J/A+A/657/A53 Wide-orbit companions to K-type stars in Sco-Cen (Bohn+, 2022)
Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3.
Bohn A.J., Ginski C., Kenworthy M.A., Mamajek E.E., Meshkat T., Pecaut M.J.,
Reggiani M., Seay C.R., Brown A.G.A., Cugno G., Henning T., Launhardt R.,
Quirrenbach A., Rickman E.L., Segransan D.
<Astron. Astrophys. 657, A53 (2022)>
=2022A&A...657A..53B 2022A&A...657A..53B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Stars, pre-main sequence ;
Stars, K-type
Keywords: binaries: visual - brown dwarfs - astrometry -
open clusters and associations: individual: Sco-Cen -
stars: individual: TYC 8252-533-1
Abstract:
The detection of low-mass companions to stellar hosts is important for
testing the formation scenarios of these systems. Companions at wide
separations are particularly intriguing objects as they are easily
accessible for variability studies of the rotational dynamics and cloud
coverage of these brown dwarfs or planetary-mass objects.
We aim to identify new low-mass companions to young stars using the
astrometric measurements provided by the Gaia space mission. When
possible, we use high-contrast imaging data collected with VLT/SPHERE.
We identified companion candidates from a sample of K-type,
pre-main-sequence stars in the Scorpius Centaurus association using
the early version of the third data release of the Gaia space mission.
Based on the provided positions, proper motions, and magnitudes, we
identified all objects within a predefined radius, whose differential
proper motions are consistent with a gravitationally bound system. As
the ages of our systems are known, we derived companion masses through
comparison with evolutionary tracks.
For seven identified companion candidates we used additional data
collected with VLT/SPHERE and VLT/NACO to assess the accuracy of the
properties of the companions based on Gaia photometry alone.
We identify 110 comoving companions that have a companionship
likelihood of more than 95%.
Further color-magnitude analysis confirms their Sco-Cen membership. We
identify ten especially intriguing companions that have masses in the
brown dwarf regime down to 20M{Jup}. Our high-contrast imaging data
confirm both astrometry and photometric masses derived from Gaia
alone. We discovered a new brown dwarf companion, TYC 8252-533-1 B,
with a projected separation of approximately 570au from its Sun-like
primary. It is likely to be located outside the debris disk around its
primary star and SED modeling of Gaia, SPHERE, and NACO photometry
provides a companion mass of 52+17-11M{Jup}. We show that the
Gaia database can identify low-mass companions at wide separations
from their host stars. For K-type Sco-Cen members, Gaia can detect
sub-stellar objects at projected separations larger than 300au and
with a sensitivity limit beyond 1000 and a lower mass limit down to
20M{Jup}. A similar analysis of other star-forming regions could
significantly enlarge the sample size of such objects and facilitate
testing of the formation and evolution theories of planetary systems.
Description:
Identifiers and properties of all identified candidate companions to K
type Sco-Cen members from Pecaut & Mamajek (2016MNRAS.461..794P 2016MNRAS.461..794P, Cat.
J/MNRAS/461/794).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablec1.dat 164 172 Identifiers and properties of all identified
candidate companions to K type Sco-Cen members
from Pecaut & Mamajek (2016).
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See also:
J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)
Byte-by-byte Description of file: tablec1.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- 2MASS1 Primary 2MASS identifier,
2MASSJHHMMSSss+DDMMSSs
24- 42 I19 --- Gaia1 Primary Gaia EDR3 identifier
44- 48 F5.2 mas Plx1 Primary parallax
50- 53 F4.2 mas e_Plx1 Primary parallax uncertainty
55- 56 I2 Myr Age1 Primary age
58- 60 F3.1 Msun Mass1 Primary mass
62- 80 I19 --- Gaia2 Secondary Gaia EDR3 identifier
82- 85 F4.1 arcsec Sep Angular separation (arcsec)
87- 90 I4 au Sepau Angular separation (au)
92- 96 F5.2 mas/yr DpmRA Differential proper motion RA
98-101 F4.2 mas/yr e_DpmRA Differential proper motion uncertainty RA
103-107 F5.2 mas/yr DpmDE Differential proper motion DE
109-112 F4.2 mas/yr e_DpmDE Differential proper motion uncertainty DE
114-118 F5.2 mag Gmag2 Secondary G-band magnitude (Gaia EDR3)
120-124 F5.2 mag (GBP-GRP)2 ?=- Secondary GBP-GRP color (Gaia EDR3)
126-129 F4.2 mag e_(GBP-GRP)2 ?=- Secondary GBP-GRP color uncertainty
(Gaia EDR3)
131-136 F6.1 Mjup Mass2 Secondary mass
138-142 F5.1 Mjup e_Mass2 ?=- Secondary mass uncertainty
144-147 F4.2 --- vproj/vmax Ratio of differential projected velocity
and maximal allowed velocity for a bound
orbit between primary and secondary
149-152 F4.2 --- e_vproj/vmax Lower uncertainty of the ratio of
differential projected velocity and
maximal allowed velocity for a bound
orbit between primary and secondary
154-157 F4.2 --- E_vproj/vmax Upper uncertainty of the ratio of
differential projected velocity and
maximal allowed velocity for a bound
orbit between primary and secondary
159-164 F6.2 % pC Companionship probability
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Acknowledgements:
Alexander Julian Bohn, ajbohn.astro(at)gmail.com,
Leiden Observatory, The Netherlands
(End) Alexander Julian Bohn [Leiden Obs.], Patricia Vannier [CDS] 08-Nov-2021