2001A&A...366..466P


Query : 2001A&A...366..466P

2001A&A...366..466P - Astronomy and Astrophysics, volume 366, 466-480 (2001/2-1)

New results on the helium stars in the Galactic Center using BEAR spectro-imagery.

PAUMARD T., MAILLARD J.P., MORRIS M. and RIGAUT F.

Abstract (from CDS):

Integral field spectroscopy of the central parsec of the Galactic Center was obtained at 2.06 µm using BEAR, an imaging Fourier Transform Spectrometer, at a spectral resolution of 74km/s. Sixteen stars were confirmed as ``helium stars" by detecting the HeI 2.058µm line in emission, providing a homogeneous set of fully resolved line profiles. These observations allow us to discard some of the earlier detections of such stars in the central cluster and to add three new stars. The sources detected in the BEAR data were compared with adaptive optics images in the K band to determine whether the emission was due to single stars. Two sub-classes of almost equal number are clearly identified from the width of their line profiles, and from the brightness of their continuum. The first class is characterized by very broad line profiles (FWHM≃1000km/s) and by their relative faintness. The other, brighter in K by an average factor of ∼9, has a much narrower emission component of width ≃200km/s. Most of the emission lines show a P Cygni profile. From these results, we propose that the latter group is formed of stars in or near the LBV phase, and the other one of stars at the WR stage. The division into two groups is also shown by their spatial distribution, with the narrow-line stars in a compact central cluster (IRS 16) and the other group distributed at the periphery of the central cluster of hot stars. In the same data cube, streamers of interstellar helium gas are also detected. The helium emission traces the densest parts of the SgrA West Mini-Spiral. Several helium stars have a radial velocity comparable to the velocity of the interstellar gas in which they are embedded. In the final discussion, all these findings are examined to present a possible scenario for the formation of very massive stars in the exceptional conditions of the vicinity of the central Black Hole.

Abstract Copyright:

Journal keyword(s): instrumentation: spectrograph - techniques: radial velocities - infrared: stars - galaxy: center - early-type - stars: wolf-rayet stars:

Nomenclature: Fig.1: [PMM2001] HeI AN (Nos N1-N3). Tables 1, 2: [PMM2001] AN (Nos N1-N7, B1-B9).

Simbad objects: 46

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Number of rows : 46
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10361 1
2 HD 18881 * 03 03 31.9447272600 +38 24 36.075859488   7.12 7.14     A0 79 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16242 1
4 * eta Car Em* 10 45 03.5377808928 -59 41 04.051599720 6.37 7.03 6.48 4.90 4.41 OBepec 2341 0
5 [BSD96] 22 WR* 17 45 39.38 -29 00 33.4           WC8/9 28 0
6 NAME Sgr A West HII 17 45 39.4 -29 00 24           ~ 366 0
7 [BSD96] 29 WR* 17 45 39.46 -29 00 31.7           WN8 29 0
8 [BSD96] 33 WR* 17 45 39.54 -29 00 35.0           Ofpe/WN9 41 0
9 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13179 0
10 GCIRS 6E WR* 17 45 39.632 -29 00 27.05           Ofpe/WN9 63 0
11 GCIRS 13E Cl* 17 45 39.73 -29 00 29.7           WN9 110 0
12 GCIRS 34W WR* 17 45 39.73 -29 00 26.6           Ofpe/WN9 57 0
13 GCIRS 3 * 17 45 39.80 -29 00 23.9           ~ 143 0
14 GCIRS 13E3 ** 17 45 39.8038 -29 00 29.627           ~ 28 1
15 GCIRS 7W WR* 17 45 39.86 -29 00 22.2           WC9 37 0
16 GCIRS 29S * 17 45 39.91 -29 00 27.3           K3III 21 0
17 GCIRS 29N WR* 17 45 39.917 -29 00 26.71           WC9 55 0
18 GCIRS 15SW WR* 17 45 39.92 -29 00 18.1           WN8/WC9 37 0
19 GCIRS 29NE1 WR* 17 45 39.9643 -29 00 26.021           WC8/9 34 0
20 GCIRS 7 * 17 45 39.987 -29 00 22.24           M2 360 0
21 GCIRS 16 Cl* 17 45 40.0 -29 00 28           ~ 336 0
22 GCIRS 33SE Em* 17 45 40.02 -29 00 31.0           Ofpe/WN9 24 0
23 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3951 3
24 GCIRS 16NW WR* 17 45 40.0451 -29 00 26.847           Ofpe/WN9 131 0
25 GCIRS 14SW * 17 45 40.07 -29 00 37.7           M0III 21 0
26 GCIRS 16C WR* 17 45 40.12 -29 00 27.6           Ofpe/WN9 177 1
27 GCIRS 16SW WR* 17 45 40.1245 -29 00 29.018           Ofpe/WN9 151 0
28 GCIRS 15NE WR* 17 45 40.15 -29 00 16.5           WN8/9 57 0
29 GCIRS 16SE1 WR* 17 45 40.181 -29 00 29.26           WC8/9 43 0
30 Tam GCHe1 PoC 17 45 40.184 -29 00 34.06           ~ 3 0
31 GCIRS 16CC s*b 17 45 40.1939 -29 00 27.532           O9.5/B0.5I 52 0
32 GCIRS 9W WR* 17 45 40.26 -29 00 33.7           WN8 31 0
33 GCIRS 35W WR* 17 45 40.26 -29 00 29.3           WN5/6 44 0
34 GCIRS 16NE WR* 17 45 40.26 -29 00 27.2           Ofpe/WN9 147 0
35 GCIRS 7SE * 17 45 40.2638 -29 00 24.703           ~ 20 0
36 [PMM2001] B9 WR* 17 45 40.2673 -29 00 24.628           WC9 17 1
37 GCIRS A22 * 17 45 40.395 -29 00 25.25           ~ 4 0
38 GCIRS 1W Em* 17 45 40.442 -29 00 27.51           Be? 102 0
39 [OEG99] 180 WR* 17 45 40.76 -29 00 27.8           WC9 15 0
40 * P Cyg s*b 20 17 47.2020844 +38 01 58.552724 4.66 5.24 4.82 4.28 4.02 B1-2Ia-0ep 1155 1
41 Tam GCHe5 PoC ~ ~           ~ 2 0
42 Tam GCHe4 PoC ~ ~           ~ 2 0
43 GCIRS 16SE IR ~ ~           ~ 11 0
44 NAME BSD WC9B ? ~ ~           ~ 2 0
45 [PMM2001] HeI N2 * ~ ~           ~ 2 0
46 GCIRS 7E2 * ~ ~           ~ 13 0

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2022.09.25-18:54:07

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