Sarah Ballard
Sagan Fellow, U. Washington

Exoplanet Characterization by Proxy for Kepler-61b: How a Nearby Star Bumped a Planet Out of the Habitable Zone

I will present the validation and characterization of Kepler-61b: a 2.5 R_Earth planet orbiting near the inner edge of the habitable zone of a low-mass star. The characterization of the host star Kepler-61 is based upon our identification of a spectroscopically similar star located 4.9 pc from Earth. This proxy star to Kepler-61 has a published direct interferometric radius and effective temperature measurement, which we apply in tandem with the Kepler photometry to characterize the planet Kepler-61b. The technique of identifying a nearby proxy star with directly measured properties allows for an independent check on stellar characterization via the traditional measurements with stellar spectra and evolutionary models. In this case, such a check had profound implications for the putative habitability of Kepler-61b.

Or Graur

Digging for buried treasure: discovery of 90 Type Ia supernovae in a spectroscopic supernova survey in the SDSS

Today, supernovae are discovered in imaging-based surveys and classified using follow-up spectroscopy. I will show how large-scale spectroscopic galaxy surveys, such as the Sloan Digital Sky Survey (SDSS), can be used to conduct spectroscopic supernova surveys. Using a code that detects and classifies supernovae buried in galaxy spectra, I have detected 90 Type Ia supernovae among ~700,000 galaxy spectra in the 7th SDSS Data Release, which I then used to measure rates and constrain this type of supernova's progenitor scenarios. The results of this survey add to a growing body of evidence that the progenitor is a binary system composed of two carbon-oxygen white dwarfs.