The Proxima Centauri Campaign—First Constraints on Millimeter Flare Rates from ALMA

Burton, Kiana, MacGregor, Meredith A., Osten, Rachel A., Howard, Ward S., Weinberger, Alycia J., Shkolnik, Evgenya, Wilner, David J., Forbrich, Jan and Barclay, Thomas (2025) The Proxima Centauri Campaign—First Constraints on Millimeter Flare Rates from ALMA. The Astrophysical Journal, 982 (1): 43. pp. 1-9. ISSN 0004-637X
Copy

Proxima Centauri (Cen) has been the subject of many flaring studies due to its proximity and potential to host habitable planets. The discovery of millimeter flares from this M dwarf with Atacama Large Millimeter/submillimeter Array (ALMA) has opened a new window into the flaring process and the space-weather environments of exoplanets like Proxima b. Using a total of ~50 hr of ALMA observations of Proxima Cen at 1.3 mm (233 GHz), we add a new piece to the stellar flaring picture and report the first cumulative flare frequency distribution (FFD) at millimeter wavelengths of any M dwarf. We detect 463 flares ranging from energies 1024 to 1027 erg. The brightest and most energetic flare in our sample reached a flux density of 119 ± 7 mJy, increasing by a factor of 1000× the quiescent flux, and reaching an energy of 1027 erg in the ALMA bandpass, with t1/2 ≈ 16 s. From a log–log linear regression fit to the FFD, we obtain a power-law index of αFFD = 2.92 ± 0.02, much steeper than αFFD values (~2) observed at X-ray to optical wavelengths. If millimeter flare rates are predictive of flare rates at extreme-UV wavelengths, the contribution of small flares to the radiation environment of Proxima b may be much higher than expected based on the shallower power-law slopes observed at optical wavelengths.


picture_as_pdf
pdf.pdf
subject
Published Version
Available under Creative Commons: BY 4.0

View Download

Atom BibTeX OpenURL ContextObject in Span OpenURL ContextObject Dublin Core MPEG-21 DIDL Data Cite XML EndNote HTML Citation METS MODS RIOXX2 XML Reference Manager Refer ASCII Citation
Export

Downloads