2022A&A...665A..76C

Query : 2022A&A...665A..76C

2022A&A...665A..76C - Astronomy and Astrophysics, volume 665A76-76 (2022/9-1)

Extended population associated with W40.

COMERON F., DJUPVIK A.A. and SCHNEIDER N.

Abstract (from CDS):


Context. W40 is a heavily obscured bipolar HII region projected in the direction of the Aquila Rift and ionized by hot stars in a central, partly embedded cluster. The study of the cluster and its surroundings has been greatly hampered thus far by the strong extinction in the region.
Aims. Our aim is to improve the characterization of the W40 central cluster in terms of the census of its members and their spectral classification. We also search for other members of the region outside the central cluster, with a particular interest in previously unidentified massive members that may contribute to the energy budget powering the expansion of the HII region.
Methods. We used the Gaia eDR3 catalog to establish astrometric membership criteria based on the population of the W40 central cluster, reassess the distance of the region, and use this information to identify new members, both inside and outside the cluster. We obtained visible spectroscopy in the red spectral region to classify both known and new members, complemented with Gaia and Spitzer photometry to assess the evolutionary status of the stellar population.
Results. Based on stars with high quality Gaia astrometry, we derive a high-confidence geometric distance to the W40 region of 502 pc ± 4 pc and we confirm the presence of a comoving extended population of stars at the same distance, spreading over the whole projected area of the HII region and beyond. Spectral classifications are presented for 21 members of the W40 region, 10 of them belonging to the central cluster. One of the newly identified B stars in the extended population is clearly interacting with the shell surrounding the HII region, giving rise to a small arc-shaped nebula that traces a bow shock. The infrared excess properties suggest that the extended population is significantly older (∼3 Myr) than the W40 central cluster (< 1 Myr).
Conclusions. The area currently occupied by the W40 HII region and its surroundings has a history of star formation extending at least several million years in the past. The formation of the W40 central cluster and the subsequent HII region is one of the latest episodes of these processes. The newly determined distance suggests that W40 is behind, as well as physically detached from, a pervasive large dust layer, which is some 60 pc foreground with respect to it, as determined by previous studies.

Abstract Copyright: © F. Comerón et al. 2022

Journal keyword(s): stars: early-type - ISM: bubbles - HII regions - open clusters and associations: individual: W40

VizieR on-line data: <Available at CDS (J/A+A/665/A76): table4.dat table5.dat>

Simbad objects: 120

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Number of rows : 120
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 Ori Complex Cld 05 35.3 -05 23           ~ 481 0
2 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 1195 1
3 NAME Serpens South molecular cloud MoC 18 30 -02.0           ~ 116 0
4 2MASS J18301462-0224422 Y*? 18 30 14.6202675977 -02 24 42.210974532           ~ 1 0
5 2MASS J18301503-0224170 Y*? 18 30 15.0343014840 -02 24 16.965423076           ~ 1 0
6 2MASS J18301837-0211372 Y*? 18 30 18.3614946569 -02 11 37.304958621           ~ 1 0
7 2MASS J18303592-0147405 Y*? 18 30 35.9375895261 -01 47 40.554895744           ~ 1 0
8 2MASS J18304355-0211022 Y*? 18 30 43.5636253521 -02 11 02.193079381           ~ 1 0
9 2MASS J18304624-0209377 Y*? 18 30 46.2484798992 -02 09 37.683201492           ~ 2 0
10 2MASS J18304825-0209483 Y*? 18 30 48.2597948736 -02 09 48.310270164           ~ 6 0
11 2MASS J18305549-0209296 Y*? 18 30 55.5015336576 -02 09 29.880700668           ~ 2 0
12 2MASS J18305563-0147161 Y*? 18 30 55.6394339993 -01 47 16.409674084           ~ 1 0
13 2MASS J18305642-0204477 Y*? 18 30 56.4150293520 -02 04 47.989782804           ~ 2 0
14 2MASS J18305813-0208024 Y*O 18 30 58.1330126016 -02 08 02.617030176           ~ 7 0
15 2MASS J18305842-0201113 Y*? 18 30 58.4273495088 -02 01 11.392037724           ~ 2 0
16 2MASS J18310431-0200358 Y*? 18 31 04.3203382920 -02 00 36.005282100           ~ 3 0
17 2MASS J18310483-0206498 Y*? 18 31 04.8286326216 -02 06 49.938716592           ~ 2 0
18 2MASS J18310501-0202475 Y*? 18 31 05.0130780096 -02 02 47.640192828           ~ 4 0
19 2MASS J18310525-0206340 Y*? 18 31 05.2428271896 -02 06 34.151470740           ~ 2 0
20 NAME Aql Region reg 18 31.1 -02 10           ~ 456 0
21 2MASS J18310967-0156081 Y*? 18 31 09.6810616920 -01 56 08.289482712           ~ 2 0
22 2MASS J18310974-0149595 Y*? 18 31 09.7461156468 -01 49 59.742294155           ~ 1 0
23 2MASS J18311173-0204192 Y*? 18 31 11.7278428080 -02 04 19.321359384           ~ 2 0
24 2MASS J18311227-0201544 Y*? 18 31 12.2774703378 -02 01 54.533529119           ~ 1 0
25 2MASS J18311327-0203515 Y*? 18 31 13.2729199656 -02 03 51.614104788           ~ 2 0
26 2MASS J18311336-0203484 Y*? 18 31 13.3601756424 -02 03 48.479714784           ~ 3 0
27 2MASS J18311503-0149020 * 18 31 15.03768 -01 49 02.0424           ~ 1 0
28 2MASS J18311526-0205355 Y*O 18 31 15.2571338616 -02 05 35.676403692           ~ 5 0
29 2MASS J18311594-0205386 Y*? 18 31 15.9339501960 -02 05 38.815919376           ~ 2 0
30 2MASS J18311599-0203543 Y*? 18 31 15.9849317736 -02 03 54.458368956           ~ 2 0
31 2MASS J18311690-0205469 Y*? 18 31 16.9044047736 -02 05 47.111436096           ~ 2 0
32 2MASS J18311732-0200461 Y*O 18 31 17.3249786616 -02 00 46.340134884           ~ 8 0
33 2MASS J18311798-0206265 Y*? 18 31 17.9824935408 -02 06 26.617973904           ~ 4 0
34 2MASS J18311877-0203360 Y*? 18 31 18.7681522704 -02 03 36.146351988           ~ 3 0
35 2MASS J18311901-0204419 Y*? 18 31 19.0139640192 -02 04 42.059476200           ~ 2 0
36 2MASS J18311905-0212327 Y*? 18 31 19.0399140095 -02 12 32.943239352           ~ 1 0
37 2MASS J18311909-0204381 Y*? 18 31 19.0946220576 -02 04 38.236427652           ~ 2 0
38 2MASS J18311995-0212359 Y*? 18 31 19.9526342184 -02 12 36.146858724           ~ 2 0
39 2MASS J18311996-0206007 Y*? 18 31 19.9612350192 -02 06 00.885145320           ~ 2 0
40 2MASS J18312074-0205181 Y*? 18 31 20.7431266296 -02 05 18.049960824           ~ 3 0
41 2MASS J18312122-0204001 Y*? 18 31 21.2309152704 -02 04 00.168087216           ~ 3 0
42 2MASS J18312170-0204529 Y*? 18 31 21.7098879024 -02 04 53.004025416           ~ 4 0
43 2MASS J18312197-0214501 Y*? 18 31 21.9744354336 -02 14 50.196386148           ~ 2 0
44 2MASS J18312199-0205265 Y*? 18 31 21.9884597280 -02 05 26.532959064           ~ 4 0
45 2MASS J18312255-0204134 Y*? 18 31 22.5600912072 -02 04 13.515653280           ~ 2 0
46 2MASS J18312285-0204125 Y*? 18 31 22.8578022504 -02 04 12.529851456           ~ 2 0
47 2MASS J18312324-0206179 Y*? 18 31 23.2464854856 -02 06 17.998267212           ~ 4 0
48 2MASS J18312327-0204386 Y*? 18 31 23.2791469968 -02 04 38.585897796           ~ 4 0
49 2MASS J18312371-0205538 Y*? 18 31 23.7177493344 -02 05 53.907588384           ~ 4 0
50 2MASS J18312393-0202088 Y*? 18 31 23.9384032052 -02 02 08.855009090           ~ 1 0
51 2MASS J18312479-0205348 Y*? 18 31 24.8055796512 -02 05 34.856254572           ~ 3 0
52 NAME W 40 Cluster Cl* 18 31 25 -02 05.8           ~ 10 2
53 2MASS J18312534-0204418 Y*? 18 31 25.3473407880 -02 04 41.906842536           ~ 2 0
54 2MASS J18312538-0203326 Y*? 18 31 25.3859337384 -02 03 32.676572592           ~ 4 0
55 2MASS J18312542-0205070 Y*? 18 31 25.428 -02 05 07.07           ~ 4 0
56 2MASS J18312592-0215465 Y*O 18 31 25.9198882128 -02 15 46.536089004           ~ 6 0
57 2MASS J18312622-0156507 Y*? 18 31 26.2200555539 -01 56 50.795440483           ~ 1 0
58 LBN 028.77+03.43 HII 18 31 26.5 -02 04 22           ~ 255 2
59 2MASS J18312734-0205074 * 18 31 27.3563423894 -02 05 07.496602381           ~ 2 0
60 2MASS J18312745-0205118 Y*? 18 31 27.4602697752 -02 05 11.934787164           ~ 9 0
61 CXOW40 J183127.58-020517.7 * 18 31 27.5834553600 -02 05 17.671107732           ~ 4 0
62 2MASS J18312788-0206162 Y*? 18 31 27.8872719340 -02 06 16.198190148           ~ 1 0
63 2MASS J18312866-0205297 Y*? 18 31 28.6632266856 -02 05 29.804888544           ~ 8 0
64 2MASS J18312981-0207444 Y*? 18 31 29.8170337416 -02 07 44.387246640           ~ 7 0
65 Gaia DR3 4270176749063423616 * 18 31 35.5958450439 -02 19 18.908987085           ~ 1 0
66 2MASS J18313683-0218406 Y*? 18 31 36.8352564853 -02 18 40.641067848           ~ 1 0
67 2MASS J18314002-0205339 Y*O 18 31 40.0218658200 -02 05 33.964142208           ~ 8 0
68 2MASS J18314083-0214194 Y*? 18 31 40.8374072347 -02 14 19.454715506           ~ 1 0
69 2MASS J18314105-0206193 Y*? 18 31 41.0586275679 -02 06 19.359571418           ~ 1 0
70 2MASS J18314128-0210080 Y*O 18 31 41.3075617608 -02 10 08.110260264           ~ 7 0
71 2MASS J18314204-0206155 Y*? 18 31 42.0484107120 -02 06 15.540255396           ~ 2 0
72 2MASS J18314261-0207434 Y*? 18 31 42.6200160888 -02 07 43.503630528           ~ 6 0
73 2MASS J18314268-0216592 Y*? 18 31 42.6878883218 -02 16 59.236768423           ~ 2 0
74 2MASS J18314313-0209286 * 18 31 43.134 -02 09 28.63           ~ 2 0
75 2MASS J18314424-0201598 Y*? 18 31 44.2467140160 -02 01 59.920359816           ~ 3 0
76 2MASS J18314447-0208437 Y*? 18 31 44.4747770304 -02 08 43.818099036           ~ 3 0
77 2MASS J18314518-0212377 Y*? 18 31 45.1855501224 -02 12 37.710926604           ~ 2 0
78 2MASS J18314596-0216573 Y*O 18 31 45.9617772360 -02 16 57.347681232           ~ 6 0
79 2MASS J18314609-0206236 Y*? 18 31 46.0904956896 -02 06 23.532819120           ~ 3 0
80 2MASS J18314610-0204309 Y*? 18 31 46.1086221412 -02 04 30.976248929           ~ 1 0
81 2MASS J18314623-0210252 Y*? 18 31 46.2434832892 -02 10 25.332124455           ~ 1 0
82 2MASS J18314635-0216548 Y*? 18 31 46.3578500964 -02 16 54.810410657           ~ 1 0
83 2MASS J18314638-0210403 Y*? 18 31 46.3802663856 -02 10 40.325526336           ~ 6 0
84 2MASS J18314643-0210325 Y*? 18 31 46.4449292760 -02 10 32.557535940           ~ 5 0
85 2MASS J18314715-0158168 Y*? 18 31 47.1462557424 -01 58 16.899873780           ~ 5 0
86 2MASS J18314799-0214075 Y*? 18 31 47.9979851427 -02 14 07.489337360           ~ 2 0
87 2MASS J18314930-0158127 Y*? 18 31 49.3091122733 -01 58 12.586757179           ~ 1 0
88 2MASS J18315037-0224014 Y*? 18 31 50.3767430550 -02 24 01.408536747           ~ 1 0
89 2MASS J18315137-0212047 Y*? 18 31 51.3728525616 -02 12 04.771189224           ~ 5 0
90 2MASS J18315137-0207417 Y*? 18 31 51.3793533059 -02 07 41.789906347           ~ 1 0
91 2MASS J18315588-0209536 Y*? 18 31 55.8912891384 -02 09 53.638385292           ~ 2 0
92 2MASS J18315591-0209206 Y*? 18 31 55.9140829435 -02 09 20.667298512           ~ 1 0
93 2MASS J18315607-0216039 Y*? 18 31 56.0717618035 -02 16 03.955001762           ~ 1 0
94 2MASS J18315822-0213180 Y*? 18 31 58.2261158393 -02 13 18.076967810           ~ 1 0
95 2MASS J18315853-0206325 Y*? 18 31 58.5385595784 -02 06 32.505558048           ~ 5 0
96 NAME Aql Rift DNe 18 32 -01.0           ~ 355 1
97 2MASS J18320046-0215297 Y*? 18 32 00.4703715107 -02 15 29.800914970           ~ 2 0
98 2MASS J18320133-0219060 Y*? 18 32 01.3353339082 -02 19 06.100149552           ~ 1 0
99 2MASS J18320400-0207058 Y*? 18 32 04.0063507959 -02 07 05.829195264           ~ 2 0
100 2MASS J18320625-0206485 Y*? 18 32 06.2564237713 -02 06 48.631385431           ~ 1 0
101 2MASS J18320815-0206247 Y*O 18 32 08.1527985408 -02 06 24.766880400           ~ 6 0
102 2MASS J18320897-0216066 Y*? 18 32 08.9792303607 -02 16 06.696452916           ~ 1 0
103 2MASS J18320899-0202332 Y*? 18 32 09.0014793346 -02 02 33.344475636           ~ 1 0
104 2MASS J18321161-0220502 Y*O 18 32 11.6182599744 -02 20 50.283364236           ~ 6 0
105 2MASS J18322057-0222435 Y*? 18 32 20.5702250928 -02 22 43.299368292           ~ 3 0
106 2MASS J18322704-0200261 Y*? 18 32 27.0433853421 -02 00 26.142475440           ~ 1 0
107 2MASS J18322767-0223207 Y*? 18 32 27.6886296386 -02 23 20.572944630           ~ 1 0
108 2MASS J18323024-0159355 Y*? 18 32 30.2415361162 -01 59 35.546173722           ~ 1 0
109 2MASS J18323178-0211497 Y*? 18 32 31.7911688593 -02 11 49.791438869           ~ 1 0
110 2MASS J18323315-0214013 Y*? 18 32 33.1533755014 -02 14 01.383927593           ~ 1 0
111 2MASS J18323469-0217550 Y*? 18 32 34.6925206017 -02 17 55.073709625           ~ 1 0
112 2MASS J18323498-0224112 Y*? 18 32 34.9868784288 -02 24 11.302798428           ~ 3 0
113 2MASS J18323627-0203288 Y*? 18 32 36.2771028542 -02 03 28.834867928           ~ 1 0
114 2MASS J18323772-0208534 Y*? 18 32 37.7208114046 -02 08 53.408858520           ~ 1 0
115 2MASS J18323787-0200344 Y*? 18 32 37.8816808817 -02 00 34.401050987           ~ 1 0
116 2MASS J18323937-0205507 Y*? 18 32 39.3760591017 -02 05 50.642656707           ~ 1 0
117 2MASS J18324062-0157377 Y*? 18 32 40.6267530277 -01 57 37.781093627           ~ 1 0
118 2MASS J18324336-0224272 Y*? 18 32 43.3663451501 -02 24 27.248514365           ~ 1 0
119 2MASS J18324386-0203181 Y*? 18 32 43.8690391431 -02 03 18.154569094           ~ 1 0
120 SH 2-106 HII 20 27 26.8 +37 22 49           ~ 453 1

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