HD 46375
Encyclopedia
HD 46375 is an 8th magnitude
K-type subgiant star
located approximately 109 light-year
s away in the constellation
of Monoceros
. This star resembles a orange dwarf
but which has a larger radius and luminosity indicating that fusion
reactions in its core are starting to cease and the star is on its way becoming a red giant
. Spectral type
of the star is K1 IV. Its advanced evolutionary stage shows that it is considerably older than our Sun
.
This star has sometimes been classified as a member of the NGC 2244
star cluster
in the Rosette Nebula
, but in reality it just happens to lie in the foreground. The distance to the cluster is much greater, about 4500 light years.
In 2000, a low-mass gas giant
was found orbiting the star.
with only three quarters the mass of Saturn
was discovered by Marcy
, Butler
, and Vogt
in California
, together with 79 Ceti b
. This planet was discovered using the "wobble method" or radial velocity method, which calculates the rate and shape of the stellar wobble
caused by the revolving planet's gravity.
Apparent 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...
K-type 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...
located approximately 109 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 Monoceros
Monoceros
Monoceros is a faint constellation on the celestial equator. Its name is Greek for unicorn. Its definition is attributed to the 17th-century Dutch cartographer Petrus Plancius. It is bordered by Orion to the west, Gemini to the north, Canis Major to the south and Hydra to the east...
. This star resembles a 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...
but which has a larger radius and luminosity indicating that fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
reactions in its core are starting to cease and the star is on its way becoming a 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...
. Spectral type
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...
of the star is K1 IV. Its advanced evolutionary stage shows that it is considerably older than our 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...
.
This star has sometimes been classified as a member of the NGC 2244
NGC 2244
NGC 2244 is an open cluster in the Rosette Nebula, which is located in the constellation Monoceros. This cluster has several O-type stars, super hot stars that generate large amounts of radiation and stellar wind....
star cluster
Star cluster
Star clusters or star clouds are groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds of thousands of very old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain less than...
in the Rosette Nebula
Rosette Nebula
The Rosette Nebula is a large, circular H II region located near one end of a giant molecular cloud in the Monoceros region of the Milky Way Galaxy...
, but in reality it just happens to lie in the foreground. The distance to the cluster is much greater, about 4500 light years.
In 2000, a low-mass gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
was found orbiting the star.
Planetary system
On March 29, 2000, the planet HD 46375 bHD 46375 b
HD 46375 b is an extrasolar planet located approximately 109 light-years away in the constellation of Monoceros, orbiting the star HD 46375. With 79 Ceti b on March 29, 2000, it was joint first known extrasolar planet less massive than Saturn orbiting a normal star. The planet is a "hot Jupiter", a...
with only three quarters 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,...
was discovered by Marcy
Geoffrey Marcy
Geoffrey W. Marcy is an American astronomer, who is currently Professor of Astronomy at the University of California, Berkeley, famous for discovering more extrasolar planets than anyone else, 70 out of the first 100 to be discovered, along with R...
, Butler
R. Paul Butler
R. Paul Butler is an astronomer who searches for extrasolar planets.He received a BA and an MS from San Francisco State University, completing a Master's thesis with Geoffrey Marcy, and then completed his doctoral studies at the University of Maryland, College Park in 1993...
, and Vogt
Steven S. Vogt
Steven Scott Vogt is an American astronomer whose main interest is the search for extrasolar planets.He is credited, along with R. Paul Butler, for discovering Gliese 581 g, the first potentially habitable planet outside of our own solar system....
in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, together with 79 Ceti b
79 Ceti b
79 Ceti b is an extrasolar planet orbiting its star every 75 days. With HD 46375 b on March 29, 2000, it was the joint first known extrasolar planet to have minimum mass less than the mass of Saturn.-External links:...
. This planet was discovered using the "wobble method" or radial velocity method, which calculates the rate and shape of the stellar wobble
Stellar wobble
Stellar wobble is a variation in the position of a star due to the gravitational influence of another body orbiting it. Stellar wobble is visible as a Doppler shift in the star's spectrum or as a motion of the star in the plane of the sky...
caused by the revolving planet's gravity.