HD 7924 b

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HD 7924 b
PlanetQuest-HD7924b.png
HD 7924 b's orbit compared to Mercury's (0.38AU).
Discovery
Discovered by Howard et al.
Discovery dateJanuary 28, 2009
radial velocity
Orbital characteristics
0.057 AU (8,500,000 km)
Eccentricity 0.17 ± 0.16
5.3978 ± 0.0015 d
4727.27 ± 0.87
25 ± 60
Star HD 7924

    HD 7924 b is an extrasolar planet located approximately 55 light years away in the constellation of Cassiopeia, orbiting the 7th magnitude K-type main sequence (slightly metal poor) star HD 7924. [1] It was published on January 28, 2009 and is the second planet discovered in the constellation Cassiopeia. Two additional planets in this system were discovered in 2015. [2]

    Contents

    Super-Earth

    HD 7924 b is a super-Earth exoplanet with a minimum mass 9.2 times that of Earth and takes only about 129.5 hours to orbit the star, at an average distance of 8,500,000 km (5,300,000 mi). When HD 7924 b was discovered in 2009, it was one of only eight planets known with a minimum mass less than 10 Earths. [1] Also a super-Earth discovery makes 2009 the fifth year in a row since 2005 to have super-Earth planets discovered.

    Characteristics

    While the radius of HD 7924 b is unknown, depending on its composition, it will be between 1.4–6 times the diameter of the Earth. [1] It is unknown whether this planet is rocky or gaseous. Since the true mass of this planet is not known, it might be gaseous if the true mass is considerably more than minimum mass. If the true mass is near the minimum mass of 9.2 ME, then this planet could be rocky.

    Related Research Articles

    HD 28185 b

    HD 28185 b is an extrasolar planet approximately 128.6 light-years away from Earth in the constellation of Eridanus. The planet was discovered orbiting the Sun-like star HD 28185 in April 2001 as a part of the CORALIE survey for southern extrasolar planets, and its existence was independently confirmed by the Magellan Planet Search Survey in 2008. HD 28185 b orbits its sun in a circular orbit that is at the inner edge of its star's habitable zone.

    Super-Earth Type of planet

    A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively. The term "super-Earth" refers only to the mass of the planet, and so does not imply anything about the surface conditions or habitability. The alternative term "gas dwarfs" may be more accurate for those at the higher end of the mass scale, although "mini-Neptunes" is a more common term.

    HD 11964 c is an extrasolar planet approximately 110 light-years away in the constellation of Cetus. The planet was discovered in a close-orbit around the yellow subgiant star HD 11964. The planet has a minimum mass 35 times the mass of Earth and is located in a mildly eccentric orbit which takes almost 38 days to complete. HD 11964 c was a possible planet discovered on the same day as HD 11964 b in 2005. HD 11964 c was first proposed in a paper published in 2007, and finally confirmed with new data presented in a review of multi-planet systems which appeared on the arXiv preprint website in 2008.

    HD 17156, named Nushagak by the IAU, is a yellow subgiant star approximately 255 light-years away in the constellation of Cassiopeia. The apparent magnitude is 8.17, which means it is not visible to the naked eye but can be seen with good binoculars. A search for a binary companion star using adaptive optics at the MMT Observatory was negative.

    HD 114762 b is a small red dwarf star, or massive brown dwarf, in the HD 114762 system, formerly thought to be a massive gaseous extrasolar planet, approximately 126 light-years (38.6 pc) away in the constellation of Coma Berenices. This optically undetected companion to the late F-type main-sequence star HD 114762 was discovered in 1989 by Latham, et al., and confirmed in an October 1991 paper by Cochran, et al. It was thought to be the first discovered exoplanet

    WASP-11/HAT-P-10 is a binary star. It is a primary main-sequence orange dwarf star. Secondary is M-dwarf with a projected separation of 42 AU. The system is located about 408 light years away in the constellation Aries.

    HD 5319 b is a gas giant exoplanet discovered in 2007 in the constellation of Cetus. This planet has a minimum mass nearly two times that of Jupiter. The planet has an almost circular orbit, with an eccentricity of only 0.02 and a period of 641 days. An additional planet in the system was discovered in 2015 and may be in a 4:3 mean motion resonance with planet b.

    HD 40307 b is an extrasolar planet orbiting the star HD 40307, located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus, in June 2008. It is the second smallest of the planets orbiting the star, after HD 40307 e. The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.

    HD 40307 c is an extrasolar planet orbiting the star HD 40307, located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the HARPS apparatus, in June 2008. Of the six proposed planets in the HD 40307 star system, it is the third-largest, and has the second-closest orbit from the star. The planet is of interest as this star has relatively low metallicity, supporting a hypothesis that different metallicities in protostars determine what kind of planets they will form.

    HD 7924 Star in the constellation Cassiopeia

    HD 7924 is a single star located 55.5 light years away from the Sun in the northern constellation of Cassiopeia, near the northern constellation border with Cepheus. It has an orange hue and is only visible by means of binoculars or a telescope due to a low apparent visual magnitude of 7.167. The star is drifting closer to the Sun with a radial velocity of –22.7 km/s, and is expected to approach to within 9.3 light-years in around 711,700 years.

    HD 240210 b is a 6.9 Jupiter-mass exoplanet discovered on June 10, 2009 by Niedzielski et al. using the Hobby-Eberly Telescope. It orbits the K3 giant star HD 240210 in the constellation of Cassiopeia. Its average orbital separation is at 1.33 Astronomical Units away from its star with a year of 501.75 days.

    HD 148427, formally named Timir, is a 7th-magnitude K-type subgiant star approximately 193 light years away in the constellation Ophiuchus. Its mass is 45% greater than the Sun, and it is three times the size and six times more luminous, although its age is 2½ billion years. In August 2009, it was found to have an object in orbit with a minimum mass of 0.96 MJ and an orbital period of 331.5 days. In 2020, this object's inclination was measured, revealing its true mass to be 136.5 MJ. This makes it a brown dwarf or low-mass red dwarf star.

    HD 1461 b is an extrasolar planet, orbiting the 6th magnitude G-type star HD 1461, 76.5 light years away in the constellation Cetus. This planet has a minimum mass 6.4 times that of Earth and orbits at a distance of 0.0634 AU with an eccentricity of less than 0.131. It is currently unknown whether the planet is a gas giant like Uranus or Neptune, or has terrestrial composition like CoRoT-7 b. This planet was announced on 13 December 2009 after it was discovered using radial velocity measurements taken at the Keck and Anglo-Australian Observatories.

    HD 156668 b is an extrasolar planet orbiting the star HD 156668 78.5 light-years away in the constellation Hercules. It has a minimum mass of 3.1 Earth masses. At the time of discovery it was the second least massive planet discovered by the radial velocity method, subject to the mass/inclination degeneracy that affects radial velocity measurements. The only radial velocity planet less massive than this planet is Gliese 581 e, which was discovered on April 21, 2009, and has a minimum mass of 1.94 Earth masses. In addition to this, it has the lowest semi-amplitude, or the speed of the stellar wobble caused by planet's gravity tugging on the star determined by radial velocity, at 2.2 m/s. This planet was discovered on January 6, 2010; it is the 8th planet discovered in 2010 after the first five planets detected by Kepler on January 4 and two planets around HD 9446 on January 5.

    HD 97658 is a star 70 light years away in the constellation of Leo. The star is slightly too dim to be seen with the naked eye, though almost any additional equipment will allow it to be seen. The star itself is a metal-poor early K-dwarf that is somewhat older than the sun.

    HD 40307 e is an extrasolar planet orbiting the star HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany.

    Kepler-68b is an exoplanet orbiting the Sun-like star Kepler-68 in the constellation of Cygnus. Discovered by planetary-transit methods by the Kepler space telescope in February 2013, it has a radius of 2.31 ± 0.07 that of Earth and a density of 2.46–4.3 g/cm3. It has an orbital period of 5.398763 days at a distance of about 0.0617 AU from its star. Doppler measurements were made to determine its mass to be 5.79 times that of Earth.

    HD 240237 b Extrasolar planet

    HD 240237 b is a super-Jupiter exoplanet orbiting the K-type giant star HD 240237 about 4,900 light-years (1,500 parsecs, or nearly 4.6×1016 km) away from Earth in the constellation Cassiopeia. It orbits outside of the habitable zone of its star at a distance of 1.9 AU. The exoplanet was found by using the radial velocity method, from radial-velocity measurements via observation of Doppler shifts in the spectrum of the planet's parent star. The planet has a mildly eccentric orbit.

    References

    1. 1 2 3 Howard, Andrew W.; et al. (2009). "The NASA-UC Eta-Earth Program. I. A Super-Earth Orbiting HD 7924". The Astrophysical Journal. 696 (1): 75–83. arXiv: 0901.4394 . Bibcode:2009ApJ...696...75H. doi:10.1088/0004-637X/696/1/75.
    2. Fulton, Benjamin J.; et al. (2015). "Three Super-Earths Orbiting HD 7924". The Astrophysical Journal. 805 (2): 175. arXiv: 1504.06629 . Bibcode:2015ApJ...805..175F. doi:10.1088/0004-637X/805/2/175.

    Coordinates: Jupiter and moon.png 01h 21m 59.1153s, +76° 42′ 37.024″