J/ApJ/955/24 A census of NUV M-dwarf flares from GALEX & XMM-OM (Rekhi+, 2023)
A census of near-UV M-dwarf flares using archival GALEX data and the gPHOTON2
pipeline.
Rekhi P., Ben-Ami S., Perdelwitz V., Shvartzvald Y.
<Astrophys. J., 955, 24 (2023)>
=2023ApJ...955...24R 2023ApJ...955...24R
ADC_Keywords: Stars, M-type; Stars, dwarfs; Stars, flare;
Photometry, ultraviolet; Stars, distances; Optical
Keywords: Red dwarf flare stars ; Stellar flares ; M dwarf stars ;
Ultraviolet astronomy ; Near ultraviolet astronomy ;
Habitable planets ; Pre-biotic astrochemistry
Abstract:
M-dwarfs are common stellar hosts of habitable-zone exoplanets.
Near-UV (NUV) radiation can severely impact the atmospheric and
surface conditions of such planets, making the characterization of NUV
flaring activity a key aspect in determining habitability. We use
archival data from the Galaxy Evolution Explorer (GALEX) and
XMM-Newton telescopes to study the flaring activity of M-dwarfs in the
NUV. The GALEX observations form the most extensive data set of
M-dwarfs in the NUV to date, with the exploitation of this data
possible due to the new gphoton2 pipeline. We run a dedicated
algorithm to detect flares in the pipeline-produced lightcurves and
find some of the most energetic flares observed to date within the NUV
bandpass, with energies of ∼1034erg. Using GALEX data, we constrain
flare frequency distributions for stars from M0-M6 in the NUV up to
105s in equivalent duration and 1034erg in energy, orders of
magnitude above any previous study in the UV. We estimate the combined
effect of NUV luminosities and flare rates of stars later than M2 to
be sufficient for abiogenesis on habitable-zone exoplanets orbiting
them. As a counterpoint, we speculate the high frequencies of
energetic UV flares and associated coronal mass ejections would
inhibit the formation of an ozone layer, possibly preventing the
genesis of complex Earth-like life-forms due to sterilizing levels of
surface UV radiation. We also provide a framework for future
observations of M-dwarfs with ULTRASAT, a wide field-of-view NUV
telescope to be launched in 2026.
Description:
Our analysis is conducted on archival data sets from GALEX in MAST and
the XMM-OM. The GALEX lightcurves are generated using the gphoton2
pipeline (St. Clair+ 2022, zenodo.org/records/7472061), while the
XMM-OM data are available in the form of pre-generated lightcurves
downloadable from the XMM-NewtonScience Archive (XSA).
We use the TESS Input Catalog v8.2 (TIC) (IV/39) to generate a list of
M-dwarfs comprising of objects with TIC effective Temperature (Teff)
below 3900K and luminosity class (LClass) "dwarf", within 200pc.
This results in a list of 1.22 million stars from which we identify
targets in GALEX and XMM-Newton data by a crossmatch after propagating
the Gaia DR2 positions (epoch J2015.5) (see I/345) of the TIC M-dwarfs
to the epochs of the observations.
GALEX is a NASA space-borne telescope that surveyed the sky in the
ultraviolet over 10yr between 2003 and 2013. GALEX carried two
microchannel plate detectors with 1.25° FoVs, observing in broad
ultraviolet bands centered at 1539Å (FUV: 1344-1786Å) and
2316Å (NUV: 1771-2831Å). During regular operation, the detectors
recorded individual photons with a time resolution of 5ms and an
angular resolution of 4'-6'.
XMM-OM offers three filters in the ultraviolet: UVW1, UVW2, and UVM2.
Observations with the UVW2 and UVM2 filters formed a small part of our
data set, and had predominantly low signal-to-noise ratios (S/Ns<3).
We thus restrict our analysis to the observations taken with the UVW1
filter centered at 2931Å with effective bandpass 2530-3330Å.
See Section 2 for further explanations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 86 4176 All stars in the GALEX sample
tabled2.dat 68 528 Most energetic flares from the list of all flares
detected in the GALEX sample
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See also:
B/xmm : XMM-Newton Observation Log (XMM-Newton Science Operation Center, 2012-)
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/A+A/327/1039 : Structure and evolution of low-mass stars (Chabrier+ 1997)
J/ApJS/173/673 : M dwarf UV flares in GALEX (Welsh+, 2007)
J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/AJ/148/64 : HAZMAT. I. FUV & NUV in early M stars (Shkolnik+, 2014)
J/AJ/154/67 : HAZMAT. II. Low-mass stars with GALEX UV obs. (Miles+, 2017)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Coll., 2018)
J/AJ/155/122 : HAZMAT. III. Low-mass stars GALEX phot. (Schneider+, 2018)
J/ApJ/883/88 : Stellar flares from GALEX & Kepler (Brasseur+, 2019)
J/ApJS/241/29 : Flare catalog through LC data of Kepler DR25 (Yang+, 2019)
J/A+A/642/A115 : CARMENES input catalogue of M dwarfs. V. (Cifuentes+, 2020)
J/AJ/159/60 : Flares from 1228 stars in TESS sectors 1 & 2 (Gunther+, 2020)
J/MNRAS/513/2615 : Study of UCD's flares from SSO survey (Murray+, 2022)
J/A+A/665/A30 : Flares and rotation of M dwarfs (Stelzer+, 2022)
http://nxsa.esac.esa.int/ : XMM-Newton Science Archive homepage
http://archive.stsci.edu/missions-and-data/galex : MAST GALEX homepage
Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- TIC [818309/2028158462] TESS Input Catalog
identifier
12- 20 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
22- 30 F9.5 deg DEdeg [-86/86] Declination in decimal degrees (J2000)
32- 33 I2 --- Nfl [0/34] Number of visually verified flares
35- 40 I6 s Exp [900/246060] Total exposure time
42- 47 F6.3 ct/s CRnuv [0.03/88] NUV band count rate
49- 53 F5.3 ct/s e_CRnuv [0.001/4.3] Uncertainty in CRnuv
55- 60 F6.3 mag NUVmag [9/22.4] Apparent NUV band magnitude
62- 66 F5.3 mag e_NUVmag [0.004/1] Uncertainty in NUVmag
68- 71 I4 K Teff [2824/3900] Effective temperature from TIC
73- 78 F6.2 pc Dist [6.46/206] Bailer-Jones+ (2021, I/352) distance
80- 86 F7.4 pc e_Dist [0.001/12] Uncertainty in Dist
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Byte-by-byte Description of file: tabled2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 I10 --- TIC [893123/468921916] TESS Input Catalog identifier
12- 21 I10 s Start [745183584/1012641756] Flare start time (1)
23- 28 I6 s ED [19/270000] Equivalent duration
30- 35 I6 s e_ED [3/113662] Uncertainty in ED
37- 44 E8.2 10-7J Energy [1.28e+29/4.6e+34] Flare energy; ergs
46- 52 E7.1 10-7J e_Energy [2.1e+28/2.6e+32] Uncertainty in Energy
54- 54 A1 --- C Flare completely observed?
56- 59 I4 s Length [30/1690] Flare length
61- 66 F6.1 --- Fp/Fq [0.4/1521] Ratio of flare peak to quiescent flux
68- 68 A1 --- f_TIC [N/Y] Flag on TIC (2)
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Note (1): Flare start times are in GALEX time = tUNIX - 315964800s.
Note (2): Did the flare reach the non-linearity regime of the detector and
thus the energy and equivalent duration are lower limits.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Dec-2025