Abstract

Derivation of the Stellar Formation History from White Dwarfs in the Solar Neighborhood

Pier-Emmanuel Tremblay (Space Telescope Science Institute)

J. S. Kalirai (STScI), D. R. Soderblom (STScI), M. Cignoni (STScI), and J. Cummings (John Hopkins University)

The study of volume complete samples in the solar neighborhood is a powerful technique to learn about the stellar formation history (SFH) and the initial mass function (IMF). Various stellar studies have been aimed at identifying the SFH of the disk, but they provide conflicting results and large uncertainties due the difficulty of measuring the age of field stars. We present an alternative method which consists of directly probing the formation history from the volume complete sample of white dwarfs within 20 pc, where accurate cooling ages and masses have been determined. The observed initial-final mass relation and theoretical stellar isochrones are employed to recover the initial mass and total age of degenerate stars in the local sample. We correct for moderate biases that are necessary to transform our results to a global stellar formation rate, and compare to similar studies based on the properties of main-sequence and turnoff stars. Our results suggest an enhanced formation rate for the solar neighborhood in the last 5 Gyr compared to the range 5 < Age (Gyr) < 10. The main shortcoming of our study is the small size of the local white dwarf sample, but we can apply the presented technique to larger samples in the future.

Mode of presentation: poster