Planetary system with mysterious object discovered

(ORDO NEWS) — An international team of astronomers has announced the discovery of a new planetary system near the star HD 18599 (or TOI-179).

Two objects revolve around it: an exoplanet with the mass of Neptune and a massive mysterious object that can be either a brown dwarf or a low-mass star.

The observations were made with NASA’s TESS (Transiting Exoplanet Survey Satellite) space telescope, designed to search for extrasolar planets using the transit method.

During transit, the brightness of a star decreases when a large celestial body, such as an exoplanet, passes against the background of the star’s disk.

TESS surveys about 200,000 of the brightest stars near the Sun, and has so far identified about 6,000 candidate exoplanets (TESS Objects of Interest, or TOI), of which 266 have been confirmed.

The planetary nature of the transit signal from the star HD 18599 of spectral type K (corresponding to orange) was confirmed by subsequent observations using the High Accuracy Radial Speed ​​Planet Searcher (HARPS) instruments at the La Silla Observatory in Chile and Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) mounted on the Very Large Telescope (VLT) at the Paranal Observatory.

Exoplanet TOI-179 b is about 2.62 times the size of Earth and 24 times as massive, giving a relatively high average density of about 7.4 grams per cubic centimeter.

It makes one revolution around its parent star every 4.14 days at a distance of 0.048 astronomical units (AU) in a relatively high eccentricity orbit.

There is also another object in the system, designated HD 18599 B, with a mass of about 83 Jupiter masses, which puts it on the borderline between brown dwarfs and very low-mass stars.

It is located at a distance of 3.3 AU. from the parent star.

The host star TOI-179 is a K2V (main sequence orange dwarf) host star with a radius of approximately 0.76 solar radii and a measured mass of 0.83 solar masses.

The age of the star is estimated at about 300-500 million years, and its effective temperature is at the level of 5145 kelvins.

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