2010A&A...521A..26P


Query : 2010A&A...521A..26P

2010A&A...521A..26P - Astronomy and Astrophysics, volume 521, A26-26 (2010/10-1)

Spectral classification and distance determination of stars in nine southern galactic HII regions.

PINHEIRO M.C., COPETTI M.V.F. and OLIVEIRA V.A.

Abstract (from CDS):

We attempt to identify the ionising stars and to determine the photometric distances of nine southern Galactic HII regions. We carried out optical spectroscopy and UBV photometry of the stellar content of these objects. The distance of individual stars were obtained by spectroscopic parallax. To avoid using a fixed value for the total-to-selective extinction ratio RV, the reddening AV was determined directly by the colour-difference approach by comparing our V apparent magnitudes and the JHK magnitudes from the 2MASS survey with the intrinsic colour indices. As types O or B, we classified 24 of the 31 stars for which optical spectra were obtained. In particular, we identified two new O stars, one in RCW98 and the other in RCW99. The values of reddening obtained correspond to a mean <RV≥3.44, which is about 10% higher than the value found for field stars. For three of the HII regions studied (Bran186, NGC2626, and RCW32), the distance estimates (with errors from 25% to 50%) were based on the data obtained for only one star. For the other six objects (NGC3503, NGC6334, RCW55, RCW87, RCW98, and RCW99), we obtained more precise photometric distances (with a mean error of ≃18%) calculated to be the median of the parallax distances obtained for two to six different stars in each nebulae. The parallax distances of individual stars belonging to a given nebula were similar to each other, with internal errors smaller than 5%, as a consequence of the method used to derive the reddening correction AV. The distance of 1.23±0.30kpc obtained for RCW87 disagrees with the value of 7.6kpc previously found. The dispersion in individual distance estimates for stars in a given nebula can be significantly reduced by calculating the reddening AV from a comparison between the V and the 2MASS JHK magnitudes instead of using AV=RV E(B-V) with a fixed value for RV. Therefore, more precise distances can be calculated with our proposed method.

Abstract Copyright:

Journal keyword(s): HII regions - stars: early-type - stars: distances

Simbad objects: 53

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Number of rows : 53
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 CPD-40 2663 Em* 08 35 22.6183905936 -40 36 36.361170072   12.46 12.32     B9Ve 20 0
2 2MASS J08353144-4040190 Y*? 08 35 31.4358526440 -40 40 19.154664732 10.07 10.43 9.90 10.03 9.54 B1V 33 1
3 NGC 2626 RNe 08 35 32 -40 40.3           ~ 31 2
4 BRAN 166 HII 08 38 08.0 -40 17 53           ~ 27 1
5 HD 73882 EB* 08 39 09.53412 -40 25 09.2608 7.07 7.59 7.19 6.67 6.30 O8.5IV 229 2
6 GUM 15 HII 08 43 52.5 -41 14 39           ~ 32 2
7 HD 74804 Y*? 08 44 40.3247349456 -41 16 37.974116352 7.13 9.26 8.84 8.31 9.41 B3/5II 59 1
8 Cl* Trumpler 10 STOCK 694 * 08 48 35.4642246528 -42 54 31.494249108   12.64 12.11 12.01 11.49 F8: 2 0
9 PN K 2-15 HII 08 48 39.0553841664 -42 53 54.005736984   12.86 12.01 11.72 10.79 B0V 67 2
10 Cl* Trumpler 10 STOCK 724 * 08 48 43.1378678664 -42 54 18.335647008   12.17 11.46 11.28 10.67 ~ 3 0
11 GSC 07683-00861 * 08 48 43.3177812936 -42 54 33.095041488   15.81 14.78 14.29 12.77 ~ 1 0
12 [DBS2003] 23 Cl* 08 48 48 -42 54.5           ~ 2 0
13 Cl* Trumpler 10 STOCK 732 * 08 48 48.1375686912 -42 54 20.898623484   12.33 12.52 12.52 11.88 ~ 4 0
14 UCAC2 3884840 * 10 56 26.9827678632 -63 00 00.358784352   13.72 13.21     B8IV 1 0
15 2MASS J10563219-6259584 * 10 56 32.1878307000 -62 59 58.493601276   12.62 12.14     B1V 3 0
16 CPD-62 1822 * 10 56 32.2695155400 -63 00 47.607681492 11.28 11.74 11.27 11.27   B1V 16 0
17 BRAN 328A HII 10 56 32.5 -63 00 46           ~ 20 0
18 CPD-62 1823 * 10 56 38.8690446000 -63 01 02.915676192   11.89 11.47 11.49 10.89 B0V 15 1
19 UCAC2 4092075 * 10 56 40.1507454048 -62 58 46.334379288   12.94 12.36   11.74 B2.5V 3 0
20 2MASS J10564031-6301044 * 10 56 40.3184757216 -63 01 04.580367996   14.36 13.81     B2.5V 4 0
21 CPD-62 1824 * 10 56 42.1982635920 -63 01 16.783410432   11.11 10.65 11.26   O8V 22 1
22 UCAC2 5563436 * 11 00 59.2633672560 -59 50 30.820976160   13.41 13.03   12.50 B8V 1 0
23 NGC 3503 RNe 11 01 15.9 -59 50 39           ~ 19 1
24 VdBH 46d * 11 01 17.1724285416 -59 51 01.940216724 10.95 11.60 11.40   10.94 B2Ve 9 0
25 CD-59 3483 * 11 01 17.7737043504 -59 50 30.356100060 9.99 10.67 10.46   9.99 B0V 11 1
26 Cl Pismis 17 3 * 11 01 18.2391653784 -59 50 57.873500304 10.97 11.62 11.40   10.93 B2V 10 0
27 CPD-59 2945s * 11 01 19.2504550608 -59 50 56.587657452 10.93 11.60 11.37     B2V 11 0
28 Cl Pismis 17 OpC 11 01 30 -59 52.4   9.63 9.4     ~ 46 0
29 TYC 8689-454-1 * 15 05 09.7776343824 -57 32 18.615126408 12.10 12.17 11.72 11.35 10.90 B4V 3 0
30 UCAC2 6636424 * 15 05 15.283 -57 31 25.10         13.86 ~ 1 0
31 NAME RCW 87 IR Cluster Cl* 15 05 18 -57 31.7           ~ 7 0
32 RCW 87 HII 15 05 19 -57 31.8           ~ 44 2
33 TYC 8689-412-1 * 15 05 36.0416550600 -57 32 58.790214744   11.98 11.59   11.00 B9III 2 0
34 RCW 98 HII 15 55.4 -54 39           ~ 15 1
35 CPD-54 6791 ** 15 55 39.60148 -54 38 36.6363 10.51 10.95 10.41 10.37 8.94 O9.5V 39 2
36 [OM80] 140 * 15 55 40.9683404400 -54 41 13.820209764   13.22 12.41     O9.5V 5 0
37 UCAC2 8092284 * 15 55 42.6384133728 -54 39 01.828152324   13.52 12.95   11.99 B2.5V 1 0
38 GRS G328.59 -00.52 bub 15 59 28.4 -53 44 57           ~ 43 1
39 UCAC2 8596465 * 15 59 31.1644725360 -53 44 32.521199892         11.88 F3V 1 0
40 IRAS 15557-5337 MIR 15 59 36.64 -53 45 53.3           ~ 19 0
41 UCAC3 73-301842 * 15 59 38.4360937104 -53 45 14.930806824   14.91 13.22   10.89 O7III 1 0
42 TYC 8697-1749-1 * 15 59 38.7559829064 -53 44 44.064843108   13.05 11.59   11.72 B2V 3 0
43 CPD-53 6912 * 15 59 54.5348242104 -53 44 46.749343956   12.27 12.70     A5: 3 0
44 HD 319699 * 17 19 30.4178180256 -35 42 36.122104260 10.17 10.31 9.63 9.81 8.91 O5V((fc)) 61 0
45 VdBH 86a B * 17 19 44.9194878144 -36 05 41.719618464       12.66 10.99 ~ 17 0
46 VdBH 86a ** 17 19 45.0424018176 -36 05 47.120670132 12.67   11.30 11.22 9.63 O6V((f))z 24 0
47 VdBH 86 RNe 17 19 46 -36 05.8           ~ 61 0
48 HD 319703 * 17 19 46.1639892408 -36 05 52.337458248 11.9 11.73 10.92 10.46 9.30 O7V((f))z 59 0
49 CD-35 11477 * 17 20 05.0829977784 -35 56 41.812824156 11.98 11.98 11.08 10.96   OB- 16 0
50 GUM 64a HII 17 20.1 -35 58           ~ 12 0
51 HD 319702 Y*O 17 20 50.6128007664 -35 51 46.033836192 10.94 11.04 10.11 10.10   O8III 50 0
52 HD 156738 * 17 20 52.6582094016 -36 04 20.565752484 10.06 10.27 9.35 9.65   O6.5III(f) 69 0
53 NGC 6334 HII 17 20 53 -36 07.9           ~ 646 0

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2022.09.29-22:31:50

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