# White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14

## TL;DR

This paper analyzes Sloan Digital Sky Survey Data Release 14 to classify and characterize over 20,000 white dwarfs, subdwarfs, and related stars, providing insights into stellar evolution and Galactic history.

## Contribution

It presents a comprehensive classification and parameter estimation for a large sample of white dwarfs and subdwarfs, expanding the catalog and understanding of these stars.

## Key findings

- Classified 20,088 white dwarfs, 415 subdwarfs, and 311 cataclysmic variables.
- Derived temperatures, gravities, and masses for various white dwarf types.
- Identified 15,793 sdAs and 447 dCs, mostly low-mass metal-poor stars.

## Abstract

White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs provide insight into the early ages of each population. Examining the spectra of all stars with $3\sigma$ proper motion in the Sloan Digital Sky Survey Data Release 14, we report the classification for 20 088 spectroscopically confirmed white dwarfs, plus 415 hot subdwarfs, and 311 cataclysmic variables. We obtain Teff, log g and mass for hydrogen atmosphere white dwarf stars (DAs), warm helium atmosphere white dwarfs (DBs), hot subdwarfs (sdBs and sdOs), and estimate photometric Teff for white dwarf stars with continuum spectra (DCs). We find 15793 sdAs and 447 dCs between the white dwarf cooling sequence and the main sequence, especially below Teff= 10000 K; most are likely low-mass metal-poor main sequence stars, but some could be the result of interacting binary evolution.