HD 219134 b

HD 219134 b
Exoplanet List of exoplanets

An artist's impression of the hot rocky exoplanet HD 219134 b.
Parent star
Star HR 8832
Constellation Cassiopeia
Right ascension (α) 23h 13m 16.9763s[1]
Declination (δ) +57° 10′ 06.082″[1]
Apparent magnitude (mV) 5.574[2]
Distance21.25[3] ly
(6.52 pc)
Spectral type K3V[4]
Mass (m) 0.794+0.037
−0.022[5] M☉
Radius (r) 0.80 (± 0.04)[6] R☉
Temperature (T) 4710[4] K
Metallicity [Fe/H] +0.20[4]
Age ~12.46[5] Gyr
Orbital elements
Semi-major axis(a) 0.0382 (± 0.0003)[7] AU
Eccentricity (e) 0.00+0.13
−0.0[7]
Orbital period(P) 3.0937 (± 0.0004)[7] d
Inclination (i) 85.058 ± 0.08[7]°
Physical characteristics
Mass(m)4.47 (± 0.47)[7] M⊕
Radius(r)1.606 (± 0.086)[7] R⊕
Density(ρ)5.89 (± 1.17)[7] g cm−3
Temperature (T) 800 K (527 °C; 980 °F)
Discovery information
Discovery date 30 July 2015
Discoverer(s)
Discovery method radial velocity method (HARPS-N)
Other detection methods transiting (Spitzer telescope)
Discovery site HARPS-N of the Telescopio Nazionale Galileo
Discovery status Published
Database references
Extrasolar Planets
Encyclopaedia		data
SIMBADdata
Exoplanet Archivedata
Open Exoplanet Cataloguedata

HD 219134 b (or HR 8832 b) is one of seven exoplanets orbiting HR 8832, a main-sequence star in the constellation of Cassiopeia.[3][7][8][9] As of July 2015, super-Earth HD 219134 b, with a size of about 1.6 Earth Radii, and a density of 6g/cm3, was reported as the closest rocky exoplanet to the Earth, at 21.25 light-years away.[3] The exoplanet was initially detected by the instrument HARPS-N of the Italian Telescopio Nazionale Galileo via the radial velocity method and subsequently observed by the Spitzer telescope as transiting in front of its star.[3][8] The exoplanet has a mass of about 4.5 times that of Earth and orbits its host star every three days.[3]

Characteristics

Mass, radius and temperature

HD 219134 b is a super-Earth, an exoplanet with a radius and mass bigger than Earth, but smaller than that of the ice giants Neptune and Uranus. Its surface temperature is around 800 K (527 °C; 980 °F). It has a radius of 1.6 R⊕ and a mass of around 4.5 M⊕.

Host star

The planet orbits a (K-type) star named HR 8832, orbited by a total of seven planets. The star has a mass of 0.79 M☉ and a radius of 0.80 R☉. It has a temperature of 4710 K and is about 12.5 billion years old, making it one of the oldest stars. In comparison, the Sun is 4.6 billion years old[10] and has a temperature of 5778 K.[11]

The star's apparent magnitude, or how bright it appears from Earth's perspective, is 5. It can be seen with the naked eye.

Orbit

HD 219134 b orbits its host star with about 28% of the Sun's luminosity with an orbital period of 3 days and an orbital radius of about 0.03 times that of Earth's (compared to the distance of Mercury from the Sun, which is about 0.38 AU).

Exoplanet HD 219134 b
Star HR 8832 (circled) lies just off the "W" shape of the constellation Cassiopeia.
Zooming in on the exoplanet
(00:53; animation; July 30, 2015).

See also

References

  1. 1 2 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357.
  2. ↑ Oja, T. (August 1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–409, Bibcode:1986A&AS...65..405O.
  3. 1 2 3 4 5 Chou, Felicia; Clavin, Whitney (30 July 2015). "NASA's Spitzer Confirms Closest Rocky Exoplanet". NASA. Retrieved 31 July 2015.
  4. 1 2 3 Frasca, A.; et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics, 508 (3): 1313–1330, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327.
  5. 1 2 Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series, 168 (2): 297–318, arXiv:astro-ph/0607235Freely accessible, Bibcode:2007ApJS..168..297T, doi:10.1086/509763.
  6. ↑ Perrin, M.-N.; Karoji, H. (1987), "Stellar radius determination from IRAS 12-micron fluxes", Astronomy and Astrophysics, 172: 235–240, Bibcode:1987A&A...172..235P.
  7. 1 2 3 4 5 6 7 8 Motalebi, F.; et al. "The HARPS-N Rocky Planet Search, I. HD 219134b: A transiting rocky planet in a multi-planet system at 6.5 pc from the Sun". Astronomy and Astrophysics. arXiv:1507.08532Freely accessible. Bibcode:2015A&A...584A..72M. doi:10.1051/0004-6361/201526822.
  8. 1 2 "PIA19832: Location of Nearest Rocky Exoplanet Known". NASA. 30 July 2015. Retrieved 30 July 2015.
  9. ↑ PLANET HOST OVERVIEW PAGE
  10. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
  11. ↑ Fraser Cain (15 September 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.

Coordinates: 23h 13m 16.98s, +57° 10′ 06.1″


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