J/A+A/650/A156 Cluster formation toward Be87/ON2. I. (de la Fuente+, 2021)
Clustered star formation toward Berkeley 87/ON2.
I. Multiwavelength census and the population overlap problem.
de la Fuente D., Roman-Zuniga C.G., Jimenez-Bailon E., Alves J., Garcia M.,
Venus S.
<Astron. Astrophys. 650, A156 (2021)>
=2021A&A...650A.156D 2021A&A...650A.156D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Infrared sources ; X-ray sources ;
Photometry, infrared ; Optical ; Stars, distances ;
Proper motions ; Parallaxes, trigonometric
Keywords: methods: observational - techniques: photometric - catalogs -
open clusters and associations: individual: Berkeley 87 -
ISM: individual objects: ON2 - stars: formation
Abstract:
Disentangling line-of-sight alignments of young stellar populations is
crucial for observational studies of star-forming complexes. This task
is particularly problematic in a Cygnus-X subregion where several
components, located at different distances, overlap: the Berkeley 87
young massive cluster, the poorly known [DB2001] Cl05 embedded
cluster, and the ON2 star-forming complex, which in turn is composed
of several HII regions.
We provide a methodology for building an exhaustive census of young
objects that can consistently treat large differences in extinction
and distance.
OMEGA2000 near-infrared observations of the Berkeley 87 / ON2 field
were merged with archival data from Gaia, Chandra, Spitzer, and
Herschel, and with cross-identifications from the literature. To
address the incompleteness effects and selection biases that arise
from the line-of-sight overlap, we adapted existing methods for
extinction estimation and young object classification. We also defined
the intrinsic reddening index, Rint, a new tool for separating
intrinsically red sources from those whose infrared color excess is
caused by extinction. Finally, we introduce a new method for finding
young stellar objects based on Rint.
We find 571 objects whose classification is related to recent or
ongoing star formation. Together with other point sources with
individual estimates of distance or extinction, we compile a catalog
of 3005 objects to be used for further membership work. A new distance
for Berkeley 87, (1673±17)pc, is estimated as a median of 13
spectroscopic members with accurate Gaia EDR3 parallaxes.
The flexibility of our approach, especially regarding the Rint
definition, allows overcoming photometric biases caused by large
variations in extinction and distance, in order to obtain homogeneous
catalogs of young sources. The multiwavelength census that results
from applying our methods to the Berkeley 87 / ON2 field will serve as
a basis for disentangling the overlapped populations.
Description:
We provide a multi-wavelength catalog of point sources in a 15'x15'
field covering the Berkeley 87 and [DB2001] Cl05 clusters. The listed
sources have at least one of the following properties estimated:
extinction, distance, or classification as an object related to recent
or ongoing star formation.
Objects:
-------------------------------------------------------------
RA (2000) DE Designation(s)
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20 21 43.01 +37 22 13.8 Berkeley 87 = Cl Berkeley 87
20 21 41.8 +37 25 50 [DB2001] Cl05 = [DB2001] Cl05
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 122 3005 Catalog of sources with extinction, distance,
or object classification results
tablec1.dat 209 3005 Astrometry and photometry for sources in
table2.dat
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/3005] Source number
7- 8 I2 h RAh Right ascension (J2000.0)
10- 11 I2 min RAm Right ascension (J2000.0)
13- 17 F5.2 s RAs Right ascension (J2000.0)
19 A1 --- DE- Declination sign (J2000.0)
20- 21 I2 deg DEd Declination (J2000.0)
23- 24 I2 arcmin DEm Declination (J2000.0)
26- 29 F4.1 arcsec DEs Declination (J2000.0)
32- 47 A16 --- ID Literature identifier (1)
50- 54 F5.2 mag Kmag ? K-band magnitude
57- 60 A4 --- dets Matched observations (2)
63- 65 A3 --- Pop Classification based on reddening level (3)
68- 70 A3 --- Cl05reg [in out] Inside or outside the Cl05 region?
72- 77 F6.3 --- Rint ? Intrinsic reddening index
80- 84 F5.2 mag AV ? V-band extinction
85 A1 --- n_AV [R] Note on AV (4)
87- 92 F6.4 kpc rest ? Distance estimate
95 A1 --- --- [-]
96-101 F6.4 kpc e_rest ? Lower error for distance estimate (5)
103 A1 --- --- [+]
104-109 F6.4 kpc E_rest ? Upper error for distance estimate (6)
112-122 A11 --- Type Source classification (7)
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Note (1): This identifier can be either a SIMBAD ID or "Cygnus 2N" and
"Cygnus 2N EAST" for the so-called components as described in Sect. 2.5.1 of
the paper or "Sk19 Ta-bb", standing for Skinner et al. (2019ApJ...871..116S 2019ApJ...871..116S,
Table a, line bb).
Note (2): List of observations where a counterpart has been found,
coded as follows:
C = Chandra, likely counterpart
c = Chandra, doubtful counterpart
G = Gaia
O = OMEGA2000 (even when 2MASS is used for photometry instead)
S = Spitzer
H = Herschel
Note (3): Classification as follows:
HRP = High-reddening population
LRP = Low-reddening population
Note (4): R for AV computed with the RJCE method.
Note (5): 15.87% quantile of the computed probability density function.
Note (6): 84.13% quantile of the computed probability density function.
Note (7): This column either shows the known spectral type or our classification
as YSO candidate according to the following abbreviations:
cI = class I
cII = class II
cIII = class III
c.protost. = candidate protostar
c.starless = candidate starless core
massiveSF = massive star-forming region
othX = other X-ray-detected candidate
Rint = identified through the Rint method
YSOc = YSO candidate
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Byte-by-byte Description of file: tablec1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- Seq [1/3005] Source number
7- 8 I2 h RAh Right ascension (J2000.0)
10- 11 I2 min RAm Right ascension (J2000.0)
13- 17 F5.2 s RAs Right ascension (J2000.0)
20 A1 --- DE- Declination sign (J2000.0)
21- 22 I2 deg DEd Declination (J2000.0)
24- 25 I2 arcmin DEm Declination (J2000.0)
27- 30 F4.1 arcsec DEs Declination (J2000.0)
33- 38 F6.3 mas Plx ? Parallax
41- 45 F5.3 mas e_Plx ? Parallax error
48- 53 F6.3 mas Plxcor ? Bias-corrected parallax
56- 61 F6.2 mas/yr pmRA ? Proper motion in right ascension
64- 67 F4.2 mas/yr e_pmRA ? Error for proper motion in right ascension
70- 75 F6.2 mas/yr pmDE ? Proper motion in declination
78- 81 F4.2 mas/yr e_pmDE ? Error for proper motion in declination
84- 87 F4.2 arcsec X-IR ? Angular separation between the X-ray source
and its infrared counterpart
90- 93 F4.2 arcsec Xsep ? Angular separation between the 2009 and 2016
Chandra detections
96-101 F6.3 mag Jmag ? J-band magnitude
104-108 F5.3 mag e_Jmag ? Error for J-band magnitude
111-116 F6.3 mag Hmag ? H-band magnitude
119-123 F5.3 mag e_Hmag ? Error for H-band magnitude
126-131 F6.3 mag Kmag ? K-band magnitude
134-138 F5.3 mag e_Kmag ? Error for K-band magnitude
141-145 F5.2 mag I1mag ? IRAC [3.6] magnitude
148-151 F4.2 mag e_I1mag ? IRAC [3.6] magnitude error
154-158 F5.2 mag I2mag ? IRAC [4.5] magnitude
161-164 F4.2 mag e_I2mag ? IRAC [4.5] magnitude error
167-171 F5.2 mag I3mag ? IRAC [5.8] magnitude
174-177 F4.2 mag e_I3mag ? IRAC [5.8] magnitude error
180-184 F5.2 mag I4mag ? IRAC [8.0] magnitude
187-190 F4.2 mag e_I4mag ? IRAC [8.0] magnitude error
193-200 F8.3 Jy P70flux ? Flux at PACS 70 micron band
202-209 F8.3 Jy P160flux ? Flux at PACS 160 micron band
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Acknowledgements:
Diego de la Fuente, diego.delafuente(at)ua.es
(End) D. de la Fuente [Univ. Alicante, Spain], P. Vannier [CDS] 20-Apr-2021