Surface rotation and photometric activity for Kepler targets. II. G and F main-sequence stars, and cool subgiant stars. (arXiv:2107.02217v2 [astro-ph.SR] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Santos_A/0/1/0/all/0/1">A. R. G. Santos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Breton_S/0/1/0/all/0/1">S. N. Breton</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mathur_S/0/1/0/all/0/1">S. Mathur</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garcia_R/0/1/0/all/0/1">R. A. García</a>
Dark magnetic spots crossing the stellar disc lead to quasi-periodic
brightness variations, which allow us to constrain stellar surface rotation and
photometric activity. The current work is the second of this series (Santos et
al. 2019; Paper I), where we analyze the Kepler long-cadence data of 132,921
main-sequence F and G stars and late subgiant stars. Rotation-period candidates
are obtained by combining wavelet analysis with autocorrelation function.
Reliable rotation periods are then selected via a machine learning (ML)
algorithm (Breton et al. 2021), automatic selection, and complementary visual
inspection. The ML training data set comprises 26,521 main-sequence K and M
stars from Paper I. To supplement the training, we analyze in the same way as
Paper I, i.e. automatic selection and visual inspection, 34,100 additional
stars. We finally provide rotation periods Prot and associated photometric
activity proxy Sph for 39,592 targets. Hotter stars are generally faster
rotators than cooler stars. For main-sequence G stars, Sph spans a wider range
of values with increasing effective temperature, while F stars tend to have
smaller Sph values in comparison with cooler stars. Overall for G stars, fast
rotators are photometrically more active than slow rotators, with Sph
saturating at short periods. The combined outcome of the two papers accounts
for average Prot and Sph values for 55,232 main-sequence and subgiant FGKM
stars (out of 159,442 targets), with 24,182 new Prot detections in comparison
with McQuillan et al. (2014). The upper edge of the Prot distribution is
located at longer Prot than found previously.
Dark magnetic spots crossing the stellar disc lead to quasi-periodic
brightness variations, which allow us to constrain stellar surface rotation and
photometric activity. The current work is the second of this series (Santos et
al. 2019; Paper I), where we analyze the Kepler long-cadence data of 132,921
main-sequence F and G stars and late subgiant stars. Rotation-period candidates
are obtained by combining wavelet analysis with autocorrelation function.
Reliable rotation periods are then selected via a machine learning (ML)
algorithm (Breton et al. 2021), automatic selection, and complementary visual
inspection. The ML training data set comprises 26,521 main-sequence K and M
stars from Paper I. To supplement the training, we analyze in the same way as
Paper I, i.e. automatic selection and visual inspection, 34,100 additional
stars. We finally provide rotation periods Prot and associated photometric
activity proxy Sph for 39,592 targets. Hotter stars are generally faster
rotators than cooler stars. For main-sequence G stars, Sph spans a wider range
of values with increasing effective temperature, while F stars tend to have
smaller Sph values in comparison with cooler stars. Overall for G stars, fast
rotators are photometrically more active than slow rotators, with Sph
saturating at short periods. The combined outcome of the two papers accounts
for average Prot and Sph values for 55,232 main-sequence and subgiant FGKM
stars (out of 159,442 targets), with 24,182 new Prot detections in comparison
with McQuillan et al. (2014). The upper edge of the Prot distribution is
located at longer Prot than found previously.
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