This page lists the papers that people want to discuss at the next AstroLunch (former AstroCoffee) session. AstroLunch takes place in the big conference room on the ground floor, SC 6333, every Tuesday at 12:00 pm. At each session, pizza is typically served and discussion will last as long as there is astronomy to discuss. Normal AstroLunch sessions will be divided into two thirty minute halves. The first half will be used to discuss papers on astro-ph selected through Vox Charta. Although, discussion of older papers on astro-ph is also welcome. The second half will be dedicated to two fifteen minute talks given by either a postdoc/postdoc pair or postdoc/faculty pair, the schedule can be viewed here. Always remember that AstroLunch is a chance for informal discussions of papers and astronomy. Therefore, the conversation will be kept at a relatively simple level, with encouragement for students to speak up and ask basic questions. 

Sometimes AstroLunch sessions will be reserved for talks given by visiting astronomers; a list of such talk can be found on the past Astro talks page.  For a list of some of the papers that have been discussed during AstroLunch, please feel free to check out the old AstroLunch and AstroCoffee papers.  

To find out when new papers are posted to this page, see the Notifications page.

Upcoming:

AstroLunch: December 16, 2014

Speaker: Chip Cox (Vanderbilt University) 

Title: Data Management for LSST

Description: tba

AstroLunch: December 10, 2013

Speaker: Kelly Holley-Bockelmann (Vanderbilt University) 

Title: Turbo charging your research with ACCRE 

Description: This talk is a department-wide event to launch a new ACCRE initiative to help increase the user footprint of ACCRE. Learn how your research can benefit from this supercomputing facility.

Previous:

AstroLunch: April 30, 2013

Speaker: Heather R. Jacobson (MIT) 

Title: Building the Milky Way: galaxy assembly as traced by chemical evolution

Abstract: The history of our galaxy is imprinted on the chemical compositions of its stars.  The relative abundances of different chemical elements, from the light elements to those beyond the Fe-peak, yield vital clues to such parameters as the initial mass function(s), star formation rate(s), and assembly history of different components of the Milky Way.  I will discuss our current understanding of the formation and evolution of the thin disk as traced by chemical abundances of open clusters, particularly by their neutron capture elements.  As the thin disk formed relatively late compared to other major components of the Milky Way, its history can be compared and contrasted to that of the halo.  In this context, I will present the latest results of our high resolution spectroscopic followup of metal-poor star candidates found in the SkyMapper survey.  Such detailed chemical abundance analyses of different stellar populations in the Milky Way offer a powerful view into the history of galaxy evolution from the earliest epochs of the universe to stars forming in spiral arms today.

AstroLunch: April 16, 2013

Speaker: Joseph Rodriguez (Vanderbilt University)

Title: Occultation of the T Tauri Star RW Aurigae A by its Tidally Disrupted Disk

Abstract: RW Aur A is a classical T Tauri star, believed to have undergone a reconfiguration of its circumstellar environment as a consequence of a recent fly-by of its stellar companion, RW Aur B. This interaction stripped away part of its circumstellar disk, leaving a tidally disrupted "arm" feature and a short truncated disk. We present photometric observations of the RW Aur system from the Kilodegree Extremely Little Telescope (KELT-North) showing a long and deep eclipse that occurred from September of 2010 until March of 2011. The eclipse has a depth of ~2 magnitudes and a duration of ~180 days, similar to individual eclipses of Epsilon Aurigae. The eclipse was confirmed by archival observations from American Association of Variable Star Observers (AAVSO). We suggest that this eclipse is the result of a portion of the tidally disrupted disk occulting RW Aur A. The calculated transverse linear velocity of the occulter is in excellent agreement with the measured relative velocity of the tidally disrupted arm. Using simple kinematic and geometric arguments, we show that the occulter cannot be a feature of the RW Aur A circumstellar disk, and we also discount other hypothesis. We also place constraints on the (projected) thickness an semi-major axis of the portion of the arm that occulted the star.

AstroLunch: April 2, 2013

Speaker: Daniel Foreman-Mackey (New York University)

Title: Data analysis using Markov chain Monte Carlo

Abstract: Markov chain Monte Carlo (MCMC) refers to a class of numerical algorithms for sampling probability distributions. In particular, these algorithms can be very effective for evaluating posterior probability functions for a set of model parameters given a set of (noisy) data. This method for "probabilistic inference" is commonly used in astronomy because it lets us learn about the parameters of justified physical models even when our data have large and heterogeneous uncertainties. In this talk, I'll explain standard MCMC techniques, best practices and shortcomings. In particular, I will try to provide some insight for how MCMC can fit into your data analysis workflow. I will also discuss -- with examples from my research and the astronomy literature -- the use of the popular "emcee" implementation (http://dan.iel.fm/emcee) including comments on various common pitfalls and techniques fro avoiding them.

AstroLunch: March 12, 2013

Speaker: Dr. Tracy Huard (University of Maryland)

Title: VeLLOs in Dense Molecular Clouds

Abstract: Very Low Luminosity Objects (VeLLOs) are sources with internal luminosities < 0.1 Lsun embedded in dense molecular clouds, environments that are known to form stars.  Since VeLLOs were first discovered a decade ago by the Cores-to-Disks Spitzer Space Telescope legacy team, the number of known VeLLOs has grown slowly, and their nature remains unclear.  They are most likely either the youngest protostars found soon after dense core collapse, proto-brown dwarfs, or typical low-mass protostars found within a quiescent stage of accretion.  The discovery of VeLLOs, growth of this class of sources, and studies that may help to elucidate their nature will be discussed.

Speaker: Dr. Jeff Bary (Colgate University)

Title: Accretion Activity in Binary Systems

Abstract: Young binary systems that possess both circumbinary and circumstellar disks are particularly interesting objects to study for those seeking a better understanding of star-star-disk-disk-disk interactions.  With opportunities for material to pass inward from the circumbinary disk to the circumstellar disks, between the circumstellar disks, and from the circumstellar disks onto the stellar surfaces, such systems are perfect laboratories in which to observe accretion activity.  Recent high-spatial resolution spectral images of the "Ring World" GG Tau show strong evidence for an accretion stream passing from the circumbinary disk into the circumstellar environoment will be presented.  Time permitting, a multi-epoch near-infrared spectroscopic survey of the tight binary DQ Tau (P = 15.8 days), which affirms the presence of orbitally-modulated accretion activity and also hints at the presence of circumstellar-circumbinary disk interactions, will also be presented.  In both cases, the star-disk and disk-disk interactions likely play an important role for determining the lifetimes of the inner and outer disks and will impact the development of planets in the multiple host star systems.

AstroLunch: December 11, 2012

SOPHIE velocimetry of Kepler transit candidates. VII. A false-positive rate of 35% for Kepler close-in giant candidates