Detections of solar-like oscillations in dwarfs and subgiants with Kepler DR25 short-cadence data

TL;DR

This study re-analyzed Kepler DR25 short-cadence data to detect solar-like oscillations in 99 stars, expanding the known sample, and compared seismic and Gaia radii, revealing systematic differences and insights into stellar properties.

Contribution

The paper reports the detection of 46 new solar-like oscillators in Kepler DR25 data, increasing the known sample and providing updated seismic parameters and radius comparisons.

Findings

Detected 46 new solar-like oscillators, increasing the sample by 8%.

Found Gaia radii overestimate seismic radii by 4.4% on average.

Confirmed seismic scaling relations for granulation and mode amplitudes.

Abstract

During the survey phase of the Kepler mission, several thousands of stars were observed in short cadence, allowing the detection of solar-like oscillations in more than 500 main-sequence and sub-giant stars. Later, the Kepler Science Office discovered an issue in the calibration that affected half of the short-cadence data, leading to a new data release (DR25) with improved corrections. We re-analyze the one-month time series of the Kepler survey phase to search for new solar-like oscillations. We study the seismic parameters of 99 stars (46 targets with new reported solar-like oscillations) increasing by around 8% the known sample of solar-like stars with asteroseismic analysis of the short-cadence data from Kepler. We compute the masses and radii using seismic scaling relations and find that this new sample populates the massive stars (above 1.2Ms and up to 2Ms) and subgiant phase. We determine the granulation parameters and amplitude of the modes, which agree with previously derived scaling relations. The stars studied here are slightly fainter than the previously known sample of main-sequence and subgiants with asteroseismic detections. We also study the surface rotation and magnetic activity levels of those stars. Our sample of has similar levels of activity compared to the previously known sample and in the same range as the Sun between the minimum and maximum of its activity cycle. We find that for 7 stars, a possible blend could be the reason for the previous non detection. We compare the radii obtained from the scaling relations with the Gaia ones and find that the Gaia radii are overestimated by 4.4% on average compared to the seismic radii and a decreasing trend with evolutionary stage. We re-analyze the DR25 of the main-sequence and sub-giant stars with solar-like oscillations previously detected and provide their global seismic parameters for a total of 526 stars.