2009AJ....137.5012C

Query : 2009AJ....137.5012C

2009AJ....137.5012C - Astron. J., 137, 5012-5021 (2009/June-0)

X-ray variability of σ Orionis young stars as observed with ROSAT.

CABALLERO J.A., LOPEZ-SANTIAGO J., DE CASTRO E. and CORNIDE M.

Abstract (from CDS):

We used the Aladin Virtual Observatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the σ Orionis cluster and a background galaxy. Five stars displayed unambiguous flares and had probabilities pvar{Gt} 99% of being actual variables. Two of the detected flares were violent and long lasting, with maximum duration of six days and amplitude of eight times above the quiescent level. We classified another four stars as possible X-ray variables, including the binary system formed by the B2Vp star σ Ori E and its close late-type companion. This makes a minimum frequency of high-amplitude X-ray variability in excess of a day of 39% among σ Orionis stars. The incidence of this kind of X-ray variability seems to be lower among classical T Tauri stars with mid-infrared flux excesses than among fast-rotating, disk-less young stars.

Abstract Copyright: ∼

Journal keyword(s): open clusters and associations: individual: sigma Orionis - stars: activity - X-rays: stars

Simbad objects: 42

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Number of rows : 42
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 * alf Per V* 03 24 19.3700924 +49 51 40.245455 2.64 2.27 1.79     F5Ib 870 1
2 V* UX Ari RS* 03 26 35.3756804760 +28 42 54.226408428 7.76 7.28 6.37     K0IV 726 0
3 HD 22468 RS* 03 36 47.2904292073 +00 35 15.943692002 7.09 6.79 5.90     K2:Vnk 1206 0
4 IC 348 OpC 03 44 31.1 +32 10 02           ~ 1476 1
5 Cl Melotte 22 OpC 03 46 38.0 +24 10 41           ~ 3679 0
6 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1453 0
7 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4971 0
8 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2514 0
9 [W96] 4771-921 Y*O 05 37 53.0357554200 -02 33 34.398831816 13.379 12.35 11.64   10.70 G2.5 28 0
10 TYC 4771-921-1 Y*O 05 37 54.4037119440 -02 39 29.792935836   11.80 10.91   10.274 G5.0 28 0
11 2MASS J05375630-0245130 G 05 37 56.3078466240 -02 45 13.187592216         16.734 ~ 10 0
12 UCAC2 30800015 TT* 05 38 07.8452154168 -02 31 31.350308952 15.277   12.72   11.41 K3.0 22 0
13 [W96] rJ053832-0235b TT* 05 38 32.8464506040 -02 35 39.259582728 17.600 15.90 14.59 13.74 12.88 K6.0 29 0
14 [W96] rJ053835-0231 TT* 05 38 35.4679746552 -02 31 51.698592264 17.174 15.48 14.19 13.37 12.55 K7.0 32 0
15 [W96] 4771-1097 TT* 05 38 35.8728104976 -02 30 43.337476944 16.679 15.13 13.94 13.18 12.41 K6e 30 0
16 [W96] rJ053838-0236 TT* 05 38 38.2273375656 -02 36 38.502644580 17.054 15.35 14.09 13.25 12.38 K8e 31 0
17 [W96] 4771-1147 TT* 05 38 38.4905614800 -02 34 55.095652092 15.117 13.49 12.35 11.73 10.97 K2.0 32 0
18 NAME sig Ori Cluster OpC 05 38 42 -02 36.0           ~ 623 0
19 [W96] rJ053843-0233 TT* 05 38 43.5573033864 -02 33 25.441109640 17.743 16.52 15.14 14.16 13.07 M1 24 0
20 [W96] 4771-1051 TT* 05 38 44.2345372944 -02 40 19.771649184 15.88 15.24 14.02 13.22 12.41 K7.5/8e 42 0
21 2MASS J05384424-0232336 TT* 05 38 44.2435528320 -02 32 33.699347484 16.18 15.21 13.89 13.01 12.13 K7.0 26 0
22 * sig Ori Y*O 05 38 44.7653828520 -02 36 00.283179888 2.54 3.58 3.79 3.87 4.11 O9.5V+B0.2V(n) 855 0
23 * sig Ori E Y*O 05 38 47.2050040320 -02 35 40.521424812 5.66 6.38 6.46 6.84 7.08 B2IV-Vp_He 486 0
24 [W96] 4771-899 TT* 05 38 48.0364463496 -02 27 14.149731420 16.327 14.490 13.254 12.630 11.54 K7e 33 0
25 [W96] rJ053849-0238 TT* 05 38 49.1743174560 -02 38 22.302143052 17.35 16.22 14.87 13.93 12.91 M0.5e 27 0
26 V* RU Ori TT* 05 38 52.0091406720 -02 46 43.719992436     14.27 13.44 12.72 K7.5 44 0
27 [W96] 4771-1049 Y*O 05 38 53.3786496600 -02 33 23.078055204 15.736 14.21 13.05 12.30 11.59 K3 19 0
28 [W96] 4771-119 TT* 05 38 54.1062760704 -02 49 29.807244084     13.31   11.95 K3(e) 29 0
29 HD 37525 Y*O 05 39 01.4927799048 -02 38 56.364214344   7.98 8.06   8.210 B5V 95 1
30 [W96] 4771-1075 TT* 05 39 05.4085005984 -02 32 30.366192804 17.541 15.79 14.42 13.54 12.70 K7e 51 0
31 [W96] 4771-1038 TT* 05 39 11.6324490456 -02 36 02.883889440 16.242 15.82 14.47 13.61 12.75 K7e 31 0
32 2MASS J05391807-0229284 Y*O 05 39 18.0734290944 -02 29 28.520484936 14.474 13.57 12.60 12.05 11.53 G7.5 28 0
33 UCAC2 30800213 TT* 05 39 32.5740847344 -02 39 44.034178500     13.64 13.07 12.38 K7.0 26 0
34 HD 294300 TT* 05 39 36.5371112376 -02 42 17.225796096   10.91 10.11   9.230 G5e 31 0
35 2MASS J05394784-0232248 TT* 05 39 47.8356697848 -02 32 24.946773792     13.75   12.256 M0.0 20 0
36 NAME Horsehead Nebula DNe 05 40 59.0 -02 27 30           ~ 555 0
37 NAME Flame Nebula HII 05 41 42.7 -01 54 44           ~ 715 1
38 * sig Gem RS* 07 43 18.7276907303 +28 53 00.631838445 6.38 5.41 4.29 3.37 2.79 K1IIIe 499 0
39 IC 2391 OpC 08 41 17.5 -53 03 00           ~ 871 0
40 * rho Oph ** 16 25 35.11766 -23 26 49.8150 4.30 4.85 4.63 4.27 3.96 B2IV+B2V 670 0
41 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 1023 0
42 NAME Ori Belt reg ~ ~           ~ 83 0

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