2008A&A...492..111C


C.D.S. - SIMBAD4 rel 1.7 - 2020.04.04CEST08:44:47

2008A&A...492..111C - Astronomy and Astrophysics, volume 492, 111-115 (2008/12-2)

On the central ionizing star of G23.96+0.15 and near-IR spectral classification of O stars.

CROWTHER P.A. and FURNESS J.P.

Abstract (from CDS):

A near-infrared study of the main ionizing star of the ultracompact HII region G23.96+0.15 (IRAS 18317-0757) is presented, along with a re-evaluation of the distance to this source, and a re-assessment of H- and K-band classification diagnostics for O dwarfs We have obtained near-IR VLT/ISAAC imaging and spectroscopy of G23.96+0.15, plus archival imaging from UKIRT/UFTI. A spectroscopic analysis was carried out using a non-LTE model atmosphere code. A quantitative H- and K-band classification scheme for O dwarfs is provided, from which we establish an O7.5V spectral subtype for the central star of G23.96+0.15. We estimate an effective temperature of Teff∼38kK from a spectral analysis. A spectroscopic distance of 2.5kpc is obtained for G23.96+0.15, substantially lower than the kinematic distance of 4.7kpc, in common with recent studies of other Milky way HII regions. Such discrepancies would be alleviated if sources are unresolved binaries or clusters.

Abstract Copyright:

Journal keyword(s): ISM: HII regions - ISM: dust, extinction - stars: early-type - stars: fundamental parameters

Nomenclature: Fig.1, Table 1: [CF2008] NWW (Nos 1-3, 3NW, 3SE).

Status at CDS:   will not be processed
// All or part of tables of objects will not be ingested in SIMBAD.

CDS comments: Paragraph 1. IRAS 8434-0242 is a misprint for IRAS 18434-0242.

Simbad objects: 11

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Number of rows : 11

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 * sig Ori Y*O 05 38 44.7665260139 -02 36 00.284709290 2.54 3.58 3.79 3.87 4.11 O9.5V 736 0
2 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11319 0
3 [WAM82] 023.955+0.152 HII 18 34 24.9 -07 54 50           ~ 70 1
4 [CF2008] 3NW NIR 18 34 24.9 -07 54 48           ~ 1 0
5 [CF2008] 1 NIR 18 34 24.9 -07 54 48           O7.5V 1 0
6 [CF2008] 3SE NIR 18 34 24.9 -07 54 48           ~ 1 0
7 [CF2008] 3 NIR 18 34 24.9 -07 54 48           ~ 1 1
8 [CF2008] 2 NIR 18 34 24.9 -07 54 48           ~ 1 0
9 [WC89] 023.96+0.15A HII 18 34 25.0 -07 54 46           ~ 3 0
10 2MASS J18342523-0754455 IR 18 34 25.24 -07 54 45.5           ~ 1 0
11 GAL 029.96-00.02 Y*O 18 46 03.7 -02 39 21           ~ 330 1

    Equat.    Gal    SGal    Ecl

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