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Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3

Bohn, Alexander J. and Ginski, Christian and Kenworthy, Matthew A. and Mamajek, Eric E. and Meshkat, Tiffany and Pecaut, Mark J. and Reggiani, Maddalena and Seay, Christopher R. and Brown, Anthony G. A. and Cugno, Gabriele and Henning, Thomas and Launhardt, Ralf and Quirrenbach, Andreas and Rickman, Emily L. and Ségransan, Damien (2022) Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3. Astronomy and Astrophysics, 657 . Art. No. A53. ISSN 0004-6361. doi:10.1051/0004-6361/202039917.

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Context. 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. Aims. 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. Methods. 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. Results. 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 20 MJup. 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 570 au 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 52₋₁₁⁺¹⁷ M_(Jup). Conclusions. 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 300 au and with a sensitivity limit beyond 1000 au and a lower mass limit down to 20 M_(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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bohn, Alexander J.0000-0003-1401-9952
Ginski, Christian0000-0002-4438-1971
Kenworthy, Matthew A.0000-0002-7064-8270
Mamajek, Eric E.0000-0003-2008-1488
Meshkat, Tiffany0000-0001-6126-2467
Pecaut, Mark J.0000-0002-7859-1504
Reggiani, Maddalena0000-0003-2911-0898
Henning, Thomas0000-0002-1493-300X
Additional Information:© ESO 2022. Received 15 November 2020; Accepted 16 September 2021. Published online 07 January 2022. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 099.C-0698(A), 0101.C-0341(A), 1101.C-0092(E), and 0104.C-0265(A). We would like to thank the anonymous referee for the detailed feedback they provided. Their comments helped the authors to improve the quality of the manuscript. We dedicate this article to the memory of France Allard, who passed away in October 2020. Her groundbreaking work on low-mass stars, brown dwarfs, and exoplanets strongly shaped our current understanding of their atmospheric physics; the models she (co-)developed – that were also used in this work and that were frequently accessed by a vast number of researchers – will remain as a crucial foundation to all future studies in this field and astronomy in general. The research of A.J.B. leading to these results has received funding from the European Research Council under ERC Starting Grant agreement 678194 (FALCONER). Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). G.C. thanks the Swiss National Science Foundation for financial support under grant number 200021_169131. This research has used the SIMBAD database, operated at CDS, Strasbourg, France (Wenger et al. 2000). This work has used data from the European Space Agency (ESA) mission Gaia (, processed by the Gaia Data Processing and Analysis Consortium (DPAC, Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported by the Spanish MINECO through grant AyA2017-84089. To achieve the scientific results presented in this article we made use of the Python programming language8, especially the SciPy (Virtanen et al. 2020), NumPy (Oliphant 2006), Matplotlib (Hunter 2007), emcee (Foreman-Mackey et al. 2013), scikit-image (Van der Walt et al. 2014), scikit-learn (Pedregosa et al. 2012), photutils (Bradley et al. 2016), and astropy (Astropy Collaboration 2013, 2018) packages.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
European Research Council (ERC)678194
Swiss National Science Foundation (SNSF)200021_169131
Gaia Multilateral AgreementUNSPECIFIED
Ministerio de Economía, Industria y Competitividad (MINECO)AyA2017-84089
Subject Keywords:binaries: visual – brown dwarfs – astrometry – open clusters and associations: individual: Sco-Cen – stars: individual: TYC 8252-533-1
Record Number:CaltechAUTHORS:20220131-39112800
Persistent URL:
Official Citation:Unveiling wide-orbit companions to K-type stars in Sco-Cen with Gaia EDR3. Alexander J. Bohn, Christian Ginski, Matthew A. Kenworthy, Eric E. Mamajek, Tiffany Meshkat, Mark J. Pecaut, Maddalena Reggiani, Christopher R. Seay, Anthony G. A. Brown, Gabriele Cugno, Thomas Henning, Ralf Launhardt, Andreas Quirrenbach, Emily L. Rickman and Damien Ségransan. A&A, 657 (2022) A53; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113186
Deposited By: Tony Diaz
Deposited On:01 Feb 2022 18:33
Last Modified:01 Feb 2022 18:33

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