J/MNRAS/492/2446 Large-scale star formation in Auriga region (Pandey+, 2020)
Large-scale star formation in Auriga region.
Pandey A.K., Sharma S., Kobayashi N., Sarugaku Y., Ogura K.
<Mon. Not. R. Astron. Soc., 492, 2446-2467 (2020)>
=2020MNRAS.492.2446P 2020MNRAS.492.2446P (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Stars, pre-main sequence ; Photometry, infrared ;
Optical ; Stars, masses ; Stars, ages ; Models
Keywords: stars: formation - stars: pre-main-sequence - HII regions
Abstract:
New observations in the VI bands along with archival data from the
2MASS and WISE surveys have been used to generate a catalogue of young
stellar objects (YSOs) covering an area of about 6°x6° in the
Auriga region centred at l∼173° and b∼1.5°. The nature of the
identified YSOs and their spatial distribution are used to study the
star formation in the region. The distribution of YSOs along with that
of the ionized and molecular gas reveals two ring-like structures
stretching over an area of a few degrees each in extent. We name these
structures as Auriga Bubbles 1 and 2. The centre of the Bubbles
appears to be above the Galactic mid-plane. The majority of Class I
YSOs are associated with the Bubbles, whereas the relatively older
population, i.e. Class II objects are rather randomly distributed.
Using the minimum spanning tree analysis, we found 26 probable
subclusters having five or more members. The subclusters are between
∼0.5 and ∼3pc in size and are somewhat elongated. The star formation
efficiency in most of the subcluster region varies between 5 per cent
and 20 per cent indicating that the subclusters could be bound
regions. The radii of these subclusters also support it.
Description:
Optical (V and I) data for nine overlapping regions of Auriga were
procured with KWFC (FOV ∼2.2°x2.2°; scale 0.946arcsec/pix;
Sako et al. 2012SPIE.8446E..6LS) on the 1.05-m Schmidt telescope at
Kiso Observatory, Japan during the nights of 2012 December 6 and 7 and
2014 December 27. KWFC, an optical wide-field 64 megapixel imager with
4 SITe and 4 MIT Lincoln Laboratory (MIT/LL) 15µm 2Kx4K CCDs is
attached to the prime focus of the Kiso Schmidt telescope. The
observations were carried out in the unbinned and slow readout mode.
In this mode, the readout noise is about 20 and 5-10 electrons for the
SITe and MIT/LL CCDs, respectively.
To investigate the star formation in the Auriga Bubble region, we also
used near-/mid-IR (NIR/MIR) data from the Two Micron All Sky Survey
(2MASS; Cutri et al. 2003tmc..book.....C 2003tmc..book.....C, Cat. II/246) and the
Wide-field Infrared Survey Explorer survey (WISE; Wright et al.
2010AJ....140.1868W 2010AJ....140.1868W) archived data in addition to the optical VI data
from the Kiso Schmidt telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 142 710 Sample of 710 identified YSOs
table7.dat 42 489 A sample table containing the stellar
parameters of the selected 489 YSOs derived by
using the SED fitting analysis
table8.dat 98 35 Data for identified subclusters and active
regions
table9.dat 77 35 Properties of the identified subclusters and
active regions
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/710] YSO identifier
5- 13 F9.6 deg RAdeg Right ascension (J2000)
15- 23 F9.6 deg DEdeg Declination (J2000)
25- 30 F6.3 mag Vmag ? KWFC V-band magnitude
32- 37 F6.4 mag e_Vmag ? Error on Vmag
39- 43 F5.3 mag V-I ? KWFC V-I colour
45- 50 F6.4 mag e_V-I ? Error on V-I
52- 57 F6.3 mag Jmag ? 2MASS J-band magnitude
59- 63 F5.3 mag e_Jmag ? Error on Jmag
65- 70 F6.3 mag Hmag ? 2MASS H-band magnitude
72- 76 F5.3 mag e_Hmag ? Error on Hmag
78- 83 F6.3 mag Kmag ? 2MASS K-band magnitude
85- 89 F5.3 mag e_Kmag ? Error on Kmag
91- 96 F6.3 mag W1mag ? WISE W1 (3.4um) band magnitude
98-102 F5.3 mag e_W1mag ? Error on W1mag
104-109 F6.3 mag W2mag ? WISE W2 (4.6um) band magnitude
111-115 F5.3 mag e_W2mag ? Error on W2mag
117-122 F6.3 mag W3mag ? WISE W3 (12um) band magnitude
124-128 F5.3 mag e_W3mag ? Error on W3mag
130-134 F5.3 mag W4mag ? WISE W4 (22um) band magnitude
136-140 F5.3 mag e_W4mag ? Error on W4mag
142 I1 --- Class [1/8] Classification of the YSO (1)
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Note (1): Classification as follows:
1 = Class I (WISE 3 Band)
2 = Class II (WISE 3 Band)
3 = Class I (WISE+2MASS, two Band each)
4 = Class II (WISE + 2MASS, two Band each)
5 = Class I (from AGN contamination list)
6 = Class II (WISE 4 BAND, Tr Disc)
7 = Class I (2MASS TCD)
8 = Class II (2MASS TCD)
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/710] YSO identifier
5 I1 --- N Number of input data points
7- 11 I5 --- Model Number of SED models fitted to the data
13- 17 F5.1 --- chi2 Reduced chi-squared for the best-fitting model
19- 22 F4.1 mag Av Extinction
24- 26 F3.1 mag e_Av Error on Av
28- 30 F3.1 Msun Mass Mass from SED fitting
32- 34 F3.1 Msun e_Mass Error on Mass
36- 38 F3.1 Myr Age Age from SED fitting
40- 42 F3.1 Myr e_Age Error on Age
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Name Name of the subcluster or active region (gNN)
5- 17 A13 --- Type Object type (Subcluster or Active region)
19- 20 I2 h RAh Right ascension (J2000)
22- 23 I2 min RAm Right ascension (J2000)
25- 30 F6.3 s RAs Right ascension (J2000)
32 A1 --- DE- Declination sign (J2000)
33- 34 I2 deg DEd Declination (J2000)
36- 37 I2 arcmin DEm Declination (J2000)
39- 43 F5.2 arcsec DEs Declination (J2000)
45- 47 I3 --- N Number of YSOs enclosed in the group
49- 50 I2 --- V Vertex of the convex hull
52- 56 F5.2 pc Rhull Hull radius
58- 62 F5.2 pc Rcir Circle radius
64- 67 F4.2 --- Aspect Aspect ratio
69- 72 F4.2 pc-2 sigmean Mean stellar density obtained by using the
isodensity contours
74- 78 F5.2 pc-2 sigpeak Peak stellar density obtained by using the
isodensity contours
80- 83 F4.2 pc MST Mean minimum spanning tree (MST) branch length
85- 88 F4.2 pc NN2 Nearest neighbour distance
90- 91 I2 --- Class1 Number of Class I YSOs
93- 95 I3 --- Class2 Number of Class II YSOs
97- 98 I2 % Frac Percentage of Class I YSOs (Class1/N*100)
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Name Name of the subcluster or active region (gNN)
5- 17 A13 --- Type Object type (Subcluster or Active region)
19- 22 F4.1 mag Avmean ? Mean extinction
24- 27 F4.1 mag Avpeak ? Peak extinction
29- 36 F8.1 Msun Mass ? Cloud mass in the convex hull derived by
using the extinction map
38- 44 F7.1 Msun Mass0.8 ? Mass of the dense cloud having AK greater
than 0.8mag
46- 49 F4.2 pc J1 ? Jeans length for Class I and Class II
sources only
51- 54 F4.2 pc J2 ? Jeans length with inclusion of assumed
missing contribution of Class III sources
56- 59 F4.2 --- Q ? Structural Q parameter
61- 64 F4.1 % SFE1 ? Star formation efficiency for Class I and
Class II sources only (1)
66- 69 F4.1 % SFE2 ? Star formation efficiency with inclusion of
assumed missing contribution of Class III
sources (1)
71- 73 F3.1 --- J/SYSO1 ? Ratio of the Jeans length to the mean
separation of YSOs for Class I and Class II
sources only
75- 77 F3.1 --- J/SYSO2 ? Ratio of the Jeans length to the mean
separation of YSOs with inclusion of assumed
missing contribution of Class III sources
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Note (1): The star formation efficiency (SFE) is defined as the percentage of
the gas mass converted into stars
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 20-Mar-2023