Brown Dwarf Astronomy with Gaia: How dry is the desert?

Stevenson, Adam (2023). Brown Dwarf Astronomy with Gaia: How dry is the desert? Postgraduate Research Poster Competition, The Open University.

Abstract

Brown dwarfs are objects in our Universe that are too massive to be a planet, but not massive enough to be a star. Many are found orbiting other stars, allowing us to detect them. However, there is a dearth of brown dwarf companions in relatively short-period orbits, compared with planetary or stellar companions - known as the brown dwarf desert.

Many studies use minimum masses from Doppler spectroscopy in their sample, but the true masses are unknown. I have used astrometry from the Gaia Data Release 3 to calculate inclination, the angle between orbital plane of the companion and our line of sight. This has allowed twelve true masses to be calculated.

Three objects remain as brown dwarfs, but nine are moved to the low-mass star regime. This shows how important it is for true masses to be used in analysis of the desert. With these objects and a sample of other known true masses, I have found that there are still two distinct populations proposed throughout literature, and appears to be a mass valley around 35 Jupiter masses.

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