HR 8799 e

HR 8799 e
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
Angular separation (ρ) 368 ± 9[5] mas
Projected separation (d) 14.5 ± 0.5[5] AU
Orbital elements
Semimajor axis (a) ~ 14.5 ± 0.5[5][note 2] AU
(~ 2175 Gm)
Orbital period (P) ~ 50[5][note 2] y
Physical characteristics
Mass (m) 9 ± 4[5] MJ
Radius (r) 1.2 RJ
Temperature (T) 1,000 K
Discovery information
Discovery date November 1, 2010 (announced)
November 22, 2010 (published)
Discoverer(s) Marois et al.
Detection method Direct imaging
Discovery site Keck and Gemini
observatories in Hawaii
Discovery status Published[5]
Other designations
HD 218396 e[6]
Database references
Extrasolar Planets
Encyclopaedia		 data
SIMBAD data

HR 8799 e is a large exoplanet, orbiting the star HR 8799, which lies 128 lightyears from Earth. This gas giant is between 5 and 10 times the mass of Jupiter[5], the largest planet in our solar system. All four planets in the HR 8799 system are large, compared to all gas giants in the Solar System.

Contents

Description

HR 8799 e is the fourth planet orbiting HR 8799 in order of discovery. It is a massive gas giant, and is fairly close to its star, lying just between the orbits of Saturn and Uranus in our solar system.[5]

HR 8799 e is the innermost known planet as it orbits closer to its star than the other three known planets in this planetary system. This planet orbits at an estimated distance of 14.5 AU based on the relationship between angular separation measured by direct imaging observations and the star's distance from Earth. The estimated period of this planet if the orbit is face-on is about 50 years.[5]

Discovery

The National Research Council's Herzberg Institute of Astrophysics discovered the planet on November 1, 2010 while taking a closer look at the HR 8799 system and published their findings three weeks later. Observations were performed at the W.M. Keck Observatory during the 2009 and 2010 seasons in the K and L spectral bands.[5]

Notes

  1. ^ a b Computed from parallax: \scriptstyle \mathrm{distance\ in\ parsecs}=\frac{1000}{\mathrm{parallax\ in\ milliarcseconds}}
  2. ^ a b Value given assuming the planet's orbit is circular and is being observed face-on.

References

  1. ^ a b c V* V342 Peg -- Variable Star of gamma Dor type, entry, SIMBAD. Accessed on line November 14, 2008.
  2. ^ 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. 
  3. ^ 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. 
  4. ^ 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. 
  5. ^ a b c d e f g h i j Marois, C.; Zuckerman, B.; Konopacky, Q. M.; MacIntosh, B.; Barman, T. (2010). "Images of a fourth planet orbiting HR 8799". Nature 468 (7327): 1080–1083. arXiv:1011.4918. Bibcode 2010Natur.468.1080M. doi:10.1038/nature09684. PMID 21150902.  edit
  6. ^ HD 218396e – Extra-solar Planet Candidate, entry, SIMBAD. Accessed on line December 11, 2010.

External links

Coordinates: 23h 07m 28.7150s, +21° 08′ 03.302″