J/A+A/623/A112 The Sco OB2 population from Gaia DR2 data (Damiani+, 2019)
Stellar population of Sco OB2 revealed by Gaia DR2 data.
Damiani F., Prisinzano L., Pillitteri I., Micela G., Sciortino S.
<Astron. Astrophys. 623, A112 (2019)>
=2019A&A...623A.112D 2019A&A...623A.112D (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Associations, stellar ;
Parallaxes, trigonometric ; Proper motions
Keywords: open clusters and associations: individual: Sco OB2 -
stars: pre-main-sequence - parallaxes - proper motions
Abstract:
The Sco OB2 association is the nearest OB association, extending over
approximately 2000 square degrees on the sky. Only its brightest and
most massive members are already known (from HIPPARCOS) across its
entire size, while studies of its lower mass population refer only to
small portions of its extent.
In this work we exploit the capabilities of Gaia DR2 measurements to
search for Sco OB2 members across its entire size and down to the
lowest stellar masses.
We used both Gaia astrometric (proper motions and parallaxes) and
photometric measurements (integrated photometry and colors) to select
association members, using minimal assumptions derived mostly from the
HIPPARCOS studies. Gaia resolves small details in both the kinematics
of individual Sco OB2 subgroups and their distribution with distance
from the Sun. We developed methods to explore the 3D kinematics of a
stellar population covering large sky areas.
We find nearly 11000 pre-main-sequence (PMS) members of Sco OB2 (with
less than 3% field-star contamination), plus ∼3600 main-sequence (MS)
candidate members with a larger (10-30%) field-star contamination. A
higher confidence subsample of ∼9200 PMS (and ∼1340 MS) members is
also selected (<1% contamination for the PMS), however this group is
affected by larger (∼15%) incompleteness. We separately classify stars
in compact and diffuse populations. Most members belong to one of
several kinematically distinct diffuse populations, whose ensemble
clearly outlines the shape of the entire association. Upper Sco is the
densest region of Sco OB2. It is characterized by a complex spatial
and kinematical structure and has no global pattern of motion. Other
dense subclusters are found in Lower Centaurus-Crux and in Upper
Centaurus-Lupus; the richest example of the latter, which has been
recently identified, is coincident with the group near V1062 Sco. Most
of the clustered stars appear to be younger than the diffuse PMS
population, suggesting star formation in small groups that rapidly
disperse and are diluted, reaching space densities lower than field
stars while keeping memory of their original kinematics. We also find
that the open cluster IC 2602 has a similar dynamics to Sco OB2, and
its PMS members are currently evaporating and forming a diffuse
(size∼10°) halo around its double-peaked core.
Description:
Two tables are provided: pre-main-sequence and upper-main-sequence
candidate members of Sco OB2, from Gaia data. In addition to the Gaia
identifiers and measurements, we provide SIMBAD identifiers where
available. Column 'Sel' has 'p' for stars selected from the
proper-motion plane, and 'pv' for stars selected from both
proper-motion and transverse-velocity data; the latter set is less
contaminated but also less complete. Column 'Pop' indicates the Sco
OB2 sub-population a star belongs to (if determined with enough
confidence). The tables also include PMS and upper-MS members of the
young cluster IC2602, as indicated in column 'Pop'.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
pms.dat 140 10839 Gaia data for PMS members of Sco OB2
ums.dat 131 3598 Gaia data for Upper-MS members of Sco OB2
list.dat 85 3 List of fits maps
fits/* . 3 Individual fits maps
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See also:
J/A+A/382/92 : Sco OB2 association (Shatsky+, 2002)
J/A+A/464/581 : Sco OB2 intermediate-mass stars (Kouwenhoven+, 2007)
J/MNRAS/416/3108 : Membership of Sco OB2 moving group (Rizzuto+, 2011)
J/A+AS/126/81 : IC 2602 VRI photometry (Foster+ 1997)
J/A+A/372/862 : Lithium abundances in IC 2602 and IC 2391 (Randich+, 2001)
J/A+A/501/553 : Equivalent widths of IC2602 + IC2391 stars (D'Orazi+, 2009)
Byte-by-byte Description of file: pms.dat ums.dat
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Bytes Format Units Label Explanations
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1- 5 I5 --- Seq [1/14437] Sequential number (1)
7- 25 I19 --- DR2Name Gaia DR2 Designation
27- 35 F9.5 deg RAdeg Right ascension (J2000.0)
37- 45 F9.5 deg DEdeg Declination (J2000.0)
47- 55 F9.5 deg GLON Galactic longitude (l)
57- 64 F8.5 deg GLAT Galactic latitude (b)
66- 70 F5.2 mas Plx Absolute stellar parallax
72- 77 F6.2 mas/yr pmGLON Proper motion in longitude direction,
pmGLON*codDE (µl )
79- 84 F6.2 mas/yr pmGLAT Proper motion in latitude direction (µb)
86- 90 F5.2 mag Gmag Gaia DR2 G-band magnitude
92- 96 F5.2 mag BP-RP Gaia DR2 BP-RP colour index
98- 99 A2 --- Sel [pv ] Selection type (2)
101-107 A7 --- Pop Association sub-population
109-140 A32 --- SIMBAD Simbad name
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Note (1): No 1-10839 for PMS members, 10840-14437 for Upper-MS members.
Note (2): Selection flag as follows:
p = PM-selection
pv = PM- and VT-selection
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [G]
2- 10 F9.5 deg GLON Galactic longitude of center (J2000)
11- 19 F9.5 deg GLAT Galactic latitude of center (J2000)
21- 23 I3 --- Nx Number of pixels along X-axis
25- 27 I3 --- Ny Number of pixels along Y-axis
29- 31 I3 Kibyte size Size of FITS file
33- 43 A11 --- FileName Name of FITS file, in subdirectory fits
45- 85 A41 --- Title Title of the FITS file
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Acknowledgements:
Francesco Damiani, francesco.damiani(at)inaf.it
(End) Francesco Damiani [INAF-OAPA], Patricia Vannier [CDS] 03-Jan-2019