- The document summarizes a survey called SEPPCoN that aims to understand the physical properties of Jupiter-Family comet nuclei, including their sizes, albedos, colors, shapes, and spin rates.
- SEPPCoN combines ground-based optical observations with Spitzer Space Telescope infrared imaging of over 100 JFCs. This will help constrain the size distribution and determine if albedos correlate with dynamical age or composition.
- Preliminary findings from SEPPCoN indicate that of the 64 JFCs detected so far, 16 showed signs of outgassing, with sizes generally less than 2km. Color and albedo distributions will help understand the composition and evolution of JFCs from
Uma equipe formada por astrônomos de Israel, da Europa, da Coreia e dos EUA, anunciou a descoberta de um exoplaneta gigante gasoso circumbinário, na zona habitável de seu par de estrelas, uma ocorrência surpreendentemente comum para os exoplanetas circumbinários descobertos pela missão Kepler/K2 da NASA.
Lembrando o planeta da ficção, Tatooine, exoplanetas circumbinários orbitam duas estrelas e assim têm dois sóis em seu céu.
O exoplaneta circumbinário, recém-descoberto, denominado de Kepler-453b, leva 240.5 dias para orbitar suas estrelas, enquanto as estrelas orbitam uma com relação a outra a cada 27.3 dias.
A estrela maior, a Kepler-453A, é similar ao nosso Sol, contendo 94% da massa do Sol, enquanto que a estrela menor, a Kepler-453B, tem cerca de 20% da massa e é mais fria e mais apagada.
O sistema binário, localiza-se na constelação de Lyra, e está a aproximadamente 1400 anos-luz de distância da Terra. Estima-se que esse sistema tenha entre 1 e 2 bilhões de anos de vida, sendo bem mais novo que o nosso Sistema Solar.
Também conhecido como KIC 9632895b, o Kepler-453b tem um raio 6.2 vezes maior que o da Terra. Sua massa não foi medida nos dados atuais, mas provavelmente ele deve ter cerca de 16 vezes a massa da Terra.
De acordo com os astrônomos, o Kepler-453b, é o terceiro planeta circumbinário da missão Kepler, descoberto na zona habitável de um par de estrelas.
Devido ao seu tamanho, e a sua natureza gasosa, o planeta pouco provavelmente deve abrigar a vida como nós a conhecemos. Contudo, ele pode, como os gigantes gasosos do Sistema Solar, ter grandes luas, e essas luas poderiam ser habitáveis. Sua órbita se manterá estável por 10 milhões de anos, aumentando a possibilidade da vida se formar nas suas luas.
Com o número de exoplanetas circumbinários conhecidos agora em dez, os cientistas podem começar a comparar diferentes sistemas e procurar uma tendência. Os sistemas tendem a ser bem compactos e podem aparecer num grande número de configurações.
Uma vez pensados como sendo raros e até mesmo impossíveis de existir, essa e outras descobertas do Kepler, confirmam que esses planetas são comuns na nossa Via Láctea.
“A diversidade e complexidade desses sistemas circumbinários é algo maravilhoso. Cada novo planeta circumbinário, é uma joia, revelando algo inesperado e desafiador”, disse o Prof. William Welsh da Universidade Estadual de San Diego, e o primeiro autor do artigo que descreve a descoberta, publicado no Astrophysical Journal.
Fonte:
http://www.sci-news.com/astronomy/science-kepler453b-circumbinary-exoplanet-03117.html
Uma equipe formada por astrônomos de Israel, da Europa, da Coreia e dos EUA, anunciou a descoberta de um exoplaneta gigante gasoso circumbinário, na zona habitável de seu par de estrelas, uma ocorrência surpreendentemente comum para os exoplanetas circumbinários descobertos pela missão Kepler/K2 da NASA.
Lembrando o planeta da ficção, Tatooine, exoplanetas circumbinários orbitam duas estrelas e assim têm dois sóis em seu céu.
O exoplaneta circumbinário, recém-descoberto, denominado de Kepler-453b, leva 240.5 dias para orbitar suas estrelas, enquanto as estrelas orbitam uma com relação a outra a cada 27.3 dias.
A estrela maior, a Kepler-453A, é similar ao nosso Sol, contendo 94% da massa do Sol, enquanto que a estrela menor, a Kepler-453B, tem cerca de 20% da massa e é mais fria e mais apagada.
O sistema binário, localiza-se na constelação de Lyra, e está a aproximadamente 1400 anos-luz de distância da Terra. Estima-se que esse sistema tenha entre 1 e 2 bilhões de anos de vida, sendo bem mais novo que o nosso Sistema Solar.
Também conhecido como KIC 9632895b, o Kepler-453b tem um raio 6.2 vezes maior que o da Terra. Sua massa não foi medida nos dados atuais, mas provavelmente ele deve ter cerca de 16 vezes a massa da Terra.
De acordo com os astrônomos, o Kepler-453b, é o terceiro planeta circumbinário da missão Kepler, descoberto na zona habitável de um par de estrelas.
Devido ao seu tamanho, e a sua natureza gasosa, o planeta pouco provavelmente deve abrigar a vida como nós a conhecemos. Contudo, ele pode, como os gigantes gasosos do Sistema Solar, ter grandes luas, e essas luas poderiam ser habitáveis. Sua órbita se manterá estável por 10 milhões de anos, aumentando a possibilidade da vida se formar nas suas luas.
Com o número de exoplanetas circumbinários conhecidos agora em dez, os cientistas podem começar a comparar diferentes sistemas e procurar uma tendência. Os sistemas tendem a ser bem compactos e podem aparecer num grande número de configurações.
Uma vez pensados como sendo raros e até mesmo impossíveis de existir, essa e outras descobertas do Kepler, confirmam que esses planetas são comuns na nossa Via Láctea.
“A diversidade e complexidade desses sistemas circumbinários é algo maravilhoso. Cada novo planeta circumbinário, é uma joia, revelando algo inesperado e desafiador”, disse o Prof. William Welsh da Universidade Estadual de San Diego, e o primeiro autor do artigo que descreve a descoberta, publicado no Astrophysical Journal.
Fonte:
http://www.sci-news.com/astronomy/science-kepler453b-circumbinary-exoplanet-03117.html
Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya)...Sérgio Sacani
Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon’s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.005°N, 301.85–304.01°E around the MHH and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.
The gaia eso_survey_stellar_content_and_elemental_abundances_in_the_massive_c...Sérgio Sacani
Estudo sobre o conteúdo estelar e os elementos que estão presentes no aglomerado estelar aberto NGC 6705, também conhecido como Aglomerado do Pato Selvagem.
This lecture was presented to the Duke Talent Identification Program (https://tip.duke.edu/node/334) at the Pisgah Astronomical Research Institute (http://www.pari.edu/).
Version 1. ( 19/Sep/2013 )
Updates:
-Finished Gameplay Guide section.
-Added Territory Customization under The World section
-More Weapon Arms Screenshots
-More and more text.
Version 1.9 will be the final before game release and 2.0 will be on game release ( when I get the game ) to confirm everything.
Detection of intact lava tubes at Marius Hills on the Moon by SELENE (Kaguya)...Sérgio Sacani
Intact lunar lava tubes offer a pristine environment to conduct scientific examination of the Moon’s composition and potentially serve as secure shelters for humans and instruments. We investigated the SELENE Lunar Radar Sounder (LRS) data at locations close to the Marius Hills Hole (MHH), a skylight potentially leading to an intact lava tube, and found a distinctive echo pattern exhibiting a precipitous decrease in echo power, subsequently followed by a large second echo peak that may be evidence for the existence of a lava tube. The search area was further expanded to 13.00–15.005°N, 301.85–304.01°E around the MHH and similar LRS echo patterns were observed at several locations. Most of the locations are in regions of underground mass deficit suggested by GRAIL gravity data analysis. Some of the observed echo patterns are along rille A, where the MHH was discovered, or on the southwest underground extension of the rille.
The gaia eso_survey_stellar_content_and_elemental_abundances_in_the_massive_c...Sérgio Sacani
Estudo sobre o conteúdo estelar e os elementos que estão presentes no aglomerado estelar aberto NGC 6705, também conhecido como Aglomerado do Pato Selvagem.
This lecture was presented to the Duke Talent Identification Program (https://tip.duke.edu/node/334) at the Pisgah Astronomical Research Institute (http://www.pari.edu/).
Version 1. ( 19/Sep/2013 )
Updates:
-Finished Gameplay Guide section.
-Added Territory Customization under The World section
-More Weapon Arms Screenshots
-More and more text.
Version 1.9 will be the final before game release and 2.0 will be on game release ( when I get the game ) to confirm everything.
En este trabajo se encontraran resueltos los ejercicios 10.41; 11.1; 11.2; 11.3 y 11.4 del libro Analisis Estructural 2da Edicion Kenneth M. - chia-Ming U
SGAC works on the international, national and local level to link together university students and young professionals to think creatively about international space policy issues and inject the new generation point of view into international space policy creation. In this presentation, SGAC members attending SSP13 will give an overview of the organisation and how ISU participants can get involved.
benefiting exposure blog engagement enhancementSiraj S
Rethinking how to: Bloggers enhancement benefit engagement exposure via various blogging platforms by making google work for you using cross functional connected tech SEO trends giving benefits in returns.
Looking into wider area of choices, getting the most of engagement that could be obtained by utilizing connected technologies by cross functional sharing with agile and innovative thinking plus workout strategy.
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.
The ALMA Survey of Star Formation and Evolution in Massive Protoclusters with...Sérgio Sacani
The ALMA Survey of Star Formation and Evolution in Massive Protoclusters with Blue Profiles
(ASSEMBLE) aims to investigate the process of mass assembly and its connection to high-mass star
formation theories in protoclusters in a dynamic view. We observed 11 massive (Mclump ≳ 103 M⊙),
luminous (Lbol ≳ 104 L⊙), and blue-profile (infall signature) clumps by ALMA with resolution of
∼2200–5500 au (median value of 3500 au) at 350 GHz (870 µm). 248 dense cores were identified, including 106 cores showing protostellar signatures and 142 prestellar core candidates. Compared to
early-stage infrared dark clouds (IRDCs) by ASHES, the core mass and surface density within the
ASSEMBLE clumps exhibited significant increment, suggesting concurrent core accretion during the
evolution of the clumps. The maximum mass of prestellar cores was found to be 2 times larger than
that in IRDCs, indicating that evolved protoclusters have the potential to harbor massive prestellar
cores. The mass relation between clumps and their most massive core (MMCs) is observed in ASSEMBLE but not in IRDCs, which is suggested to be regulated by multiscale mass accretion. The
mass correlation between the core clusters and their MMCs has a steeper slope compared to that
observed in stellar clusters, which can be due to fragmentation of the MMC and stellar multiplicity.
We observe a decrease in core separation and an increase in central concentration as protoclusters
evolve. We confirm primordial mass segregation in the ASSEMBLE protoclusters, possibly resulting
from gravitational concentration and/or gas accretion.
The Gaia-ESO Survey: Empirical estimates of stellar ages from lithium equival...Sérgio Sacani
We present an empirical model of age-dependent photospheric lithium depletion, calibrated using a large, homogeneouslyanalysed sample of 6200 stars in 52 open clusters, with ages from 2–6000Myr and −0.3 < [Fe/H] < 0.2, observed in the
Gaia-ESO spectroscopic survey. The model is used to obtain age estimates and posterior age probability distributions from
measurements of the Li I 6708Å equivalent width for individual (pre) main sequence stars with 3000 < Teff/K < 6500,
a domain where age determination from the HR diagram is either insensitive or highly model-dependent. In the best cases,
precisions of 0.1 dex in log age are achievable; even higher precision can be obtained for coeval groups and associations where
the individual age probabilities of their members can be combined. The method is validated on a sample of exoplanet-hosting
young stars, finding agreement with claimed young ages for some, but not others. We obtain better than 10 per cent precision
in age, and excellent agreement with published ages, for seven well-studied young moving groups. The derived ages for young
clusters (< 1 Gyr) in our sample are also in good agreement with their training ages, and consistent with several published,
model-insensitive lithium depletion boundary ages. For older clusters there remain systematic age errors that could be as large
as a factor of two. There is no evidence to link these errors to any strong systematic metallicity dependence of (pre) main
sequence lithium depletion, at least in the range −0.29 < [Fe/H] < 0.18. Our methods and model are provided as software –
"Empirical AGes from Lithium Equivalent widthS" (EAGLES).
TEMPORAL EVOLUTION OF THE HIGH-ENERGY IRRADIATION AND WATER CONTENT OF TRAPPI...Sérgio Sacani
The ultracool dwarf star TRAPPIST-1 hosts seven Earth-size transiting planets, some of which could
harbour liquid water on their surfaces. UV observations are essential to measure their high-energy
irradiation, and to search for photodissociated water escaping from their putative atmospheres. Our
new observations of TRAPPIST-1 Ly-α line during the transit of TRAPPIST-1c show an evolution of
the star emission over three months, preventing us from assessing the presence of an extended hydrogen
exosphere. Based on the current knowledge of the stellar irradiation, we investigated the likely history
of water loss in the system. Planets b to d might still be in a runaway phase, and planets within the
orbit of TRAPPIST-1g could have lost more than 20 Earth oceans after 8 Gyr of hydrodynamic escape.
However, TRAPPIST-1e to h might have lost less than 3 Earth oceans if hydrodynamic escape stopped
once they entered the habitable zone. We caution that these estimates remain limited by the large
uncertainty on the planet masses. They likely represent upper limits on the actual water loss because
our assumptions maximize the XUV-driven escape, while photodissociation in the upper atmospheres
should be the limiting process. Late-stage outgassing could also have contributed significant amounts
of water for the outer, more massive planets after they entered the habitable zone. While our results
suggest that the outer planets are the best candidates to search for water with the JWST, they also
highlight the need for theoretical studies and complementary observations in all wavelength domains
to determine the nature of the TRAPPIST-1 planets, and their potential habitability.
Keywords: planetary systems - Stars: individual: TRAPPIST-1
The most luminous_galaxies_discovered_by_wiseSérgio Sacani
Artigo descreve estudo feito por astrônomos e com a ajuda da sonda WISE da NASA para identificar as galáxias do tipo ELIRGs, entre elas a mais luminosa galáxia do universo, com um buraco negro gigantesco em seu interior e localizada a cerca de 12.8 bilhões de anos de distância da Terra.
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.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Nutraceutical market, scope and growth: Herbal drug technologyLokesh Patil
As consumer awareness of health and wellness rises, the nutraceutical market—which includes goods like functional meals, drinks, and dietary supplements that provide health advantages beyond basic nutrition—is growing significantly. As healthcare expenses rise, the population ages, and people want natural and preventative health solutions more and more, this industry is increasing quickly. Further driving market expansion are product formulation innovations and the use of cutting-edge technology for customized nutrition. With its worldwide reach, the nutraceutical industry is expected to keep growing and provide significant chances for research and investment in a number of categories, including vitamins, minerals, probiotics, and herbal supplements.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
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.
This pdf is about the Schizophrenia.
For more details visit on YouTube; @SELF-EXPLANATORY;
https://www.youtube.com/channel/UCAiarMZDNhe1A3Rnpr_WkzA/videos
Thanks...!
1. Comets: Delving Into the
Heart of the Matter
By Ryan Laird
PhD Supervisor: Dr Stephen Lowry
School of Physical Sciences
Postgraduate Colloquium
Friday 23rd September, 2011 1
Survey of Ensemble Physical
Properties of Cometary Nuclei
(SEPPCoN)
Optical ObservationsOptical Observations
2. SEPPCoN
S. C. Lowry (UKC) (Supervisor)
Y. Fernández (UCF)
M. F. A’Hearn (U-Md)
J. M. Bauer (JPL)
H. Campins (UCF)
A. Fitzsimmons (QUB)
O. Groussin (LAM)
H. Hsieh (QUB)
M. Kelley (U-Md)
P. Lamy (LAM)
J. Licandro (IAC, UL)
C. M. Lisse (JHU/APL)
K. J. Meech (UH-IfA)
J. Pittichová (UH-IfA, AI)
W. T. Reach (Caltech/IPAC)
C. Snodgrass (ESO/MPI)
I. Toth (K. Obs.)
H. A. Weaver (JHU/APL)
P. Weissman (JPL)
2
SEPPCoNSEPPCoN
School of Physical Sciences Colloquium 2011
By Ryan Laird
• SEPPCoN (Survey of the Ensemble Physical Properties of Cometary Nuclei)
This is a survey to understand the sizes, albedos, colours, shapes, and spin rates of Jupiter-
Family comets - critical for understanding their origins and evolutionary processes as they
dynamically evolve from the Kuiper Belt.
• Spitzer Large Proposal – 100 hrs – MIPS & IRS imaging obtained during SST Cycle 3,
July 2006 – July 2007
• Ground based optical data (3.5-10m telescopes), ~42 nights – BVRI photometry
3. School of Physical Sciences Colloquium 2011
Ryan Laird
SEPPCoNSEPPCoN –– Ground-Based Optical CampaignGround-Based Optical Campaign (400-790 nm), CCD imaging
ESO – 8.2m VLT
Antu, FORS
(3 nights)
ESO – 3.6m NTT
with
EMMI/EFOSC2
(11 nights)
Apache Point
Observatory ARC 3.5m,
New Mexico (1.5 nights)
2m Robotic
Liverpool
Telescope, La
Palma (0.1 night)
Palomar
Observatory:
5m Hale Telescope
with LFC, California
(14.2 nights)
UH 2.2m (2
nights) and Keck
10m (2 nights),
Mauna Kea
2.6m, Nordic
Optical
Telescope, La
Palma (0.2
nights)
SOAR 4.1m at
Cerro Pachón,
Chile (2.8 nights).
4.2m William
Herschel
Telescope,
La Palma (5
nights)
3
4. 4
Jupiter-Family CometsJupiter-Family Comets
Jupiter-Family Comets
• Orbital period < 20 years
• Direct orbits with inclination < 40 degrees
• Most observationally accessible of the comet groups
• Heliocentric distances 3 AU <Rh< 7 AU
• Tisserand parameter, 2 <TJ< 3 => dynamically distinct group.
For a small body with semimajor axis, a, eccentricity, e, and
inclination, i, relative to the orbit of a perturbing larger body
(Jupiter) with semimajor axis aP
School of Physical Sciences Colloquium 2011
Ryan Laird
6. SEPPCoNSEPPCoN –– Survey of Ensemble Physical Properties of Cometary NucleiSurvey of Ensemble Physical Properties of Cometary Nuclei
1. Use complementary ground-based visible-wavelength and thermal-IR
observations to derive the nuclei’s geometric albedos and sizes.
2. Test for correlations between the albedos and other properties of the
nuclei, such as composition and dynamical age.
3. Compare the cometary albedo distribution with those of Centaurs, TNOs,
Trojans, and extinct comet candidates to test the proposed evolutionary
processes.
4. Resolve once and for all the question of just how safe it is to assume an
albedo for a cometary nucleus. A cautionary tale is the TNO albedo story,
where 4% was long assumed and turned out to be very wrong.
6
School of Physical Sciences Colloquium 2011
Ryan Laird
7. SEPPCoNSEPPCoN –– Survey of Ensemble Physical Properties of Cometary NucleiSurvey of Ensemble Physical Properties of Cometary Nuclei
5. Investigate the colour distribution of JFCs to help constrain the
composition and surface processes of JFC nuclei.
6. Determine the rotation and bulk density of JFC nuclei to compare with
other minor bodies to investigate any possible trends.
7. Determine the most robust size distribution of JFCs in relation to
ascertaining the KBO size distribution.
7
School of Physical Sciences Colloquium 2011
Ryan Laird
8. 8
Size DistributionSize Distribution
Size and Rotation Period
Distributions:
• Is it influenced by collisional
history? By erosion? By
fragmentation? Is it at all similar to
Trojans?
• Is there a paucity of sub-km
objects?
• How does the spin-rate
distributions compare to KBOs, and
what can be learned about their
internal structure?
• We investigate the size distribution
down to ~ 1km. Size distributions
truncated < 2km. Most of targets <
2km by observational and theoretical
indications (Meech at al. 2004,
Samarasinha 2001) so to constrain
low end of size distribution is
dependent on sample.
School of Physical Sciences Colloquium 2011
Ryan Laird
One of several size distributions estimated for JFCs (Weissman & Lowry 2003).
9. Rotation and Bulk Density• We can use the rotation
period and elongation of
the nucleus to put limits on
the bulk density of the
nucleus (Pravec & Harris.
2000).
• Time-series photometry
and light curve amplitude
compared between JFCs
and all available data for
KBOs and Centaurs.
• Together this can reveal
information about the
internal structure of minor
body populations.
Rotation and Bulk DensityRotation and Bulk Density
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Available cometary nucleus light-curve data (Snodgrass, 2006). Comet data
are shown as open circles, KBOs as filled circles and Centaurs as filled
triangles. Like comets, KBOs all lie above 0.6 gcm-3
with the exception of the
large object 2003 EL61.
10. Summary of SEPPCoN
findings
Summary of SEPPCoN findingsSummary of SEPPCoN findings
To date we have attempted observations of 91% of our sample of 100
JFCs, at least 64 of those were successfully detected. Of those 64
detected comets just 16 showed signs of outgassing. In most cases
the comets were at heliocentric distances between 3.0 and 6.5 AU.
Examples of processed optical R-band imaging of three comets successfully detected at
the ESO 3.6-m NTT telescope in May 2007. Comet Lovas 1 shows clear signs of
activity, whereas comets NEAT and Klemola appear unresolved.
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12. Investigating colours allows us to constrain composition
and surface properties.
Groupings have been reported between Centaurs and
KBOs.
Large scale survey from ESO imply a taxonomy of KBOs
based on their composition.
We look for trends in JFC nuclei, developing compositional
links with KBOs.
Colour DistributionColour Distribution
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13. Lamy et al. 2004 – review of 65 ecliptic comets. Albedo
range for cometary nuclei narrow, namely 0.02 to 0.06.
Looking for trends in this narrow range is difficult.
Evolutionary processes such as solar-UV, cosmic ray
darkening, space weathering, collisions, and
resurfacing from outgassing can alter the original
albedo of a comet.
Hypotheses show a trend of albedo with time that elapsed
since the object left the KBO region.
AlbedoAlbedo
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14. Size DistributionSize Distribution
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Reflectance Properties:
– How good is the 4% albedo assumption?
– What are the colourand albedo distributions?
Thermal Properties: – Do all comets have the same thermal properties (e.g. like Tempel 1) ?
(See Lowry et al. 2008. In TheSolarSystemBeyondNeptune)