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Title: FLARES ON A-TYPE STARS: EVIDENCE FOR HEATING OF SOLAR CORONA BY NANOFLARES?

Abstract

We analyzed the occurrence rates of flares on stars of spectral types K, G, F, and A, observed by Kepler . We found that the histogram of occurrence frequencies of stellar flares is systematically shifted toward a high-energy tail for A-type stars compared to stars of cooler spectral types. We extrapolated the fitted power laws toward flares with smaller energies (nanoflares) and made estimates for total energy flux to stellar atmospheres by flares. We found that, for A-type stars, the total energy flux density was at least four-times smaller than for G stars. We speculate that this deficit in energy supply may explain the lack of hot coronae on A-type stars. Our results indicate the importance of nanoflares for heating and formation of the solar corona.

Authors:
 [1];  [2]
  1. Astronomical Institute, Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-18000 Prague 8 (Czech Republic)
  2. Astronomical Institute (v. v. i.), Czech Academy of Sciences, Fričova 298, CZ-25165 Ondřejov (Czech Republic)
Publication Date:
OSTI Identifier:
22667283
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 831; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; FLUX DENSITY; HEAT EXCHANGERS; HEATING; SOLAR CORONA; STARS; STELLAR FLARES

Citation Formats

Švanda, Michal, and Karlický, Marian. FLARES ON A-TYPE STARS: EVIDENCE FOR HEATING OF SOLAR CORONA BY NANOFLARES?. United States: N. p., 2016. Web. doi:10.3847/0004-637X/831/1/9.
Švanda, Michal, & Karlický, Marian. FLARES ON A-TYPE STARS: EVIDENCE FOR HEATING OF SOLAR CORONA BY NANOFLARES?. United States. https://doi.org/10.3847/0004-637X/831/1/9
Švanda, Michal, and Karlický, Marian. 2016. "FLARES ON A-TYPE STARS: EVIDENCE FOR HEATING OF SOLAR CORONA BY NANOFLARES?". United States. https://doi.org/10.3847/0004-637X/831/1/9.
@article{osti_22667283,
title = {FLARES ON A-TYPE STARS: EVIDENCE FOR HEATING OF SOLAR CORONA BY NANOFLARES?},
author = {Švanda, Michal and Karlický, Marian},
abstractNote = {We analyzed the occurrence rates of flares on stars of spectral types K, G, F, and A, observed by Kepler . We found that the histogram of occurrence frequencies of stellar flares is systematically shifted toward a high-energy tail for A-type stars compared to stars of cooler spectral types. We extrapolated the fitted power laws toward flares with smaller energies (nanoflares) and made estimates for total energy flux to stellar atmospheres by flares. We found that, for A-type stars, the total energy flux density was at least four-times smaller than for G stars. We speculate that this deficit in energy supply may explain the lack of hot coronae on A-type stars. Our results indicate the importance of nanoflares for heating and formation of the solar corona.},
doi = {10.3847/0004-637X/831/1/9},
url = {https://www.osti.gov/biblio/22667283}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 831,
place = {United States},
year = {Tue Nov 01 00:00:00 EDT 2016},
month = {Tue Nov 01 00:00:00 EDT 2016}
}