2020A&A...634A...6D


Query : 2020A&A...634A...6D

2020A&A...634A...6D - Astronomy and Astrophysics, volume 634A, 6-6 (2020/2-1)

The NGC 346 massive star census. Nitrogen abundances for apparently single, narrow lined, hydrogen core burning B-type stars.

DUFTON P.L., EVANS C.J., LENNON D.J. and HUNTER I.

Abstract (from CDS):

Previous analyses of two large spectroscopic surveys of early-type stars in the Large Magellanic Cloud (LMC) have found an excess of nitrogen enriched B-type targets with a vesini≤40km/s compared with the predictions of single star evolutionary models that incorporate rotational mixing. By contrast, the number of such targets with 40<vesini≤80km/s was consistent with such models. We have undertaken a similar analysis for 61 B-type targets which lie towards the young cluster, NGC 346 in the Small Magellanic Cloud (SMC). These again have projected rotational velocities, vesini≤80km/s, are not classified as supergiants, and are apparently single. Approximately 65% of these SMC targets could have nitrogen enhancements of less than 0.3dex, which is consistent with them having experienced only small amounts of mixing due to their low rotational velocities. However, as with the previous LMC surveys, an excess of stars with low projected rotational velocities, ve sini≤40km/s, and significant nitrogen enrichments is found. This is estimated to be approximately 5% of the total population of apparently single B-type stars or 40% of all stars with current rotational velocities of less than 40km/s; these percentages are similar to those found previously for the two LMC samples. For all three surveys, the presence of undetected binaries and other uncertainties imply that these percentages might be underestimated and that it is indeed possible for all the single stars with current rotational velocities of less than 40km/s to be nitrogen enriched. Two possible explanations incorporate the effects of the magnetic field, via either a stellar merger followed by magnetic braking or the evolution of a single star with a large magnetic field. Both mechanisms would appear to be compatible with the observed frequency of nitrogen-enriched stars in the Magellanic Clouds. Differences in the properties of the nitrogen-enriched stars compared with the remainder of the sample would be consistent with the former mechanism. For the latter, a qualitative comparison with Galactic evolutionary models that incorporate magnetic fields is encouraging in terms of the amount of nitrogen enrichment and its presence in stars near the zero-age main sequence.

Abstract Copyright: © ESO 2020

Journal keyword(s): stars: abundances - stars: rotation - stars: early-type - Magellanic Clouds - galaxies: star clusters: individual: NGC 346

Simbad objects: 72

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Number of rows : 72
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 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10199 1
2 Cl* NGC 330 ELS 116 * 00 55 26.5159858464 -72 27 33.771621960 15.59 16.43 16.55   16.71 B3III 5 0
3 Cl* NGC 330 ELS 111 * 00 56 17.7106332360 -72 28 37.876642716 15.37 16.30 16.32   16.53 B1-3 5 0
4 Cl* NGC 330 ELS 101 * 00 56 35.3647775184 -72 28 06.725539128 15.37 16.18 16.31   16.56 B2.5III 6 0
5 Cl* NGC 330 ELS 103 * 00 56 52.3175688048 -72 31 18.741510804 15.39 16.31 16.39   16.55 B1-3 4 0
6 2dFS 1188 * 00 57 02.9656718040 -72 07 59.816666640 14.58 15.67 15.93   16.18 B0V 4 0
7 Cl* NGC 346 ELS 47 * 00 57 03.2448434184 -72 09 15.146543520 14.33 15.23 15.39   15.57 B2.5III 8 0
8 Cl* NGC 330 ELS 102 * 00 57 12.1276079832 -72 27 10.529209368 15.35 16.21 16.28   16.48 B2-3III 4 0
9 [BLK2010] flames1227 * 00 57 16.7535899496 -72 12 39.039284016           B3V 3 0
10 [BLK2010] flames1141 * 00 57 20.1440986512 -72 11 15.313817040           B2III 3 0
11 OGLE SMC719.26.000536 EB* 00 57 29.9207555568 -72 04 59.876163300     16.396   16.531 B2.5V 5 0
12 OGLE SMC-SC8 56348 * 00 57 41.1795011832 -72 11 20.098651308 13.98 15.01 15.18   15.39 B0.5III 6 0
13 [BLK2010] flames1153 * 00 57 49.1347198200 -72 13 31.013651496 15.09 16.05 16.17   16.37 B2V 3 0
14 [BLK2010] flames1200 * 00 57 53.0785415640 -72 14 21.815935080 15.31 16.28 16.43   16.57 B1V 3 0
15 [BLK2010] flames1113 * 00 57 53.3305896528 -72 14 47.449869540 14.82 15.76 15.93   16.12 B3III 3 0
16 [BLK2010] flames1109 * 00 57 57.0055444752 -72 16 07.011531480 14.67 15.68 15.82   16.02 B1.5III 3 0
17 [BLK2010] flames1207 * 00 57 57.1850497704 -72 12 37.087409952 15.46 16.34 16.53   16.69 B3V 3 0
18 [BLK2010] flames1028 * 00 58 02.9723546352 -72 16 33.998171376 13.70 14.68 14.78   14.94 B2.5III 3 0
19 OGLE SMC-SC8 55319 * 00 58 03.3529728312 -72 16 29.262839088 14.36 15.42 15.52   15.76 B1III 5 0
20 [BLK2010] flames1133 * 00 58 06.9905769024 -72 16 24.553849872 14.86 15.89 16.05   16.26 B1V 3 0
21 [BLK2010] flames1093 * 00 58 11.4011358792 -72 14 29.353244208           B1V 3 0
22 Cl* NGC 346 MPG 11 Y*O 00 58 13.9512028416 -72 09 19.107879408 14.02 15.12 15.27   15.46 B0V 14 0
23 Cl* NGC 346 MPG 12 * 00 58 14.0865065520 -72 10 44.292892764   19.15 17.98   16.72 B0IV(Nstr) 31 0
24 [BLK2010] flames1076 * 00 58 14.9263813080 -72 16 36.680976804 14.33 15.34 15.47   15.71 B1III 3 0
25 [BLK2010] flames1239 * 00 58 15.5452839936 -72 16 45.852523860           B2V 3 0
26 [BLK2010] flames1041 * 00 58 19.34 -72 17 56.5           B2III-II 3 0
27 [BLK2010] flames1173 * 00 58 20.3658120240 -72 12 54.949896180           B1V 3 0
28 Cl* NGC 346 MPG 46 * 00 58 21.4159374336 -72 12 28.214409960   16.30 16.49     B2.5V 4 0
29 [BLK2010] flames1150 * 00 58 27.8049105456 -72 16 08.262522516 14.96 16.01 16.14   16.33 B1V 3 0
30 Cl* NGC 346 MPG 111 EB* 00 58 31.4286771672 -72 12 24.693236496 15.25 16.46 16.67   16.84 B0.2V 8 0
31 OGLE SMC-SC8 107312 * 00 58 31.6824143616 -72 15 49.958533476 14.30 15.32 15.46   15.63 B0.7III 5 0
32 [BLK2010] flames1125 * 00 58 32.1609533520 -72 14 38.768518644   15.16 15.12     B0V 4 0
33 LIN 342 Em* 00 58 41.8185973272 -72 11 17.784001428 13.71 14.89 14.95   14.80 B0.2:(Be-Fe) 15 0
34 OGLE SMC-SC8 110238 * 00 58 42.7174669584 -72 14 28.399002036 13.89 14.83 15.01   15.22 B2.5III-II 5 0
35 OGLE SMC-SC8 107276 * 00 58 45.6614076744 -72 17 16.814617404 14.24 15.04 15.11   15.34 B1.5II 6 0
36 OGLE SMC-SC8 107537 EB* 00 58 47.69 -72 16 07.2   17.67 17.73 17.75 17.73 B3V 9 0
37 Cl* NGC 346 MPG 279 * 00 58 53.0509444824 -72 10 03.361519128   16.17 16.39     B0V 7 0
38 Cl* NGC 346 MPG 310 * 00 58 56.1124005840 -72 09 33.953825700 14.18 15.26 15.39   15.81 B0V 9 0
39 Cl* NGC 346 MPG 309 * 00 58 56.5000722048 -72 13 13.539191844 14.43 15.37 15.52   15.63 B1V 7 0
40 [MBF2010] NGC 346 43 Em* 00 58 58.00 -72 06 25.1 15.87 16.65 16.75   16.81 B3V 4 0
41 Cl* NGC 346 MPG 329 * 00 58 58.88 -72 13 18.0   19.76 18.52     B2.5V 4 0
42 NGC 346 Cl* 00 59 05.090 -72 10 33.24           ~ 459 0
43 [BLK2010] flames1221 * 00 59 07.34 -72 13 12.8           B0.5V 3 0
44 Cl* NGC 346 MPG 550 * 00 59 10.02 -72 11 30.3   16.45 16.70     B1V 5 0
45 [MA93] 1123 Em* 00 59 10.8649354728 -72 18 28.374969960 14.74 15.79 15.72   15.73 B1-2(Be-Fe) 6 0
46 Cl* NGC 346 ELS 98 * 00 59 11.0257343856 -72 13 04.074556836   15.87 16.09     B1.5V 9 0
47 Cl* NGC 346 MPG 595 * 00 59 11.959 -72 10 56.10 14.44 15.26 15.47   15.72 B0III 8 0
48 [BLK2010] flames1176 * 00 59 15.9156874872 -72 17 38.917265100 15.21 16.20 16.19   16.44 B1.5V 3 0
49 [BLK2010] flames1080 * 00 59 18.3444483168 -72 04 21.073431252 14.41 15.45 15.66   15.95 B0.5III 5 0
50 Cl* NGC 346 ELS 21 * 00 59 19.58 -72 14 50.5 13.69 14.72 14.86   15.07 B1III 11 0
51 Cl* NGC 346 MPG 701 * 00 59 20.60 -72 09 58.0 15.69 16.74 16.87   16.73 B2III 5 0
52 Cl* NGC 346 MPG 753 Em* 00 59 26.4913203144 -72 13 11.756190612 14.18 15.17 15.36   15.56 B1II 11 0
53 [BLK2010] flames1142 * 00 59 29.2012751088 -72 08 39.345644724           B1.5III 3 0
54 OGLE SMC-SC8 160746 * 00 59 38.6250661512 -72 14 01.683423276 15.21 16.28 16.48   16.69 B1.5V 4 0
55 [BLK2010] flames1186 * 00 59 43.7054058864 -72 07 37.629538572 15.48 16.35 16.54   16.71 B2V 3 0
56 [BLK2010] flames1217 * 00 59 44.8144439352 -72 15 26.822886804 15.62 16.49 16.48   16.63 B2.5V 3 0
57 [BLK2010] flames1029 EB* 00 59 47.9061997440 -72 04 50.873134980 13.90 14.73 14.96   15.12 B2.5III 6 0
58 [MA93] 1166 Em* 00 59 51.5646412464 -72 16 20.336030652 15.35 16.34 16.40   16.30 B1-3e 4 0
59 [BLK2010] flames1119 * 00 59 52.3992488640 -72 08 02.762564496 14.91 15.86 15.99   16.16 B1V 3 0
60 [MA93] 1169 Em* 00 59 52.93 -72 06 31.1 14.62 16.39 16.46   15.81 B2.5III 11 0
61 Cl* NGC 346 ELS 62 * 00 59 56.6315021640 -72 05 08.629222488 14.47 15.51 15.71   16.01 B0.2V 7 0
62 Cl* NGC 346 ELS 94 * 00 59 57.2342097552 -72 07 00.344670708   15.7 16.01     B0.7V 7 0
63 2MASS J01001665-7214344 * 01 00 16.6984976904 -72 14 34.276285104 14.29 15.37 15.60   15.79 B0III+B 6 0
64 [BLK2010] flames1131 * 01 00 17.1874614288 -72 07 44.469627024 15.16 15.94 16.06   16.20 B3III 3 0
65 [BLK2010] flames1223 * 01 00 19.4758749480 -72 12 58.422459528           B1V 3 0
66 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6282 1
67 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15998 1
68 VFTS 95 * 05 37 38.5130215104 -69 06 04.424553252   16.04 16.06     B0.2V 8 0
69 VFTS 214 * 05 37 58.0064935488 -69 13 09.484140720   16.11 15.84     B0IV-III 8 0
70 RMC 136 Cl* 05 38 42.396 -69 06 03.36           ~ 1857 1
71 [P93] 1786 * 05 38 56.859 -69 06 38.47   16.22 16.17     B0.2V 9 0
72 * tau Sco * 16 35 52.9528530 -28 12 57.661515 1.55 2.56 2.81 2.93 3.18 B0.2V 887 0

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2022.05.24-23:29:15

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