J/A+A/665/A76 Extended population associated with W40 (Comeron+, 2022)
Extended population associated with W40.
Comeron F., Djupvik A.A., Schneider N.
<Astron. Astrophys. 665, A76 (2022)>
=2022A&A...665A..76C 2022A&A...665A..76C (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Clusters, open ; H II regions ;
Stars, OB ; Stars, pre-main sequence ; YSOs
Keywords: stars: early-type - ISM: bubbles - HII regions -
open clusters and associations: individual: W40
Abstract:
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. We aim 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 particular interest in previously
unidentified massive members that may contribute to the energy budget
powering the expansion of the HII region. We use 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
identify in this way new members, both inside and outside the cluster.
We obtain 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. Based on stars with high quality Gaia astrometry we derive
a high-confidence geometric distance to the W40 region of
502pc±4pc and 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). 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, of which the formation of the
W40 central cluster and the subsequent HII region is one of the latest
episodes. The newly determined distance suggests that W40 is behind,
and physically detached from, a pervasive large dust layer which is
some 60∼pc foreground to it as determined by previous studies.
Description:
Table 4 presents Gaia eDR3 astrometric data and photometry of
candidate members of the W40 region, selected according to relaxed
constraints on the parallax and the astrometric solution than the bona
fide members of the W40 cluster and surrounding region.
Table 5 presents photometry of high-confidence and candidate members
of the W40 region in the J, H and Ks infrared bands as well as
Spitzer/IRAC photometry in the I1 (3.6 microns) and I2 (4.5 microns)
bands.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 133 113 Additional candidate members with relative proper
motion less than 2 mas/yr and parallax
between 1.0 and 3.0mas
table5.dat 120 135 Infrared photometry of high-confidence and
candidate members
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Object Object name (JHHMMSS.ss+DDMMSS.s)
22- 23 I2 h RAh Right ascension (J2000.0)
25- 26 I2 min RAm Right ascension (J2000.0)
28- 32 F5.2 s RAs Right ascension (J2000.0)
35 A1 --- DE- Declination sign (J2000.0)
36- 37 I2 deg DEd Declination (J2000.0)
39- 40 I2 arcmin DEm Declination (J2000.0)
42- 45 F4.1 arcsec DEs Declination (J2000.0)
47- 53 F7.4 mas Plx Gaia eDR3 Parallax
55- 61 F7.4 mas e_Plx Error in Parallax
63- 69 F7.3 mas/yr pmRA Gaia eDR3 Proper motion in right ascension
71- 76 F6.3 mas/yr e_pmRA Error in proper motion in right ascension
78- 84 F7.3 mas/yr pmDE Gaia eDR3 Proper motion in declination
86- 91 F6.3 mas/yr e_pmDE Error in proper motion in declination
93- 98 F6.3 --- RUWE Gaia eDR3 renormalized unit-weight error
100-106 F7.3 mag BPmag Gaia eDR3 Bp magnitude
108-113 F6.3 mag e_BPmag Error in Bp magnitude
115-121 F7.3 mag RPmag Gaia eDR3 Rp magnitude
123-128 F6.3 mag e_RPmag Error in Rp magnitude
130-133 I4 --- KGF ? Source number in Kuhn et al.
(2010ApJ...725.2485K 2010ApJ...725.2485K, Cat. J/ApJ/725/2485),
[KGF2010] NNN in Simbad
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Object Object name (JHHMMSS.ss+DDMMSS.s)
22- 23 I2 h RAh Right ascension (J2000.0)
25- 26 I2 min RAm Right ascension (J2000.0)
28- 32 F5.2 s RAs Right ascension (J2000.0)
35 A1 --- DE- Declination sign (J2000.0)
36- 37 I2 deg DEd Declination (J2000.0)
39- 40 I2 arcmin DEm Declination (J2000.0)
42- 45 F4.1 arcsec DEs Declination (J2000.0)
47- 53 F7.3 mag Jmag ? J magnitude
55- 60 F6.3 mag e_Jmag ? Error in the J magnitude
62- 68 F7.3 mag Hmag ? H magnitude
70- 75 F6.3 mag e_Hmag ? Error in the H magnitude
77- 83 F7.3 mag Ksmag ? Ks magnitude
85- 90 F6.3 mag e_Ksmag ? Error in the Ks magnitude
92- 98 F7.3 mag IRAC1mag ? Spitzer IRAC I1 magnitude
100-105 F6.3 mag e_IRAC1mag ? Error in the Spitzer IRAC I1 magnitude
107-113 F7.3 mag IRAC2mag ? Spitzer IRAC I2 magnitude
115-120 F6.3 mag e_IRAC2mag ? Error in the Spitzer IRAC I2 magnitude
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Acknowledgements:
Fernando Comeron, fcomeron(at)eso.org
(End) Fernando Comeron [ESO, Germany], Patricia Vannier [CDS] 22-Jul-2022