HD 8574 b
Encyclopedia
HD 8574 b is an extrasolar planet
discovered in 2001 by a team of European astronomers using Doppler spectroscopy
as part of the ELODIE Planet Search Survey, and was published in a paper with five other planets. HD 8574 b is in the orbit of host star HD 8574
. The planet is at most two times the mass of Jupiter, orbiting every 227 days at three quarters of the distance between the Earth and Sun. HD 8574 b has a very elliptical orbit, far more than that of Jupiter.
at the Haute-Provence Observatory
in southeastern France, was a large-scale search for extrasolar planet
s orbiting G-type and F-type dwarf stars visible from the Northern Hemisphere through use of the radial velocity method (the orbit of a planet tugs on its host star as it orbits, causing a perceived Doppler effect
in the star's spectrum
). This survey, which started in 1994, led to the discovery of 51 Pegasi b
, the first extrasolar planet discovered in the orbit of a sunlike star. By 2003, the discovery of six new planets, including HD 8574 b, was announced, bringing ELODIE's planet discovery count to eighteen.
HD 8574, one of the target stars of ELODIE, had been previously catalogued by the European Space Agency
with the release of the Hipparcos
catalogue in 1997. Most of HD 8574's characteristics were extracted from this catalogue for use in searching for a planet around HD 8574. The spectrum was then analyzed to see if HD 8574 were active, a factor that could mask or mimic the signal of an orbiting planet. It was found that the star was not significantly active.
In the case of HD 8574, ELODIE obtained 41 radial velocity
measurements, which had, at the time of the discovery paper, been collected since January 11, 1998. Analysis of the collected data confirmed the existence of a planet orbiting HD 8574. Of the six, the planet HD 8574 b had the shortest orbital period
, orbiting its host star under three years (unlike the five other planets that had been discovered by ELODIE at the same time).
HD 8574 b was announced by the European Southern Observatory
on April 4, 2001. The findings addressing HD 8574's discovery were published in 2003.
s (144 light years) away from Earth. HD 8574 has an estimated mass of 1.17 times the mass
of the Sun. The star also has a radius that is estimated at 1.37 times that of the Sun's. HD 8574 has an effective temperature
of 6080 K, hotter than the Sun, and a metallicity
estimated at [Fe/H] = 0.05 (12% more iron than in the Sun). Additionally, with a luminosity
of 2.25, HD 8574 releases more than twice the energy released by the Sun.
The star has an apparent magnitude
of 7.12, and is thus extremely faint (if visible at all) as seen from the unaided eye of an observer on Earth.
, or 77% the mean distance between the Earth and the Sun. HD 8574 b has, of the six planets announced in a November 2003 discovery paper, the shortest orbit. The planet has an estimated mass
of 2.11 times Jupiter's mass. HD 8574 b has a measured orbital eccentricity
of 0.288, denoting an elliptical orbit. Jupiter, in comparison, orbits the Sun with an orbital eccentricity of 0.016, which is far more circular.
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 in 2001 by a team of European astronomers using Doppler spectroscopy
Doppler spectroscopy
Doppler spectroscopy, also known as radial velocity measurement, is a spectroscopic method for finding extrasolar planets. It involves the observation of Doppler shifts in the spectrum of the star around which the planet orbits....
as part of the ELODIE Planet Search Survey, and was published in a paper with five other planets. HD 8574 b is in the orbit of host star HD 8574
HD 8574
HD 8574 is a yellow-white star in the constellation Pisces. It has an apparent magnitude of +7.12 and absolute magnitude of +3.90. The stellar distance is 44.15 parsecs or 144 light years from our solar system....
. The planet is at most two times the mass of Jupiter, orbiting every 227 days at three quarters of the distance between the Earth and Sun. HD 8574 b has a very elliptical orbit, far more than that of Jupiter.
Discovery
The ELODIE Planet Search Survey, undertaken using the ELODIE spectrographELODIE spectrograph
ELODIE was an echelle type spectrograph installed at the Observatoire de Haute-Provence 1.93m reflector in south-eastern France for the . Its optical instrumentation was developed by André Baranne from the Marseille Observatory. The purpose of this instrument was extrasolar planet detection by the...
at the Haute-Provence Observatory
Haute-Provence Observatory
The Observatoire de Haute-Provence was established in 1937 as a national facility for French astronomers. Astronomical observations began in 1943 using the 1.20 m telescope, and the first research papers based on observations made at the observatory were published in 1944...
in southeastern France, was a large-scale search for 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...
s orbiting G-type and F-type dwarf stars visible from the Northern Hemisphere through use of the radial velocity method (the orbit of a planet tugs on its host star as it orbits, causing a perceived Doppler effect
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...
in the star's spectrum
Spectrum
A spectrum is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word saw its first scientific use within the field of optics to describe the rainbow of colors in visible light when separated using a prism; it has since been applied by...
). This survey, which started in 1994, led to the discovery of 51 Pegasi b
51 Pegasi b
51 Pegasi b , sometimes though unofficially named Bellerophon, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus...
, the first extrasolar planet discovered in the orbit of a sunlike star. By 2003, the discovery of six new planets, including HD 8574 b, was announced, bringing ELODIE's planet discovery count to eighteen.
HD 8574, one of the target stars of ELODIE, had been previously catalogued by the European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...
with the release of the Hipparcos
Hipparcos
Hipparcos was a scientific mission of the European Space Agency , launched in 1989 and operated between 1989 and 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky...
catalogue in 1997. Most of HD 8574's characteristics were extracted from this catalogue for use in searching for a planet around HD 8574. The spectrum was then analyzed to see if HD 8574 were active, a factor that could mask or mimic the signal of an orbiting planet. It was found that the star was not significantly active.
In the case of HD 8574, ELODIE obtained 41 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...
measurements, which had, at the time of the discovery paper, been collected since January 11, 1998. Analysis of the collected data confirmed the existence of a planet orbiting HD 8574. Of the six, the planet HD 8574 b had the shortest 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...
, orbiting its host star under three years (unlike the five other planets that had been discovered by ELODIE at the same time).
HD 8574 b was announced by the European Southern Observatory
European Southern Observatory
The European Southern Observatory is an intergovernmental research organisation for astronomy, supported by fifteen countries...
on April 4, 2001. The findings addressing HD 8574's discovery were published in 2003.
Host star
HD 8574 is an F-type dwarf star that lies 44.2 parsecParsec
The parsec is a unit of length used in astronomy. It is about 3.26 light-years, or just under 31 trillion kilometres ....
s (144 light years) away from Earth. HD 8574 has an estimated mass of 1.17 times the mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
of the Sun. The star also has a radius that is estimated at 1.37 times that of the Sun's. HD 8574 has an effective temperature
Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation...
of 6080 K, hotter than the Sun, and a metallicity
Metallicity
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...
estimated at [Fe/H] = 0.05 (12% more iron than in the Sun). Additionally, with a luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
of 2.25, HD 8574 releases more than twice the energy released by the Sun.
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 7.12, and is thus extremely faint (if visible at all) as seen from the unaided eye of an observer on Earth.
Characteristics
HD 8574 is a large planet that orbits its host star every 227.55 days at a distance of 0.77 AUAstronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
, or 77% the mean distance between the Earth and the Sun. HD 8574 b has, of the six planets announced in a November 2003 discovery paper, the shortest orbit. The planet has an estimated mass
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
of 2.11 times Jupiter's mass. HD 8574 b has a measured 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 0.288, denoting an elliptical orbit. Jupiter, in comparison, orbits the Sun with an orbital eccentricity of 0.016, which is far more circular.