83 Leonis
Encyclopedia
83 Leonis, abbreviated 83 Leo, is a binary star
system approximately 58 light-year
s away in the constellation
of Leo
(the Lion
). The primary star of the system is a cool orange subgiant star
, while the secondary star is an orange dwarf
star. The two stars are separated by at least 515 astronomical unit
s from each other. Both stars are presumed to be cooler than the Sun
.
In 2005, an extrasolar planet
was confirmed to be orbiting the secondary star within the system.
In 2010 the second planet was discovered.
star. It is not visible to the unaided eye, but easily visible with small binoculars
. The star is classified as a subgiant, meaning that it has ceased fusing hydrogen
in its core and started to evolve
towards red giant
hood.
The secondary component, 83 Leonis B, is an 8th magnitude orange dwarf, somewhat less massive (0.88 MSun), smaller and cooler than our Sun. It is visible only with binoculars or better equipment. Components A and B share common proper motion
, which confirms them as a physical pair. The projected separation between the stars is 515 AU, but the true separation may be much higher.
There is yet another, magnitude 14.4 component listed in the Washington Double Star Catalog
. However, this star is moving into a different direction and is therefore not a true member of the 83 Leonis system.
was discovered in Jan 2005 by the California and Carnegie Planet Search team, who use the radial velocity method to detect planets. The planet's minimum mass is less than half of the mass of Saturn
. It orbits very close to the star, completing one orbit in about 17 day
s.
In 2010 the second planet 83 Leonis Bc was discovered.
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system approximately 58 light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
of Leo
Leo (constellation)
Leo is one of the constellations of the zodiac. Its name is Latin for lion. Its symbol is . Leo lies between dim Cancer to the west and Virgo to the east.-Stars:...
(the Lion
Lion
The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...
). The primary star of the system is a cool orange subgiant star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
, while the secondary star is an orange dwarf
Orange dwarf
A K-type main-sequence star , also referred to orange dwarf, are main-sequence stars of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars and yellow G-type main-sequence stars...
star. The two stars are separated by at least 515 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
s from each other. Both stars are presumed to be cooler than the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
.
In 2005, an extrasolar planet
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
was confirmed to be orbiting the secondary star within the system.
In 2010 the second planet was discovered.
Stellar system
The primary component, 83 Leonis A, is a 6th magnitudeApparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
star. It is not visible to the unaided eye, but easily visible with small binoculars
Binoculars
Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...
. The star is classified as a subgiant, meaning that it has ceased fusing hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
in its core and started to evolve
Stellar evolution
Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime. Depending on the mass of the star, this lifetime ranges from only a few million years to trillions of years .Stellar evolution is not studied by observing the life of a single...
towards red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
hood.
The secondary component, 83 Leonis B, is an 8th magnitude orange dwarf, somewhat less massive (0.88 MSun), smaller and cooler than our Sun. It is visible only with binoculars or better equipment. Components A and B share common proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...
, which confirms them as a physical pair. The projected separation between the stars is 515 AU, but the true separation may be much higher.
There is yet another, magnitude 14.4 component listed in the Washington Double Star Catalog
Washington Double Star Catalog
The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for 102,387 pairs of double stars. The catalog also includes multiple stars...
. However, this star is moving into a different direction and is therefore not a true member of the 83 Leonis system.
Planetary system
Planet 83 Leonis Bb83 Leonis Bb
83 Leonis Bb, also catalogued as HD 99492 b or abbreviated 83 Leo Bb, is an extrasolar planet approximately 58 light-years away in the constellation of Leo . The planet was discovered in January 2005 by the California and Carnegie Planet Search team, who use the Doppler spectroscopy method to...
was discovered in Jan 2005 by the California and Carnegie Planet Search team, who use the radial velocity method to detect planets. The planet's minimum mass is less than half of the mass of Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
. It orbits very close to the star, completing one orbit in about 17 day
Day
A day is a unit of time, commonly defined as an interval equal to 24 hours. It also can mean that portion of the full day during which a location is illuminated by the light of the sun...
s.
In 2010 the second planet 83 Leonis Bc was discovered.