2013A&A...557A..51C


Query : 2013A&A...557A..51C

2013A&A...557A..51C - Astronomy and Astrophysics, volume 557A, 51-51 (2013/9-1)

CEN 34 - high-mass YSO in M 17 or background post-AGB star ?

CHEN Z., NUERNBERGER D.E.A., CHINI R., LIU Y., FANG M. and JIANG Z.

Abstract (from CDS):

We investigate the proposed high-mass young stellar object(YSO) candidate CEN34, thought to be associated with the star-forming region M17. Its optical to near-infrared (550-2500nm) spectrum reveals several photospheric absorption features, such as Hα, the CaII triplet, and the CO bandhead, but lacks emission lines. The spectral features in the range 8375-8770Å are used to constrain an effective temperature Teff=5250±250K (early-/mid-G) and a logg=2.0±0.3 (supergiant). The spectral energy distribution (SED) displays a faint infrared excess that resembles that of a high-mass YSO or an evolved star of intermediate mass. Moreover, the observed temperature and surface gravity are identical for high-mass YSOs and evolved stars. The radial velocity of CEN34 relative to the local standard of rest (VLSR) as obtained from various photospheric lines is of the order of -60km/s and thus distinct from the +25km/s found for several OB stars in the cluster and for the associated molecular cloud. The SED modeling yields ∼10–4M of circumstellar material, which contributes only a tiny fraction to the total visual extinction (11mag). The distance of CEN34 is between 2.0kpc and 4.5kpc. In the case of a YSO, a dynamical ejection process is proposed to explain the VLSR difference between CEN34 and M17. Additionally, to match the temperature and luminosity, we speculate that CEN34 had accumulated the bulk of its mass with an accretion rate >4x10–3M/yr over a very short time span (∼103yrs), and it is currently undergoing a phase of gravitational contraction without any further mass gain. However, all the aforementioned characteristics of CEN34 are compatible with an evolved star of 5-7M and an age of 50-100Myr, so it is most likely a background post-AGB star with a distance between 2.0kpc and 4.5kpc. We consider the latter classification as the more likely interpretation. Further discrimination of the two possible scenarios should come from the stricter confinement of CEN34's distance.

Abstract Copyright:

Journal keyword(s): stars: late-type - stars: AGB and post-AGB - stars: formation - stars: pre-main sequence

Simbad objects: 21

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Number of rows : 21
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 * psi03 Psc * 01 09 49.2008972448 +19 39 30.264861132   6.263 5.562     F9IIIa 127 0
2 * eps Leo V* 09 45 51.0733004 +23 46 27.320834 4.23 3.79 2.98 2.36 1.93 G1IIIa 330 0
3 HD 100858 V* 11 37 42.3191105712 +77 35 44.518079148   8.097 6.486     K5 16 0
4 * alf Boo RG* 14 15 39.67207 +19 10 56.6730 2.46 1.18 -0.05 -1.03 -1.68 K1.5IIIFe-0.5 2232 0
5 * 5 Ser Ro* 15 19 18.7974409923 +01 45 55.466382064   5.60   4.8   F8IV 331 0
6 CD-38 10980 WD* 16 23 33.8380498896 -39 13 46.161043572 9.916 10.885 11.029 10.936 10.841 DA2 464 0
7 * 84 Her PM* 17 43 21.5645208624 +24 19 40.156969404   6.394 5.729     G2IIIb 140 0
8 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13094 0
9 Cl* NGC 6618 B 358 * 18 20 21.3564651432 -16 09 59.556267072           O8V 11 0
10 NAME M 17 SW SFR 18 20 23.1 -16 11 43           ~ 263 0
11 NAME M 17 UC1 HII 18 20 24.82 -16 11 34.9           ~ 53 1
12 Cl* NGC 6618 B 275 * 18 20 25.17 -16 10 26.7     15.6     B2V 21 0
13 NAME M 17 North MoC 18 20 40.19 -16 09 29.0           ~ 44 0
14 NGC 6618 OpC 18 20 47 -16 10.3           ~ 1554 0
15 HD 185018 * 19 36 52.4545556280 +11 16 23.522333484   6.834 5.975     G0Ib-II 66 0
16 HD 193896 * 20 23 00.7898095776 -09 39 16.957882044   7.194 6.283     G5IIIa 36 0
17 * 9 Peg V* 21 44 30.6958139 +17 21 00.057062 6.48 5.52 4.35 3.53 2.98 G5Ib 265 0
18 NAME Outer Arm PoG 21 48 +69.4           ~ 271 0
19 * alf Aqr * 22 05 47.0359315 -00 19 11.456766 4.65 3.90 2.94 2.27 1.76 G2Ib 428 0
20 IRAS 23304+6147 pA* 23 32 44.7858431592 +62 03 49.090372272   15.36 12.99 12.23 10.50 G2Ia 110 0
21 V* OU And Ro* 23 49 40.9595121216 +36 25 31.013370732   6.69 5.90     G1IIICaIIem 136 0

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2022.08.12-14:02:45

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