HAZMAT. IV. Flares and Superflares on Young M Stars in the Far Ultraviolet

R. O. Parke Loyd, Evgenya L. Shkolnik, Adam C. Schneider, Travis S Barman, Victoria S. Meadows, Isabella Pagano, Sarah Peacock

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

M stars are powerful emitters of far-ultraviolet light. Over long timescales, a significant, possibly dominant, fraction of this emission is produced by stellar flares. Characterizing this emission is critical to understanding the atmospheres of the stars producing it and the atmospheric evolution of the orbiting planets subjected to it. Ultraviolet emission is known to be elevated for several hundred million years after M stars form. Whether or not the same is true of ultraviolet flare activity is a key concern for the evolution of exoplanet atmospheres. Hubble Space Telescope (HST) observations by the HAZMAT program (HAbitable Zones and M dwarf Activity across Time) detected 18 flares on young (40 Myr) early M stars in the Tucana-Horologium association over 10 hr of observations, 10 having energy >1030 erg. These imply that flares on young M stars are 100-1000× more energetic than those occurring at the same rate on "inactive," field age M dwarfs. However, when energies are normalized by quiescent emission, there is no statistical difference between the young and field age samples. The most energetic flare observed, dubbed the "Hazflare," emitted an energy of 1032.1 erg in the FUV, 30× more energetic than any stellar flare previously observed in the FUV with HST's COS or STIS spectrographs. It was accompanied by 15,500 ± 400 K blackbody emission bright enough to designate it as a superflare (E > 1033 erg), with an estimated bolometric energy of erg. This blackbody emitted % of its flux in the FUV (912-1700), where molecules are generally most sensitive to photolysis. Such hot superflares in young, early M stars could play an important role in the evolution of nascent planetary atmospheres.

Original languageEnglish (US)
Article number70
JournalAstrophysical Journal
Volume867
Issue number1
DOIs
StatePublished - Nov 1 2018

Fingerprint

M stars
flares
erg
stellar flares
early stars
energetics
energy
atmospheres
planetary atmosphere
planetary atmospheres
atmosphere
ultraviolet emission
extrasolar planets
photolysis
Hubble Space Telescope
ultraviolet radiation
spectrographs
planets
emitters
planet

Keywords

  • planets and satellites: atmospheres
  • stars: activity
  • stars: evolution
  • stars: flare
  • stars: late-type

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Parke Loyd, R. O., Shkolnik, E. L., Schneider, A. C., Barman, T. S., Meadows, V. S., Pagano, I., & Peacock, S. (2018). HAZMAT. IV. Flares and Superflares on Young M Stars in the Far Ultraviolet. Astrophysical Journal, 867(1), [70]. https://doi.org/10.3847/1538-4357/aae2ae

HAZMAT. IV. Flares and Superflares on Young M Stars in the Far Ultraviolet. / Parke Loyd, R. O.; Shkolnik, Evgenya L.; Schneider, Adam C.; Barman, Travis S; Meadows, Victoria S.; Pagano, Isabella; Peacock, Sarah.

In: Astrophysical Journal, Vol. 867, No. 1, 70, 01.11.2018.

Research output: Contribution to journalArticle

Parke Loyd, RO, Shkolnik, EL, Schneider, AC, Barman, TS, Meadows, VS, Pagano, I & Peacock, S 2018, 'HAZMAT. IV. Flares and Superflares on Young M Stars in the Far Ultraviolet', Astrophysical Journal, vol. 867, no. 1, 70. https://doi.org/10.3847/1538-4357/aae2ae
Parke Loyd, R. O. ; Shkolnik, Evgenya L. ; Schneider, Adam C. ; Barman, Travis S ; Meadows, Victoria S. ; Pagano, Isabella ; Peacock, Sarah. / HAZMAT. IV. Flares and Superflares on Young M Stars in the Far Ultraviolet. In: Astrophysical Journal. 2018 ; Vol. 867, No. 1.
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