The Palomar Transient Factory (PTF) uses the 48-inch Samuel Oschin Telescope at Palomar Observatory to discover transients and variables in the sky. It aims to study extragalactic and galactic phenomena such as supernovae, tidal disruption events, cataclysmic variables, and structures in the Milky Way. The PTF uses a wide-field imager to discover objects and then coordinates follow-up with spectrographs on the Palomar 200-inch and other telescopes. It has discovered over 2,000 supernovae and published numerous science papers. The Zwicky Transient Facility (ZTF) will improve on the PTF with a larger field of view
The Large Interferometer For Exoplanets (LIFE) II: Key Methods and TechnologiesAdvanced-Concepts-Team
The LIFE initiative has the goal to develop the science, the technology and a roadmap for an aspiring space mission that will allow humankind to detect and characterize, via nulling interferometry, the atmospheres of hundreds of nearby extrasolar planets including dozens that may be similar to Earth. This follow-up talk will tackle more of the techniques and technologies that will enable such an ambitious undertaking. I will outline the underlying measuring principle, and provide some overview over essential technologies, their current status and necessary developments.
The Square Kilometre Array (SKA), even in its first phase (SKA Phase 1, or SKA1) will be the largest ground-based astronomical facility ever built, with unprecedented sensitivity in the frequency ranges for local to highly redshifted HI, and future expansion up to 25 GHz. The range of science cases that the SKA telescopes will cater for will also be the largest of any research facility, from the Epoch of Reionization (EoR) and the Cosmic Down (CD), to tests of Einstein’s General Relativity, to finding all detectable pulsars in the Milky Way, and helping with the Cradle of Life case for Astrobiology. In this talk we will go through the different science cases, with emphasis in those with the most cosmological significance, such as EoR, CD, and probing General Relativity. (Talk presented at CosmoAndes 2018.)
Ultra-fast Outflows from Active Galactic Nuclei of Seyfert I GalaxiesAshkbiz Danehkar
High Energy Phenomena Seminar, Harvard CfA, Cambridge, USA, September 7, 2016, https://doi.org/10.6084/m9.figshare.13699048 https://youtu.be/7q_wv61ou1E
Applications Of Computer Science in AstronomyAhmed Abuzuraiq
A presentations I did for an Astronomy course about the role that computer science plays in in astronomy , Examples included are
Adaptive Optics,Automated Ground Observatory,Galaxies Classifications and Simulations.
Bayesian X-ray Spectral Analysis of the Symbiotic Star RT CruAshkbiz Danehkar
Talk presented at Chandra Data Science: Novel Methods in Computing and Statistics for X-ray Astronomy, Virtual Meeting, Chandra X-ray Center, USA, August 18, 2021
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 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.
American Astronautical Society, Astronauts and Robots: Partners in Space Exploration, May 12-13, 2015 - http://astronautical.org/event/astronauts-robots
The Large Interferometer For Exoplanets (LIFE) II: Key Methods and TechnologiesAdvanced-Concepts-Team
The LIFE initiative has the goal to develop the science, the technology and a roadmap for an aspiring space mission that will allow humankind to detect and characterize, via nulling interferometry, the atmospheres of hundreds of nearby extrasolar planets including dozens that may be similar to Earth. This follow-up talk will tackle more of the techniques and technologies that will enable such an ambitious undertaking. I will outline the underlying measuring principle, and provide some overview over essential technologies, their current status and necessary developments.
The Square Kilometre Array (SKA), even in its first phase (SKA Phase 1, or SKA1) will be the largest ground-based astronomical facility ever built, with unprecedented sensitivity in the frequency ranges for local to highly redshifted HI, and future expansion up to 25 GHz. The range of science cases that the SKA telescopes will cater for will also be the largest of any research facility, from the Epoch of Reionization (EoR) and the Cosmic Down (CD), to tests of Einstein’s General Relativity, to finding all detectable pulsars in the Milky Way, and helping with the Cradle of Life case for Astrobiology. In this talk we will go through the different science cases, with emphasis in those with the most cosmological significance, such as EoR, CD, and probing General Relativity. (Talk presented at CosmoAndes 2018.)
Ultra-fast Outflows from Active Galactic Nuclei of Seyfert I GalaxiesAshkbiz Danehkar
High Energy Phenomena Seminar, Harvard CfA, Cambridge, USA, September 7, 2016, https://doi.org/10.6084/m9.figshare.13699048 https://youtu.be/7q_wv61ou1E
Applications Of Computer Science in AstronomyAhmed Abuzuraiq
A presentations I did for an Astronomy course about the role that computer science plays in in astronomy , Examples included are
Adaptive Optics,Automated Ground Observatory,Galaxies Classifications and Simulations.
Bayesian X-ray Spectral Analysis of the Symbiotic Star RT CruAshkbiz Danehkar
Talk presented at Chandra Data Science: Novel Methods in Computing and Statistics for X-ray Astronomy, Virtual Meeting, Chandra X-ray Center, USA, August 18, 2021
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 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.
American Astronautical Society, Astronauts and Robots: Partners in Space Exploration, May 12-13, 2015 - http://astronautical.org/event/astronauts-robots
Science with small telescopes - exoplanetsguest8aa6ebb
The search for extrasolar planets has become one of the most attractive problems in modern astrophysics. The biggest observatories in the world are involved in this task as well as little amateur instruments. There is also a huge variety of astronomical methods used for their investigation. Here I present the projects for searching for exoplanets by transit method and our observations of the planet WASP-2b. We observed a transit on 3/4 August 2008 with a 354 mm Schmidt-Cassegrain Celestron telescope and CCD SBIG STL 11000M camera. By precise photometry made using MaximDL software we obtained the light curve of the star system. Decrease of brightness by 0.02m is detected. Analyzing our data we estimate the radius of the planet and inclination of its orbit. Our results are in good correlation with the published information in literature.
We discovered two transient events in the Kepler eld with light curves that strongly suggest they
are type II-P supernovae. Using the fast cadence of the Kepler observations we precisely estimate
the rise time to maximum for KSN2011a and KSN2011d as 10.50:4 and 13.30:4 rest-frame days
respectively. Based on ts to idealized analytic models, we nd the progenitor radius of KSN2011a
(28020 R) to be signicantly smaller than that for KSN2011d (49020 R) but both have similar
explosion energies of 2.00:3 1051 erg.
The rising light curve of KSN2011d is an excellent match to that predicted by simple models of
exploding red supergiants (RSG). However, the early rise of KSN2011a is faster than the models
predict possibly due to the supernova shockwave moving into pre-existing wind or mass-loss from the
RSG. A mass loss rate of 10 4 M yr 1 from the RSG can explain the fast rise without impacting
the optical
ux at maximum light or the shape of the post-maximum light curve.
No shock breakout emission is seen in KSN2011a, but this is likely due to the circumstellar inter-
action suspected in the fast rising light curve. The early light curve of KSN2011d does show excess
emission consistent with model predictions of a shock breakout. This is the rst optical detection of
a shock breakout from a type II-P supernova.
Artigo que descreve a descoberta do exoplaneta Kepler-432b, um exoplaneta mais massivo que Júpiter que orbita uma estrela gigante vermelha bem próximo e numa órbita extremamente alongada.
No signature of_ejecta_interaction_with_a_stellar_companion_in_three_type_ia_...Sérgio Sacani
ARtigo descreve estudos de supernovas feitos com o Kepler e mostram que explosões podem ser geradas por estrelas anãs brancas simples, se chocando com outras ou se fundindo com outras.
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.
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.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Mammalian Pineal Body Structure and Also Functions
Producing science with_ptf
1. Producing Science with the Palomar
Transient Factory
Branimir Sesar (MPIA, formerly Caltech)
2. Survey Goals
(Law et al. 2009, Rau et al. 2009)
• Goal: to study the transient and variable sky
• Extragalactic
• Transients in nearby galaxies, CC SNe, TDE, Hα Sky Survey,
search for eLIGO/EM counterparts
• Galactic
• AM CVn systems (H + He WD), CVs, RR Lyrae stars, Milky
Way structure and dynamics
• Solar System: KBOs, small asteroids (prospect for growth
→ asteroid retrieval mission)
4. P48 wide-field imager →
Discovery engine
P48 wide-field imager →
Discovery engine
P200
Spec. followup
P200
Spec. followup
P60
Photo. followup
P60
Photo. followup
Fast spectroscopic typing
with SED Machine (R~100,
PI: Nick Konidaris, Caltech)
Fast spectroscopic typing
with SED Machine (R~100,
PI: Nick Konidaris, Caltech)
R~100 spectra of various transients and variables
→ important spectral features are still discernible
R~100 spectra of various transients and variables
→ important spectral features are still discernible
5. P48 Overview
• 7.26 deg2
field-of-view → will
be upgraded to 47 deg2
for
ZTF (2015-2016)
• 1” / pixel resolution → barely
sampled at median 2” seeing
→ PSF photometry possible
• Robotic telescope &
scheduler → automatic
selection of fields → time &
money saver
• g', R, and 2 Hα filters
• ~250 images / night
CFHT12k camera
(some cosmetics, ghosts)
CFHT12k camera
(some cosmetics, ghosts)
8. IPAC Pipeline (variables & light curves)
• Repeatability of < 0.01 mag
• R-band 5σ limit @ 20.6 mag
(aperture), 20.9 mag (PSF)
• 12,000 deg2
with >30 epochs
• 1st
PTF/iPTF data release (M81, M44, M42, Cas A, Kepler)
http://www.ptf.caltech.edu/page/first_data_release
• Public release of PTF, iPTF and ZTF data (w/ NSF funding)
coverage of the Galactic plane (|b| < 5 deg)coverage of the Galactic plane (|b| < 5 deg)
9. Science
• 2,254 spectroscopically
confirmed SNe
• 88 publications (5 in
Nature)
SN Ia in M101 (PTF11kly;
Nugent et al. 2011, Li et al. 2011)
SN Ia in M101 (PTF11kly;
Nugent et al. 2011, Li et al. 2011)
10. An outburst from a massive star 40 days
before a supernova explosion (Ofek+ 2013)
No detection @ -60 daysNo detection @ -60 days
Outburst!Outburst!
Explosion!Explosion!
11. Localization of an optical afterglow in 71
deg2
(Singer et al. 2013)
ZTF will cover this area
with ~2 images
ZTF will cover this area
with ~2 images
12. GRB 130702A to iPTF13bxl Timeline
• 00:05 Fermi GMB trigger (UT July 2nd)
• 01:05 position refined by human (GBM group)
• 03:08 Sun sets at Palomar
• 04:17 PTF starts observations
• 04:17 PTF starts observations (10 fields, 2x60-s per field; 72 square degrees)
• 4214 "candidates": 44 were known asteroids, 1744 were coincident with stars (r<21) → 43
viable candidates
• Human inspection reduced this to 6 excellent candidates
• iPTF13bxh core of a bright galaxy, iPTF13bxr known quasar, iPTF13bxt was close to a
star in SDSS
• Remaining candidates: iPTFbxl(RB2=0.86), iPTFbxk (RB2=0.83) and iPTFbxj (RB2=0.49)
• Sunrise in California
13. GRB 130702A to iPTF13bxl Timeline
• 00:50 Swift observations for iPTF13bxl requested → X-ray
source detected
• 04:10 Robotic observations of these candidates at P60 →
iPTFbxl showed decline relative to first P48 observation (!)
• 04:24 Spectral observations on the Palomar 200-inch →
spectrum is featureless (!!)
• 08:24 Announced iPTF13bxl as afterglow (ATEL, GCN)
• 17:34 LAT localization (3.2 square degrees)
• 19:03 IPN announces annulus of width 0.9 degrees
• 23:17 Magellan observations led to z=0.145
14. Small, but potentially hazardous asteroids
Adam Waszczak
(grad student @
Caltech)
Adam Waszczak
(grad student @
Caltech)
NEA 2014 JG55 (diameter: 10 m, closest approach: ¼ Earth-Moon distance)NEA 2014 JG55 (diameter: 10 m, closest approach: ¼ Earth-Moon distance)
15. ~180 RRab stars between 60 and 100 kpc
Orange – Sgr?Orange – Sgr?
16. ΛCDM prediction: Hundreds of ultra-faint
dSph galaxies orbiting the MW
ultra-faint
dSph
ultra-faint
dSph
Tollerud et al. (2008)Tollerud et al. (2008)
Predicted number of observable
faint MW satellites
Predicted number of observable
faint MW satellites
• LSST should be able to
observe ~300 ultra-faint
dSphs
• About 50 ultra-faint dSphs
in ~10,000 sq. deg and
between 60 - 100 kpc
17. Segue I (MV
= -1.5, D = 23 kpc, rh
= 30 pc)
MSTOMSTO
RRcRRc
BHBBHB
Only 6
RGB stars!
Only 6
RGB stars!
Seg RGB → orange
Seg MS → blue
Seg RGB → orange
Seg MS → blue
18. “Segue I”-like ultra-faint dSph at 60 kpc
dSph RGB → orange
foreground → white
dSph RGB → orange
foreground → white
19. Segue I (MV
= -1.5, D = 23 kpc, rh
= 30 pc)
MSTOMSTO
RRcRRc
BHBBHB
Only 6
RGB stars!
Only 6
RGB stars!
Seg RGB → orange
Seg MS → blue
Seg RGB → orange
Seg MS → blue
20. RR Lyrae Stars
• Old, evolved stars (> 9 Gyr) →
trace old populations of stars
• Standard candles → identify
them → know their distance
(with ~6% uncertainty)
• Bright (V ~ 21 at 110 kpc)
• Variable stars (P ~ 0.6 day)
with distinct light curves ( ~1
mag amplitude) → easily
identifiable
• Repeated observations (~30 or
more) are needed
Light curve of an RR Lyrae type abLight curve of an RR Lyrae type ab
21. Table 4 of Boettcher, Willman et al. (2013)
Boo III 1 -2.0 (Sesar, submitted to ApJ)
Boo II 1? ? (within 1.5' of Boo II @ 33 kpc)
Boo III 1 -2.0 (Sesar, submitted to ApJ)
Boo II 1? ? (within 1.5' of Boo II @ 33 kpc)
22. “Segue I”-like ultra-faint dSph at 60 kpc
dSph RGB → orange
foreground → white
dSph RGB → orange
foreground → white
33. Sensitivity of the detection method
Black pixels: parameter
space where a detection
is possible
Black pixels: parameter
space where a detection
is possible
34. RR Lyrae stars in SDSS Stripe 82 (Sesar, Ivezić+ 2010)RR Lyrae stars in SDSS Stripe 82 (Sesar, Ivezić+ 2010)
“Smooth” inner halo ends at 30 kpc → only streams
and dSphs beyond 30 kpc?
“Smooth” inner halo ends at 30 kpc → only streams
and dSphs beyond 30 kpc?
35. Be Aware of the Contamination
• Sesar et al. (2007):
• Smaller number of epochs
in SDSS Stripe 82
• Could not properly
remove non-RR Lyrae
stars
• ~30% contamination in
our RR Lyrae sample
• Detection of false halo
substructures
PscPsc