The K2 Galactic Archaeology Program Data Release 2: Asteroseismic results from campaigns 4, 6, & 7

Abstract

Studies of Galactic structure and evolution have benefitted enormously from Gaia kinematic information, though additional, intrinsic stellar parameters like age are required to best constrain Galactic models. Asteroseismology is the most precise method of providing such information for field star populations $\text{en masse}$, but existing samples for the most part have been limited to a few narrow fields of view by the CoRoT and Kepler missions. In an effort to provide well-characterized stellar parameters across a wide range in Galactic position, we present the second data release of red giant asteroseismic parameters for the K2 Galactic Archaeology Program (GAP). We provide ${\nu }_{\max }$ and $\Delta \nu$ based on six independent pipeline analyses; first-ascent red giant branch (RGB) and red clump (RC) evolutionary state classifications from machine learning; and ready-to-use radius & mass coefficients, ${\kappa }_R$ & ${\kappa }_M$, which, when appropriately multiplied by a solar-scaled effective temperature factor, yield physical stellar radii and masses. In total, we report 4395 radius and mass coefficients, with typical uncertainties of $3.3\%(stat.)\pm 1\%(syst.)$ for ${\kappa }_R$ and $7.7\%(stat.)\pm 2\%(syst.)$ for ${\kappa }_M$ among RGB stars, and $5.0\%(stat.)\pm 1\%(syst.)$ for ${\kappa }_R$ and $10.5\%(stat.)\pm 2\%(syst.)$ for ${\kappa }_M$ among RC stars. We verify that the sample is nearly complete -- except for a dearth of stars with ${\nu }_{\max }\lesssim 10-20\mu$Hz -- by comparing to Galactic models and visual inspection. Our asteroseismic radii agree with radii derived from Gaia Data Release 2 parallaxes to within $2.2\pm 0.3\%$ for RGB stars and $2.0\pm 0.6\%$ for RC stars.

Published in ApJS

References in corpus (18)

• The NumPy array: a structure for efficient numerical computation
• The K2 Mission: Characterization and Early results
• A Technique for Extracting Highly Precise Photometry for the Two-Wheeled Kepler Mission
• A new implementation of the infrared flux method using the 2MASS catalogue
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• Asteroseismology and Gaia: Testing Scaling Relations Using 2200 Kepler Stars with TGAS Parallaxes
• Distances and parallax bias in Gaia DR2
• The TESS-HERMES survey Data Release 1: high-resolution spectroscopy of the TESS southern continuous viewing zone
• Dissecting simulated disc galaxies II: the age-velocity relation
• The K2 Galactic Archaeology Program Data Release 1: Asteroseismic results from Campaign 1
• Testing the radius scaling relation with $Gaia$ DR2 in the $Kepler$ field
• Deep Learning Classification in Asteroseismology
• Challenges for asteroseismic analysis of Sun-like stars
• Testing asteroseismology with Gaia DR2: Hierarchical models of the Red Clump
• Seismic performance
• Evidence for spatially-correlated $Gaia$ parallax errors in the $Kepler$ field
• Comparison of the Asteroseismic Mass Scale of Red Clump Giants with Photometric Mass Estimates
• Clumpiness: Time-domain classification of red-giant evolutionary states

Cited by in corpus (1)

• An Intermediate-age Alpha-rich Galactic Population in K2