HIP 79431 b
Encyclopedia
HIP 79431 b is an extrasolar planet
discovered by the W. M. Keck Observatory in 2010. The planet is found in an M type dwarf star
catalogued as HIP 79431
and is located within the Scorpius
constellation approximately 47 light years
away from the Earth. Its orbital period
lasts about 111.7 days and has an orbital eccentricity
of 0.29. The planet is the 6th giant planet to be detected in the Doppler surveys of M dwarfs and is considered to be one of the most massive planets found around M dwarf stars
.
had been challenging to be assessed due to the uncertainties within the molecular data line however it has not been typical for M Dwarfs to have strong emissions from the core data lines. This led to the inclusion of the HIP 79431 star to the KECK program in April 2009 as part of the exoplanet studies for low mass stars. During this study, 13 Doppler measurements
of the star were done over a 6 month period using the High Resolution Echelle Spectrometer (HIRES). The exposure times used in its observation was 600 seconds which yielded a signal-to-noise ratio
of just under 100. Each program observation required the use of iodine absorption lines in order to model the wavelength scale as well as the instrumental profile of the telescope and spectrometer optics. The Doppler experiments derived radial velocities fit the Keplerian model
showing an unambiguous signal and orbital parameters which best fit planetary gravitational pull, this revealed the presence of the planet HIP 79431 b. However, there is no evidence that any additional planets was found.
mainly due to its semi-major axis orientation. Another observation with regard to its eccentricity orbit is that it brings the planet closer to its star periastron
increasing the probability of a transit, which was estimated as a meager 0.5%. According to the KECK program, if a transit would occur, the depth would be remarkable mainly due to the calculated mass of the 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...
discovered by the W. M. Keck Observatory in 2010. The planet is found in an M type dwarf star
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...
catalogued as HIP 79431
HIP 79431
HIP 79431 is an 11th magnitude M-type main sequence star located approximately 49 light years away in the constellation Scorpius. This star is smaller, cooler, dimmer, and less massive than our Sun. Also its metal content is 2.5 times as much as the Sun. In 2010, a superjovian planet was found in...
and is located within the Scorpius
Scorpius
Scorpius, sometimes known as Scorpio, is one of the constellations of the zodiac. Its name is Latin for scorpion, and its symbol is . It lies between Libra to the west and Sagittarius to the east...
constellation approximately 47 light years
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
away from the Earth. Its orbital period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
lasts about 111.7 days and has an orbital eccentricity
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...
of 0.29. The planet is the 6th giant planet to be detected in the Doppler surveys of M dwarfs and is considered to be one of the most massive planets found around M dwarf stars
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
.
Observations
HIP 79431 b is located in orbit around a star whose metallicityMetallicity
In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
had been challenging to be assessed due to the uncertainties within the molecular data line however it has not been typical for M Dwarfs to have strong emissions from the core data lines. This led to the inclusion of the HIP 79431 star to the KECK program in April 2009 as part of the exoplanet studies for low mass stars. During this study, 13 Doppler measurements
Doppler effect
The Doppler effect , named after Austrian physicist Christian Doppler who proposed it in 1842 in Prague, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from...
of the star were done over a 6 month period using the High Resolution Echelle Spectrometer (HIRES). The exposure times used in its observation was 600 seconds which yielded a signal-to-noise ratio
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
of just under 100. Each program observation required the use of iodine absorption lines in order to model the wavelength scale as well as the instrumental profile of the telescope and spectrometer optics. The Doppler experiments derived radial velocities fit the Keplerian model
Orbital elements
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are generally considered in classical two-body systems, where a Kepler orbit is used...
showing an unambiguous signal and orbital parameters which best fit planetary gravitational pull, this revealed the presence of the planet HIP 79431 b. However, there is no evidence that any additional planets was found.
Low transit possibility
The planet HIP 79431 b has a low transit probabilityAstronomical transit
The term transit or astronomical transit has three meanings in astronomy:* A transit is the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point...
mainly due to its semi-major axis orientation. Another observation with regard to its eccentricity orbit is that it brings the planet closer to its star periastron
Apsis
An apsis , plural apsides , is the point of greatest or least distance of a body from one of the foci of its elliptical orbit. In modern celestial mechanics this focus is also the center of attraction, which is usually the center of mass of the system...
increasing the probability of a transit, which was estimated as a meager 0.5%. According to the KECK program, if a transit would occur, the depth would be remarkable mainly due to the calculated mass of the planet.