Jan 18

"The Berkeley SuperNova Ia Program (BSNIP): Dataset and Initial Analysis"
Jeffrey Silverman, University of California, Berkeley

I will present spectroscopic data from the Berkeley SuperNova Ia Program (BSNIP), their initial analysis, and the results of attempts to use spectral information to improve cosmological distance determinations to Type Ia supernova (SNe Ia). The dataset consists of 1298 low-redshift (z < 0.2) optical spectra of 582 SNe Ia observed from 1989 through the end of 2008. The sheer size of the BSNIP dataset and the consistency of the observation and reduction methods make this sample unique among all other published SN Ia datasets. I will also discuss measurements of the spectral features of about one-third of the spectra which were obtained within 20 days of maximum light. I will briefly describe the adopted method of automated, robust spectral-feature definition and measurement which expands upon similar previous studies. Comparisons of these measurements of SN Ia spectral features to photometric observables will be presented with an eye toward using spectral information to calculate more accurate cosmological distances.

Feb 8

"Empirical Constraints on the Formation and Evolution of Low-Mass Stars and Brown Dwarfs: A Data-Intensive Approach"
Keivan Stassun, Vanderbilt University

Recent and ongoing large surveys, both from the ground and from space, are enabling new data-intensive approaches to a variety of problems in stellar astrophysics. This talk describes three such projects, each serving as a vignette of a different but complementary mode of data-intensive research into low-mass star formation and evolution. The X10000 Project takes a panchromatic, time-domain approach to study the structures of young stellar coronae in order to understand the role of extreme coronal mass ejections in the angular momentum evolution of young stars. As a by-product of this work, we have determined the first robust empirical relationship between X-ray flare energy and coronal mass loss for the Sun. The SLoWPoKES project takes an ensemble, data-mining approach to extract from the Sloan Digital Sky Survey the largest sample of wide low-mass binaries ever assembled, which can be used to constrain binary formation theory and for refining the fundamental mass-age-activity-rotation-metallicity relations for low-mass stars. The EB Factory project takes a time-domain, data-mining approach to identify rare, but astrophysically very interesting, case studies from among the large numbers of eclipsing binaries being harvested by surveys for transiting exoplanets. We will highlight recent discoveries from this work, and will draw these results together to elucidate the physical interrelationships between stellar rotation, magnetic field generation, and stellar structure during the star-formation process.

Mar 7

"Empirical Constraints on the Formation and Evolution of Low-Mass Stars and Brown Dwarfs: A Data-Intensive Approach"
Katrien Kolenberg, Harvard-Smithsonian Center for Astrophysics & Katholieke Universiteit Leuven, Belgium

The spectacular data delivered by NASA's Kepler mission not only boost the discoveries of planets orbiting other stars, but they also open a window on the inner workings of the stars themselves. Kepler has been a breakthrough for the study of RR Lyrae stars and the still mysterious Blazhko effect. I will present some of the most interesting results obtained so far.

To date, over 40 RR Lyrae stars have been found in the Kepler field. The outstandingly high-precision data of these stars are investigated within the RR Lyrae working group as part of the Kepler Asteroseismic Science Consortium (KASC).

Apr 25

"The HD128311 System Remixed with Data from HST, HET and T12 APT"
Barbara McArthur, University of Texas at Austin

We have used high-cadence radial velocity measurements from the Hobby- Eberly Telescope with published velocities from the Lick 3 meter Shane Telescope, combined with astrometric data from the Hubble Space Telescope Fine Guidance Sensors to refine the orbital parameters of the HD128311 system. The combined radial velocity data also reveal a short period signal which could indicate a third planet in the system or stellar phenomena. Photometry from the T12 0.8 m Automatic Photometric Telescope (APT) at Fairborn Observatory and HST are used to determine a photometric period close to, but not within the errors to the radial velocity signal. Dynamical integrations of the proposed system show long term stability with the new orbital parameters of over ten million years. Our new orbital elements do not support the claims of HD128311 b and c being in mean motion resonance.