English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

As part of the NASA Kepler Guest Observer program, we requested and obtainedlong-cadence data on about 2700 faint (magnitude 14-16) Kepler stars witheffective temperatures and surface gravities that lie near or within thepulsation instability region for main-sequence gamma Doradus and delta Scutipulsating variables. These variables are of spectral type A-F with masses of1.4 to 2.5 solar masses. The delta Scuti stars pulsate in radial and non-radialacoustic modes, with periods of a few hours (frequencies around 10 cycles/day),while gamma Doradus variables pulsate in nonradial gravity modes with periods0.3 to 3 days (frequencies around 1 cycle/day). Here we consider the lightcurves and Fourier transforms of 633 stars in an unbiased sample observed byKepler in Quarters 6-13 (June 2010-June 2012). We show the location of thesestars in the log surface gravity--effective temperature diagram compared to theinstability region limits established from ground-based observations, andtaking into account uncertainties and biases in the Kepler Input Catalog T_effvalues. While hundreds of variables have been discovered in the Kepler data,about 60% of the stars in our sample do not show any frequencies between 0.2and 24.4 cycles per day with amplitude above 20 parts per million. We find thatsix of these apparently constant stars lie within the pulsation instabilityregion. We discuss some possible reasons that these stars do not showphotometric variability in the Kepler data. We also comment on the non-constantstars, and on 26 variable-star candidates, many of which also do not lie withinthe expected instability regions.

The Occurrence of Non-Pulsating Stars in the gamma Doradus/delta Scuti Pulsation Instability Region