2008ApJ...683..796S


Query : 2008ApJ...683..796S

2008ApJ...683..796S - Astrophys. J., 683, 796-812 (2008/August-3)

High-resolution Chandra X-ray imaging and spectroscopy of the σ Orionis cluster.

SKINNER S.L., SOKAL K.R., COHEN D.H., GAGNE M., OWOCKI S.P. and TOWNSEND R.D.

Abstract (from CDS):

We present results of a 90 ks Chandra X-ray observation of the young σ Orionis cluster (age∼3 Myr) obtained with the HETGS. We use the high-resolution grating spectrum and moderate-resolution CCD spectrum of the massive central star σ Ori AB (O9.5 V+B0.5 V) to test wind shock theories of X-ray emission and also analyze the high spatial resolution zero-order ACIS-S image of the central cluster region. Chandra detected 42 X-ray sources on the primary CCD (ACIS-S3). All but five have near-IR or optical counterparts and about one-fourth are variable. Notable high-mass stellar detections are σ Ori AB, the magnetic B star σ Ori E, and the B5 V binary HD 37525. Most of the other detections have properties consistent with lower mass K- or M-type stars. We present the first X-ray spectrum of the unusual infrared source IRS 1, located ~3" north of σ Ori AB. Its X-ray properties and elongated mid-IR morphology suggest that it is an embedded low-mass T Tauri star whose disk/envelope is being photoevaporated by σ Ori AB. We focus on the radiative wind shock interpretation of the soft luminous X-ray emission from σ Ori AB, but also consider possible alternatives including magnetically confined wind shocks and colliding wind shocks. Its emission lines show no significant asymmetries or centroid shifts and are moderately broadened to HWHM~264 km/s, or one-fourth the terminal wind speed. Forbidden lines in He-like ions are formally undetected, implying strong UV suppression. The Mg XI triplet forms in the wind acceleration zone within one stellar radius above the surface. These X-ray properties are consistent in several respects with the predictions of radiative wind shock theory for an optically thin wind, but explaining the narrow line widths presents a challenge to the theory.

Abstract Copyright:

Journal keyword(s): Galaxy: Open Clusters and Associations: Individual: Name: (σ Orionis) - Stars: Formation - stars: individual (σ Orionis AB) - Stars: Pre-Main-Sequence - X-Rays: Stars

Nomenclature: Table 2: [SSC2008] NN (Nos 1-42).

CDS comments: Table 2: Several 2MASS ID are not the exact 2MASS ID as in the II/246 2MASS catalog.

Simbad objects: 67

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Number of rows : 67
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* SU Aur Or* 04 55 59.3866872552 +30 34 01.499608092   10.33 9.30 9.17   G2IIIne 570 0
2 * alf Aur SB* 05 16 41.35871 +45 59 52.7693 1.33 0.88 0.08 -0.52 -0.96 G3III: 1164 0
3 V* IQ Aur a2* 05 19 00.0284573784 +33 44 54.220806888   5.201 5.371     A0p 283 0
4 * del Ori SB* 05 32 00.40009 -00 17 56.7424 0.96 2.02 2.41 2.32 2.54 O9.5IINwk 759 0
5 Ass Ori OB 1b As* 05 34.0 -01 30           ~ 256 0
6 HD 245059 Y*O 05 34 34.9060262317 +10 07 06.329811125   10.71 9.926   8.865 G8e 41 0
7 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2192 1
8 M 42 HII 05 35 01.5 -05 26 24           ~ 3953 0
9 * tet01 Ori A Ae* 05 35 15.8254015008 -05 23 14.334699480 5.87 6.75 6.73 6.42 6.21 B0V 474 1
10 * tet01 Ori C SB* 05 35 16.4662967280 -05 23 22.921811880 4.20 5.15 5.13 4.91 4.73 O7Vp 1361 1
11 * tet01 Ori D Y*O 05 35 17.2574479992 -05 23 16.570738104 6.08 6.79 6.70 6.40 6.20 B1.5Vp 319 0
12 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 545 0
13 NAME Ori Complex Cld 05 35.3 -05 23           ~ 404 0
14 * tet02 Ori A SB* 05 35 22.9012398264 -05 24 57.832632108 5.37 6.30 6.39 6.30 6.35 O9.5IVp 525 0
15 [W96] rJ053828-0236 LM* 05 38 29.1236063736 -02 36 02.754623664 19.390 17.83 16.28 15.22 13.98 M1.5 18 0
16 Haro 5-11 TT* 05 38 31.4247760176 -02 36 33.894690768 16.59 17.36 16.42 15.22 13.82 M3.5 22 0
17 [W96] rJ053831-0235 TT* 05 38 31.5873593664 -02 35 15.081924804 19.243 17.17 15.85 14.88 13.77 M0e 23 0
18 [W96] rJ053832-0235b LM* 05 38 32.8464506040 -02 35 39.259582728 17.600 15.90 14.59 13.74 12.88 K6.0 20 0
19 2MASS J05383335-0236176 Y*O 05 38 33.3605595192 -02 36 17.684774892 18.08 17.30 15.83 14.72 13.40 M2.5 16 0
20 [W96] rJ053833-0236 TT* 05 38 34.0608899664 -02 36 37.589513328 19.530   16.39 15.24 13.72 M3-M4e 31 0
21 2MASS J05383431-0235000 TT* 05 38 34.3155897720 -02 35 00.166471512 17.079 15.25 13.95 13.13 12.35 K7.0 18 0
22 [SSC2008] 8 X 05 38 35.21 -02 34 38.1           ~ 1 0
23 [W96] rJ053838-0236 LM* 05 38 38.2273375656 -02 36 38.502644580 17.054 15.35 14.09 13.25 12.38 K8e 22 0
24 [W96] 4771-1147 Y*O 05 38 38.4905614800 -02 34 55.095652092 15.117 13.49 12.35 11.73 10.97 K2.0 20 0
25 2MASS J05383972-0240197 Y*O 05 38 39.7321268352 -02 40 19.762638060 20.69 20.16 18.70 17.28 15.48 M3.5 11 0
26 DENIS J053841.2-023737 * 05 38 41.2343533488 -02 37 37.751237472         17.55 ~ 11 1
27 UCAC2 30800097 TT* 05 38 41.2928547432 -02 37 22.626301404 16.93 15.86 14.54 14.192 12.78 M0.0 22 0
28 [BNM2013] 92.01 23 LM* 05 38 41.3591638344 -02 36 44.554940316   17.76   15.86 14.45 M2.0 13 0
29 NAME sigma Orionis Cluster MGr 05 38 42 -02 36.0           ~ 532 0
30 2MASS J05384227-0237147 TT* 05 38 42.2801182536 -02 37 14.821687344 17.36 16.69 15.27 14.27 13.22 M0.5 23 0
31 2MASS J05384301-0236145 Y*O 05 38 43.0201961184 -02 36 14.636669328 12.79 14.23 14.87 14.28 13.30 M1.0 14 0
32 2MASS J05384386-0237068 TT* 05 38 43.8691779528 -02 37 06.911503896 13.559   17.93 16.59 14.80 ~ 23 0
33 * sig Ori C Y*? 05 38 44.1189397296 -02 36 06.310060884   8.77 8.79   9.63 A2Vn 27 0
34 [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 27 0
35 * 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) 779 0
36 NAME sig Ori IRS 1 * 05 38 44.9 -02 35 57           ~ 15 0
37 V* V595 Ori Or* 05 38 45.37536 -02 41 59.4240 17.75 17.08 15.61 15.19 13.45 M1.5 22 0
38 * sig Ori D Y*O 05 38 45.6253355112 -02 35 58.894678824 5.7 6.51 6.69   6.98 B2V 54 0
39 [BNM2013] 90.02 216 LM* 05 38 46.8532193544 -02 36 43.607139732 13.332 15.86 16.63 16.61 15.20 M5.0 17 0
40 * 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 435 0
41 UCAC4 438-011202 TT* 05 38 47.4634997136 -02 35 25.322448264 12.01 14.96 14.82 15.071 13.10 M0.5 19 0
42 [W96] rJ053847-0237 TT* 05 38 47.91648 -02 37 19.2360 16.81 16.78 15.51 15.01 13.39 M1.0 22 0
43 2MASS J05384828-0236409 Y*O 05 38 48.2919091608 -02 36 41.075987652 14.930 17.29   15.60 13.89 M4.5 14 0
44 [BNM2013] 90.02 90 LM* 05 38 48.6872974992 -02 36 16.297363080 13.474   15.45 14.24 13.37 M1.5 16 0
45 [W96] rJ053849-0238 LM* 05 38 49.1743174560 -02 38 22.302143052 17.35 16.22 14.87 13.93 12.91 M0.5e 21 0
46 [BNM2013] 93.03 5 LM* 05 38 49.2233239032 -02 41 25.201346748     15.98 14.73 13.23 M3.5 17 0
47 2MASS J05384970-0234526 Y*O 05 38 49.7044756272 -02 34 52.679689680   19.12 17.96 16.84 14.79 ~ 17 0
48 2MASS J05385003-0237354 Y*O 05 38 50.0383707336 -02 37 35.548478076 19.47 18.95 18.00 16.69 14.93 ~ 16 0
49 [SSC2008] 32 X 05 38 50.16 -02 36 54.6           ~ 1 0
50 [BNM2013] 90.02 91 LM* 05 38 51.4560020472 -02 36 20.641613616 16.090 18.23 17.47 16.09 14.38 K5V 15 0
51 [BNM2013] 90.02 293 LM* 05 38 51.7468872456 -02 36 03.425317272 15.494 19.63 17.89 16.84 15.04 ~ 14 0
52 [SSC2008] 35 X 05 38 51.85 -02 33 33.0           ~ 1 0
53 [W96] rJ053852-0238 LM* 05 38 53.0748520464 -02 38 53.714969592 17.35 16.30 14.82 13.83 12.75 M1.0 10 0
54 [W96] 4771-1049 Y*O 05 38 53.3786496600 -02 33 23.078055204 15.736 14.21 13.05 12.30 11.59 K3 14 0
55 [SSC2008] 38 X 05 38 58.24 -02 38 51.5           ~ 1 0
56 [SSC2008] 39 X 05 38 59.03 -02 34 13.2           ~ 2 0
57 [SSC2008] 40 X 05 38 59.51 -02 35 28.6           ~ 2 0
58 [W96] 4771-1056 Y*O 05 39 00.5298756288 -02 39 39.085792200 14.96 14.43 13.52 12.99 12.49 G3.5 6 0
59 HD 37525 Y*O 05 39 01.4927799048 -02 38 56.364214344   7.98 8.06   8.210 B5V 73 1
60 * zet Ori ** 05 40 45.52666 -01 56 33.2649 0.50 1.56 1.77 1.85 2.05 O9.7Ib+B0III 344 0
61 * nu. Ori SB* 06 07 34.3258759 +14 46 06.506096 3.6 4.240 4.397     B3IV 226 0
62 * zet Pup BY* 08 03 35.04754 -40 00 11.3321 0.89 1.98 2.25 2.36 2.58 O4I(n)fp 1133 1
63 NAME Chandra Deep Field-North reg 12 36.8 +62 13           ~ 647 0
64 * bet Cru bC* 12 47 43.26877 -59 41 19.5792 0.03 1.02 1.25 1.38 1.64 B1IV 333 0
65 * tau Sco * 16 35 52.9528530 -28 12 57.661515 1.55 2.56 2.81 2.93 3.18 B0.2V 894 0
66 HD 150136 SB* 16 41 20.4155898816 -48 45 46.730465028 4.98 5.78 5.65 6.93   O3.5-4III(f*)+O6IV 182 0
67 [FPS2006] NX 99 X ~ ~           ~ 2 0

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2022.12.04-18:51:36

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