TESS Discovers Its First Brown Dwarf | Astronomy – Sci-News.com
Astronomers using NASA’s Transiting Exoplanet Survey Satellite (TESS) have discovered an intermediate-mass brown dwarf orbiting a young star about 841 light-years from Earth. Named TOI-503b, the object is the first brown dwarf discovered by TESS.
An artist’s impression of TOI-503b and its star. Image credit: Sci-News.com.
Brown dwarfs are cool, dim objects that have a size between that of a gas giant, such as Jupiter or Saturn, and that of a Sun-like star.
Sometimes called failed stars, they are too small to sustain hydrogen fusion reactions at their cores, yet they have star-like attributes.
Typically, they have masses between 11-16 Jupiters (the approximate mass at which deuterium fusion can be sustained) and 75-80 Jupiters (the approximate mass to sustain hydrogen fusion).
The newly-discovered brown dwarf, TOI-503b, is just 1.34 times bigger than Jupiter but 53.7 times more massive.
It orbits its host star, TOI-503, once every 3.7 days at a distance of only 0.06 AU in a circular orbit.
Also known as BD+13 1880, TIC 186812530 and TYC 802-751-1, TOI-503 is an A-type star with 1.8 times the Sun’s mass and a radius that’s 1.7 times larger than the Sun.
The star has a surface temperature of 13,311 degrees Fahrenheit (7,377 degrees Celsius) and is just 180 million years old.
“We argue that this brown dwarf formed in-situ, based on the young age of the system and the long circularization timescale for this brown dwarf around its host star,” said lead author Dr. Jan Subjak and colleagues.
“TOI-503b joins a growing number of known short-period, intermediate-mass brown dwarfs orbiting main sequence stars, and is the second such brown dwarf known to transit an A star, after HATS-70b.”
“With the growth in the population in this regime, the driest region in the brown dwarf desert (35-55 Jupiter masses) is reforesting and its mass range shrinking.”
The team’s paper will be published in the Astronomical Journal.
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Ján Šubjak et al. 2019. TOI-503: The first known brown dwarf-Am star binary from the TESS mission. AJ, in press; arXiv: 1909.07984
