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


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.16CET03:55:02

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 - 2020
#notes
1 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9107 1
2 HD 18881 * 03 03 31.9447787130 +38 24 36.074494463   7.12 7.14     A0 75 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14346 1
4 * eta Car Em* 10 45 03.5455050 -59 41 03.951060 6.37 7.034 6.21 4.90 4.41 OBepec 2151 0
5 [BSD96] 22 WR* 17 45 39.38 -29 00 33.4           WC8/9 27 0
6 NAME Sgr A West HII 17 45 39.4 -29 00 24           ~ 345 0
7 [BSD96] 29 WR* 17 45 39.46 -29 00 31.7           WN8 26 0
8 [BSD96] 33 WR* 17 45 39.54 -29 00 35.0           Ofpe/WN9 38 0
9 GCIRS 6E WR* 17 45 39.632 -29 00 27.05           Ofpe/WN9 59 0
10 GCIRS 13E Cl* 17 45 39.73 -29 00 29.7           WN9 90 0
11 GCIRS 34W WR* 17 45 39.73 -29 00 26.6           Ofpe/WN9 52 0
12 GCIRS 3 * 17 45 39.80 -29 00 23.9           ~ 137 0
13 GCIRS 13E3 ** 17 45 39.8038 -29 00 29.627           ~ 23 1
14 GCIRS 7W WR* 17 45 39.86 -29 00 22.2           WC9 35 0
15 GCIRS 29S * 17 45 39.91 -29 00 27.3           K3III 20 0
16 GCIRS 29N WR* 17 45 39.917 -29 00 26.71           WC9 53 0
17 GCIRS 15SW WR* 17 45 39.92 -29 00 18.1           WN8/WC9 35 0
18 GCIRS 29NE1 WR* 17 45 39.9643 -29 00 26.021           WC8/9 32 0
19 GCIRS 7 * 17 45 39.987 -29 00 22.24           M2 337 0
20 GCIRS 16 Cl* 17 45 40.0 -29 00 28           ~ 294 0
21 GCIRS 33SE Em* 17 45 40.02 -29 00 31.0           Ofpe/WN9 24 0
22 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3283 3
23 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11047 0
24 GCIRS 16NW WR* 17 45 40.0454 -29 00 26.874           Ofpe/WN9 126 0
25 GCIRS 14SW * 17 45 40.07 -29 00 37.7           M0III 19 0
26 GCIRS 16C WR* 17 45 40.12 -29 00 27.6           Ofpe/WN9 163 1
27 GCIRS 16SW WR* 17 45 40.123 -29 00 29.09           Ofpe/WN9 140 0
28 GCIRS 15NE WR* 17 45 40.15 -29 00 16.5           WN8/9 52 0
29 GCIRS 16SE1 WR* 17 45 40.181 -29 00 29.26           WC8/9 41 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 51 0
32 GCIRS 9W WR* 17 45 40.26 -29 00 33.7           WN8 27 0
33 GCIRS 35W WR* 17 45 40.26 -29 00 29.3           WN5/6 40 0
34 GCIRS 16NE WR* 17 45 40.26 -29 00 27.2           Ofpe/WN9 137 0
35 GCIRS 7SE * 17 45 40.2638 -29 00 24.703           ~ 19 0
36 [PMM2001] B9 WR* 17 45 40.2673 -29 00 24.628           WC9 15 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? 94 0
39 [OEG99] 180 WR* 17 45 40.76 -29 00 27.8           WC9 14 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 1126 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

    Equat.    Gal    SGal    Ecl

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2019.11.16-03:55:02

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