TESS discovers a rare brown dwarf orbiting a massive, aging star

Astronomers have discovered a rare brown dwarf orbiting a massive, aging star, potentially offering new insights into the formation of these planet-like bodies. The brown dwarf, named HIP 61637 b, is located in the middle of the "brown dwarf desert," a region where such objects are scarce. The host star is an aging A-type star nearly three times the mass of the Sun, and it is the brightest, most massive star ever found to host a transiting brown dwarf. The system's age is estimated to be about 396 million years, making HIP 61637 b the seventh brown dwarf with a reliably known age. The discovery was made using NASA's Transiting Exoplanet Survey Satellite (TESS), which captured the dimming of the star when HIP 61637 b passed in front of it. The brown dwarf's size and orbit suggest it may have formed planet-like, rather than through direct collapse, but its mass is still within the limits of what disk accretion is thought capable of producing.

• "HIP 61637 b" is a brown dwarf with a mass of 48 Jupiter masses.
• The host star is an aging A-type star nearly three times the mass of the Sun.
• The system's age is estimated to be about 396 million years.
• The brown dwarf's orbit is near circular, which is unusual for brown dwarfs, which are typically thought to have more eccentric, elongated orbits.
• The discovery adds a valuable data point to a small number of well-characterized transiting brown dwarfs with well-defined ages.

This observation challenges the conventional understanding of how brown dwarfs form, as it suggests they may not have formed through direct cloud collapse but rather through accretion within the accretion disks of massive stars. The results highlight the importance of TESS in discovering such rare objects and provide a basis for future research into the formation mechanisms of these enigmatic bodies. The discovery also underscores the complexity of the processes involved in the formation of brown dwarfs and the need for further study to determine their exact nature.

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