J/A+A/617/A63 Star formation in the Vela Molecular Ridge (Prisinzano+, 2018)
Low-mass star formation and subclustering in the H II regions RCW 32, 33, and 27
of the Vela Molecular Ridge. A photometric diagnostics for identifying M-type
stars.
Prisinzano L., Damiani F., Guarcello M. G., Micela G., Sciortino S.,
Tognelli E., Venuti L.
<Astron. Astrophys. 617, A63 (2018)>
=2018A&A...617A..63P 2018A&A...617A..63P (SIMBAD/NED BibCode)
ADC_Keywords: Stars, M-type ; Stars, pre-main sequence ; YSOs ; Accretion ;
Fundamental catalog ; Photometry, SDSS ; Photometry, infrared ;
Stars, ages
Keywords: techniques: photometric - stars: low-mass - stars: pre-main sequence -
stars: formation - H II regions -
open clusters and associations: general
Abstract:
Most stars born in clusters and recent results suggest that star
formation (SF) preferentially occurs in subclusters. Studying the
morphology and SF history of young clusters is crucial to
understanding early SF. We identify the embedded clusters of young
stellar objects (YSOs) down to M stars, in the HII regions RCW33,
RCW32 and RCW27 of the Vela Molecular Ridge.
Our aim is to characterise their properties, such as morphology and
extent of the clusters in the three HII regions, derive stellar ages
and the connection of the SF history with the environment.
Through public photometric surveys such as Gaia, VPHAS, 2MASS and
Spitzer/GLIMPSE, we identify YSOs with IR, Halpha and UV excesses, as
signature of circumstellar disks and accretion. In addition, we
implement a method to distinguish M dwarfs and giants, by comparing
the reddening derived in several optical/IR color-color diagrams
assuming suitable theoretical models. Since this diagnostic is
sensitive to stellar gravity, the procedure allows us to identify
pre-main sequence stars.
We find a large population of YSOs showing signatures of circumstellar
disks with or without accretion. In addition, with the new technique
of M-type star selection, we find a rich population of young M stars
with a spatial distribution strongly correlated to the more massive
population. We find evidence of three young clusters, with different
morphology. In addition, we identify field stars falling in the same
region, by securely classifying them as giants and foreground MS
stars. We identify the embedded population of YSOs, down to about
0.1M☉, associated with the HII regions RCW33, RCW32 and RCW27
and the clusters Vela T2, Cr197 and Vela T1, respectively, showing
very different morphologies. Our results suggest a decreasing SF rate
in Vela T2 and triggered SF in Cr197 and Vela T1.
Description:
Astrometric and photometric data used in this work come from the
public APASS9 (Cat. II/336), VPHAS+ (Cat. II/341) and 2MASS (Cat.
II/246) catalogs. In addition, we used TGAS Gaia DR1 (I/337) kinematic
data and public X-ray data obtained by ROSAT High Resolution Imager
(HRI, 1RXH, third Release, Cat. IX/28) and Chandra Data Archive (Wang
et al., 2016, Cat. J/ApJS/224/40). In table 2 we present astrometry,
photometry and membership information of the young stellar objects
(YSO) selected with classical methods, that is, from Halpha, IR
excesses, kinematics, and X-ray detection. In table 3 we present
astrometry and photometry of the M-type YSOs, selected with the new
photometry technique described in the paper. For these latter objects,
we also give the extinction and the ages.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 92 907 Astrometry, optical/NIR photometry and membership
information for the YSOs selected from Halpha,
IR excesses, kinematics, and X-ray detection
table3.dat 91 1200 Astrometry, optical/NIR photometry, extinction
and ages of M-type YSOs
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See also:
IX/28 : ROSAT HRI Pointed Observations (1RXH) (ROSAT Team, 2000)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
II/336 : AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)
II/341 : VPHAS+ DR2 survey (Drew+, 2016)
J/ApJS/224/40 : Catalog of Chandra ACIS point like sources (Wang+, 2016)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CName Target name (HHMMSSss+DDMMSSs)
18- 26 F9.5 deg RAdeg Right ascension (J2000.0)
28- 36 F9.5 deg DEdeg Declination (J2000)
38- 42 F5.2 mag umag ? SDSS u magnitude
44- 48 F5.2 mag gmag ? SDSS g magnitude
50- 54 F5.2 mag rmag ? SDSS r magnitude
56- 60 F5.2 mag imag ? SDSS i magnitude
62- 66 F5.2 mag Hamag ? SDSS Halpha magnitude
68- 72 F5.2 mag Jmag ? 2MASS J magnitude
74- 78 F5.2 mag Hmag ? 2MASS H magnitude
80- 84 F5.2 mag Kmag ? 2MASS K magnitude
86 I1 --- M1 [0,1] Halpha excess membership flag
88 I1 --- M2 [0,1] NIR excess membership flag
90 I1 --- M3 [0,1] TGAS Gaia membership flag
92 I1 --- M4 [0,1] X-ray membership flag
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- CName Target name (HHMMSSss+DDMMSSs)
18- 26 F9.5 deg RAdeg Right ascension (J2000.0)
28- 36 F9.5 deg DEdeg Declination (J2000)
38- 42 F5.2 mag rmag ? SDSS r magnitude
44- 48 F5.2 mag imag ? SDSS i magnitude
50- 54 F5.2 mag Jmag ? 2MASS J magnitude
56- 60 F5.2 mag Hmag ? 2MASS H magnitude
62- 66 F5.2 mag Kmag ? 2MASS K magnitude
68- 71 F4.2 mag AV ? Absorption in the V band
73- 76 F4.2 mag e_AV ? Uncertainty of the absorption in V band
78- 81 F4.2 yr logt ? Log of stellar age
83- 86 F4.2 yr b_logt ? Log of lower limit of stellar age
88- 91 F4.2 yr B_logt ? Log of upper limit of stellar age
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Acknowledgements:
Loredana Prisinzano, loredana.prisinzano(at)inaf.it
(End) Patricia Vannier [CDS] 22-Jun-2018