Two low-mass stars and one brown dwarf have been discovered around old stars

(ORDO NEWS) — Using the Transiting Exoplanet Survey Satellite (TESS), a team of astronomers discovered three old star companions – two low-mass stars and one brown dwarf.

These objects are the size of Jupiter, but they are 70 times more massive than the largest planet in the solar system.

TESS is conducting a study of about 200,000 of the brightest stars near the Sun in order to search for transiting exoplanets.

So far, the satellite has identified almost 6,000 candidate exoplanets (TESS Objects of Interest, TOI), 266 of which have already been confirmed.

TESS also helps astronomers search for brown dwarfs and companion stars.

A team of astronomers from Tsinghua University in Beijing reported the detection of transit signals around the three old subgiants TOI-2336, TOI-1608 and TOI-2521, which have spectral types F and G.

Subsequent observations using ground-based observatories showed that the signals are not caused by exoplanets, but much more massive objects.

The brown dwarf TOI-2336 b has a radius of 1.05 Jupiter radii and a mass of almost 70 Jupiter masses, giving a density of 75 g/cm3. TOI-2336 b orbits its parent star every 7.71 days at a distance of about 0.08 AU.

TOI-1608 b is about 21% larger and at least 90 times more massive than Jupiter, with a density of 63.7 g/cm3.

According to the study, the object is at a distance of 0.04 AU. from TOI-1608, and its orbital period is approximately 59 hours. Scientists suggest that TOI-1608 b is a low-mass M-dwarf.

TOI-2521 b is an object the size of Jupiter, but about 77.5 times as massive as the largest planet in the solar system. Its density is about 93 g/cm3.

TOI-2521 b is also considered a low-mass M-dwarf with an orbital period of 5.56 days. It is located at a distance of about 0.06 AU. from TOI-2521.

Summing up, the researchers emphasized that all three objects are “bloated”.

“We found that all three companions have overestimated radii compared to models for the evolution of brown dwarfs and low-mass stars,” the authors of the paper said.


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