J/ApJ/916/32 X-ray superflares from PMS stars in MYStIX & SFiNCs (Getman+, 2021)
X-ray superflares from pre-main-sequence stars: flare energetics and frequency.
Getman K.V., Feigelson E.D.
<Astrophys. J., 916, 32 (2021)>
=2021ApJ...916...32G 2021ApJ...916...32G
ADC_Keywords: X-ray sources; Surveys; Stars, pre-main sequence; Stars, flare;
Stars, masses; Stars, ages; Star Forming Region; Infrared sources
Keywords: Planetary atmospheres ; Pre-main sequence stars ; Protostars ;
Protoplanetary disks ; Stellar x-ray flares ; X-ray stars
Abstract:
Solar-type stars exhibit their highest levels of magnetic activity
during their early convective pre-main-sequence (PMS) phase of
evolution. The most powerful PMS flares, superflares and megaflares,
have peak X-ray luminosities of log(LX)=30.5-34.0erg/s and total
energies log(EX)=34-38erg. Among >24000 X-ray-selected young
(t≲5Myr) members of 40 nearby star-forming regions from our earlier
Chandra MYStIX and SFiNCs surveys, we identify and analyze a
well-defined sample of 1086 X-ray superflares and megaflares, the
largest sample ever studied. Most are considerably more powerful than
optical/X-ray superflares detected on main-sequence stars. This study
presents energy estimates of these X-ray flares and the properties of
their host stars. These events are produced by young stars of all
masses over evolutionary stages ranging from protostars to diskless
stars, with the occurrence rate positively correlated with stellar
mass. Flare properties are indistinguishable for disk- bearing and
diskless stars indicating star-disk magnetic fields are not involved.
A slope of α∼2 in the flare energy distributions
dN/dEX∝EX-α is consistent with that of
optical/X-ray flaring from older stars and the Sun. Megaflares
(log(EX)>36.2erg) from solar-mass stars have an occurrence rate of
1.7-0.6+1.0 flares/star/year and contribute at least 10%-20% to
the total PMS X-ray energetics. These explosive events may have
important astrophysical effects on protoplanetary disk
photoevaporation, ionization of disk gas, production of spallogenic
radionuclides in disk solids, and hydrodynamic escape of young
planetary atmospheres. Our following paper details plasma and magnetic
loop modeling of the >50 brightest X-ray megaflares.
Description:
Our group has conducted two in-depth analyses of the Chandra archive
of star-forming region observations during the first 10 years of the
mission. The MYStIX (Feigelson+ 2013ApJS..209...26F 2013ApJS..209...26F) survey covers
20 regions dominated by multiple O stars, most at distances
1.5≤d≤2.5kpc, while the SFiNCs (Getman+ 2017, J/ApJS/229/28) survey
covers 22 regions dominated by single O or multiple ∼B stars, most at
distances 0.3≤d≤0.8kpc.
Out of 42 MYStIX and SFiNCs target regions, we study here superflares
from 40 regions that host over 24000 young stellar objects detected by
Chandra. See Section 2.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 57 42 MYStIX and SFiNCs regions
table2.dat 101 1027 MYStIX and SFiNCs F+R+D flare host star properties
table3.dat 73 1086 MYStIX and SFiNCs F+R+D super-flares
table4.dat 78 8 Super-flares from protostellar candidates
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
II/341 : VPHAS+ DR2 survey (Drew+, 2016)
II/348 : VISTA Variable in the Via Lactea Survey DR2 (Minniti+, 2017)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VI/156 : M-dwarf Lum-Temp-Radius relationships (Morrell+, 2019)
J/ApJS/160/319 : COUP: observations and source lists (Getman+, 2005)
J/A+A/474/495 : X-ray flares from Cygnus OB2 stars (Albacete Colombo+, 2007)
J/ApJS/169/353 : Chandra sources in M17 (Broos+, 2007)
J/A+A/468/353 : XMM-Newton Extended Survey of Taurus (Guedel+, 2007)
J/A+A/492/277 : Analysis of Collinder 69 stars with VOSA (Bayo+, 2008)
J/ApJ/688/418 : X-ray flares in Orion young stars. I. (Getman+, 2008)
J/ApJ/708/1760 : Flux estimations of faint X-ray sources (Getman+, 2010)
J/ApJS/209/32 : Probable young stars in the MYStIX project (Broos+, 2013)
J/ApJS/209/27 : MYStIX: the Chandra X-ray sources (Kuhn+, 2013)
J/ApJS/209/29 : MYStIX: Mid-IR observations and catalogs (Kuhn+, 2013)
J/ApJS/208/9 : Intrinsic colors & temperatures of PMS stars (Pecaut+, 2013)
J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)
J/ApJS/209/5 : Superflares of Kepler stars. I. (Shibayama+, 2013)
J/ApJ/787/108 : Age estimates for massive SFR stellar pop. (Getman+, 2014)
J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)
J/ApJ/814/35 : Flare events in M dwarf of M37 (Chang+, 2015)
J/ApJ/812/131 : Structure of young stellar clusters. III. (Kuhn+, 2015)
J/ApJ/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)
J/A+A/593/A7 : NH and AV Towards YSOs in the ONC (Hasenberger+, 2016)
J/ApJS/229/28 : SFiNCs: X-ray, IR and membership catalogs (Getman+, 2017)
J/ApJ/869/L41 : DSHARP I. Sample, ALMA obs. log & overview (Andrews+, 2018)
J/A+A/618/A93 : Gaia DR2 open clusters in the MW (Cantat-Gaudin+, 2018)
J/A+A/620/A55 : Magnetic flaring from PMS stars spectra (Flaccomio+, 2018)
J/MNRAS/477/298 : Young star clusters in nearby MoCs (Getman+, 2018)
J/MNRAS/477/5191 : Ggalactic young stellar cluster lifetimes (Richert+, 2018)
J/A+A/609/A10 : NGC2264 structure and star formation history (Venuti+, 2018)
J/ApJ/869/72 : IN-SYNC. VIII. YSOs in NGC1333, IC348 & Orion A (Yao+, 2018)
J/AJ/158/235 : X-ray sources in IRAS 09002-4732 region (Getman+, 2019)
J/ApJ/878/111 : Members in Serpens MoC with Gaia DR2 (Herczeg+, 2019)
J/ApJ/881/9 : EvryFlare. I. Cool stars's flares (Howard+, 2019)
J/A+A/622/A133 : M45, M44 and M67 flare stars (Ilin+, 2019)
J/ApJ/870/32 : Kinematics in young star clusters & assoc. (Kuhn+, 2019)
J/A+A/637/A22 : M dwarfs rotation-activity relations & flares (Raetz+, 2020)
J/A+A/648/A121 : X-ray activity and accretion in the ONC (Flaischlen+, 2021)
J/A+A/645/A42 : Flares in 5 open clusters (Ilin+, 2021)
J/ApJ/906/72 : 2344 superflares on 266 solar-type stars (Okamoto+, 2021)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Region Star forming region shortname used
in Tables 2-4
14- 27 A14 --- SFR Star forming region
29- 33 F5.1 deg RAdeg SFR right ascension, decimal degrees (J2000)
35- 39 F5.1 deg DEdeg SFR declination, decimal degrees (J2000)
41- 44 I4 pc Dist [296/3790] Distance from the Sun
46- 49 I4 --- NXobs [39/6751] Number of observed X-ray emitting
young stars (2)
51- 55 I5 --- Ntot [39/37899] Total inferred stellar population (3)
57- 57 I1 --- r_Dist [1/7] Reference for Dist (1)
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Note (1): Distance from the Sun and sources references as follows:
1 = Gaia-based distance from Kuhn+ (2019, J/ApJ/870/32);
2 = Gaia-based distance from Fissel+ (2019ApJ...878..110F 2019ApJ...878..110F);
3 = Gaia-based distance from Getman+ (2019MNRAS.487.2977G 2019MNRAS.487.2977G);
4 = Gaia-based distance from Herczeg+ (2019, J/ApJ/878/111);
5 = Gaia-based distance from Getman+ (2019, J/AJ/158/235);
6 = Gaia-based distance from Cantat-Gaudin+ (2018, J/A+A/618/A93);
7 = The original MYStIX/SFiNCs distances from
Feigelson+ (2013ApJS..209...26F 2013ApJS..209...26F); Getman+ (2017, J/ApJS/229/28).
Note (2): Number of observed X-ray emitting young stars from
Broos+ (2013, J/ApJS/209/32).
Note (3): Total stellar population down to 0.1Msun inferred from the X-ray
luminosity function.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Region Star forming region (See Table 1)
14- 31 A18 --- Name Star name (HHMMSS.ss+DDMMSS.s; J2000)
33- 42 F10.6 deg RAdeg Right Ascension, decimal degrees (J2000)
44- 53 F10.6 deg DEdeg Declination, decimal degrees (J2000)
55- 57 F3.1 keV ME [0.9/5.8] X-ray median energy (1)
59- 62 F4.1 [10-7W] logLx [30/32.7] Log of intrinsic X-ray luminosity,
in erg/s units (1)
64- 68 F5.1 mag Av [-12/53.3]? Reddening, V-band (2)
70- 72 F3.1 Myr Age [0.4/5]? Age (2)
74- 77 F4.2 [K] logTeff [3.4/4.8]? log of surface effective
temperature (2)
79- 83 F5.2 [Lsun] logLbol [-1.4/7]? log of bolometric luminosity (2)
85- 89 F5.1 Msun Mstar [0.1/320.2]? Mass (2)
91- 94 F4.1 Rsun Rstar [0.9/31.4]? Radius (2)
96- 99 F4.1 --- alpha [-4.3/4.4]? IRAC SED slope (2)
101-101 A1 --- Flag Flag (2)
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Note (1): Source's X-ray median energy and intrinsic X-ray luminosity averaged
across all available Chandra observations using the XPHOT procedure.
Note (2): Source's visual extinction, age, effective temperature, bolometric
luminosity, mass, and radius as derived as given by the Flag column:
1 = stellar properties are obtained using the methods based on the X-ray
and NIR photometry (Appendix C);
2 = Stellar properties for five stars (180416.78-242837.2,
180452.94-242705.5, 182001.70-160529.2, 052309.48+332425.2,
085843.86-472856.8), with degeneracy in X-ray-NIR-derived Teff and
Lbol, are obtained through the VOSA SED fitting.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Region Star forming region (See Table 1)
14- 31 A18 --- Name Flare host star name
(HHMMSS.ss+DDMMSS.s; J2000) (G1)
33- 33 I1 --- ObsID [1/9] Relative sequence number of the
X-ray Chandra observation (G1) (1)
35- 39 F5.1 ks Exp [11.8/154] Chandra ObsID Exposure
41- 41 A1 --- Class Flare class (2)
43- 47 I5 ct Nphot [15/19891] Flare X-ray counts
49- 51 F3.1 keV ME [0.9/5.7] Flare median photon energy
53- 53 A1 --- l_Dur Limit flag on Dur
55- 59 F5.1 ks Dur [1.9/153.9] Flare duration
61- 61 A1 --- l_logLxpk Limit flag on logLxpk
63- 66 F4.1 [10-7W] logLxpk [30.6/33.8] log of peak X-ray luminosity,
in erg/s units
68- 68 A1 --- l_logEx Limit flag on logEx
70- 73 F4.1 [10-7J] logEx [34.1/37.6] log of flare energy, in erg units
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Note (1): The relative number of the X-ray Chandra observation, during which
the flare is detected. Complete lists of the MYStIX and SFiNCs Chandra
observations with full ObsID names are available in
Kuhn+ (2013, J/ApJS/209/27); Townsley+ (2014, J/ApJS/213/1);
Getman+ (2017, J/ApJS/229/28).
Note (2): Flare class as follows:
F = Full (648 occurrences);
R = Rise (289 occurrences);
D = Decay (149 occurrences).
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Region Star forming region (See Table 1)
9- 26 A18 --- Name X-ray host star name (G1)
27 A1 --- --- [_]
28 I1 --- ObsID [1/6] X-ray Chandra observation
as in Table 3 (G1)
30- 39 F10.6 deg RAdeg [52.2/344.1] Right Ascension (J2000)
41- 50 F10.6 deg DEdeg [-47.6/75.2] Declination (J2000)
52- 54 F3.1 --- alpha [0.3/2.1]? IRAC SED slope, α
56- 56 A1 --- Class Flare Class (1)
58- 60 I3 ct Nphot [21/296] Flare X-ray counts
62- 64 F3.1 keV ME [5/5.7] Flare median photon energy
66- 66 A1 --- l_logLxpk Limit flag on logLxpk
68- 71 F4.1 [10-7W] logLxpk [31.3/33.8] log of peak X-ray luminosity,
in erg/s units
73- 73 A1 --- l_logEx Limit flag on logEx
75- 78 F4.1 [10-7J] logEx [34.9/37.6] log of flare energy, in erg units
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Note (1): Flare class as follows:
F = Full (5 occurrences);
R = Rise (3 occurrences).
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Global notes:
Note (G1): A unique X-ray flare name is composed of the X-ray host star
name and the relative number of the X-ray Chandra observation, during
which the flare is detected.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Dec-2022