2006A&A...455..561B


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.04CEST21:40:02

2006A&A...455..561B - Astronomy and Astrophysics, volume 455, 561-576 (2006/8-4)

VLT K-band spectroscopy of massive young stellar objects in (ultra-)compact HII regions.

BIK A., KAPER L. and WATERS L.B.F.M.

Abstract (from CDS):

High-quality K-band spectra of strongly reddened point sources, deeply embedded in (ultra-)compact HII regions, have revealed a population of 20 young massive stars showing no photospheric absorption lines, but sometimes strong Brγ emission. The Brγ equivalent widths occupy a wide range (from about 1 to over 100Å); the line widths of 100-200km/s indicate a circumstellar rather than a nebular origin. The K-band spectra exhibit one or more features commonly associated with massive young stellar objects (YSOs) surrounded by circumstellar material: a very red colour (J-K)>2, CO bandhead emission, hydrogen emission lines (sometimes doubly peaked), and FeII and/or MgII emission lines. The large number of objects in our sample allows a more detailed definition and thorough investigation of the properties of the massive YSOs. In the (K, J-K) colour-magnitude diagram (CMD) the massive YSO candidates are located in a region delimited by the OB zero-age main sequence, Be stars, Herbig Ae and Be stars, and B[e] supergiants. The massive YSO distribution in the CMD suggests that the majority of the objects are of similar spectral type as the Herbig Be stars, but some of them are young O stars. The spectral properties of the observed objects do not correlate with the location in the CMD. The CO emission must come from a relatively dense (∼1010cm–3) and hot (T∼2000-5000K) region, sufficiently shielded from the intense UV radiation field of the young massive star. The hydrogen emission is produced in an ionised medium exposed to UV radiation. The best geometrical solution is a dense and neutral circumstellar disk causing the CO bandhead emission, and an ionised upper layer where the hydrogen lines are produced. We present arguments that the circumstellar disk is more likely a remnant of the accretion process than the result of rapid rotation and mass loss such as in Be/B[e] stars.

Abstract Copyright:

Journal keyword(s): infrared: stars - stars: formation - stars: early-type - stars: circumstellar matter - stars: pre-main sequence

Nomenclature: Table 3, text: [BKH2005] HHMMmnrNNNNA N=29 added.

Simbad objects: 34

goto Full paper

goto View the reference in ADS

Number of rows : 34

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 V* V2254 Ori Or* 05 35 14.11296 -05 22 22.7316           B 286 2
2 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1071 1
3 [BCB89] IRS 2b * 05 41 45.50 -01 54 28.7           O8V 34 1
4 [BCB89] IRS 2 * 05 41 45.81 -01 54 29.8           B 93 0
5 RAFGL 5180 SFR 06 08 54.1 +21 38 25           ~ 110 0
6 [KCW94] 188.793+01.030 HII 06 09 06.743 +21 50 41.18           ~ 6 0
7 [KCW94] 188.794+01.031 HII 06 09 06.984 +21 50 41.40           ~ 6 0
8 2MASS J06090728+2150402 Y*O 06 09 07.284 +21 50 40.24           ~ 10 0
9 IRAS 06061+2151 SFR 06 09 07.8 +21 50 39           ~ 81 0
10 NGC 2183 RNe 06 10 46.75 -06 12 44.9           ~ 73 1
11 GGD 14 HH 06 10.8 -06 12           ~ 53 1
12 RAFGL 890S IR 06 10 50.60928 -06 11 51.2772           ~ 74 1
13 NAME GGD 12-15 OpC 06 10 52 -06 12.8           ~ 138 1
14 IRAS 06412-0105 IR 06 43 48.51912 -01 08 19.0248           ~ 19 0
15 DG 121 HII 07 32 09.9 -16 58 14           ~ 50 0
16 MSX5C G265.1485+01.4474 HII 08 59 25.2 -43 45 46           ~ 33 1
17 NGC 3576 HII 11 11 49.8 -61 18 14           ~ 225 2
18 NAME NGC 3576 IRS 1 HII 11 11 54.8 -61 18 26           ~ 30 1
19 IRAS 15411-5352 HII 15 44 59.448 -54 02 13.92           ~ 32 2
20 IRAS 16164-5046 HII 16 20 14.1 -50 53 20           ~ 26 0
21 * 36 Her * 16 40 35.1505728617 +04 12 25.927818306   7.06 6.93     B9V 62 0
22 [DBS2003] 113 Cl* 17 00 35.5 -40 33 31           ~ 31 0
23 GM 1-24 HII 17 17 04.0 -36 21 14           ~ 45 0
24 IRAS 17258-3637 HII 17 29 16.7 -36 40 13           ~ 52 0
25 M 8 HII 18 03 37 -24 23.2           ~ 552 1
26 IRAS 18006-2422 HII 18 03 45.7 -24 22 41           ~ 22 0
27 W 31 SFR 18 10 28.6 -19 55 51           ~ 241 0
28 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1484 0
29 OH 34.26 +0.15 SFR 18 53 18.54 +01 14 57.9           ~ 460 0
30 NAME SH 2-106 IR Y*O 20 27 26.502 +37 22 42.03           ~ 157 1
31 SH 2-106 HII 20 27 26.8 +37 22 49           ~ 409 2
32 V* V645 Cyg Ae* 21 39 58.2775729406 +50 14 21.002745087   14.23 13.10 13.82   O6/9eq 255 0
33 SH 2-140 OpC 22 19 07.8 +63 17 07           ~ 634 2
34 IRAS 22176+6303 Y*O 22 19 17.978 +63 18 52.92           ~ 589 0

    Equat.    Gal    SGal    Ecl

To bookmark this query, right click on this link: simbad:objects in 2006A&A...455..561B and select 'bookmark this link' or equivalent in the popup menu


2020.07.04-21:40:02

© Université de Strasbourg/CNRS

    • Contact