Abstract by Morgan Fouesneau
The PHAT survey is an ongoing Hubble Treasury program, which aim to map
1/3 of the disk of M31 from the UV to NIR. The survey is expected to
find more than 3000 clusters in M31, creating one of the largest and
most complete samples of clusters known in any galaxy. The six-filter
PHAT imaging enables studies of clusters' integrated properties and
their resolved stellar content. We detect clusters with masses as low as
~100 Msun, orders of magnitude lower than previous extragalactic studies
and ground-based studies of M31. We detail our efforts to identify and
quantify the completeness of the PHAT cluster sample, and to determine
cluster ages, masses, stellar mass function, and structural parameters
down to the very low-mass regime. I will present results using our
initial cluster sample to understand the efficiency of star cluster
formation, the cluster mass function, and the dissolution of clusters.
Wednesday, January 16, 2013
Friday, November 30, 2012
Friday December 7th: Dust production of massive stars
Abstract by Christa Gall
Dust plays an essential role in the formation of stars and evolution of galaxies. Large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift, bear witness of a rapid production of dust. Massive stars ending their lives as either asymptotic giant branch stars or supernovae have been contemplated as the prime sources of dust, but it is uncertain whether their dust production efficiency is sufficient to account for the large dust masses observed. I shall address the challenge of determining dust masses observationally and discuss the contribution of stellar dust sources to the dust budget in the high redshift universe as well as in Local Group galaxies.
Dust plays an essential role in the formation of stars and evolution of galaxies. Large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift, bear witness of a rapid production of dust. Massive stars ending their lives as either asymptotic giant branch stars or supernovae have been contemplated as the prime sources of dust, but it is uncertain whether their dust production efficiency is sufficient to account for the large dust masses observed. I shall address the challenge of determining dust masses observationally and discuss the contribution of stellar dust sources to the dust budget in the high redshift universe as well as in Local Group galaxies.
Thursday, November 29, 2012
Friday Nov. 30th at 12pm: Joint meeting with the galaxy club
Life Cycles of Star Clusters
Michael Fall (STScI)
This talk presents an overview of the life cycles of star clusters from their their birth in dense molecular clouds to their eventual dissolution in the diffuse stellar field. The talk summarizes several of our recent observational and theoretical studies. One of our main findings is a remarkable similarity in the populations of clusters in different galaxies (giant and dwarf, interacting and quiescent). We discuss the most likely physical reasons for this similarity. The resulting picture helps to unify a mostly descriptive subject with a complicated nomenclature (including associations and open, populous, super, and globular clusters).
The structural evolution of galaxies from z=2.5 to z=0
Daniel Szomoru (Leiden)
Massive galaxies have undergone tremendous changes in their structure and morphology since z=2.5. Although observational and theoretical uncertainties remain significant, a coherent picture of the evolution of massive galaxies over the past 11 Gyr is starting to emerge. I will discuss recent results, focusing on the structure of high-redshift quiescent galaxies, their rapid evolution, and the implications of these results on our knowledge of galaxy evolution.
Michael Fall (STScI)
This talk presents an overview of the life cycles of star clusters from their their birth in dense molecular clouds to their eventual dissolution in the diffuse stellar field. The talk summarizes several of our recent observational and theoretical studies. One of our main findings is a remarkable similarity in the populations of clusters in different galaxies (giant and dwarf, interacting and quiescent). We discuss the most likely physical reasons for this similarity. The resulting picture helps to unify a mostly descriptive subject with a complicated nomenclature (including associations and open, populous, super, and globular clusters).
The structural evolution of galaxies from z=2.5 to z=0
Daniel Szomoru (Leiden)
Massive galaxies have undergone tremendous changes in their structure and morphology since z=2.5. Although observational and theoretical uncertainties remain significant, a coherent picture of the evolution of massive galaxies over the past 11 Gyr is starting to emerge. I will discuss recent results, focusing on the structure of high-redshift quiescent galaxies, their rapid evolution, and the implications of these results on our knowledge of galaxy evolution.
Thursday, November 8, 2012
Thursday November 15th: New ideas in stellar magnetism, and the magnetorotational instability
Abstract by Geoff Vasil
Understanding the mechanisms behind solar magnetism remains one of the longest-standing unsolved problems in physics. Despite an impressive amount of observations, from early counts of sunspots to the recent data coming from the Solar Dynamics Observatory and the Kepler mission, no one understands how the sun's global magnetic dynamo machine operates. Over the last few decades theories have risen and fallen and radically new ideas are needed to make progress. In this talk, I will present a new model of the dynamics of the sun's layers. It is based on the magneto-rotational instability (MRI) and is equivalent to the dynamics of a buckling elastic beam under an applied load. While still only a qualitative model, it can possibly explain the migration of the equator branch of the solar torsional oscillation pattern, which correlates highly with sunspot migration, a phenomenon that has strongly resisted explanation to date.
Understanding the mechanisms behind solar magnetism remains one of the longest-standing unsolved problems in physics. Despite an impressive amount of observations, from early counts of sunspots to the recent data coming from the Solar Dynamics Observatory and the Kepler mission, no one understands how the sun's global magnetic dynamo machine operates. Over the last few decades theories have risen and fallen and radically new ideas are needed to make progress. In this talk, I will present a new model of the dynamics of the sun's layers. It is based on the magneto-rotational instability (MRI) and is equivalent to the dynamics of a buckling elastic beam under an applied load. While still only a qualitative model, it can possibly explain the migration of the equator branch of the solar torsional oscillation pattern, which correlates highly with sunspot migration, a phenomenon that has strongly resisted explanation to date.
Friday, October 26, 2012
Nov. 2nd: Dust production of massive stars MOVED TO Friday December 7th
Abstract by Christa Gall
Dust plays an essential role in the formation of stars and evolution of galaxies. Large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift, bear witness of a rapid production of dust. Massive stars ending their lives as either asymptotic giant branch stars or supernovae have been contemplated as the prime sources of dust, but it is uncertain whether their dust production efficiency is sufficient to account for the large dust masses observed. I shall address the challenge of determining dust masses observationally and discuss the contribution of stellar dust sources to the dust budget in the high redshift universe as well as in Local Group galaxies.
Dust plays an essential role in the formation of stars and evolution of galaxies. Large amounts of dust detected in sub-millimeter galaxies and quasars at high redshift, bear witness of a rapid production of dust. Massive stars ending their lives as either asymptotic giant branch stars or supernovae have been contemplated as the prime sources of dust, but it is uncertain whether their dust production efficiency is sufficient to account for the large dust masses observed. I shall address the challenge of determining dust masses observationally and discuss the contribution of stellar dust sources to the dust budget in the high redshift universe as well as in Local Group galaxies.
Monday, October 15, 2012
Friday October 19th: Counting Milky Way M-dwarfs in WFC3 surveys
Abstract by Benne Holwerda
Counting stars is one of the oldest techniques to determine the shape and size of the Milky Way. Long the realm of bright stars, the discovery space in deep WFC3 imaging of the high-redshift Universe covers the same luminosity and color ranges that probe dwarf stars belonging to our own Milky Way.
The BoRG pure-parallel WFC3 survey probes many lines-of-sight out of our own Galaxy with four filters. I present a way to identify the stars in this survey, and calibrate their spectral type from the colors. The ultimate goal is to characterize the shape and size of the components of the Milky Way (thin and thick disk, possible the spheroid) using these bona-fide M-dwarf stars.
Counting stars is one of the oldest techniques to determine the shape and size of the Milky Way. Long the realm of bright stars, the discovery space in deep WFC3 imaging of the high-redshift Universe covers the same luminosity and color ranges that probe dwarf stars belonging to our own Milky Way.
The BoRG pure-parallel WFC3 survey probes many lines-of-sight out of our own Galaxy with four filters. I present a way to identify the stars in this survey, and calibrate their spectral type from the colors. The ultimate goal is to characterize the shape and size of the components of the Milky Way (thin and thick disk, possible the spheroid) using these bona-fide M-dwarf stars.
Friday October 12th: Informal discussion on SN2009ip
SN2009ip, Luminous Blue Variable or actual Super Nova Type II?
In July of this year a new outburst of SN2009ip was discovered. There has been important discussion among the field on whether this object has indeed become a Core-Colapse Super Nova Type II or not. If you are interested I suggest to read the following papers... they are fun to read, so enjoy!
Jon C. Mauerhan, Nathan Smith, Alexei Filippenko, Kyle Blanchard, Peter Blanchard, Chadwick F. E. Casper, S. Bradley Cenko, Kelsey I. Clubb, Daniel Cohen, Gary Li, & Jeffrey M. Silverman
http://arxiv.org/abs/1209.6320
J. L. Prieto, J. Brimacombe, A. J. Drake, & S. Howerton
http://arxiv.org/abs/1210.3347
In July of this year a new outburst of SN2009ip was discovered. There has been important discussion among the field on whether this object has indeed become a Core-Colapse Super Nova Type II or not. If you are interested I suggest to read the following papers... they are fun to read, so enjoy!
Jon C. Mauerhan, Nathan Smith, Alexei Filippenko, Kyle Blanchard, Peter Blanchard, Chadwick F. E. Casper, S. Bradley Cenko, Kelsey I. Clubb, Daniel Cohen, Gary Li, & Jeffrey M. Silverman
http://arxiv.org/abs/1209.6320
J. L. Prieto, J. Brimacombe, A. J. Drake, & S. Howerton
http://arxiv.org/abs/1210.3347
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