A Volume-Limited Photometric Survey of 114 gamma Doradus Candidates

TL;DR

This study conducted a comprehensive photometric and spectroscopic survey of 114 gamma Doradus candidates within a volume-limited sample, identifying 25 new or known gamma Doradus variables and establishing their incidence and space density.

Contribution

It provides the first complete, volume-limited survey of gamma Doradus candidates, confirming 15 new variables and updating the catalog of known gamma Doradus stars.

Findings

22% incidence of gamma Doradus variability among candidates

Identified 15 new gamma Doradus variables

Estimated space density of gamma Doradus stars as 94 per million cubic parsecs

Abstract

We have carried out a photometric survey of a complete, volume-limited sample of gamma Doradus candidates. The sample was extracted from the Hipparcos catalog and consists of 114 stars with colors and absolute magnitudes within the range of known gamma Doradus stars. We devoted one year of observing time with our T12 0.8 m automatic photometric telescope to acquire nightly observations of the complete sample of stars. From these survey observations, we identify 37 stars with intrinsic variability of 0.002 mag or more. Of these 37 variables, eight have already been confirmed as gamma Doradus stars in our earlier papers; we scheduled the remaining 29 variables on our T3 0.4 m automatic telescope to acquire more intensive observations over the next two years. We obtained complementary spectroscopic observations with the Kitt Peak coude feed telescope. Analysis of our new photometric and spectroscopic data reveals 15 new gamma Doradus variables (and confirms two others), eight new delta Scuti variables (and confirms one other), and three new variables with unresolved periodicity. Of the 114 gamma Doradus candidates in our volume-limited sample, we find 25 stars that are new or previously-known gamma Doradus variables. This results in an incidence of 22% for gamma Doradus variability among candidate field stars for this volume of the solar neighborhood. The corresponding space density of gamma Doradus stars is 0.094 stars per 10^3 pc^3 or 94 stars per 10^6 pc^3. We provide an updated list of 86 bright, confirmed, gamma Doradus field stars.