J/ApJ/688/418 X-ray flares in Orion young stars. I. (Getman+, 2008)
X-ray flares in Orion young stars.
I. Flare characteristics.
Getman K.V., Feigelson E.D., Broos P.S., Micela G., Garmire G.P.
<Astrophys. J., 688, 418-436 (2008)>
=2008ApJ...688..418G 2008ApJ...688..418G
ADC_Keywords: Clusters, open ; Stars, pre-main sequence ; X-ray sources ;
Photometry, infrared
Keywords: open clusters and associations: individual (Orion Nebula Cluster) -
stars: flare - stars: pre-main sequence - X-rays: stars
Abstract:
Pre-main-sequence (PMS) stars are known to produce powerful X-ray
flares, which resemble magnetic reconnection solar flares scaled by
factors up to 104. However, there are numerous puzzles, including the
structure of X-ray-emitting coronae and magnetospheres, the effects
of protoplanetary disks, and the effects of stellar rotation. To
investigate these issues in detail, we examine 216 of the brightest
flares from 161 PMS stars observed in the Chandra Orion Ultradeep
Project (COUP, Getman et al. Cat. J/ApJS/160/319). The current study
(Paper I) examines the flare morphologies, and provides a general
comparison of COUP flare characteristics with those of other active
X-ray stars and the Sun.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 216 Flare properties 1
table2.dat 96 216 Flare properties 2
table3.dat 116 161 COUP star properties
table4.dat 55 216 Time-resolved spectroscopy analysis
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See also:
J/ApJ/574/258 : X-ray-emitting young stars in the Orion nebula (Feigelson+,
2002)
J/PASJ/55/653 : Chandra X-ray flares in rho Ophiuchi (Imanishi+, 2003)
J/ApJS/160/319 : COUP: observations and source lists (Getman+, 2005)
J/ApJS/160/353 : Membership of the Orion nebula population (Getman+, 2005)
J/ApJS/160/450 : X-ray emission in Orion Nebula young stars (Flaccomio+, 2005)
J/A+A/474/495 : X-ray flares from Cygnus OB2 young stars (Albacete Colombo+,
2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- COUP COUP source number
6 I1 --- FNo Flare number
8- 12 I5 ct NCf Net flare counts
14- 18 F5.1 ct bgf Background counts in flare
20- 23 F4.2 keV MEf X-ray median energy of flare counts
25- 30 F6.1 ks tchar1 Start time of characteristic state
32- 37 F6.1 ks tchar2 Stop time of characteristic state
39- 44 F6.1 ks tFl1 Flare start time
46- 51 F6.1 ks tFl2 Flare stop time
53- 56 F4.1 ct/ks CRchar Count rate in characteristic state
58- 63 F6.1 ct/ks CRFlpk Peak flare count rate
65- 68 F4.1 ct/ks e_CRFlpk Error in CRFlpk
70- 75 F6.1 ks tCRpk Time of maximum flare count rate
77- 82 F6.1 ks tTpk Time of maximum flare temperature
84- 89 F6.1 ks tEMpk Time of maximum flare emission measure
91- 96 F6.1 ks texp Time point for pure exponential decay (1)
98-103 F6.1 ks tsep Separation time point (2)
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Note (1): Time point until which the lightcurve exhibits a pure exponential
decay.
Note (2): Separation time point between two distinct decay phases.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- COUP COUP source number
6 I1 --- FNo Flare number
8- 12 F5.1 ks taur Rise e-folding timescale
14- 18 F5.1 ks taud1 Initial decay e-folding timescale
20- 24 F5.1 ks taud2 Full decay e-folding timescale
26- 30 F5.2 [10-7W] Lxpk Flare peak X-ray luminosity (log scale)
32- 37 F6.2 MK Tobspk Flare peak observed plasma temperature
39- 44 F6.2 10+53cm-3 EMpk Flare peak emission measure
46- 51 F6.2 MK TEMpk Plasma temperature at maximum emission measure
53- 56 F4.1 --- zeta1 Slope over the full decay
58- 61 F4.1 --- zeta2 Slope within the initial decay
63- 67 F5.1 --- zeta3 Slope within the late decay
69- 74 F6.2 10+10cm L1 Low boundary of the inferred loop length range
76- 81 F6.2 10+10cm L2 High boundary of the inferred loop length range
83- 89 F7.2 10+10cm Llim Limiting maximum loop length using Serio's law
91- 92 I2 --- Flag1 Flag for a dominant slope(s) (1)
94- 96 A3 --- Type Flare morphology (2)
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Note (1): Flag defines the best or dominant slope or a combination of slopes
which, in combination with decay timescales taud1 and taud2, are
used to estimate loop size range; as follows:
01 = ζ1;
02 = ζ2;
03 = ζ3;
12 = ζ1, ζ2;
13 = ζ1, ζ3;
23 = ζ2, ζ3;
44 = unable to estimate loop size.
Note (2): The following morphological classes are defined:
typ = typical;
stp = flares with step decay;
srf = slow-rise-and/or-top-flat flares;
dbl = double flares;
inc = incomplete, interrupted by COUP observational gaps;
oth = other, purely defined shapes generally due to their lower
counting statistics.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- COUP COUP source number (1)
6- 10 I5 ct NC Source net counts (1)
12- 14 I3 ct bg Background counts in source region (1)
16- 19 F4.2 keV ME Source's X-ray median energy (1)
21- 25 F5.2 [cm-2] NH Source's inferred column density (1)
27- 31 F5.2 mag Jmag ?=-9.99 2MASS J-band magnitude (1)
33- 37 F5.2 mag Hmag 2MASS H-band magnitude (1)
39- 43 F5.2 mag Ksmag 2MASS Ks-band magnitude (1)
45- 50 A6 --- Qual IR source and quality flag (1)
52- 56 F5.2 mag d(H-K) ?=-9.99 IR color excess (2)
58- 63 F6.3 mag 3.6mag ?=-9.999 IR 3.6 micron band magnitude
65- 70 F6.3 mag e_3.6mag ?=-9.999 Error in 3.6mag
72- 77 F6.3 mag 4.5mag ?=-9.999 IR 4.5 micron band magnitude
79- 84 F6.3 mag e_4.5mag ?=-9.999 Error in 4.5mag
86- 90 F5.2 Msun Mass ?=-9.99 Stellar mass (1)
92- 96 F5.2 10+8m Rad ?=-9.99 Stellar radius (1)
98-102 F5.2 d Per ?=-9.99 Stellar rotation period (3)
104-109 F6.2 10+8m Rcor ?=-9.99 Keplerian co-rotation radius
111-116 F6.2 0.1nm EW(CaII) ?=-99.99 Equivalent width of Ca II line (1)
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Note (1): Values for these quantities are from Getman et al. (2005, Cat.
J/ApJS/160/353): 3 letters for 2MASS quality flags and 3 characters
for the 2MASS contamination and confusion flag.
Note (2): Color excess measured from the rightmost reddening vector on the
J-H vs. H-Ks color-color diagram (originating at 0.1M☉ assuming
an age of 1Myr and using PMS models of Siess et al.
(2000A&A...358..593S 2000A&A...358..593S)).
Note (3): Stellar rotation periods with extended rotation data collected in
Flaccomio et al. (2005, Cat. J/ApJS/160/450).
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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- 4 I4 --- COUP COUP source number
6 I1 --- FNo Flare number
8- 10 A3 --- Type Flare morphology (1)
12- 13 I2 --- SNo Number of time-resolved spectroscopy (TRS)
segments
15- 18 I4 ct Nseg Average number of counts in TRS segment
20- 23 I4 ct Nchar Number of counts in characteristic segment
25- 29 F5.2 MK Tchar Characteristic plasma temperature
31- 36 F6.2 MK TpknCH Peak flare plasma temperature in "noCH" case (2)
38- 43 F6.2 MK TpkCH Peak flare plasma temperature in "CH" case (2)
45- 49 F5.2 --- znCH Full decay slope in "noCH" case (2)
51- 55 F5.2 --- zCH Full decay slope in "CH" case (2)
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Note (1): The following morphological classes are defined:
typ = typical;
stp = flares with step decay;
srf = slow-rise-and/or-top-flat flares;
dbl = double flares;
inc = incomplete, interrupted by COUP observational gaps;
oth = other, purely defined shapes generally due to their lower
counting statistics.
Note (2): Inferred peak flare plasma temperatures and slopes of temperature-
density trajectories without ("noCH") and with ("CH") account for
the "characteristic" background.
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History:
From electronic version of the journal
References:
Getman et al. Paper II. 2008ApJ...688..437G 2008ApJ...688..437G
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 14-Jan-2011