NGC 2423-3
Encyclopedia
NGC 2423-3 is a red giant
star
approximately 2498 light-year
s away in the constellation
of Puppis
. The star is part of the NGC 2423 open cluster
(hence the name NGC 2423-3). The star has an apparent magnitude
of nine and an absolute magnitude
of zero, with a mass of 2.4 times the Sun
. As of 2007, it has been confirmed that an extrasolar planet
orbits the star.
is an exoplanet 10.6 times more massive than Jupiter
, even more massive than Pi Mensae b
, which has mass about 10.3 times Jupiter. Only the minimum mass
is known since the orbital inclination is not known, so it is likely to be a brown dwarf
instead, like NGC 4349-127 b. The planet orbits at 10.2 μpc, taking 1.956 years to orbit eccentrically around the star. Its eccentricity is about the same as Mercury
, but less than Pluto
. The planet has semi-amplitude
of 71.5 m/s since if 10.6 MJ planet orbits at 2.1 AU from 2.4 MS star.
This planet was discovered by Chad Lovis and Michel Mayor
in July 2007. Lovis had also found three Neptune
-mass planets orbiting HD 69830
in May 2006, also in Puppis.
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...
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...
approximately 2498 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 Puppis
Puppis
Puppis is a constellation in the southern sky. Its name is the Latin word for the poop deck of a ship, and Puppis represents the deck of the ship and its deckhouses...
. The star is part of the NGC 2423 open cluster
Open cluster
An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist...
(hence the name NGC 2423-3). The star has an apparent magnitude
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...
of nine and an absolute magnitude
Absolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
of zero, with a mass of 2.4 times 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...
. As of 2007, it has been confirmed that 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...
orbits the star.
Planetary system
NGC 2423-3 bNGC 2423-3 b
NGC 2423-3b is an extrasolar planet approximately 2498 light-years away in the constellation of Puppis. The planet was announced in 2007 to be orbiting the red giant star NGC 2423-3 . The planet has a mass at least 10.6 times that of Jupiter...
is an exoplanet 10.6 times more massive than Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, even more massive than Pi Mensae b
Pi Mensae b
Pi Mensae b , also known as HD 39091 b, is an extrasolar planet approximately 59 light-years away in the constellation of Mensa...
, which has mass about 10.3 times Jupiter. Only the minimum mass
Minimum mass
In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars and binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets...
is known since the orbital inclination is not known, so it is likely to be a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
instead, like NGC 4349-127 b. The planet orbits at 10.2 μpc, taking 1.956 years to orbit eccentrically around the star. Its eccentricity is about the same as Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
, but less than Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
. The planet has semi-amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
of 71.5 m/s since if 10.6 MJ planet orbits at 2.1 AU from 2.4 MS star.
This planet was discovered by Chad Lovis and Michel Mayor
Michel Mayor
Dr. Michel G. E. Mayor is a Swiss astrophysicist and professor emeritus at the University of Geneva's Department of Astronomy. He formally retired in 2007, but remains active as a researcher at the Observatory of Geneva...
in July 2007. Lovis had also found three Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
-mass planets orbiting HD 69830
HD 69830
HD 69830 is an orange dwarf star approximately 41 light-years away in the constellation of Puppis. It has the Gould designation 285 G. Puppis, though this is infrequently used. In 2005, the Spitzer Space Telescope discovered a debris disk orbiting the star. The disk contains substantially more...
in May 2006, also in Puppis.