The First Naked-eye Superflare Detected from Proxima Centauri

Ward S. Howard, Matt A. Tilley, Hank Corbett, Allison Youngblood, R. O.Parke Loyd, Jeffrey K. Ratzloff, Nicholas M. Law, Octavi Fors, Daniel Del Ser, Evgenya Shkolnik, Carl Ziegler, Erin E. Goeke, Aaron D. Pietraallo, Joshua Haislip

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Proxima b is a terrestrial-mass planet in the habitable zone of Proxima Centauri. Proxima Centauri's high stellar activity, however, casts doubt on the habitability of Proxima b: sufficiently bright and frequent flares and any associated proton events may destroy the planet's ozone layer, allowing lethal levels of UV flux to reach its surface. In 2016 March, the Evryscope observed the first naked-eye-brightness superflare detected from Proxima Centauri. Proxima increased in optical flux by a factor of ∼68 during the superflare and released a bolometric energy of 1033.5 erg, ∼10× larger than any previously detected flare from Proxima. Over the last two years the Evryscope has recorded 23 other large Proxima flares ranging in bolometric energy from 1030.6 to 1032.4 erg; coupling those rates with the single superflare detection, we predict that at least five superflares occur each year. Simultaneous high-resolution High Accuracy Radial velocity Planet Searcher (HARPS) spectroscopy during the Evryscope superflare constrains the superflare's UV spectrum and any associated coronal mass ejections. We use these results and the Evryscope flare rates to model the photochemical effects of NOx atmospheric species generated by particle events from this extreme stellar activity, and show that the repeated flaring may be sufficient to reduce the ozone of an Earth-like atmosphere by 90% within five years; complete depletion may occur within several hundred kyr. The UV light produced by the Evryscope superflare would therefore have reached the surface with ∼100× the intensity required to kill simple UV-hardy microorganisms, suggesting that life would have to undergo extreme adaptations to survive in the surface areas of Proxima b exposed to these flares.

Original languageEnglish (US)
Article numberL30
JournalAstrophysical Journal Letters
Volume860
Issue number2
DOIs
StatePublished - Jun 20 2018

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flares
planet
erg
stellar activity
planets
coronal mass ejection
energy
habitability
ozonosphere
surface area
microorganism
spectroscopy
ozone
Earth atmosphere
microorganisms
atmosphere
radial velocity
casts
brightness
depletion

Keywords

  • planets and satellites: terrestrial planets
  • stars: flare
  • surveys
  • ultraviolet: planetary systems
  • ultraviolet: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Howard, W. S., Tilley, M. A., Corbett, H., Youngblood, A., Loyd, R. O. P., Ratzloff, J. K., ... Haislip, J. (2018). The First Naked-eye Superflare Detected from Proxima Centauri. Astrophysical Journal Letters, 860(2), [L30]. https://doi.org/10.3847/2041-8213/aacaf3

The First Naked-eye Superflare Detected from Proxima Centauri. / Howard, Ward S.; Tilley, Matt A.; Corbett, Hank; Youngblood, Allison; Loyd, R. O.Parke; Ratzloff, Jeffrey K.; Law, Nicholas M.; Fors, Octavi; Del Ser, Daniel; Shkolnik, Evgenya; Ziegler, Carl; Goeke, Erin E.; Pietraallo, Aaron D.; Haislip, Joshua.

In: Astrophysical Journal Letters, Vol. 860, No. 2, L30, 20.06.2018.

Research output: Contribution to journalArticle

Howard, WS, Tilley, MA, Corbett, H, Youngblood, A, Loyd, ROP, Ratzloff, JK, Law, NM, Fors, O, Del Ser, D, Shkolnik, E, Ziegler, C, Goeke, EE, Pietraallo, AD & Haislip, J 2018, 'The First Naked-eye Superflare Detected from Proxima Centauri', Astrophysical Journal Letters, vol. 860, no. 2, L30. https://doi.org/10.3847/2041-8213/aacaf3
Howard WS, Tilley MA, Corbett H, Youngblood A, Loyd ROP, Ratzloff JK et al. The First Naked-eye Superflare Detected from Proxima Centauri. Astrophysical Journal Letters. 2018 Jun 20;860(2). L30. https://doi.org/10.3847/2041-8213/aacaf3
Howard, Ward S. ; Tilley, Matt A. ; Corbett, Hank ; Youngblood, Allison ; Loyd, R. O.Parke ; Ratzloff, Jeffrey K. ; Law, Nicholas M. ; Fors, Octavi ; Del Ser, Daniel ; Shkolnik, Evgenya ; Ziegler, Carl ; Goeke, Erin E. ; Pietraallo, Aaron D. ; Haislip, Joshua. / The First Naked-eye Superflare Detected from Proxima Centauri. In: Astrophysical Journal Letters. 2018 ; Vol. 860, No. 2.
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