BEAST begins: sample characteristics and survey performance of the B-star Exoplanet Abundance Study^★,★★

¹ Institutionen för astronomi, Stockholms Universitet, Stockholm, Sweden
e-mail: markus.janson@astro.su.se
² Dipartimento di Fisica e Astronomia “Galileo Galilei” Università di Padova, Padova, Italy
³ INAF – Osservatorio Astronomico di Padova, Padova, Italy
⁴ Univ. Grenoble Alpes, IPAG, Grenoble, France
⁵ Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Heidelberg, Germany
⁶ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
⁷ Department of Physics and Astronomy, University of Rochester, Rochester, NY, USA
⁸ Aix-Marseille Université, CNRS, LAM, Marseille, France
⁹ CRAL, CNRS, Université Lyon, Saint Genis Laval, France
¹⁰ ETH Zurich, Zurich, Switzerland
¹¹ Departemento de Astronomía, Universidad de Chile, Santiago, Chile
¹² Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, Zurich, Switzerland
¹³ Institut für Astronomie und Astrophysik, Eberhard Karls Universität Tübingen, Tübingen, Germany
¹⁴ Physikalisches Institut, Universität Bern, Bern, Switzerland
¹⁵ Max Planck Institut für Astronomie, Heidelberg, Germany
¹⁶ Leiden Observatory, Leiden University, Leiden, The Netherlands
¹⁷ Department of Astronomy, University of Michigan, Ann Arbor, MI, USA
¹⁸ College of Charleston, Charleston, SC, USA

Received: 15 October 2020
Accepted: 19 December 2020

Abstract

While the occurrence rate of wide giant planets appears to increase with stellar mass at least up through the A-type regime, B-type stars have not been systematically studied in large-scale surveys so far. It therefore remains unclear up to what stellar mass this occurrence trend continues. The B-star Exoplanet Abundance Study (BEAST) is a direct imaging survey with the extreme adaptive optics instrument SPHERE, targeting 85 B-type stars in the young Scorpius-Centaurus (Sco-Cen) region with the aim to detect giant planets at wide separations and constrain their occurrence rate and physical properties. The statistical outcome of the survey will help determine if and where an upper stellar mass limit for planet formation occurs. In this work, we describe the selection and characterization of the BEAST target sample. Particular emphasis is placed on the age of each system, which is a central parameter in interpreting direct imaging observations. We implement a novel scheme for age dating based on kinematic sub-structures within Sco-Cen, which complements and expands upon previous age determinations in the literature. We also present initial results from the first epoch observations, including the detections of ten stellar companions, of which six were previously unknown. All planetary candidates in the survey will need follow up in second epoch observations, which are part of the allocated observational programme and will be executed in the near future.