Probing the shape of the brown dwarf desert around main-sequence A-F-G-type stars using post-common-envelope WD−BD binaries

¹ School of Physics and Astronomy, Sun Yat-sen University, Zhuhai 519082, PR China
e-mail: chenzhliang@mail2.sysu.edu.cn; mabo8@mail.sysu.edu.cn
² CSST Science Center for the Guangdong-HongKong-Macau Great Bay Area, Sun Yat-sen University, Zhuhai 519082, PR China
³ Yunnan Observatories, Chinese Academy of Sciences, 396 YangFangWang, Guandu District, Kunming 650216, PR China
e-mail: gehw@ynao.ac.cn
⁴ Key Laboratory for Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, PO Box 110 Kunming 650216, PR China
⁵ International Centre of Supernovae, Yunnan Key Laboratory, Kunming 650216, PR China

Received: 7 December 2023
Accepted: 30 March 2024

Abstract

Context. Brown dwarfs (BDs) with masses in the range 40−60 M_Jup are rare around solar-type main-sequence (MS) stars, which gives rise to the brown dwarf desert (BDD). One caveat associated with previous studies of BDD is the relatively limited sample size of MS−BD binaries with accurately determined BD masses.

Aims. We aim to produce a large sample of BD companions with precisely determined masses around MS A-F-G-type stars using observations of post-common-envelope white dwarf (WD)−BD binaries.

Methods. We employed the rapid binary evolution code COMPAS to deduce the properties of MS−BD binary progenitors from post-common-envelope WD−BD binaries. With this method, we increase the sample of directly observed MS−BD binaries, enriching the data available for analyzing the BDD around MS A-F-G-type stars.

Results. Our study opens a new window for studying the shape of the BDD around A-F-G-type MS stars in the short-period regime. We find tentative evidence, albeit with a small sample size, that the “driest” part of the BDD around A-F-G-type stars may extend into an orbital period of several hundred days. More post-common-envelope WD−BD binaries detected in the future will advance our understanding of the BDD around A-F-G-type stars.