2007A&A...474..495A

Query : 2007A&A...474..495A

2007A&A...474..495A - Astronomy and Astrophysics, volume 474495-504 (2007/11-1)

X-ray flaring from the young stars in Cygnus OB2.

ALBACETE COLOMBO J.F., CARAMAZZA M., FLACCOMIO E., MICELA G. and SCIORTINO S.

Abstract (from CDS):

We characterize individual and ensemble properties of X-ray flares from stars in the Cygnus OB2 and ONC star-forming regions.We analyzed X-ray lightcurves of 1003 Cygnus OB2 sources observed with Chandra for 100ks and of 1616 ONC sources detected in the ``Chandra Orion Ultra-deep Project'' 850ks observation. We employed a binning-free maximum likelihood method to segment the light-curves into intervals of constants signal and identified flares on the basis of both the amplitude and the time-derivative of the source luminosity. We then derived and compared the flare frequency and energy distribution of Cygnus OB2 and ONC sources. The effect of the length of the observation on these results was investigated by repeating the statistical analysis on five 100ks-long segments extracted from the ONC data.We detected 147 and 954 flares from the Cygnus OB2 and ONC sources, respectively. The flares in Cygnus OB2 have decay times ranging from ≲0.5 to about 10h. The flare energy distributions of all considered flare samples are described at high energies well by a power law with index α=-(2.1±0.1). At low energies, the distributions flatten, probably because of detection incompleteness. We derived average flare frequencies as a function of flare energy. The flare frequency is seen to depend on the source's intrinsic X-ray luminosity, but its determination is affected by the length of the observation. The slope of the high-energy tail of the energy distribution is, however, affected little. A comparison of CygnusOB2and ONC sources, accounting for observational biases, shows that the two populations, known to have similar X-ray emission levels, have very similar flare activity.Studies of flare activity are only comparable if performed consistently and taking the observation length into account. Flaring activity does not vary appreciably between the age of the ONC (∼1Myr) and that of Cygnus OB2 (∼2Myr). The slope of the distribution of flare energies is consistent with the micro-flare explanation of the coronal heating.

Abstract Copyright: ∼

Journal keyword(s): stars: activity - stars: corona - stars: low-mass, brown dwarfs - X-rays: stars

VizieR on-line data: <Available at CDS (J/A+A/474/495): table1.dat>

Simbad objects: 144

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Number of rows : 144
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2514 0
2 CXOCyg J203225.09+411019.6 * 20 32 25.090 +41 10 19.60           ~ 2 0
3 2MASS J20322768+4113169 * 20 32 27.6813691128 +41 13 16.871737044           ~ 2 0
4 2MASS J20322913+4114012 * 20 32 29.14 +41 14 01.3           ~ 2 0
5 2MASS J20323249+4113131 * 20 32 32.4833725152 +41 13 13.124172072           ~ 2 0
6 2MASS J20323592+4112505 * 20 32 35.9379800760 +41 12 50.591940444           ~ 2 0
7 2MASS J20323661+4122147 * 20 32 36.6111617808 +41 22 14.721278592     16.19     ~ 4 0
8 2MASS J20323751+4117121 * 20 32 37.52 +41 17 12.2           ~ 2 0
9 2MASS J20323784+4122087 * 20 32 37.8352356504 +41 22 08.775803208           ~ 2 0
10 2MASS J20323810+4112442 * 20 32 38.0979779424 +41 12 44.187484140           ~ 2 0
11 2MASS J20323989+4113488 * 20 32 39.89 +41 13 48.8           ~ 2 0
12 2MASS J20324009+4110346 * 20 32 40.0902567264 +41 10 34.645398060           ~ 4 0
13 2MASS J20324032+4122473 * 20 32 40.32 +41 22 47.3           ~ 2 0
14 2MASS J20324063+4111113 * 20 32 40.63 +41 11 11.3           ~ 2 0
15 2MASS J20324288+4119148 * 20 32 42.8780107224 +41 19 14.843206956           ~ 2 0
16 2MASS J20324342+4111034 * 20 32 43.42 +41 11 03.4           ~ 2 0
17 2MASS J20324492+4115203 * 20 32 44.9061141984 +41 15 20.172366576           ~ 3 0
18 2MASS J20324860+4108117 * 20 32 48.6048185976 +41 08 11.778492084           ~ 2 0
19 2MASS J20325011+4116270 * 20 32 50.0918065656 +41 16 26.697672840           ~ 2 0
20 CXOCyg J203250.98+411245.6 * 20 32 50.980 +41 12 45.61           ~ 2 0
21 CXOCyg J203251.13+411253.5 * 20 32 51.130 +41 12 53.58           ~ 2 0
22 2MASS J20325218+4118160 * 20 32 52.1711141616 +41 18 16.140870648           ~ 5 0
23 2MASS J20325351+4120195 * 20 32 53.5129218648 +41 20 19.460108724           ~ 2 0
24 2MASS J20325377+4115134 EB? 20 32 53.7690613560 +41 15 13.384828872       18.77 17.06 ~ 7 0
25 2MASS J20325480+4112034 * 20 32 54.7888600152 +41 12 03.400473348           ~ 2 0
26 2MASS J20325514+4113148 * 20 32 55.1296526784 +41 13 14.860252380           ~ 2 0
27 2MASS J20325525+4108321 * 20 32 55.2630705936 +41 08 32.079794640           ~ 2 0
28 2MASS J20325648+4110531 Y*? 20 32 56.4780653352 +41 10 53.161056948           ~ 3 0
29 CXOCyg J203257.32+412047.5 * 20 32 57.330 +41 20 47.51           ~ 2 0
30 2MASS J20325803+4110582 * 20 32 58.0312125432 +41 10 58.304373888           ~ 2 0
31 2MASS J20325828+4112511 * 20 32 58.29 +41 12 51.2           ~ 2 0
32 CXOCyg J203258.44+411105.4 * 20 32 58.450 +41 11 05.50           ~ 2 0
33 2MASS J20325874+4112266 * 20 32 58.7212239192 +41 12 26.562458664           ~ 2 0
34 2MASS J20325883+4111095 * 20 32 58.7528316912 +41 11 09.869302500           ~ 2 0
35 Schulte 41 SB* 20 32 59.6317342392 +41 15 14.679727632 16.54 15.59 13.49     O9.7III(n) 37 0
36 CXOCyg J203259.77+411345.4 * 20 32 59.770 +41 13 45.48           ~ 2 0
37 2MASS J20325987+4108488 * 20 32 59.87 +41 08 48.9           ~ 2 0
38 CXOCyg J203300.52+411550.1 * 20 33 00.530 +41 15 50.15           ~ 2 0
39 2MASS J20330058+4118594 * 20 33 00.5877472152 +41 18 59.509889964           ~ 3 0
40 2MASS J20330106+4117564 * 20 33 01.07 +41 17 56.5           ~ 3 0
41 2MASS J20330119+4109182 * 20 33 01.1904384168 +41 09 18.229028688           ~ 2 0
42 2MASS J20330133+4110562 * 20 33 01.33 +41 10 56.3           ~ 2 0
43 CXOCyg J203301.35+411223.6 * 20 33 01.360 +41 12 23.61           ~ 2 0
44 2MASS J20330176+4111107 CV* 20 33 01.7776959048 +41 11 10.798287972     16.73 18.10 16.95 ~ 8 0
45 2MASS J20330285+4107068 * 20 33 02.8348381344 +41 07 06.848208552           ~ 2 0
46 CXOCyg J203303.03+411740.1 * 20 33 03.030 +41 17 40.19           ~ 2 0
47 2MASS J20330356+4112539 Y*? 20 33 03.5529891048 +41 12 53.821369836           ~ 3 0
48 2MASS J20330611+4122434 * 20 33 06.1056373104 +41 22 43.517777232           ~ 2 0
49 2MASS J20330684+4112245 * 20 33 06.8356034544 +41 12 24.467481540           ~ 2 0
50 CXOCyg J203307.07+411604.3 * 20 33 07.080 +41 16 04.36           ~ 2 0
51 2MASS J20330718+4115206 * 20 33 07.18 +41 15 20.7           ~ 2 0
52 2MASS J20330736+4110014 * 20 33 07.36 +41 10 01.4           ~ 2 0
53 2MASS J20330746+4112266 * 20 33 07.4573145120 +41 12 26.506885212           ~ 2 0
54 2MASS J20330747+4120324 * 20 33 07.47 +41 20 32.4           ~ 2 0
55 2MASS J20330808+4111091 * 20 33 08.0875223256 +41 11 09.107428344           ~ 2 0
56 CXOCyg J203308.56+411435.9 * 20 33 08.560 +41 14 35.91           ~ 2 0
57 [AFM2007] 432 * 20 33 08.6403538464 +41 15 14.674577148           ~ 2 0
58 CXOCyg J203308.90+411243.5 * 20 33 08.910 +41 12 43.59           ~ 2 0
59 2MASS J20330892+4122276 * 20 33 08.9214610512 +41 22 27.691919940           ~ 2 0
60 CXOCyg J203308.95+411705.7 * 20 33 08.960 +41 17 05.71           ~ 2 0
61 CXOCyg J203309.06+411227.8 * 20 33 09.060 +41 12 27.89           ~ 2 0
62 2MASS J20330911+4113094 * 20 33 09.1266708456 +41 13 08.770293840           ~ 2 0
63 CXOCyg J203309.26+411302.1 * 20 33 09.270 +41 13 02.10           ~ 2 0
64 [AFM2007] 459 * 20 33 09.8497845912 +41 22 14.319514164           ~ 2 0
65 CXOCyg J203310.23+411533.1 * 20 33 10.240 +41 15 33.15           ~ 2 0
66 2MASS J20331047+4109257 * 20 33 10.47 +41 09 25.8           ~ 2 0
67 2MASS J20331060+4121041 * 20 33 10.60 +41 21 04.1           ~ 2 0
68 CXOCyg J203310.99+411241.8 * 20 33 10.990 +41 12 41.88           ~ 2 0
69 2MASS J20331123+4108338 * 20 33 11.2377620400 +41 08 33.791651484           ~ 2 0
70 2MASS J20331148+4113481 * 20 33 11.4822331392 +41 13 48.061163388           ~ 2 0
71 2MASS J20331180+4111502 * 20 33 11.7994637208 +41 11 50.075672640           ~ 2 0
72 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 1023 0
73 2MASS J20331206+4116495 * 20 33 12.0631182936 +41 16 49.529479008           ~ 3 0
74 CXOCyg J203312.66+411913.6 * 20 33 12.660 +41 19 13.62           ~ 2 0
75 CXOCyg J203312.87+411154.4 * 20 33 12.880 +41 11 54.50           ~ 2 0
76 2MASS J20331304+4115393 * 20 33 13.0395115848 +41 15 39.352431672           ~ 2 0
77 CXOCyg J203313.23+411319.1 * 20 33 13.230 +41 13 19.13           ~ 2 0
78 2MASS J20331366+4120052 * 20 33 13.6696826976 +41 20 05.142372252           ~ 2 0
79 2MASS J20331442+4106320 * 20 33 14.4497331864 +41 06 31.955457276           ~ 2 0
80 CXOCyg J203314.58+411837.1 * 20 33 14.580 +41 18 37.12           ~ 2 0
81 2MASS J20331480+4114215 * 20 33 14.80 +41 14 21.5           ~ 2 0
82 2MASS J20331513+4113106 Y*? 20 33 15.1446479328 +41 13 10.578266688           ~ 3 0
83 2MASS J20331523+4113277 Y*? 20 33 15.24 +41 13 27.7           ~ 3 0
84 2MASS J20331546+4118162 * 20 33 15.47 +41 18 16.3           ~ 2 0
85 [AFM2007] 581 V* 20 33 15.5791021656 +41 21 33.498288936       16.98 15.68 ~ 5 0
86 CXOCyg J203315.84+412115.0 * 20 33 15.840 +41 21 15.04           ~ 2 0
87 CXOCyg J203316.34+411858.9 * 20 33 16.340 +41 18 58.96           ~ 2 0
88 CXOCyg J203316.50+411653.9 * 20 33 16.500 +41 16 53.97           ~ 2 0
89 2MASS J20331660+4112589 * 20 33 16.6186225464 +41 12 59.128321104           ~ 2 0
90 CXOCyg J203316.72+411833.1 * 20 33 16.730 +41 18 33.12           ~ 2 0
91 CXOCyg J203317.38+411653.9 * 20 33 17.390 +41 16 53.97           ~ 2 0
92 2MASS J20331744+4107242 * 20 33 17.44 +41 07 24.2           ~ 2 0
93 2MASS J20331754+4120416 * 20 33 17.54 +41 20 41.6           ~ 2 0
94 2MASS J20331817+4111010 * 20 33 18.18 +41 11 01.0           ~ 2 0
95 CXOCyg J203318.42+411240.4 * 20 33 18.430 +41 12 40.43           ~ 2 0
96 CXOCyg J203319.16+411906.7 * 20 33 19.160 +41 19 06.78           ~ 2 0
97 2MASS J20331924+4117567 * 20 33 19.2331802448 +41 17 56.707663452           ~ 2 0
98 2MASS J20331962+4118043 * 20 33 19.6136309520 +41 18 04.279924584           ~ 2 0
99 2MASS J20331968+4121025 * 20 33 19.6720578432 +41 21 02.493407376           ~ 2 0
100 2MASS J20332028+4116478 * 20 33 20.29 +41 16 47.8           ~ 2 0
101 ZTF J203320.44+412033.3 RS* 20 33 20.4422346768 +41 20 33.186257340     15.56     ~ 10 0
102 CXOCyg J203321.04+411708.8 * 20 33 21.050 +41 17 08.88           ~ 2 0
103 2MASS J20332112+4117570 Y*? 20 33 21.1217838072 +41 17 57.094081008           ~ 3 0
104 Schulte 62 * 20 33 21.2637786240 +41 18 39.568692456     16.59     ~ 6 0
105 [AFM2007] 697 * 20 33 21.6117382368 +41 12 29.609221500           ~ 2 0
106 2MASS J20332206+4110044 * 20 33 22.06 +41 10 04.4           ~ 2 0
107 CXOCyg J203322.06+412153.8 * 20 33 22.070 +41 21 53.86           ~ 2 0
108 2MASS J20332224+4117446 Pu* 20 33 22.2427166664 +41 17 44.629370808       17.02 15.52 ~ 5 0
109 2MASS J20332247+4117368 Y*? 20 33 22.4712491184 +41 17 36.752124552           ~ 3 0
110 CXOCyg J203324.31+412106.7 * 20 33 24.320 +41 21 06.76           ~ 2 0
111 2MASS J20332440+4120330 * 20 33 24.4039002720 +41 20 33.026887032           ~ 2 0
112 2MASS J20332453+4115339 * 20 33 24.53 +41 15 34.0           ~ 4 0
113 2MASS J20332464+4110596 * 20 33 24.6377184264 +41 10 59.707132680           ~ 2 0
114 2MASS J20332481+4122235 * 20 33 24.8072214384 +41 22 23.774256336           ~ 2 0
115 2MASS J20332511+4107248 * 20 33 25.1205778488 +41 07 24.836022696           ~ 2 0
116 CXOCyg J203326.44+411048.5 * 20 33 26.450 +41 10 48.58           ~ 2 0
117 2MASS J20332742+4116263 * 20 33 27.4608341592 +41 16 26.578598844           ~ 2 0
118 2MASS J20332845+4119373 * 20 33 28.4508801432 +41 19 37.340970816           ~ 3 0
119 2MASS J20332851+4119152 * 20 33 28.52 +41 19 15.3           ~ 2 0
120 2MASS J20332853+4107172 * 20 33 28.5296423928 +41 07 17.171194080           ~ 2 0
121 2MASS J20333104+4120258 * 20 33 31.0414935360 +41 20 25.944339984           ~ 2 0
122 2MASS J20333137+4109123 * 20 33 31.3839037200 +41 09 12.251848428           ~ 2 0
123 2MASS J20333215+4118023 * 20 33 32.15 +41 18 02.3           ~ 2 0
124 CXOCyg J203332.92+412147.2 * 20 33 32.930 +41 21 47.24           ~ 2 0
125 2MASS J20333478+4120502 * 20 33 34.79 +41 20 50.3           ~ 2 0
126 2MASS J20333481+4107473 * 20 33 34.8073186896 +41 07 47.338328136           ~ 2 0
127 2MASS J20333535+4118221 * 20 33 35.3533771704 +41 18 22.173622812           ~ 2 0
128 2MASS J20333585+4106506 * 20 33 35.8574192592 +41 06 50.749705512           ~ 2 0
129 2MASS J20333640+4118189 * 20 33 36.3970109928 +41 18 18.954593784           ~ 2 0
130 2MASS J20333902+4108340 Y*? 20 33 39.0310134696 +41 08 34.041059628           ~ 6 0
131 CXOCyg J203339.71+411524.9 * 20 33 39.710 +41 15 24.95           ~ 2 0
132 CXOCyg J203340.74+411415.2 * 20 33 40.740 +41 14 15.22           ~ 2 0
133 2MASS J20334092+4109362 V* 20 33 40.9305940800 +41 09 36.104874156       21.56 19.52 ~ 3 0
134 CXOCyg J203340.97+410849.8 * 20 33 40.970 +41 08 49.82           ~ 2 0
135 2MASS J20334128+4107342 * 20 33 41.2764897024 +41 07 34.132356876           ~ 2 0
136 CXOCyg J203341.93+411128.7 * 20 33 41.940 +41 11 28.72           ~ 2 0
137 CXOCyg J203343.00+411504.3 * 20 33 43.000 +41 15 04.40           ~ 2 0
138 2MASS J20334329+4110343 * 20 33 43.2849951480 +41 10 34.264228296           ~ 2 0
139 2MASS J20334461+4109067 * 20 33 44.62 +41 09 06.7           ~ 3 0
140 CXOCyg J203345.29+411503.8 * 20 33 45.290 +41 15 03.82           ~ 2 0
141 2MASS J20334710+4120061 * 20 33 47.1095900544 +41 20 06.074484900           ~ 2 0
142 CXOCyg J203348.10+411842.3 * 20 33 48.110 +41 18 42.34           ~ 2 0
143 2MASS J20335310+4111193 EB? 20 33 53.0981225496 +41 11 19.283749368       16.82 15.34 ~ 5 0
144 2MASS J20335426+4113397 * 20 33 54.2694506760 +41 13 39.780360984           ~ 2 0

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