HD 208487
Encyclopedia
HD 208487 is a 7th magnitude
G-type main sequence star
located approximately 144 light-year
s away in the constellation
of Grus
. It has the same spectral type as our sun
, G2V. However, it is probably slightly less massive and more luminous, indicating that it is slightly older. As of 2008, there is one known extrasolar planet
confirmed to be orbiting the star.
. It has a mass at least half that of Jupiter
and is located in an eccentric
130-day orbit.
The discovery of a second planet in the system was announced on September 13, 2005, by P.C. Gregory. The discovery was made using Bayesian analysis of the radial velocity dataset to determine the planetary parameters. However, further analysis revealed that an alternative 2-planet solution for the HD 208487 system was possible, with a planet in a 28-day orbit instead of the 908-day orbit postulated, and it was concluded that activity on the star is more likely to be responsible for the residuals to the one-planet solution than the presence of a second planet.
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...
G-type main sequence 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 144 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 Grus
Grus (constellation)
Grus is a constellation in the southern sky. Its name is Latin for the crane, a species of bird. It was introduced in the late sixteenth century.-History:The stars that form Grus were originally considered part of Piscis Austrinus...
. It has the same spectral type as 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...
, G2V. However, it is probably slightly less massive and more luminous, indicating that it is slightly older. As of 2008, there is one known 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...
confirmed to be orbiting the star.
Planetary system
There is one known planet orbiting the star HD 208487, which is designated HD 208487 bHD 208487 b
HD 208487 b is an extrasolar planet located approximately 144 light-years away in the constellation of Grus, orbiting the star HD 208487. This planet has a minimum mass close to half that of Jupiter and is most probably a gas giant. The planet orbits the star in a close, eccentric orbit. One...
. It has a mass at least half 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,...
and is located in an eccentric
Orbital eccentricity
The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...
130-day orbit.
The discovery of a second planet in the system was announced on September 13, 2005, by P.C. Gregory. The discovery was made using Bayesian analysis of the radial velocity dataset to determine the planetary parameters. However, further analysis revealed that an alternative 2-planet solution for the HD 208487 system was possible, with a planet in a 28-day orbit instead of the 908-day orbit postulated, and it was concluded that activity on the star is more likely to be responsible for the residuals to the one-planet solution than the presence of a second planet.