2025ApJ...979..246H

Query : 2025ApJ...979..246H

2025ApJ...979..246H - Astrophys. J., 979, 246 (2025/February-1)

Fast-rotating A- and F-type Stars with Hα Emissions in NGC 3532: Candidate UV-dim Stars?

HE C., LI C. and LI G.

Abstract (from CDS):

Extended main-sequence stars that are dim in the ultraviolet passbands of the Hubble Space Telescope (UV-dim stars) are found in several young and intermediate-age star clusters in the Magellanic Clouds (MCs). The obscuring of the dust in the disks of stars expelled as a result of fast rotation has been suggested to be responsible for the appearance of UV-dim stars and to play an important role in the formation of extended main sequences. In this paper, we report a population of A- and F-type stars that show Hα emission features in their spectra in the young (∼340 Myr old) neighboring Galactic star cluster NGC 3532. By fitting the observed absorption profiles, we found that most Hα emitters are fast-rotating stars, indicating that they form decretion disks by fast rotation like Be stars. As A- and F-type stars dominate the extended main-sequence turnoff regions of intermediate-age clusters, their appearance provides observational evidence to support the dust extinction scenario for these clusters, and they might be the counterparts of UV-dim stars that are detected in remote MC star clusters such as NGC 1783.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Early-type stars - Stellar rotation - Open star clusters

Simbad objects: 46

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Number of rows : 46
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
2 NGC 1783 GlC 04 59 08.590 -65 59 15.84   10.9 10.93     ~ 273 0
3 NGC 1850 Cl* 05 08 50.190 -68 45 35.65   8.84 8.96     ~ 298 1
4 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
5 HD 49330 bC* 06 47 57.2679459720 +00 46 34.035384504 8.45 9.14 8.95     Bnn(e) 98 0
6 Cl* NGC 3532 FERN 679 * 11 02 06.0808415496 -58 34 45.979828680   11.40 11.19     ~ 21 0
7 Cl* NGC 3532 FERN 653 * 11 02 19.7360461440 -58 56 38.672749140   11.36 11.27     ~ 21 0
8 Cl* NGC 3532 FERN 604 * 11 02 45.8601614304 -58 51 38.159909280   12.01 11.61 11.56   ~ 18 0
9 CPD-58 2966 * 11 02 47.2789285248 -58 52 45.868599120   11.22 11.00     ~ 21 0
10 Cl* NGC 3532 FERN 530 * 11 02 58.1485263000 -58 36 17.166511008   11.93 12.32     ~ 20 0
11 Cl* NGC 3532 BUT 22 * 11 02 58.4550856992 -58 57 24.737794956   11.698 11.383 11.173 10.973 ~ 22 0
12 HD 303735 * 11 03 17.9991537096 -58 29 18.406731048   11.654 11.32 11.24 10.944 A 30 0
13 CPD-57 4161 * 11 03 40.6646721024 -58 32 33.137545956   11.20 10.77 10.52 16.768 ~ 19 0
14 Cl* NGC 3532 FERN 427 * 11 03 44.3072255208 -58 57 39.202508124   11.940 11.538 11.21   ~ 24 0
15 Cl* NGC 3532 FERN 423 * 11 03 48.1900734216 -58 48 43.868895012           ~ 19 0
16 CPD-57 4171 * 11 03 54.1484530776 -58 25 05.177436024           ~ 21 0
17 Cl* NGC 3532 FERN 543 * 11 04 13.0880861424 -59 03 21.986838288   11.46 11.58     ~ 16 0
18 Cl* NGC 3532 FERN 428 * 11 04 15.9404198568 -58 57 29.719000224           ~ 20 0
19 NGC 3532 31 gD* 11 04 23.1443884416 -58 41 20.444061048   11.733 11.381 11.187 10.988 B8/9 25 0
20 NGC 3532 39 * 11 04 33.4049748528 -58 41 05.450129376 11.79 11.725 11.337 11.098 10.862 ~ 10 0
21 CPD-57 4193 gD* 11 04 35.7624176880 -58 28 17.408430660   10.96 10.52     ~ 13 0
22 CPD-57 4196 * 11 04 39.6372329664 -58 39 42.845553360   11.441 11.122 10.958 10.776 ~ 23 0
23 CPD-57 4220 * 11 05 13.6728488592 -58 36 14.403052800   11.559 11.232 11.008 10.793 ~ 25 0
24 2MASS J11051438-5844332 * 11 05 14.3873976528 -58 44 33.245373804           ~ 19 0
25 NGC 3532 97 * 11 05 27.6841260984 -58 51 39.774078396   11.753 11.386 11.182 10.973 ~ 23 0
26 CPD-58 3067 * 11 05 33.1169825640 -58 54 37.639844748   11.276 11.010 10.840 10.690 ~ 24 0
27 NGC 3532 OpC 11 05 33.9 -58 42 13           ~ 414 0
28 NGC 3532 102 * 11 05 36.6316229736 -58 53 04.583879520   11.940 11.562 11.313 11.096 ~ 22 0
29 Cl* NGC 3532 FERN 485 * 11 05 48.1231261824 -59 00 18.648270576   11.68 11.35 11.34   ~ 19 0
30 Cl* NGC 3532 FERN 435 SB* 11 05 49.6754049552 -58 56 22.019680428           ~ 22 0
31 Cl* NGC 3532 FERN 615 * 11 05 52.2419511744 -59 06 57.898007352           ~ 21 0
32 Cl* NGC 3532 FERN 436 * 11 05 57.8299107768 -58 56 34.509774156           ~ 11 0
33 CPD-57 4256 * 11 06 06.9997155504 -58 39 52.047444240 11.58 11.485 11.182 11.010 10.809 ~ 23 0
34 Cl* NGC 3532 FERN 437 * 11 06 10.1780648712 -58 56 28.476762288           ~ 20 0
35 NGC 3532 137 * 11 06 10.8138941280 -58 47 11.971210704   11.929 11.559 11.341 11.102 ~ 23 0
36 CPD-57 4261 * 11 06 11.9097141360 -58 39 39.477411432   11.414 11.091 10.922 10.736 ~ 23 0
37 CPD-58 3105 * 11 06 15.3661955880 -58 47 02.181784128   11.340 11.040 10.870 10.702 ~ 17 0
38 Cl* NGC 3532 AR 134 * 11 06 18.8680395912 -58 28 25.899204936           ~ 19 0
39 NGC 3532 151 * 11 06 25.3146474312 -58 34 34.164292872   11.782 11.332 11.038 10.774 ~ 19 0
40 CPD-58 3118 * 11 06 34.2536959368 -58 50 42.159877944   11.399 11.076 10.907 10.759 ~ 24 0
41 2MASS J11064336-5904484 * 11 06 43.3650467616 -59 04 48.333503208           ~ 16 0
42 Cl* NGC 3532 FERN 219 * 11 06 45.5199514776 -58 41 24.172184508   11.76 11.23     ~ 20 0
43 Cl* NGC 3532 FERN 359 * 11 07 12.2041643784 -58 43 11.881898868           ~ 20 0
44 CPD-57 4300 * 11 07 15.9058652760 -58 28 29.358710652           ~ 20 0
45 Cl* NGC 3532 FERN 571 * 11 08 05.5650918744 -58 39 25.614501444   11.72 11.37 11.37   ~ 20 0
46 Cl Trumpler 20 OpC 12 39 33.0 -60 38 10           ~ 138 0

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