Gliese 163 is a faint red dwarf star with multiple exoplanetary companions in the southern constellation of

Dorado Dorado () is a constellation in the southern sky. It was named in the late 16th century and is now one of the 88 modern constellations. Its name refers to the dolphinfish (''Coryphaena hippurus''), which is known as ''dorado'' in Spanish, altho ...

. Other stellar catalog names for it include HIP 19394 and LHS 188. It is too faint to be visible to the naked eye, having an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 11.79 and an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...

of 10.91. This system is located at a distance of 49.4 light-years from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

based on parallax measurements. Judging by its space velocity components, it is most likely a

thick disk The thick disk is one of the structural components of about 2/3 of all disk galaxies, including the Milky Way. It was discovered first in external edge-on galaxies. Soon after, it was proposed as a unique galactic structure in the Milky Way, diff ...

star. This is a small M-type main-sequence star with a stellar classification of M3.5V. It has a relatively low activity level for a red dwarf of its mass, suggesting it is an old star with an age of at least two billion years. This star has 41% of the mass and radius of the Sun. It is spinning slowly with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ...

of 0.85 km/s and has a rotation period of 61 days. The star is radiating just 2% of the luminosity of the Sun from its photosphere at an effective temperature of 3,460 K.

Planetary system

In September 2012, astronomers using the HARPS instrument announced the discovery of two planets orbiting Gliese 163. The first planet, Gliese 163 b, is a super-Earth or mini-Neptune with an orbital period of 9 days, therefore far too hot to be considered habitable. However, Gliese 163 c, with an orbital period of 26 days and a minimum mass of 6.9 Earth masses, was considered to potentially be in the star's

habitable zone In astronomy and astrobiology, the circumstellar habitable zone (CHZ), or simply the habitable zone, is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressure.J. F. Kast ...

, although it is hotter than Earth, with a temperature of 60 deg. C (140 deg. F). It has an eccentricity estimated to be about 0.03, giving it a fairly circular orbit. Evidence was also found for a third planet orbiting further out than c and b. In June 2013, it was concluded that at least 3 planets orbit around the star with a fourth planet being a possibility, and in a paper submitted to

arXiv arXiv (pronounced "archive"—the X represents the Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not peer review. It consists of ...

in June 2019, that and another planet were found, thus giving the system a total of five planets.

References

{{DEFAULTSORT:Gliese 163 M-type main-sequence stars Planetary systems with five confirmed planets Dorado (constellation) 019394 TIC objects