EvryFlare. II. Parameters of 122 cool flare stars Virtual Observatory Resource

Authors
  1. Howard W.S.
  2. Corbett H.
  3. Law N.M.
  4. Ratzloff J.K.
  5. Galliher N.
  6. Glazier A.,Fors O.
  7. del Ser D.
  8. Haislip J.
  9. Published by
    CDS
Abstract

We measure rotation periods and sinusoidal amplitudes in Evryscope light curves for 122 two-minute K5-M4 TESS targets selected for strong flaring. The Evryscope array of telescopes has observed all bright nearby stars in the south, producing 2-minute cadence light curves since 2016. Long-term, high-cadence observations of rotating flare stars probe the complex relationship between stellar rotation, starspots, and superflares. We detect periods from 0.3487 to 104days and observe amplitudes from 0.008 to 0.216 g'mag. We find that the Evryscope amplitudes are larger than those in TESS with the effect correlated to stellar mass (p-value=0.01). We compute the Rossby number (Ro) and find that our sample selected for flaring has twice as many intermediate rotators (0.04<Ro<0.4) as fast (Ro<0.04) or slow (Ro>0.44) rotators; this may be astrophysical or a result of period detection sensitivity. We discover 30 fast, 59 intermediate, and 33 slow rotators. We measure a median starspot coverage of 13% of the stellar hemisphere and constrain the minimum magnetic field strength consistent with our flare energies and spot coverage to be 500G, with later-type stars exhibiting lower values than earlier-type stars. We observe a possible change in superflare rates at intermediate periods. However, we do not conclusively confirm the increased activity of intermediate rotators seen in previous studies. We split all rotators at Ro~0.2 into bins of PRot<10days and PRot>10 days to confirm that short-period rotators exhibit higher superflare rates, larger flare energies, and higher starspot coverage than do long-period rotators, at p-values of 3.2x10^-5^, 1.0x10^-5^, and 0.01, respectively.

Keywords
  1. stellar-flares
  2. stellar-masses
  3. stellar-radii
  4. stellar-spectral-types
  5. effective-temperature
  6. visible-astronomy
Bibliographic source Bibcode
2020ApJ...895..140H
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/895/140
IVOA Identifier IVOID
ivo://CDS.VizieR/J/ApJ/895/140
Document Object Identifer DOI
doi:10.26093/cds/vizier.18950140

Access

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http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/895/140
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/895/140
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/895/140
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https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/895/140/table1?
http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/895/140/table1?

History

2021-10-08T06:50:28Z
Resource record created
2021-10-08T06:50:28Z
Created
2022-03-15T07:38:49Z
Updated

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr