Abstracts
"The Berkeley SuperNova Ia Program (BSNIP): Dataset and Initial Analysis"
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. |
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"Empirical Constraints on the Formation and Evolution of Low-Mass Stars and Brown Dwarfs: A Data-Intensive Approach"
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. |
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"Empirical Constraints on the Formation and Evolution of Low-Mass Stars and Brown Dwarfs: A Data-Intensive Approach"
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. |
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"The HD128311 System Remixed with Data from HST, HET and T12 APT" 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. |