J/ApJS/271/57 Flares in hot subdwarf & WDs from TESS photometry (Xing+, 2024)
Flare hunting in hot subdwarf and white dwarf stars from cycles 1-5 of TESS
photometry.
Xing K., Zong W., Silvotti R., Fu J.-N., Charpinet S., Cang T.,
Hermes J.J., Ma X.-Y., Wang H., Wang X., Wu T., Wang J.
<Astrophys. J. Suppl. Ser., 271, 57 (2024)>
=2024ApJS..271...57X 2024ApJS..271...57X
ADC_Keywords: Stars, flare; Stars, white dwarf; Stars, subdwarf; Photometry;
Optical
Keywords: White dwarf stars ; B subdwarf stars ; Stellar flares ;
Photometry ; Random Forests
Abstract:
Stellar flares are critical phenomena on stellar surfaces, which are
closely tied to stellar magnetism. While extensively studied in
main-sequence (MS) stars, their occurrence in evolved compact stars,
specifically hot subdwarfs and white dwarfs (WDs), remains scarcely
explored. Based on Cycles 1-5 of TESS photometry, we conducted a
pioneering survey of flare events in ∼12000 compact stars,
corresponding to ∼38000 light curves with a 2 minute cadence. Through
dedicated techniques for detrending light curves, identifying
preliminary flare candidates, and validating them via machine
learning, we established a catalog of 1016 flares from 193 compact
stars, including 182 from 58 sdB/sdO stars and 834 from 135 WDs,
respectively. However, all flaring compact stars showed signs of
contamination from nearby objects or companion stars, preventing sole
attribution of the detected flares. For WDs, it is highly probable
that the flares originated from their cool MS companions. In contrast,
the higher luminosities of sdB/sdO stars diminish companion
contributions, suggesting that detected flares originated from sdB/sdO
stars themselves or through close magnetic interactions with
companions. Focusing on a refined sample of 23 flares from 13 sdB/sdO
stars, we found their flare frequency distributions were slightly
divergent from those of cool MS stars; instead, they resemble those of
hot B/A-type MS stars having radiative envelopes. This similarity
implies that the flares on sdB/sdO stars, if these flares did
originate from them, may share underlying mechanisms with hot MS
stars, which warrants further investigation.
Description:
Based on Cycles 1-5 (2018 Jul to 2023 Aug) of Transiting Exoplanet
Survey Satellite (TESS) photometry, we comprehensively investigated
the flaring activity observed in sdB/sdO stars and white dwarfs (WDs)
and identified 1016 flare events from 193 compact stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 89 1016 Catalog of all 1016 flares observed across
38102 light curves of 11618 compact stars at
120 second cadence during TESS cycles 1-5
table4.dat 82 193 Catalog of all 193 flaring compact stars
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
IV/34 : K2 Ecliptic Plane Input Catalog (EPIC) (Huber+, 2017)
IV/38 : TESS Input Catalog - v8.0 (TIC-8) (Stassun+, 2019)
IV/39 : TESS Input Catalog version 8.2 (TIC v8.2) (Paegert+, 2021)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/AJ/141/50 : White-light flares on cool stars from Kepler (Walkowicz+, 2011)
J/ApJS/207/15 : M dwarf flare spectra (Kowalski+, 2013)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/ApJ/809/77 : Transiting Exoplanet Survey Satellite (TESS) (Sullivan+, 2015)
J/ApJS/216/12 : OGLE-III Gal. bulge microlensing events (Wyrzykowski+, 2015)
J/ApJ/829/23 : Stellar flares from Q0-Q17 Kepler LCs (Davenport, 2016)
J/MNRAS/458/3012 : OGLE-III Parallax microlensing events (Wyrzykowski+, 2016)
J/ApJS/232/26 : Catalog of Kepler flare stars (Van Doorsselaere+, 2017)
J/MNRAS/490/2112 : Rotational frequencies in A and B stars (Balona, 2019)
J/ApJS/241/29 : Flare catalog through LC data of Kepler DR25 (Yang+, 2019)
J/AJ/159/60 : Flares from 1228 stars in TESS sectors 1 & 2 (Gunther+, 2020)
J/A+A/645/A42 : Flares in 5 open clusters (Ilin+, 2021)
J/A+A/662/A40 : Hot subdwarf stars studied with Gaia (Culpan+, 2022)
J/ApJ/926/204 : TESS monitoring of low-mass flare stars (Howard+, 2022)
J/AJ/164/17 : GJ 1243 flares properties with Kepler and TESS (Mendoza+, 2022)
J/A+A/669/A48 : Short-period pulsating hot-subdwarf stars (Baran+, 2023)
J/A+A/669/A15 : TESS flare events and physical parameters (Yang+, 2023)
http://heasarc.gsfc.nasa.gov/docs/tess/ : TESS Science Support Center homepage
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 I10 -- TIC Identifier, TESS input catalog
12- 13 I2 -- sector [1/69] TESS Sector
15- 23 F9.4 d tstart [1325.37/3205.44] Flare start time, TESS
Barycentric Julian Date
25- 33 F9.4 d tpeak [1325.37/3205.44] Flare peak time, TESS
Barycentric Julian Date
35- 43 F9.4 d tstop [1325.39/3205.45] Flare stop time, TESS
Barycentric Julian Date
45- 50 F6.2 -- SNR [3/382] Photometric S/N of the peak
52- 57 F6.3 -- Amp [0.002/43] Peak flare amplitude in fractional
flux units
59- 65 F7.1 s ED [0.8/33762] Equivalent duration
67- 71 F5.1 s e_ED [0.1/308] Uncertainty in ED
73- 80 E8.2 10-7J ETESS [1.8e+30/1.3e+36]? Flare energy,
in the TESS bandpass
82- 89 E8.2 10-7J e_ETESS [3.6e+29/5e+35]? Uncertainty in ETESS
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 I10 -- TIC Identifier, TESS input catalog
12- 24 A13 -- SpT Spectral type given by the TASC WG8
target list (1)
26- 46 A21 -- OType Object type queried from the SIMBAD database
48- 55 E8.2 10-7W LTESS [6e+28/1.2e+34]? Luminosity in the
TESS bandpass; erg/s
57- 64 E8.2 10-7W e_LTESS [3.9e+26/2e+33]? Uncertainty in LTESS
66- 67 I2 -- Nfl [1/96] Number of flares
69- 74 F6.3 -- Freq [0.03/17] Frequency of flares per TESS Sector
76- 80 F5.2 -- logfLum [-7.4/-1.8] Log, fractional flare luminosity,
in the TESS bandpass
82 I1 -- PL [0/2]? Pollution level (2)
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Note (1): The TESS Asteroseismic Science Consortium (TASC) Working Group 8
(WG8) focuses on variability in evolved compact stars (see, e.g.,
Charpinet+ 2019A&A...632A..90C 2019A&A...632A..90C & Bognar+ 2020A&A...638A..82B 2020A&A...638A..82B).
http://tasoc.dk/ = TASC homepage
Note (2): Pollution level code as follows:
0 = the target is the only object within the aperture,
without any significant polluting photometry from nearby stars.
1 = the target is the brightest object within the aperture,
but there are other dim stars present.
2 = the target is not the brightest object within the aperture
or near a much brighter star.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 20-Jun-2024