permaneceram inacessíveis para quase todos os instrumentos a bordo da sonda.
Devido a uma combinação de sua forma em lobo duplo e a inclinação do seu eixo de rotação, o cometa da Rosetta, tem um padrão sazonal muito peculiar durante a sua órbita de 6.5 anos. As estações estão distribuídas de maneira muito assimétrica entre os dois hemisférios, cada um deles compreende parte tanto dos lobos como do pescoço do cometa.
Na maior parte da órbita do cometa, o hemisfério norte experimenta um verão muito longo, durando cerca de 5.5 anos, e o hemisfério sul passa por um longo, frio e escuro inverno. Contudo, poucos meses antes do cometa passar pelo seu periélio, o ponto na sua órbita, mais próximo do Sol, a situação muda, e o hemisfério sul passa por um breve porém quente verão.
The shadow _of_the_flying_saucer_a_very_low_temperature_for_large_dust_grainsSérgio Sacani
Os astrónomos usaram o ALMA e os telescópios do IRAM para fazer a primeira medição direta da temperatura dos grãos de poeira grandes situados nas regiões periféricas de um disco de formação planetária que se encontra em torno de uma estrela jovem. Ao observar de forma inovadora um objeto cujo nome informal é Disco Voador, os astrónomos descobriram que os grãos de poeira são muito mais frios do que o esperado: -266º Celsius. Este resultado surpreendente sugere que os modelos teóricos destes discos precisam de ser revistos.
Uma equipa internacional liderada por Stephane Guilloteau do Laboratoire d´Astrophysique de Bordeaux, França, mediu a temperatura de enormes grãos de poeira que se encontram em torno da jovem estrela 2MASS J16281370-2431391 na região de formação estelar Rho Ophiuchi, a cerca de 400 anos-luz de distância da Terra.
Esta estrela encontra-se rodeada por um disco de gás e poeira — chamado disco protoplanetário, uma vez que se encontra na fase inicial da formação de um sistema planetário. Este disco é visto de perfil quando observado a partir da Terra e a sua aparência em imagens no visível levou a que se lhe desse o nome informal de Disco Voador.
Os astrónomos utilizaram o ALMA para observar o brilho emitido pelas moléculas de monóxido de carbono no disco da 2MASS J16281370-2431391. As imagens revelaram-se extremamente nítidas e descobriu-se algo estranho — em alguns casos o sinal recebido era negativo. Normalmente um sinal negativo é fisicamente impossível, mas neste caso existe uma explicação, que leva a uma conclusão surpreendente.
The extremely high albedo of LTT 9779 b revealed by CHEOPSSérgio Sacani
Optical secondary eclipse measurements of small planets can provide a wealth of information about the reflective properties
of these worlds, but the measurements are particularly challenging to attain because of their relatively shallow depth. If such signals
can be detected and modeled, however, they can provide planetary albedos, thermal characteristics, and information on absorbers in
the upper atmosphere.
Aims. We aim to detect and characterize the optical secondary eclipse of the planet LTT 9779 b using the CHaracterising ExOPlanet
Satellite (CHEOPS) to measure the planetary albedo and search for the signature of atmospheric condensates.
Methods. We observed ten secondary eclipses of the planet with CHEOPS. We carefully analyzed and detrended the light curves using
three independent methods to perform the final astrophysical detrending and eclipse model fitting of the individual and combined light
curves.
Results. Each of our analysis methods yielded statistically similar results, providing a robust detection of the eclipse of LTT 9779 b
with a depth of 115±24 ppm. This surprisingly large depth provides a geometric albedo for the planet of 0.80+0.10
−0.17, consistent with
estimates of radiative-convective models. This value is similar to that of Venus in our own Solar System. When combining the eclipse
from CHEOPS with the measurements from TESS and Spitzer, our global climate models indicate that LTT 9779 b likely has a super
metal-rich atmosphere, with a lower limit of 400× solar being found, and the presence of silicate clouds. The observations also reveal
hints of optical eclipse depth variability, but these have yet to be confirmed.
Conclusions. The results found here in the optical when combined with those in the near-infrared provide the first steps toward
understanding the atmospheric structure and physical processes of ultrahot Neptune worlds that inhabit the Neptune desert.
An almost dark galaxy with the mass of the Small Magellanic CloudSérgio Sacani
Almost Dark Galaxies are objects that have eluded detection by traditional surveys such as the Sloan Digital Sky Survey (SDSS). The
low surface brightness of these galaxies (µr(0)> 26 mag/arcsec2
), and hence their low surface stellar mass density (a few solar masses
per pc2 or less), suggests that the energy density released by baryonic feedback mechanisms is inefficient in modifying the distribution
of the dark matter halos they inhabit. For this reason, almost dark galaxies are particularly promising for probing the microphysical
nature of dark matter. In this paper, we present the serendipitous discovery of Nube, an almost dark galaxy with < µV >e∼ 26.7
mag/arcsec2
. The galaxy was identified using deep optical imaging from the IAC Stripe82 Legacy Project. Follow-up observations
with the 100m Green Bank Telescope strongly suggest that the galaxy is at a distance of 107 Mpc. Ultra-deep multi-band observations
with the 10.4m Gran Telescopio Canarias favour an age of ∼ 10 Gyr and a metallicity of [Fe/H]∼ −1.1. With a stellar mass of ∼ 4×108
M⊙ and a half-mass radius of Re = 6.9 kpc (corresponding to an effective surface density of < Σ >e∼ 0.9 M⊙/pc2
), Nube is the most
massive and extended object of its kind discovered so far. The galaxy is ten times fainter and has an effective radius three times larger
than typical ultra-diffuse galaxies with similar stellar masses. Galaxies with comparable effective surface brightness within the Local
Group have very low mass (tens of 105 M⊙) and compact structures (effective radius Re < 1 kpc). Current cosmological simulations
within the cold dark matter scenario, including baryonic feedback, do not reproduce the structural properties of Nube. However, its
highly extended and flattened structure is consistent with a scenario where the dark matter particles are ultra-light axions with a mass
of mB=(0.8
+0.4
−0.2
)×10−23 eV
ALMA Measurement of 10 kpc-scale Lensing Power Spectra towards the Lensed Qua...Sérgio Sacani
The lensing power spectra for gravitational potential, astrometric shift, and convergence perturbations are powerful probes to investigate dark matter structures on small
scales. We report the first lower and upper bounds of these lensing power spectra on
angular scale ∼ 1
′′ towards the anomalous quadruply lensed quasar MG J0414+0534
at a redshift z = 2.639. To obtain the spectra, we conducted observations of
MG J0414+0534 using the Atacama Large Millimeter/submillimeter Array (ALMA)
with high angular resolution (0.
′′02-0.
′′05). We developed a new partially non-parametric
method in which Fourier coefficients of potential perturbation are adjusted to minimize
the difference between linear combinations of weighted mean de-lensed images. Using
positions of radio jet components, extended dust emission on scales > 1 kpc, and midinfrared flux ratios, the range of measured convergence, astrometric shift, and potential
powers at an angular scale of ∼ 1.
′′1 (corresponding to an angular wave number of
l = 1.2 × 106 or ∼ 9 kpc in the primary lens plane) within 1 σ are ∆κ = 0.021 − 0.028,
∆α = 7 − 9 mas, and ∆ψ = 1.2 − 1.6 mas2
, respectively. Our result is consistent with
the predicted abundance of halos in the line of sight and subhalos in cold dark matter
models. Our partially non-parametric lens models suggest a presence of a clump in
the vicinity of object Y, a possible dusty dwarf galaxy and some small clumps in the
vicinity of other lensed quadruple images. Although much fainter than the previous
report, we detected weak continuum emission possibly from object Y with a peak flux
of ∼ 100 µJy beam−1
at the ∼ 4 σ level.
Hot Earth or Young Venus? A nearby transiting rocky planet mysterySérgio Sacani
Venus and Earth provide astonishingly different views of the evolution of a rocky planet, raising the question of why these two rock y worlds evolv ed so differently. The recently disco v ered transiting Super-Earth LP 890-9c (TOI-4306c, SPECULOOS-2c) is a key to the question. It circles a nearby M6V star in 8.46 d. LP890-9c receives similar flux as modern Earth, which puts it very close to the inner edge of the Habitable Zone (HZ), where models differ strongly in their prediction of how long rocky planets can hold onto their water. We model the atmosphere of a hot LP890-9c at the inner edge of the HZ, where the planet could sustain several very different environments. The resulting transmission spectra differ considerably between a hot, wet exo-Earth, a steamy planet caught in a runaway greenhouse, and an exo-Venus. Distinguishing these scenarios from the planet’s spectra will provide critical new insights into the evolution of hot terrestrial planets into exo-Venus. Our model and spectra are available online as a tool to plan observations. They show that observing LP890-9c can provide key insights into the evolution of a rocky planet at the inner edge of the HZ as well as the long-term future of Earth.
Isotopic evidence of long-lived volcanism on IoSérgio Sacani
Jupiter’s moon Io hosts extensive volcanism, driven by tidal heating. The isotopic composition of Io's inventory of volatile chemical elements, including sulfur and chlorine, reflects its outgassing and mass loss history, and thus records information about its evolution. We used millimeter observations of Io’s atmosphere to measure sulfur isotopes in gaseous SO2 and SO, and chlorine isotopes in gaseous NaCl and KCl. We find 34S/32S = 0.0595 ± 0.0038 (equivalent to δ34S = +347 ± 86‰), which is highly enriched compared to average Solar System values and indicates that Io has lost 94 to 99% of its available sulfur. Our measurement of 37Cl/35Cl = 0.403 ± 0.028 (δ37Cl = +263 ± 88‰) shows that chlorine is similarly enriched. These results indicate that Io has been volcanically active for most (or all) of its history, with potentially higher outgassing and mass-loss rates at earlier times.
Exocometary gas in_th_hd_181327_debris_ringSérgio Sacani
An increasing number of observations have shown that gaseous debris discs are not an
exception. However, until now we only knew of cases around A stars. Here we present the first
detection of 12CO (2-1) disc emission around an F star, HD 181327, obtained with ALMA
observations at 1.3 mm. The continuum and CO emission are resolved into an axisymmetric
disc with ring-like morphology. Using a Markov chain Monte Carlo method coupled with
radiative transfer calculations we study the dust and CO mass distribution. We find the dust is
distributed in a ring with a radius of 86:0 0:4 AU and a radial width of 23:2 1:0 AU. At
this frequency the ring radius is smaller than in the optical, revealing grain size segregation
expected due to radiation pressure. We also report on the detection of low level continuum
emission beyond the main ring out to 200 AU. We model the CO emission in the non-LTE
regime and we find that the CO is co-located with the dust, with a total CO gas mass ranging
between 1:2 10 6 M and 2:9 10 6 M, depending on the gas kinetic temperature and
collisional partners densities. The CO densities and location suggest a secondary origin, i.e.
released from icy planetesimals in the ring. We derive a CO cometary composition that is
consistent with Solar system comets. Due to the low gas densities it is unlikely that the gas is
shaping the dust distribution.
The atacama cosmology_telescope_measuring_radio_galaxy_bias_through_cross_cor...Sérgio Sacani
A radiação cósmica de micro-ondas aponta para a matéria escura invisível, marcando o ponto onde jatos de material viajam a velocidades próximas da velocidade da luz, de acordo com uma equipe internacional de astrônomos. O principal autor do estudo, Rupert Allison da Universidade de Oxford apresentou os resultados no dia 6 de Julho de 2015 no National Astronomy Meeting em Venue Cymru, em Llandudno em Wales.
Atualmente, ninguém sabe ao certo do que a matéria escura é feita, mas ela é responsável por cerca de 26% do conteúdo de energia do universo, com galáxias massivas se formando em densas regiões de matéria escura. Embora invisível, a matéria escura se mostra através do efeito gravitacional – uma grande bolha de matéria escura puxa a matéria normal (como elétrons, prótons e nêutrons) através de sua própria gravidade, eventualmente se empacotando conjuntamente para criar as estrelas e galáxias inteiras.
Muitas das maiores dessas são galáxias ativas com buracos negros supermassivos em seus centros. Alguma parte do gás caindo diretamente na direção do buraco negro é ejetada como jatos de partículas e radiação. As observações feitas com rádio telescópios mostram que esses jatos as vezes se espalham por milhões de anos-luz desde a galáxia – mais distante até mesmo do que a extensão da própria galáxia.
Os cientistas esperam que os jatos possam viver em regiões onde existe um excesso de concentração da matéria escura, maior do que o da média. Mas como a matéria escura é invisível, testar essa ideia não é algo tão direto.
Observation of Io’s Resurfacing via Plume Deposition Using Ground-based Adapt...Sérgio Sacani
Since volcanic activity was first discovered on Io from Voyager images in 1979, changes
on Io’s surface have been monitored from both spacecraft and ground-based telescopes.
Here, we present the highest spatial resolution images of Io ever obtained from a groundbased telescope. These images, acquired by the SHARK-VIS instrument on the Large
Binocular Telescope, show evidence of a major resurfacing event on Io’s trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images
show that a plume deposit from a powerful eruption at Pillan Patera has covered part
of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io’s surface using adaptive
optics at visible wavelengths.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
Gliese 12 b: A Temperate Earth-sized Planet at 12 pc Ideal for Atmospheric Tr...Sérgio Sacani
Recent discoveries of Earth-sized planets transiting nearby M dwarfs have made it possible to characterize the
atmospheres of terrestrial planets via follow-up spectroscopic observations. However, the number of such planets
receiving low insolation is still small, limiting our ability to understand the diversity of the atmospheric
composition and climates of temperate terrestrial planets. We report the discovery of an Earth-sized planet
transiting the nearby (12 pc) inactive M3.0 dwarf Gliese 12 (TOI-6251) with an orbital period (Porb) of 12.76 days.
The planet, Gliese 12 b, was initially identified as a candidate with an ambiguous Porb from TESS data. We
confirmed the transit signal and Porb using ground-based photometry with MuSCAT2 and MuSCAT3, and
validated the planetary nature of the signal using high-resolution images from Gemini/NIRI and Keck/NIRC2 as
well as radial velocity (RV) measurements from the InfraRed Doppler instrument on the Subaru 8.2 m telescope
and from CARMENES on the CAHA 3.5 m telescope. X-ray observations with XMM-Newton showed the host
star is inactive, with an X-ray-to-bolometric luminosity ratio of log 5.7 L L X bol » - . Joint analysis of the light
curves and RV measurements revealed that Gliese 12 b has a radius of 0.96 ± 0.05 R⊕,a3σ mass upper limit of
3.9 M⊕, and an equilibrium temperature of 315 ± 6 K assuming zero albedo. The transmission spectroscopy metric
(TSM) value of Gliese 12 b is close to the TSM values of the TRAPPIST-1 planets, adding Gliese 12 b to the small
list of potentially terrestrial, temperate planets amenable to atmospheric characterization with JWST.
Gliese 12 b, a temperate Earth-sized planet at 12 parsecs discovered with TES...Sérgio Sacani
We report on the discovery of Gliese 12 b, the nearest transiting temperate, Earth-sized planet found to date. Gliese 12 is a
bright (V = 12.6 mag, K = 7.8 mag) metal-poor M4V star only 12.162 ± 0.005 pc away from the Solar system with one of the
lowest stellar activity levels known for M-dwarfs. A planet candidate was detected by TESS based on only 3 transits in sectors
42, 43, and 57, with an ambiguity in the orbital period due to observational gaps. We performed follow-up transit observations
with CHEOPS and ground-based photometry with MINERVA-Australis, SPECULOOS, and Purple Mountain Observatory,
as well as further TESS observations in sector 70. We statistically validate Gliese 12 b as a planet with an orbital period of
12.76144 ± 0.00006 d and a radius of 1.0 ± 0.1 R⊕, resulting in an equilibrium temperature of ∼315 K. Gliese 12 b has excellent
future prospects for precise mass measurement, which may inform how planetary internal structure is affected by the stellar
compositional environment. Gliese 12 b also represents one of the best targets to study whether Earth-like planets orbiting cool
stars can retain their atmospheres, a crucial step to advance our understanding of habitability on Earth and across the galaxy.
The importance of continents, oceans and plate tectonics for the evolution of...Sérgio Sacani
Within the uncertainties of involved astronomical and biological parameters, the Drake Equation
typically predicts that there should be many exoplanets in our galaxy hosting active, communicative
civilizations (ACCs). These optimistic calculations are however not supported by evidence, which is
often referred to as the Fermi Paradox. Here, we elaborate on this long-standing enigma by showing
the importance of planetary tectonic style for biological evolution. We summarize growing evidence
that a prolonged transition from Mesoproterozoic active single lid tectonics (1.6 to 1.0 Ga) to modern
plate tectonics occurred in the Neoproterozoic Era (1.0 to 0.541 Ga), which dramatically accelerated
emergence and evolution of complex species. We further suggest that both continents and oceans
are required for ACCs because early evolution of simple life must happen in water but late evolution
of advanced life capable of creating technology must happen on land. We resolve the Fermi Paradox
(1) by adding two additional terms to the Drake Equation: foc
(the fraction of habitable exoplanets
with significant continents and oceans) and fpt
(the fraction of habitable exoplanets with significant
continents and oceans that have had plate tectonics operating for at least 0.5 Ga); and (2) by
demonstrating that the product of foc
and fpt
is very small (< 0.00003–0.002). We propose that the lack
of evidence for ACCs reflects the scarcity of long-lived plate tectonics and/or continents and oceans on
exoplanets with primitive life.
A Giant Impact Origin for the First Subduction on EarthSérgio Sacani
Hadean zircons provide a potential record of Earth's earliest subduction 4.3 billion years ago. Itremains enigmatic how subduction could be initiated so soon after the presumably Moon‐forming giant impact(MGI). Earlier studies found an increase in Earth's core‐mantle boundary (CMB) temperature due to theaccumulation of the impactor's core, and our recent work shows Earth's lower mantle remains largely solid, withsome of the impactor's mantle potentially surviving as the large low‐shear velocity provinces (LLSVPs). Here,we show that a hot post‐impact CMB drives the initiation of strong mantle plumes that can induce subductioninitiation ∼200 Myr after the MGI. 2D and 3D thermomechanical computations show that a high CMBtemperature is the primary factor triggering early subduction, with enrichment of heat‐producing elements inLLSVPs as another potential factor. The models link the earliest subduction to the MGI with implications forunderstanding the diverse tectonic regimes of rocky planets.
Climate extremes likely to drive land mammal extinction during next supercont...Sérgio Sacani
Mammals have dominated Earth for approximately 55 Myr thanks to their
adaptations and resilience to warming and cooling during the Cenozoic. All
life will eventually perish in a runaway greenhouse once absorbed solar
radiation exceeds the emission of thermal radiation in several billions of
years. However, conditions rendering the Earth naturally inhospitable to
mammals may develop sooner because of long-term processes linked to
plate tectonics (short-term perturbations are not considered here). In
~250 Myr, all continents will converge to form Earth’s next supercontinent,
Pangea Ultima. A natural consequence of the creation and decay of Pangea
Ultima will be extremes in pCO2 due to changes in volcanic rifting and
outgassing. Here we show that increased pCO2, solar energy (F⨀;
approximately +2.5% W m−2 greater than today) and continentality (larger
range in temperatures away from the ocean) lead to increasing warming
hostile to mammalian life. We assess their impact on mammalian
physiological limits (dry bulb, wet bulb and Humidex heat stress indicators)
as well as a planetary habitability index. Given mammals’ continued survival,
predicted background pCO2 levels of 410–816 ppm combined with increased
F⨀ will probably lead to a climate tipping point and their mass extinction.
The results also highlight how global landmass configuration, pCO2 and F⨀
play a critical role in planetary habitability.
Constraints on Neutrino Natal Kicks from Black-Hole Binary VFTS 243Sérgio Sacani
The recently reported observation of VFTS 243 is the first example of a massive black-hole binary
system with negligible binary interaction following black-hole formation. The black-hole mass (≈10M⊙)
and near-circular orbit (e ≈ 0.02) of VFTS 243 suggest that the progenitor star experienced complete
collapse, with energy-momentum being lost predominantly through neutrinos. VFTS 243 enables us to
constrain the natal kick and neutrino-emission asymmetry during black-hole formation. At 68% confidence
level, the natal kick velocity (mass decrement) is ≲10 km=s (≲1.0M⊙), with a full probability distribution
that peaks when ≈0.3M⊙ were ejected, presumably in neutrinos, and the black hole experienced a natal
kick of 4 km=s. The neutrino-emission asymmetry is ≲4%, with best fit values of ∼0–0.2%. Such a small
neutrino natal kick accompanying black-hole formation is in agreement with theoretical predictions.
Detectability of Solar Panels as a TechnosignatureSérgio Sacani
In this work, we assess the potential detectability of solar panels made of silicon on an Earth-like
exoplanet as a potential technosignature. Silicon-based photovoltaic cells have high reflectance in the
UV-VIS and in the near-IR, within the wavelength range of a space-based flagship mission concept
like the Habitable Worlds Observatory (HWO). Assuming that only solar energy is used to provide
the 2022 human energy needs with a land cover of ∼ 2.4%, and projecting the future energy demand
assuming various growth-rate scenarios, we assess the detectability with an 8 m HWO-like telescope.
Assuming the most favorable viewing orientation, and focusing on the strong absorption edge in the
ultraviolet-to-visible (0.34 − 0.52 µm), we find that several 100s of hours of observation time is needed
to reach a SNR of 5 for an Earth-like planet around a Sun-like star at 10pc, even with a solar panel
coverage of ∼ 23% land coverage of a future Earth. We discuss the necessity of concepts like Kardeshev
Type I/II civilizations and Dyson spheres, which would aim to harness vast amounts of energy. Even
with much larger populations than today, the total energy use of human civilization would be orders of
magnitude below the threshold for causing direct thermal heating or reaching the scale of a Kardashev
Type I civilization. Any extraterrrestrial civilization that likewise achieves sustainable population
levels may also find a limit on its need to expand, which suggests that a galaxy-spanning civilization
as imagined in the Fermi paradox may not exist.
Jet reorientation in central galaxies of clusters and groups: insights from V...Sérgio Sacani
Recent observations of galaxy clusters and groups with misalignments between their central AGN jets
and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet – bubble
connection in cooling cores, and the processes responsible for jet realignment. To investigate the
frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and
groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare
it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample
and selected subsets, we consistently find that there is a 30% – 38% chance to find a misalignment
larger than ∆Ψ = 45◦ when observing a cluster/group with a detected jet and at least one cavity. We
determine that projection may account for an apparently large ∆Ψ only in a fraction of objects (∼35%),
and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned
systems, we exclude environmental perturbation as the main driver of cavity – jet misalignment.
Moreover, we find that large misalignments (up to ∼ 90◦
) are favored over smaller ones (45◦ ≤ ∆Ψ ≤
70◦
), and that the change in jet direction can occur on timescales between one and a few tens of Myr.
We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we
discuss several engine-based mechanisms that may cause these dramatic changes.
The solar dynamo begins near the surfaceSérgio Sacani
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating
region of sunspot emergence appears around 30° latitude and vanishes near the
equator every 11 years (ref. 1). Moreover, longitudinal flows called torsional oscillations
closely shadow sunspot migration, undoubtedly sharing a common cause2. Contrary
to theories suggesting deep origins of these phenomena, helioseismology pinpoints
low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface
shear layer3,4. Within this zone, inwardly increasing differential rotation coupled with
a poloidal magnetic field strongly implicates the magneto-rotational instability5,6,
prominent in accretion-disk theory and observed in laboratory experiments7.
Together, these two facts prompt the general question: whether the solar dynamo is
possibly a near-surface instability. Here we report strong affirmative evidence in stark
contrast to traditional models8 focusing on the deeper tachocline. Simple analytic
estimates show that the near-surface magneto-rotational instability better explains
the spatiotemporal scales of the torsional oscillations and inferred subsurface
magnetic field amplitudes9. State-of-the-art numerical simulations corroborate these
estimates and reproduce hemispherical magnetic current helicity laws10. The dynamo
resulting from a well-understood near-surface phenomenon improves prospects
for accurate predictions of full magnetic cycles and space weather, affecting the
electromagnetic infrastructure of Earth.
Extensive Pollution of Uranus and Neptune’s Atmospheres by Upsweep of Icy Mat...Sérgio Sacani
In the Nice model of solar system formation, Uranus and Neptune undergo an orbital upheaval,
sweeping through a planetesimal disk. The region of the disk from which material is accreted by
the ice giants during this phase of their evolution has not previously been identified. We perform
direct N-body orbital simulations of the four giant planets to determine the amount and origin of solid
accretion during this orbital upheaval. We find that the ice giants undergo an extreme bombardment
event, with collision rates as much as ∼3 per hour assuming km-sized planetesimals, increasing the
total planet mass by up to ∼0.35%. In all cases, the initially outermost ice giant experiences the
largest total enhancement. We determine that for some plausible planetesimal properties, the resulting
atmospheric enrichment could potentially produce sufficient latent heat to alter the planetary cooling
timescale according to existing models. Our findings suggest that substantial accretion during this
phase of planetary evolution may have been sufficient to impact the atmospheric composition and
thermal evolution of the ice giants, motivating future work on the fate of deposited solid material.
Exomoons & Exorings with the Habitable Worlds Observatory I: On the Detection...Sérgio Sacani
The highest priority recommendation of the Astro2020 Decadal Survey for space-based astronomy
was the construction of an observatory capable of characterizing habitable worlds. In this paper series
we explore the detectability of and interference from exomoons and exorings serendipitously observed
with the proposed Habitable Worlds Observatory (HWO) as it seeks to characterize exoplanets, starting
in this manuscript with Earth-Moon analog mutual events. Unlike transits, which only occur in systems
viewed near edge-on, shadow (i.e., solar eclipse) and lunar eclipse mutual events occur in almost every
star-planet-moon system. The cadence of these events can vary widely from ∼yearly to multiple events
per day, as was the case in our younger Earth-Moon system. Leveraging previous space-based (EPOXI)
lightcurves of a Moon transit and performance predictions from the LUVOIR-B concept, we derive
the detectability of Moon analogs with HWO. We determine that Earth-Moon analogs are detectable
with observation of ∼2-20 mutual events for systems within 10 pc, and larger moons should remain
detectable out to 20 pc. We explore the extent to which exomoon mutual events can mimic planet
features and weather. We find that HWO wavelength coverage in the near-IR, specifically in the 1.4 µm
water band where large moons can outshine their host planet, will aid in differentiating exomoon signals
from exoplanet variability. Finally, we predict that exomoons formed through collision processes akin
to our Moon are more likely to be detected in younger systems, where shorter orbital periods and
favorable geometry enhance the probability and frequency of mutual events.
Emergent ribozyme behaviors in oxychlorine brines indicate a unique niche for...Sérgio Sacani
Mars is a particularly attractive candidate among known astronomical objects
to potentially host life. Results from space exploration missions have provided
insights into Martian geochemistry that indicate oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to
its toxicity. However, it can also provide potential benefits, such as producing
brines by deliquescence, like those thought to exist on present-day Mars. Here
we show perchlorate brines support folding and catalysis of functional RNAs,
while inactivating representative protein enzymes. Additionally, we show
perchlorate and other oxychlorine species enable ribozyme functions,
including homeostasis-like regulatory behavior and ribozyme-catalyzed
chlorination of organic molecules. We suggest nucleic acids are uniquely wellsuited to hypersaline Martian environments. Furthermore, Martian near- or
subsurface oxychlorine brines, and brines found in potential lifeforms, could
provide a unique niche for biomolecular evolution.
Continuum emission from within the plunging region of black hole discsSérgio Sacani
The thermal continuum emission observed from accreting black holes across X-ray bands has the potential to be leveraged as a
powerful probe of the mass and spin of the central black hole. The vast majority of existing ‘continuum fitting’ models neglect
emission sourced at and within the innermost stable circular orbit (ISCO) of the black hole. Numerical simulations, however,
find non-zero emission sourced from these regions. In this work, we extend existing techniques by including the emission
sourced from within the plunging region, utilizing new analytical models that reproduce the properties of numerical accretion
simulations. We show that in general the neglected intra-ISCO emission produces a hot-and-small quasi-blackbody component,
but can also produce a weak power-law tail for more extreme parameter regions. A similar hot-and-small blackbody component
has been added in by hand in an ad hoc manner to previous analyses of X-ray binary spectra. We show that the X-ray spectrum
of MAXI J1820+070 in a soft-state outburst is extremely well described by a full Kerr black hole disc, while conventional
models that neglect intra-ISCO emission are unable to reproduce the data. We believe this represents the first robust detection of
intra-ISCO emission in the literature, and allows additional constraints to be placed on the MAXI J1820 + 070 black hole spin
which must be low a• < 0.5 to allow a detectable intra-ISCO region. Emission from within the ISCO is the dominant emission
component in the MAXI J1820 + 070 spectrum between 6 and 10 keV, highlighting the necessity of including this region. Our
continuum fitting model is made publicly available.
WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 RpSérgio Sacani
Studying the escaping atmospheres of highly irradiated exoplanets is critical for understanding the physical
mechanisms that shape the demographics of close-in planets. A number of planetary outflows have been observed
as excess H/He absorption during/after transit. Such an outflow has been observed for WASP-69b by multiple
groups that disagree on the geometry and velocity structure of the outflow. Here, we report the detection of this
planet’s outflow using Keck/NIRSPEC for the first time. We observed the outflow 1.28 hr after egress until the
target set, demonstrating the outflow extends at least 5.8 × 105 km or 7.5 Rp This detection is significantly longer
than previous observations, which report an outflow extending ∼2.2 planet radii just 1 yr prior. The outflow is
blueshifted by −23 km s−1 in the planetary rest frame. We estimate a current mass-loss rate of 1 M⊕ Gyr−1
. Our
observations are most consistent with an outflow that is strongly sculpted by ram pressure from the stellar wind.
However, potential variability in the outflow could be due to time-varying interactions with the stellar wind or
differences in instrumental precision.
X-rays from a Central “Exhaust Vent” of the Galactic Center ChimneySérgio Sacani
Using deep archival observations from the Chandra X-ray Observatory, we present an analysis of
linear X-ray-emitting features located within the southern portion of the Galactic center chimney,
and oriented orthogonal to the Galactic plane, centered at coordinates l = 0.08◦
, b = −1.42◦
. The
surface brightness and hardness ratio patterns are suggestive of a cylindrical morphology which may
have been produced by a plasma outflow channel extending from the Galactic center. Our fits of the
feature’s spectra favor a complex two-component model consisting of thermal and recombining plasma
components, possibly a sign of shock compression or heating of the interstellar medium by outflowing
material. Assuming a recombining plasma scenario, we further estimate the cooling timescale of this
plasma to be on the order of a few hundred to thousands of years, leading us to speculate that a
sequence of accretion events onto the Galactic Black Hole may be a plausible quasi-continuous energy
source to sustain the observed morphology
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
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Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
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3d modeling of_gj1214b_atmosphere_formation_of_inhomogeneous_high_cloouds_and_observational_implications
1. Draft version October 7, 2015
Preprint typeset using LATEX style emulateapj v. 5/2/11
3D MODELING OF GJ1214B’S ATMOSPHERE:
FORMATION OF INHOMOGENEOUS HIGH CLOUDS AND OBSERVATIONAL IMPLICATIONS
B. Charnay1,2,3
, V. Meadows1,2
, A. Misra1,2
, J. Leconte4,5
and G. Arney1,2
1Astronomy Department, University of Washington, Seattle, WA 98125, USA
2NASA Astrobiology Institutes Virtual Planetary Laboratory, Seattle, WA 98125, USA
3NASA Postdoctoral Program Fellow
4Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S3H8, Canada.
5Center for Planetary Sciences, Department of Physical and Environmental Sciences,
University of Toronto Scarborough, Toronto, ON M1C 1A4, Canada.
Draft version October 7, 2015
ABSTRACT
The warm sub-Neptune GJ1214b has a featureless transit spectrum which may be due to the
presence of high and thick clouds or haze. Here, we simulate the atmosphere of GJ1214b with a
3D General Circulation Model for cloudy hydrogen-dominated atmospheres, including cloud radiative
effects. We show that the atmospheric circulation is strong enough to transport micrometric cloud
particles to the upper atmosphere and generally leads to a minimum of cloud at the equator. By
scattering stellar light, clouds increase the planetary albedo to 0.4-0.6 and cool the atmosphere below
1 mbar. However, the heating by ZnS clouds leads to the formation of a stratospheric thermal
inversion above 10 mbar, with temperatures potentially high enough on the dayside to evaporate
KCl clouds. We show that flat transit spectra consistent with HST observations are possible if cloud
particle radii are around 0.5 µm, and that such clouds should be optically thin at wavelengths > 3
µm. Using simulated cloudy atmospheres that fit the observed spectra we generate transit, emission
and reflection spectra and phase curves for GJ1214b. We show that a stratospheric thermal inversion
would be readily accessible in near and mid-infrared atmospheric spectral windows. We find that the
amplitude of the thermal phase curves is strongly dependent on metallicity, but only slightly impacted
by clouds. Our results suggest that primary and secondary eclipses and phase curves observed by the
James Webb Space Telescope in the near to mid-infrared should provide strong constraints on the
nature of GJ1214b’s atmosphere and clouds.
Subject headings: planets and satellites: atmospheres - planets and satellites: individual (GJ1214b)
1. INTRODUCTION
As a fundamental planetary phenomenon, clouds are
expected to play a major role in the chemistry, thermal
structure and observational spectra of extrasolar plan-
ets (Marley et al. 2013). Clouds have clearly been de-
tected on hot Jupiters (Pont et al. 2013; Demory et al.
2013). But they are likely more common on smaller plan-
ets containing a larger fraction of heavy elements and
condensable species in their atmospheres. Featureless
transmission spectra suggesting the presence of clouds or
haze have been obtained for one warm Neptune (Knut-
son et al. 2014a) and two warm sub-Neptunes (Kreid-
berg et al. 2014; Knutson et al. 2014b). In particular,
GJ1214b is a warm mini-Neptune or waterworld (i.e.
with a hydrogen-rich or a water-rich atmosphere) orbit-
ing around a nearby M dwarf. Measurements by the
Hubble Space Telescope (HST) revealed a very flat spec-
trum between 1.15 and 1.65 µm (Kreidberg et al. 2014).
This has been interpreted as the presence of high clouds
or haze with a cloud-top at around 0.1-0.01 mbar, de-
pending on the atmospheric metallicity (Kreidberg et al.
2014). A Titan-like organic haze may be photochemically
produced, but the actual mechanism is not yet known for
such a warm atmosphere. Condensate clouds of potas-
sium chloride or zinc sulfide (KCl and ZnS) may also
form (Miller-Ricci Kempton et al. 2012; Morley et al.
bcharnay@uw.edu
2013), but would form deeper in the atmosphere, at 0.1-
1 bar (see Fig. 1a). A featureless transit spectrum due to
condensate clouds would therefore require a strong atmo-
spheric circulation, lofting particles to lower pressures.
Here we use the observed spectra of GJ1214b as a test
case to constrain mechanisms for the possible formation
of high condensate clouds on GJ1214b and similar exo-
planets. We use a three-dimensional General Circulation
Model (GCM), simulating GJ1214b for H-dominated at-
mospheres with KCl and ZnS clouds. In section 2, we
describe the model. In section 3, we present our results
concerning the cloud distribution and the atmospheric
thermal structure. In section 4, we describe the impact
of clouds on the spectra. Finally, we discuss all these
results and their implications for future observations in
section 5.
2. MODEL
2.1. The Generic LMDZ GCM
We performed simulations of GJ1214b’s atmosphere
using the Generic LMDZ GCM (Wordsworth et al. 2011;
Charnay et al. 2015). The model and simulations for
cloud-free atmospheres of GJ1214b are fully described in
Charnay et al. (2015). The radiative transfer is based
on the correlated-k method. k-coefficients are computed
using high resolution spectra from HITRAN 2012 (Roth-
man et al. 2013) and HITEMP 2010 (Rothman et al.
2010). Here, we considered a H2-rich atmosphere at
arXiv:1510.01706v1[astro-ph.EP]6Oct2015
2. 2 Charnay et al.
100×solar metallicity, which we found optimal for the
cloud vertical mixing (Charnay et al. 2015). The com-
position is assumed to be at thermochemical equilibrium
in each GCM cell. We used the same orbital, physical
and stellar parameters as in Charnay et al. (2015). In
particular, we assumed that GJ1214b is synchronously
rotating.
We ran simulations with a 64×48 horizontal resolution
and with 50 layers equally spaced in log pressure, span-
ning 80 bars to 6×10−6
bar. Simulations were started
from a 1D temperature profile computed with the 1D ver-
sion of the model. We ran simulations without cloud ra-
diative effects for 1600 days. The simulations with cloud
radiative effects required a radiative timestep 10 times
shorter. In these cases, we ran simulations for only 300
days. To accelerate the convergence, the first 200 days
were run by increasing the radiative heating/cooling by
a factor proportional to the pressure when it is higher
than 0.1 bar. This technique resulted in simulations close
to equilibrium after 300 days, with a relative difference
between total emitted radiation and total absorbed radi-
ation less than 1%.
2.2. Cloud microphysics and optical properties
We considered only KCl and ZnS clouds, although
Na2S and other iron or silicate clouds could form in the
deeper atmosphere and be removed (Morley et al. 2013).
We fixed the radius of cloud particles everywhere in the
atmosphere, and treated the cloud particle radius as a
free parameter. We ran simulations with cloud particle
radii from 0.1 to 10 µm, with the same radii for KCl and
ZnS clouds. The abundance of cloud particles evolves
through condensation, evaporation, transport and sedi-
mentation.
The formation of KCl and ZnS cloud occurs through
the thermochemical reactions (Morley et al. 2012):
KCl = KCl(s) (1)
H2S + Zn = ZnS(s) + H2 (2)
We used the saturation vapor pressures of KCl and ZnS
from Visscher et al. (2006) and Morley et al. (2012). For
simplicity, we considered only the transport of atomic Zn
(the limiting element in equation 2) as an idealized ZnS
vapor. We then considered both reactions as simple gas-
solid phase changes with no supersaturation and with
a latent heat of 2923 kJ/kg for KCl and 3118 kJ/kg for
ZnS. We fixed the abundance of KCl vapor to 2.55×10−5
mol/mol (4.3×10−4
kg/kg) and the abundance of ZnS
vapor to 8.5×10−6
mol/mol (1.8×10−4
kg/kg) in the
deep atmosphere, corresponding to values from Lodders
(2003) for a 100×solar metallicity. Cloud particles were
assumed to be spherical, with a density of 2000 kg/m3
(KCl) and 4000 kg/m3
(ZnS), and to sediment at a ter-
minal velocity given in Charnay et al. (2015).
We computed the optical cloud properties for the dif-
ferent radii using a log-normal size distribution and opti-
cal indices from Querry (1987). KCl is purely scattering
in the visible and near-infrared while ZnS has large ab-
sorption bands centered near 0.2 and 1 µm.
3. RESULTS
3.1. Simulations with non-radiatively active clouds
400 600 800 1,000 1,200 1,400
10
5
10
4
10
3
10
2
10
1
10
0
10
1
10
2
Temperature at substellar and anti stellar point
Temperature (K)
Pressure(bar)
non radiative cloud
radiative cloud (r=0.5 µm)
radiative cloud (r=0.1 µm)
KCl condensation
ZnS condensation
0 1 2 3 4 5
x 10
4
10
5
10
4
10
3
10
2
10
1
10
0
KCl cloud mixing ratio
Mixing ratio (kg/kg)
Pressure(bar)
r=0.1 µm
r=0.3 µm
r=0.5 µm
r=1 µm
r=3 µm
Fig. 1.— Top panel: temperature profiles at the substellar point
(solid color lines) and the anti-stellar point (dashed color lines)
for the 100×solar metallicity composition with non-radiative cloud
(blue) and with radiative cloud particles with radii of 1 µm (or-
ange) and 0.1 µm (red). Dashed and dashed-dotted black lines
correspond to the condensation curves of KCl and ZnS. Bottom
panel: KCl cloud mixing ratio for particle radii from 0.1 to 3 µm.
The dashed line corresponds to the case with radiatively active
cloud.
We first ran simulations with non-radiatively active
clouds. The latent heat release due to cloud conden-
sation has no impact on the atmospheric dynamics, as is
seen in the cloud-free case described in Charnay et al.
(2015). Temperature variations between the dayside
and the nightside mostly occur above 10 mbar (see Fig.
1a). The altitude above which clouds form drops from
around 40 mbar at the equator to around 200 mbar at
the poles because of latitudinal temperature gradients
(see Fig. 2). Above this condensation altitude, temper-
atures are never high enough to significantly evaporate
clouds. Cloud particles are therefore stable and act as
simple tracers. Because the sedimentation timescale is
generally much longer than the advection timescale, their
distribution is mostly driven by the zonal mean circula-
tion. For a synchronously-rotating planet, the circula-
tion is shaped by the strong day-night temperature con-
trast and standing planetary waves (Showman & Polvani
2011). This pattern is globally associated with upwelling
on the dayside and equatorial downwelling on the night-
side (Charnay et al. 2015). The latter is mostly produced
by two very strong equatorial downdrafts close to the
3. Clouds on GJ1214b 3
terminators and dominates below 1 mbar for 100×solar
metallicity. Therefore, the zonal mean circulation glob-
ally exhibits an anti-Hadley circulation below 1 mbar
and a Hadley circulation above (Charnay et al. 2015).
This anti-Hadley circulation occurs in the region where
clouds form, and strongly impacts their global distribu-
tion, leading to a cloud minimum at the equator and a
maximum between 40-60◦
latitude in both hemispheres
for pressures lower than 0.1 mbar (see top left panel in
Fig 2). This equatorial minimum is reinforced above 1
mbar by a net poleward cloud transport (see top right
panel in Fig 2). Fig. 1b shows the global mean mixing
ratio of condensed KCl cloud for particle radii from 0.1
to 3 µm. Cloud particles are well mixed to high altitudes
for radii of 0.1 µm. For particles larger than 1 µm, the
upper atmosphere (above 10 mbar) is depleted in cloud.
3.2. Simulations with radiatively active clouds
The 3D modeling of radiatively active clouds in
GJ1214b’s atmosphere is challenging. Because of cloud
opacity, the atmospheric radiative timescale becomes
shorter in the upper atmosphere and the condensation
occurs deeper in the atmosphere, where the sedimenta-
tion timescale is longer. With the current computational
resources, it is impossible to obtain a fully converged 3D
simulation at pressure significantly greater than around
1 bar. However, all results (e.g. cloud vertical mixing,
thermal structure and observational spectra) for the up-
per atmosphere can be valid. We ran simulations with
radiatively active clouds for 300 days, accelerating ther-
mal convergence (see section 2). These simulations were
thermally converged up to around 1 bar and the cloud
distribution is locally at equilibrium up to 10 mbar (see
Charnay et al. (2015)). Since the simulations were not
converged in the deep atmosphere, they may overesti-
mate cloud abundance in the upper atmosphere.
With radiatively active clouds, the planetary albedo
increases from almost 0 to 0.4 for 3 µm particles, and
up to 0.6 for 0.1 µm particles. Stellar radiation pen-
etrates less deeply in the atmosphere, cooling pressures
higher than ∼1 mbar (see Fig. 1a). Consequently, clouds
form deeper, at around 0.6 bar for 0.5 µm particles. At
this pressure, there is almost no latitudinal temperature
variation and so clouds form at the same altitude glob-
ally (see Fig. 2). Above 10 mbar, the cloud vertical
mixing is similar with and without cloud radiative ef-
fects (see Fig. 1b). With radiatively active clouds, the
anti-Hadley circulation appears reinforced with a clear
minimum of cloud at the equator (see Fig. 2).
Above 10 mbar, the absorption of stellar radiation by
ZnS clouds forms a stratospheric thermal inversion on the
dayside. At the substellar point, the difference between
the maximal and the minimal stratospheric temperature
reaches around 350 K, 225 K and 50 K for particle radii
of 0.1, 0.5 and 1 µm respectively. In contrast, the tem-
perature at the anti-stellar point is not affected by the
presence of clouds, which are optically thin to the ther-
mal emission. For 0.1 µm particles, the heating by ZnS
is strong enough to evaporate KCl clouds in the dayside
above 1 mbar (see Fig. 1a and Fig. 2). The evapora-
tion of ZnS clouds stops this heating, producing a strong
negative feedback which stabilizes the temperature be-
low the ZnS evaporation curve (see Fig. 1a). For 0.5
µm particles, the evaporation of KCl cloud is limited to
pressures lower than 0.1 mbar.
4. OBSERVATIONAL SPECTRA
Using the GCM outputs, we produced transit, emission
and reflection spectra and phase curves. The primary
goal was to determine the planetary conditions required
to match the observations of GJ1214b. The secondary
goal was to reveal the best observational techniques and
wavelengths to obtain information about the composition
of GJ1214b’s atmosphere.
4.1. Transit spectra
We computed transit spectra using the Spectral Map-
ping and Atmospheric Radiative Transfer code (SMART)
(Meadows & Crisp 1996; Crisp 1997; Misra et al. 2014).
We computed spectra using HITRAN 2012 and using
GCM temperature and cloud profiles, averaged at the
limbs. Because the cloud inhomogeneities are weak at
limbs, these averaged profiles are an excellent approxi-
mation to more accurate spectra obtained by combining
apparent planetary radii from each latitudinal point at
the limb (see Fig 3a).
Fig 3a shows transit spectra with a cloud particle ra-
dius of 0.5 µm for the 100×solar metallicity case. Dif-
ferences between transit spectra from GCM simulations
with radiatively and non-radiatively active clouds are
negligible. The reference case (non-radiatively active
cloud) always matches the data at less than 2σ (reduced
χ2
=1.3 compared to 1.0 for a perfectly flat spectrum). In
these simulations, the cloud-top pressure (τtransit ≈ 1)
is around 0.02 mbar, 10-100 times higher than retrieved
by Kreidberg et al. (2014) for the same metallicity. Yet,
there are several differences between these studies. Un-
like our study, they use a gray cloud opacity, and their
temperature and gravity are different (580 K and 8.48
m/s2
versus our ∼460 K at limbs and 8.9 m/s2
). They
also only consider water as a heavy element, so their
mean molecular mass is smaller than ours (3.6 versus our
4.38 g/mol). These changes make their atmosphere scale
height 60% higher than ours, requiring higher clouds to
get a flat spectrum.
Fig. 3b shows transit spectra for the 100×solar metal-
licity case without cloud, and with cloud particle radii of
0.1, 0.5 and 1 µm. Major atmospheric molecular bands
between 1 and 10 µm are indicated in the figure. Particle
radii of 0.3 µm or less lead to a strong slope in the visible
and near-infrared and cannot match the observations at
any abundance. For micrometric sizes (e.g. 0.5 and 1
µm), the transit spectrum is flat and featureless in the
visible. In the infrared, large molecular features appear
at wavelengths longer than around 3 µm (e.g. peak of
CO2 at 4.3 µm) where the clouds are optically thin. In
addition, a slope can be clearly identified between 3 and
10 µm for 0.5 µm particles, whereas it remains very weak
for 1 µm particles. According to our model, the cloud
particle radius of 0.5 µm is the optimal size, allowing
both strong mixing and a flatter transit spectrum with
a reduced slope.
In Fig. 3c, we tested deviations of cloud abundances
compared to the reference case, assuming that it is pro-
portional to KCl and ZnS vapor abundances in the deep
atmosphere (as suggested by the limited impact of la-
tent heat and cloud radiative effects on the vertical mix-
ing). An enhancement by a factor 3 slightly flattens the
4. 4 Charnay et al.
KCl cloud mixing ratio (0.5 µm, non radiatively active)
Pressure(bar)
Latitude (°)
80 60 40 20 0 20 40 60 80
10
5
10
4
10
3
10
2
10
1
10
0
0
1
2
3
4
5
KCl cloud mixing ratio (0.5 µm, non radiatively active)
Longitude (°)
Latitude(°)
180 90 0 90 180
80
60
40
20
0
20
40
60
80
0
1
2
3
4
5
KCl cloud mixing ratio (0.5 µm, radiatively active)
Pressure(bar)
Latitude (°)
80 60 40 20 0 20 40 60 80
10
5
10
4
10
3
10
2
10
1
10
0
0
1
2
3
4
5
KCl cloud mixing ratio (0.5 µm, radiatively active)
Longitude (°)
Latitude(°)
180 90 0 90 180
80
60
40
20
0
20
40
60
80
0
1
2
3
4
5
KCl cloud mixing ratio (0.1 µm, radiatively active)
Pressure(bar)
Latitude (°)
80 60 40 20 0 20 40 60 80
10
5
10
4
10
3
10
2
10
1
10
0
0
1
2
3
4
5
KCl cloud mixing ratio (0.1 µm, radiatively active)
Longitude (°)
Latitude(°)
180 90 0 90 180
80
60
40
20
0
20
40
60
80
0
1
2
3
4
5
Fig. 2.— Zonally averaged KCl cloud mixing ratio (left panels) and KCl cloud mixing ratio at 0.1 mbar (right panels) in 10−4kg/kg. Top
panels are for non-radiatively active clouds with 0.5 µm particles. Middle panels are for radiatively active clouds with 0.5 µm particles.
Bottom panels are for radiatively active clouds with 0.1 µm particles.
spectrum. However, cloud abundances could be strongly
limited by condensation occurring below 10 bars (see Fig
1a).
Finally, Fig. 3b shows transit spectra for the 1, 10 and
100×solar metallicity cases, with 0.5 µm particles. Only
the 100×solar case can match the observational data.
4.2. Emission spectra and phase curves
Fig. 4a shows planetary emission spectra centered on
the substellar (i.e. secondary eclipse) and the anti-stellar
point (i.e. primary eclipse) for the 100×solar metallicity,
with and without cloud. These spectra were obtained by
running the GCM for one day with a spectral resolution
of 0.1 µm and using the GCM output fluxes directly.
Without cloud, a strong emission peak with a bright-
ness temperature of around 700 K is present at ∼4 µm
corresponding to a water spectral window. A secondary
peak is present at 4.5 µm and a third one at 8.2-10 µm
corresponding to other spectral windows. The thermal
emission strongly varies between the dayside and night-
side in the water and methane absorption bands between
5.2 and 8.2 µm. At these wavelengths, the photosphere
is located at around 0.5 mbar, where the temperature
variations are strong (see Fig. 1a).
0.5 µm cloud particles strongly impact the emission
spectra. The thermal emission is generally reduced with
5. Clouds on GJ1214b 5
1.1 1.2 1.3 1.4 1.5 1.6 1.7
150
100
50
0
50
100
150
200Relativetransitdepth(ppm)
Impact of radiative effects and limb integration (100×sol)
Wavelength (µm)
with cloud (r=0.5 µm)
with cloud (r=0.5 µm, radiatively active)
with cloud (r=0.5 µm, limb integrated)
0.4 0.6 0.8 1 2 3 4 5 10
1500
1000
500
0
500
1000
1500
2000
Wavelength (µm)
Relativetransitdepth(ppm)
Impact of cloud particle radii (100×sol)
H2
O H2
O H2
O H2
O H
2
O
CH4
CH4
CH4
CH4
CH
4 CH4
CO2
CO
no cloud
with cloud (r=0.1 µm)
with cloud (r=0.5 µm)
with cloud (r=1 µm)
1.1 1.2 1.3 1.4 1.5 1.6 1.7
150
100
50
0
50
100
150
200
Relativetransitdepth(ppm)
Impact of cloud abundance (100×sol, r=0.5 µm)
Wavelength (µm)
cloud abundance×0.3
cloud abundance×1
cloud abundance×3
0.4 0.6 0.8 1 2 3 4 5 10
1500
1000
500
0
500
1000
1500
2000
Wavelength (µm)
Relativetransitdepth(ppm)
Impact of metallicity (with cloud, r=0.5 µm)
H
2
O H
2
O H
2
O H
2
O H
2
O
CH4
CH4
CH4
CH4
CH4
CH4
CO2
CO
1×solar
10×solar
100×solar
Fig. 3.— Transit spectra (relative transit depth in ppm) derived from the outputs of the GCM for non-radiatively active clouds. The top
left panel shows spectra between 1.1 and 1.7µm with cloud particle radius of 0.5 µm, using the mean temperature and cloud profile at the
limb (orange). The blue line is computed by integrating limb profiles at each GCM latitudinal point. The red line is computed from the
GCM simulation with radiatively active clouds. The top right panel shows spectra between 0.4 and 10 µm without or with cloud (particle
radii of 0.1, 0.5 and 1 µm). Major atmospheric molecular bands between 1 and 10 µm are indicated with black lines. The bottom left
panel shows spectra with cloud abundances multiplied everywhere by 0.3 (red) and 3 (black) compared to the reference case (blue). The
bottom right panel shows spectra for metallicity of 1, 10 and 100×solar, with KCl and ZnS abundances scaled consequently. In all panels,
black dots correspond to data by Kreidberg et al. (2014) with error bars.
clouds, except in the atmospheric absorption bands (e.g.
5.2-8.2 µm) where it is slightly enhanced. Clouds cool
the atmosphere below 1 mbar and so the brightness tem-
perature never exceeds 600K. The emission peaks at 4,
4.5 and 10 µm are reversed on the dayside because of the
stratospheric thermal inversion. Globally, the presence
of clouds has a limited impact on the amplitude of the
phase curves (see Fig 4b), which primarily depends on
the atmospheric metallicity (Menou 2012). Therefore,
the observation of thermal emission variations, in par-
ticular in the 6.3 µm water band (between 5.2 and 7.3
µm), is an excellent probe of the atmospheric metallicity
of GJ1214b.
4.3. Reflection spectra
Fig. 5a shows reflection spectra for a non-cloudy at-
mosphere with 100×solar metallicity and for cloudy at-
mospheres with KCl, ZnS or Titan-like organic haze par-
ticles. We used GCM profiles for 0.5 µm particles. KCl
clouds are purely scattering and produce a constant re-
flectivity in the visible. ZnS clouds absorb over most
of the visible but do not absorb at 0.5 µm, producing
a peak of reflectivity. Organic haze strongly absorbs at
short visible wavelengths. For wavelengths higher than
around 1 µm, strong atmospheric molecular bands of wa-
ter and methane are present.
Using these reflection spectra, we evaluated the appar-
ent (human eye) colors of GJ1214b for clouds or haze
illuminated by a GJ1214-like star and the Sun (see Fig.
5b). If cloudy, GJ1214b would appear orange. Orbiting
around a Sun-like star, a cloudy GJ1214b could appear
white, green or orange.
5. DISCUSSION
According to our model, micrometric cloud particles
could be lofted to the upper atmosphere of GJ1214b with
a very strong impact on transit spectra. However, a tran-
sit spectrum consistent with HST observations could only
be obtained for cloud particles with a radius around 0.5
µm. In reality, clouds should have a size distribution de-
pending on altitude and latitude. Larger particles would
sediment faster and decrease the amount of cloud in the
upper atmosphere, whereas smaller particles would pro-
duce a stronger slope in the transit spectrum. A more
realistic cloud distribution would likely produce a less
flat transit spectrum. However, other effects such as
metallicity and photochemistry may help to flatten the
spectrum. A higher metallicity than the 100×solar con-
sidered here would require a lower cloud-top (Kreidberg
et al. 2014) and imply a higher amount of cloud but still
6. 6 Charnay et al.
2 3 4 5 6 7 8 9 10
100
200
300
400
500
600
700
800
900
1000
Thermal emission spectra
Wavelength (µm)
Planetstarfluxratio(ppm)
100xsolar without cloud
100xsolar with cloud
T=700 K
T=570 K
T=430 K
2 3 4 5 6 7 8 9 10
0
100
200
300
400
500
Amplitude of thermal phase curves
Wavelength (µm)
maxminplanetstarfluxratio(ppm)
H
2
O
1×solar
10×solar
100×solar
Fig. 4.— Thermal emission and phase curves with and without cloud. Left panel shows the thermal emission with (red) and without
(black) cloud with particle radius of 0.5 µm. Solid lines correspond to emission from the dayside and dashed lines to emission from the
nightside. The blue lines are blackbody curves. Right panel shows the amplitude of thermal phase curves without cloud (solid lines) and
with clouds (dashed lines for radii of 0.5 µm and dotted line for radii of 0.1 µm) for metallicity of 1, 10, 100 and a pure water atmosphere.
For simplicity, we used a blackbody at 3026 K for the stellar flux.
0.4 0.6 0.8 1 2
0
0.1
0.2
0.3
0.4
0.5
0.6
Wavelength (µm)
Reflectivity
Reflectivity spectra (100×sol, r=0.5 µm)
no cloud
KCl cloud
ZnS cloud
KCl+ZnS cloud
organic haze
Fig. 5.— Top panel: reflectivity spectra with clouds (KCl only,
ZnS only, KCl+ZnS or organic haze) or without cloud using GCM
results for 0.5 µm particles and assuming a stellar zenith angle of
60◦. Organic haze particles were assumed spherical with the same
concentration as KCl clouds. Bottom panel: color of GJ1214b
orbiting a GJ1214-like M dwarf (AD Leo, top), and orbiting a Sun-
like star (bottom) calculated by convolving spectral brightness with
eye response (www.brucelindbloom.com).
with a similar vertical mixing. It could efficiently flatten
the transit spectrum. Also, we assumed thermochemical
equilibrium in this study. However, the absorption bands
seen between 1 and 2 µm in the cloudy transit spectra
(Fig 3) come predominantly from pressures lower than
0.01 mbar. At such low pressures, the atmosphere is
far from chemical equilibrium, and water and methane
can be strongly photolyzed (Miller-Ricci Kempton et al.
2012). While other absorbing species are produced or
enhanced, the decrease of the two major absorbers may
significantly flatten the transit spectrum between 1 and
2 µm.
If we assume that JWST will reach 30% of the photo
noise limit (see Koll & Abbot (2015)), the 3σ uncertainty
for one primary or secondary transit (duration around 50
min) will be around 95 ppm for the CO2 band at 4.2-4.4
µm, around 120 ppm for the H2O band at 5.2-7.3 µm and
around 185/170 ppm for the window wavelength ranges
4.0-4.1/9-10 µm. According to Fig. 3, one transit of
GJ1214b observed by JWST should therefore be enough
to detect molecules (i.e. H2O, CO2 and CH4) and the
Mie slope for particle radii lower than 1 µm. According
to Fig. 4, one secondary eclipse should allow detection of
the thermal inversion (both at 4 and 10 µm), while one
full phase curve should provide a good estimation of the
atmospheric metallicity. The combination of phase curve
and secondary eclipse would allow estimation of the bond
albedo (Cowan & Agol 2011). The observation of a few
primary/secondary eclipses or full orbits by JWST could
provide very precise spectra and phase curves revealing
GJ1214b’s atmospheric composition and providing clues
on the size and optical properties (i.e. absorbing or not)
of clouds. Non-absorbing clouds would suggest KCl par-
ticles. Absorbing clouds would favor ZnS particles or
organic haze. In that case, the best way for determin-
ing the composition of cloud particles would be direct
imaging or secondary eclipses/phase curves of reflected
light in the visible. The different clouds/haze have char-
acteristic features in visible reflectivity spectra. Future
large telescopes such as ELT may have the capabilities
for measuring this.
Finally, our results concerning cloud distribution, ra-
diative effects and impacts on spectra for GJ1214b are
very general and can be applied to many warm mini-
Neptunes. Some current missions (e.g. K2) and future
missions (e.g. TESS and PLATO) should detect several
GJ1214b-like planets. A global survey of these objects
by future telescopes (e.g. JWST, ELT or future EChO-
class telescopes) would provide insight into the nature
and origin of clouds on extrasolar planets by collecting
statistical information on the atmospheric conditions re-
quired for cloud and haze formation.
7. Clouds on GJ1214b 7
Acknowledgments: — We are grateful to Eddie Schwieter-
man for help concerning the use of SMART and to Do-
rian Abbot for a helpful review. B.C. acknowledges sup-
port from an appointment to the NASA Postdoctoral
Program, administered by Oak Ridge Affiliated Univer-
sities. This work was performed as part of the NASA
Astrobiology Institute’s Virtual Planetary Laboratory,
supported by NASA under Cooperative Agreement No.
NNA13AA93A. This work was facilitated though the use
of the Hyak supercomputer system at the University of
Washington.
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