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HR 8799 c

Coordinates: Sky map 23h 07m 28.7150s, +21° 08′ 03.302″
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HR 8799 c is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. This planet has a mass between 5 and 10 Jupiter masses and a radius from 20 to 30% larger than Jupiter's. It orbits at 38 AU from HR 8799 with an unknown eccentricity and a period of 190 years; it is the 2nd planet discovered in the HR 8799 system. Along with two other planets orbiting HR 8799, this planet was discovered on November 13, 2008 by Marois et al., using the Keck and the Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique.[1][2][3][4][5] In January 2010, HR 8799 c became the 3rd exoplanet to have a portion of its spectrum directly observed (following 2M1207b and 1RXS J1609b), confirming the feasibility of direct spectrographic studies of exoplanets.[6][7]

Spectra

Spectrum of planet around HR8799. Credit: ESO/M. Janson.
The spectrum of the planet HR 8799 c. The spectrum of the star and the planet was obtained with the NACO adaptive optics instrument on ESO’s Very Large Telescope.

Near infrared spectroscopy from 995 to 1769 nanometers made with the Palomar Observatory show evidence of Ammonia, perhaps some Acetylene but neither Carbon Dioxide nor substantial Methane.[8] High resolution spectroscopy with the OSIRIS instrument on the Keck Observatory show numerous well resolved lines of molecular absorption in the planet's atmosphere in the K band. Although methane is absent, the planet's atmosphere contains both water and carbon monoxide; the carbon-to-oxygen ratio of HR 8799 c is higher than that of its star, suggesting that the planet formed through the core accretion process.[9][10]

See also

Notes


References

  1. ^ Cite error: The named reference Marois2008 was invoked but never defined (see the help page).
  2. ^ "Astronomers capture first images of newly-discovered solar system" (Press release). W. M. Keck Observatory. 2008-11-13. Retrieved 2008-12-02.
  3. ^ "Gemini Releases Historic Discovery Image of Planetary First Family" (Press release). Gemini Observatory. 2008-11-13. Retrieved 2008-12-02.
  4. ^ Achenbach, Joel (2008-11-13). "Scientists Publish First Direct Images of Extrasolar Planets". The Washington Post. The Washington Post Company. Retrieved 2008-12-02.
  5. ^ Fabrycky; Murray-Clay (1 December 2008). "Stability of the directly imaged multiplanet system HR 8799: resonance and masses". Astrophys. J. 710 (2): 1408–1421. arXiv:0812.0011. Bibcode:2010ApJ...710.1408F. doi:10.1088/0004-637X/710/2/1408. {{cite journal}}: Unknown parameter |displayauthors= ignored (|display-authors= suggested) (help)
  6. ^ Jason, M.; C. Bergfors; M. Goto; W. Brandner; D. Lafrenière (2010). "Spatially resolved spectroscopy of the exoplanet HR 8799 c" (PDF). The Astrophysical Journal. arXiv:1001.2017. Bibcode:2010ApJ...710L..35J. doi:10.1088/2041-8205/710/1/l35. Retrieved 2010-01-13.
  7. ^ Janson, M. (13 January 2010). "VLT Captures First Direct Spectrum of an Exoplanet". ESO. La Silla Observatory. Retrieved 2010-01-13.
  8. ^ B. R. Oppenheimer. "Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy". Cornell University. arXiv:1303.2627. Bibcode:2013ApJ...768...24O. doi:10.1088/0004-637X/768/1/24. {{cite journal}}: Cite journal requires |journal= (help)
  9. ^ Alien planet’s atmosphere contains water and carbon monoxide
  10. ^ Giant Alien Planet in Supersized Solar System May Solve Mystery

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