J/A+A/634/A98 Corona-Australis DANCe. I. (Galli+, 2020)
Corona-Australis DANCe. I. Revisiting the census of stars with Gaia-DR2 data.
Galli P.A.B., Bouy H., Olivares J., Miret-Roig N., Sarro L.M., Barrado D.,
Berihuete A. Brandner W.
<Astron. Astrophys. 634, A98 (2020)>
=2020A&A...634A..98G 2020A&A...634A..98G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Proper motions ; Parallaxes, trigonometric ;
Radial velocities
Keywords: open clusters and associations: individual: Corona-Australis -
stars: formation - stars: distances - methods: statistical -
parallaxes - proper motions
Abstract:
Corona-Australis is one of the nearest regions to the Sun with recent
and ongoing star formation, but the current picture of its stellar
(and substellar) content is not complete yet. We take advantage of the
second data release of the Gaia space mission to revisit the stellar
census and search for additional members of the young stellar
association in Corona-Australis. We applied a probabilistic method to
infer membership probabilities based on a multidimensional astrometric
and photometric data set over a field of 128deg2 around the dark
clouds of the region. We identify 313 high-probability candidate
members to the Corona-Australis association, 262 of which had never
been reported as members before. Our sample of members covers the
magnitude range between G≳5mag and G≲20mag, and it reveals the
existence of two kinematically and spatially distinct subgroups. There
is a distributed 'off-cloud' population of stars located in the north
of the dark clouds that is twice as numerous as the historically known
'on-cloud' population that is concentrated around the densest cores.
By comparing the location of the stars in the HR-diagram with
evolutionary models, we show that these two populations are younger
than 10Myr. Based on their infrared excess emission, we identify 28
Class II and 215 Class III stars among the sources with available
infrared photometry, and we conclude that the frequency of Class∼II
stars (i.e. `disc-bearing' stars) in the on-cloud region is twice as
large as compared to the off-cloud population. The distance derived
for the Corona-Australis region based on this updated census is
d=149.4+0.4-0.4pc, which exceeds previous estimates by about 20
pc. In this paper we provide the most complete census of stars in
Corona-Australis available to date that can be confirmed with Gaia
data. Furthermore, we report on the discovery of an extended and more
evolved population of young stars beyond the region of the dark
clouds, which was extensively surveyed in the past.
Description:
Properties of the 313 cluster members in Corona-Australis, membership
probability of all sources in the field and empirical isochrone of the
association, derived using data from Gaia DR2.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 190 313 Properties of the 313 cluster members
tablea2.dat 138 10618999 Membership probabilities for all sources
tablea3.dat 40 400 Empirical isochrone
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- --- [GaiaDR2]
8- 26 I19 --- GaiaDR2 Source identifier from Gaia-DR2 catalogue
29- 30 I2 h RAh Right Ascension (ICRS) at Ep=2015.5
32- 33 I2 min RAm Right Ascension (ICRS) at Ep=2015.5
35- 39 F5.2 s RAs Right Ascension (ICRS) at Ep=2015.5
43 A1 --- DE- Declination sign (ICRS) at Ep=2015.5
44- 45 I2 deg DEd Declination (ICRS) at Ep=2015.5
47- 48 I2 arcmin DEm Declination (ICRS) at Ep=2015.5
50- 53 F4.1 arcsec DEs Declination (ICRS) at Ep=2015.5
57- 62 F6.3 mas/yr pmRA Proper motion in right ascension, pmRA*cosDE
64- 68 F5.3 mas/yr e_pmRA Proper motion in right ascension error
71- 77 F7.3 mas/yr pmDE Proper motion in declination
79- 83 F5.3 mas/yr e_pmDE Proper motion in declination error
86- 90 F5.3 mas plx Parallax
92- 96 F5.3 mas e_plx Parallax error
99-104 F6.4 --- prob Membership probability
107-111 F5.1 pc d Distance
113-116 F4.1 pc E_d Upper uncertainty for the distance
119-122 F4.1 pc e_d Lower uncertainty for the distance
124-127 F4.1 km/s VRA Velocity in right ascension
129-131 F3.1 km/s E_VRA Velocity in right ascension (upper uncertainty)
134-136 F3.1 km/s e_VRA Velocity in right ascension (lower uncertainty)
139-143 F5.1 km/s VDE Velocity in declination
145-147 F3.1 km/s E_VDE Velocity in declination (upper uncertainty)
150-152 F3.1 km/s e_VDE Velocity in declination (lower uncertainty)
155-163 A9 --- Pop Population
166-190 A25 --- YSO YSO subclass
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- --- [Gaia DR2 -]
10- 28 I19 --- GaiaDR2 Source identifier from Gaia-DR2 catalogue
30- 50 E21.17 --- P050 [0/1] membership probability for pin=0.5
52- 72 E21.17 --- P060 [0/1] membership probability for pin=0.6
74- 94 E21.17 --- P070 [0/1] membership probability for pin=0.7
96-116 E21.17 --- P080 [0/1] membership probability for pin=0.8
118-138 E21.17 --- P090 [0/1] membership probability for pin=0.9
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
2- 18 F17.14 mag RPmag RP magnitude from Gaia-DR2
21- 40 F20.17 mag G-RP G-RP color from Gaia-DR2
--------------------------------------------------------------------------------
Acknowledgements:
Phillip Galli, phillip.galli(at)u-bordeaux.fr
(End) Phillip Galli [LAB, France], Patricia Vannier [CDS] 15-Jan-2020