HR 8799 b
| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
 |
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| Parent star | ||
| Star | HR 8799 | |
| Constellation | Pegasus | |
| Right ascension | (α) | 23h 07m 28.7150s[1] |
| Declination | (δ) | +21° 08′ 03.302″[1] |
| Apparent magnitude | (mV) | 5.964[1] |
| Distance | 129 ± 4[2][note 1] ly (39 ± 1[2][note 1] pc) |
|
| Spectral type | kA5 hF0 mA5 V; λ Boo[3][4] | |
| Observed separation Observation epoch 2008-09-18 |
||
| Angular separation | (ρ) | 1724[5][note 2] mas |
| Position angle | (θ) | 62.42[5][note 2]° |
| Projected separation | (d) | 68[5] AU |
| Orbital elements | ||
| Semimajor axis | (a) | ~ 68[5][note 3] AU (~ 10000 Gm) |
| Orbital period | (P) | ~ 460[5][note 3] y |
| Physical characteristics | ||
| Mass | (m) | 5+2 −1[6] MJ |
| Radius | (r) | 1.2 ± 0.1[5] RJ |
| Temperature | (T) | 870+30 −70[5] K |
| Discovery information | ||
| Discovery date | November 13, 2008 | |
| Discoverer(s) | Marois et al. | |
| Detection method | Direct imaging | |
| Discovery site | Keck and Gemini observatories in Hawaii |
|
| Discovery status | Published | |
| Other designations | ||
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
HR 8799 b is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. It has a mass between 4 and 7 [6]Jupiter masses and a radius from 10 to 30% larger than Jupiter's. It orbits at 68 AU from HR 8799 (or 7 AU inside the inner edge of the dust disk orbiting the star) with an unknown eccentricity and a period of 460 years, and is the outermost known planet in the HR 8799 system. Along with two other planets orbiting HR 8799, the planet was discovered on November 13, 2008 by Marois et al., using the Keck and Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique.[5][8][9][10][11]
In 2009 it was discovered that the Hubble Space Telescope had in fact directly imaged HR 8799 b eleven years earlier, in 1998, suggesting that more exoplanets might be revealed through analysis of HST photographic archives.[12] Additional precovery images were also obtained by reanalyzing data taken in 2002 at the Subaru Telescope, and in 2004 and 2007 at the W.M Keck Observatory.
Near infrared H band and K band spectroscopy of HR8799b published in March 2011 indicate a hydrogen rich, dusty atmosphere with disequilibrium CO / CH4 chemistry.[13]
[edit] Notes
- ^ a b Computed from parallax:
- ^ a b Calculated from the separations in the East and North directions which are 1.528 and 0.798 arcseconds respectively.
- ^ a b Value given assuming the planet's orbit is circular and is being observed face-on.
[edit] See also
[edit] References
- ^ a b c V* V342 Peg -- Variable Star of gamma Dor type, entry, SIMBAD. Accessed on line November 14, 2008.
- ^ a b van Leeuwen, F. (2007). "HIP 114189". Hipparcos, the New Reduction. http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=113804. Retrieved 2008-10-13.
- ^ Gray, R.O. and Kaye, A.B. (1999). "HR 8799: A Link between γ Doradus Variables and λ Bootis Stars". The Astronomical Journal 118 (6): 2993–2996. Bibcode 1999AJ....118.2993G. doi:10.1086/301134.
- ^ Kaye, A.B. et al. (1999). "Gamma Doradus Stars: Defining a New Class of Pulsating Variables". PASP 111 (761): 840–844. arXiv:astro-ph/9905042. Bibcode 1999PASP..111..840K. doi:10.1086/316399.
- ^ a b c d e f g h Marois, Christian; et al. (November 2008). "Direct Imaging of Multiple Planets Orbiting the Star HR 8799". Science 322 (5906): 1348–1352. arXiv:0811.2606. Bibcode 2008Sci...322.1348M. doi:10.1126/science.1166585. PMID 19008415.
- ^ a b Marois; Zuckerman; Konopacky; Macintosh; Barman (2010). "Images of a fourth planet orbiting HR 8799". arXiv:1011.4918 [astro-ph.EP].
- ^ HD 218396b -- Extra-solar Planet Candidate, entry, SIMBAD. Accessed on line December 6, 2008.
- ^ "Astronomers capture first images of newly-discovered solar system" (Press release). W. M. Keck Observatory. 2008-11-13. http://www.keckobservatory.org/article.php?id=231. Retrieved 2008-12-02.
- ^ "Gemini Releases Historic Discovery Image of Planetary First Family" (Press release). Gemini Observatory. 2008-11-13. http://www.gemini.edu/node/11151. Retrieved 2008-12-02.
- ^ Achenbach, Joel (2008-11-13). "Scientists Publish First Direct Images of Extrasolar Planets". The Washington Post (The Washington Post Company). http://www.washingtonpost.com/wp-dyn/content/article/2008/11/13/AR2008111302267.html. Retrieved 2008-12-02.
- ^ Fabrycky et al.; Murray-Clay (1 December 2008). "Stability of the directly imaged multiplanet system HR 8799: resonance and masses". Astrophys.J.710:1408-1421,2010 710 (2): 1408–1421. arXiv:0812.0011. Bibcode 2010ApJ...710.1408F. doi:10.1088/0004-637X/710/2/1408.
- ^ Lafrenière et al.; Marois, Christian; Doyon, René; Barman, Travis (18 February 2009). "HST/NICMOS detection of HR 8799 b in 1998". The Astrophysical Journal 694 (2): L148–L152. arXiv:0902.3247. doi:10.1088/0004-637X/694/2/L148.
- ^ Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b. Cornell University Library. 2011-03-20. http://arxiv.org/pdf/1103.3895v1. Retrieved 2011-03-20.
[edit] External links
Media related to HR 8799 b at Wikimedia Commons
- "HR 8799 b". Exoplanets. http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HR+8799&planete=b.
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Coordinates: 
23h 07m 28.7150s, +21° 08′ 03.302″
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