Gamma Cephei Ab
Encyclopedia
Gamma Cephei Ab is an extrasolar planet
approximately 45 light-year
s away in the constellation
of Cepheus
(the King
). The planet was confirmed to be in orbit around Gamma Cephei
in 2002, but was first suspected to exist around 1988 (making this planet arguably the first true extrasolar planet discovered).
team of astronomers led by Bruce Campbell, Gordon Walker, and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first true extrasolar planet
, and it was hypothesized based on the same radial velocity
technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery.
, Artie P. Hatzes
, et al.) at the Planetary Systems and their Formation Workshop announced the preliminary confirmation of a long-suspected planet Gamma Cephei Ab with a minimum mass of 1.59 MJ (1.59 times that of Jupiter
). The parameters were later recalculated when direct detection of the secondary star Gamma Cephei B allowed astronomers to better constrain the properties of the system. Gamma Cephei Ab moves in an elliptical orbit with a semimajor axis of 2.044 AU which takes almost two and a half years to complete. The eccentricity is 0.115, which means it moves between 1.81 and 2.28 AUs in orbital distance around Gamma Cephei A
, which would place it beyond the orbit of Mars
in the solar system
.
Hipparcos data taken in 2006 constrains its mass below "13.3 MJ at the 95% confidence level, and 16.9 MJ at the 99.73% (3 σ) confidence level". This is not much to go on, but it is enough to verify that it is not another unseen red or brown dwarf.
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...
approximately 45 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 Cepheus
Cepheus (constellation)
Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations.-Stars:...
(the King
King
- Centers of population :* King, Ontario, CanadaIn USA:* King, Indiana* King, North Carolina* King, Lincoln County, Wisconsin* King, Waupaca County, Wisconsin* King County, Washington- Moving-image works :Television:...
). The planet was confirmed to be in orbit around Gamma Cephei
Gamma Cephei
Gamma Cephei , traditionally named Errai, Er Rai, and or Alrai, is a binary star system approximately 45 light-years away in the constellation of Cepheus. Gamma Cephei contains an apparent magnitude of 3.22. The visible part of the system is a stellar class K1III-IV orange subgiant star on its...
in 2002, but was first suspected to exist around 1988 (making this planet arguably the first true extrasolar planet discovered).
1988 claims
The first indications of Gamma Cephei Ab were reported in July 1988. The planet was tentatively identified by a CanadianCanada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
team of astronomers led by Bruce Campbell, Gordon Walker, and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first true 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...
, and it was hypothesized based on the same radial velocity
Radial velocity
Radial velocity is the velocity of an object in the direction of the line of sight . In astronomy, radial velocity most commonly refers to the spectroscopic radial velocity...
technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery.
2002 confirmation
On September 24, 2002, Gamma Cephei Ab was finally confirmed. The team of astronomers (including William D. CochranWilliam D. Cochran
William Duscharme "Pink Cheeks" Cochran was an American football player. He played guard and tackle for the University of Michigan from 1913 to 1915. He was a first-team All-Western lineman and the captain of Michigan's 1915 football team. He later operated a freight trucking line based in the...
, Artie P. Hatzes
Artie P. Hatzes
Artie P. Hatzes is an American astronomer. He is a professor at the Friedrich Schiller University of Jena and director of the Karl Schwarzschild Observatory ....
, et al.) at the Planetary Systems and their Formation Workshop announced the preliminary confirmation of a long-suspected planet Gamma Cephei Ab with a minimum mass of 1.59 MJ (1.59 times that of 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,...
). The parameters were later recalculated when direct detection of the secondary star Gamma Cephei B allowed astronomers to better constrain the properties of the system. Gamma Cephei Ab moves in an elliptical orbit with a semimajor axis of 2.044 AU which takes almost two and a half years to complete. The eccentricity is 0.115, which means it moves between 1.81 and 2.28 AUs in orbital distance around Gamma Cephei A
Gamma Cephei
Gamma Cephei , traditionally named Errai, Er Rai, and or Alrai, is a binary star system approximately 45 light-years away in the constellation of Cepheus. Gamma Cephei contains an apparent magnitude of 3.22. The visible part of the system is a stellar class K1III-IV orange subgiant star on its...
, which would place it beyond the orbit of Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
in the solar system
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
Hipparcos data taken in 2006 constrains its mass below "13.3 MJ at the 95% confidence level, and 16.9 MJ at the 99.73% (3 σ) confidence level". This is not much to go on, but it is enough to verify that it is not another unseen red or brown dwarf.
See also
- 51 Pegasi b51 Pegasi b51 Pegasi b , sometimes though unofficially named Bellerophon, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus...
- HD 114762 bHD 114762 bHD 114762 b is a candidate extrasolar planet, approximately 132 light years away in the constellation of Coma Berenices, and is probably a brown dwarf. This optically undetected companion to the late F-type star HD 114762 was discovered in 1989 by David Latham and others...
- Iota Horologii bIota Horologii bIota Horologii b , often catalogued HR 810 b, is an extrasolar planet approximately 50 light-years away in the constellation of Horologium...
- PSR B1257+12 BPSR B1257+12 BPSR B1257+12B is an extrasolar planet in the constellation of Virgo . PSR B1257+12B was the first planet ever discovered outside the Solar system, and is the second object known to be orbiting the pulsar PSR B1257+12, which it circles at a distance of 0.36 AU with an orbital period of...
- PSR B1257+12 CPSR B1257+12 CPSR B1257+12C is an extrasolar planet approximately 980 light-years away in the constellation of Virgo . PSR B1257+12C was one of the first planets ever discovered outside the Solar system, and is currently the third object known to be orbiting the pulsar PSR B1257+12...