Astronomy:HR 8799 c

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HR 8799 c
Size comparison of HR 8799 c (gray) with Jupiter.
Discovery
Discovered byMarois et al.
Discovery siteKeck and Gemini
observatories in Hawaii
Discovery dateNovember 13, 2008
Direct imaging
Orbital characteristics
41.00±0.15[1]: 6  AU
Eccentricity0.050±0.003[1]: 6 
Orbital period209.5[2]: 5  years
Inclination26.5±0.5[1]: 6  °
StarHR 8799
Physical characteristics
Mean radius1.10±0.01[3]: 23  |♃|J}}}}}}
Mass7.8±0.6[1]: 6  |♃|J}}}}}}
Mean density4.702 g/cm3[4]
104.26+0.02
−0.03[3]: 23  cgs
Physics1159+11
−12[3]: 23  K


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 7.8 times the mass of Jupiter and 1.10 times the radius. It orbits at 41.0 AU from HR 8799 with an low eccentricity and a period of 210 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.[5][6][7][8][9] In January 2010, HR 8799 c became the 9th exoplanet candidate to have a portion of its spectrum directly observed (following 2M1207b, DH Tau b, GQ Lup b, AB Pic b, CHXR 73 b, HD 203030 b, CT Cha b and 1RXS J1609b), confirming the feasibility of direct spectrographic studies of exoplanets. [10][11]

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.[12] 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.[13][14]

Later, in November 2018, researchers confirmed the existence of water and the absence of methane in the atmosphere of HR 8799c, using high-resolution spectroscopy and near-infrared adaptive optics (NIRSPAO) at the Keck Observatory.[15][16]

The detection of water and carbon monoxide in the planetary atmosphere was announced in 2021.[17]

References

  1. ↑ 1.0 1.1 1.2 1.3 Zurlo, A.; Goździewski, K.; Lazzoni, C.; Mesa, D.; Nogueira, P.; Desidera, S.; Gratton, R.; Marzari, F. et al. (2022-10-19). "Orbital and dynamical analysis of the system around HR 8799. New astrometric epochs from VLT/SPHERE and LBT/LUCI" (in en). Astronomy and Astrophysics 666: A133. doi:10.1051/0004-6361/202243862. ISSN 0004-6361. Bibcode: 2022A&A...666A.133Z. 
  2. ↑ Gozdziewski, Krzysztof; Migaszewski, Cezary (2020). "An exact, generalised Laplace resonance in the HR 8799 planetary system". The Astrophysical Journal 902 (2): L40. doi:10.3847/2041-8213/abb881. Bibcode: 2020ApJ...902L..40G. 
  3. ↑ 3.0 3.1 3.2 Nasedkin, E.; Mollière, P.; Lacour, S.; Nowak, M.; Kreidberg, L.; Stolker, T.; Wang, J. J.; Balmer, W. O. et al. (July 2024). "Four-of-a-kind? Comprehensive atmospheric characterisation of the HR 8799 planets with VLTI/GRAVITY". Astronomy & Astrophysics 687: A298. doi:10.1051/0004-6361/202449328. ISSN 0004-6361. Bibcode: 2024A&A...687A.298N. 
  4. ↑ "Exoplanet HR 8799 c". https://www.stellarcatalog.com/exoplanet.php?planetID=100841. 
  5. ↑ Marois, Christian; Macintosh, Bruce; Barman, Travis; Zuckerman, B.; Song, Inseok; Patience, Jennifer; Lafrenière, David; Doyon, René (November 2008). "Direct Imaging of Multiple Planets Orbiting the Star HR 8799". Science 322 (5906): 1348–1352. doi:10.1126/science.1166585. PMID 19008415. Bibcode: 2008Sci...322.1348M. 
  6. ↑ "Astronomers capture first images of newly-discovered solar system" (Press release). W. M. Keck Observatory. 2008-11-13. Archived from the original on 2013-11-26. Retrieved 2008-12-02.
  7. ↑ "Gemini Releases Historic Discovery Image of Planetary First Family" (Press release). Gemini Observatory. 2008-11-13. Retrieved 2008-12-02.
  8. ↑ Achenbach, Joel (2008-11-13). "Scientists Publish First Direct Images of Extrasolar Planets". The Washington Post. https://www.washingtonpost.com/wp-dyn/content/article/2008/11/13/AR2008111302267.html. Retrieved 2008-12-02. 
  9. ↑ Fabrycky et al. (2010). "Stability of the directly imaged multiplanet system HR 8799: resonance and masses". Astrophys. J. 710 (2): 1408–1421. doi:10.1088/0004-637X/710/2/1408. Bibcode: 2010ApJ...710.1408F. 
  10. ↑ Jason, M.; C. Bergfors; M. Goto; W. Brandner; D. Lafrenière (2010). "Spatially resolved spectroscopy of the exoplanet HR 8799 c". The Astrophysical Journal 710 (1): L35–L38. doi:10.1088/2041-8205/710/1/l35. Bibcode: 2010ApJ...710L..35J. http://www.eso.org/public/archives/releases/sciencepapers/eso1002/eso1002.pdf. Retrieved 2010-01-13. 
  11. ↑ Janson, M. (13 January 2010). "VLT Captures First Direct Spectrum of an Exoplanet". ESO (La Silla Observatory): 2. Bibcode: 2010eso..pres....2.. https://www.eso.org/public/news/eso1002/. Retrieved 2010-01-13. 
  12. ↑ B. R. Oppenheimer (2013). "Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy". The Astrophysical Journal (Cornell University) 768 (1): 24. doi:10.1088/0004-637X/768/1/24. Bibcode: 2013ApJ...768...24O. 
  13. ↑ "Alien planet's atmosphere contains water and carbon monoxide". http://www.salon.com/2013/03/14/alien_planets_atmosphere_contains_water_and_carbon_monoxide/. 
  14. ↑ "Giant Alien Planet in Supersized Solar System May Solve Mystery". 2013-03-14. http://www.space.com/20230-giant-planet-atmosphere-solar-system.html. 
  15. ↑ W. M. Keck Observatory (20 November 2018). "Exoplanet stepping stones - Researchers are perfecting technology to one day look for signs of alien life". EurekAlert!. https://www.eurekalert.org/pub_releases/2018-11/wmko-ess112018.php. Retrieved 21 November 2018. 
  16. ↑ Wang, Ji (20 November 2018). "Detecting Water in the Atmosphere of HR 8799 c with L-band High-dispersion Spectroscopy Aided by Adaptive Optics". The Astronomical Journal 156 (6): 272. doi:10.3847/1538-3881/aae47b. Bibcode: 2018AJ....156..272W. 
  17. ↑ Wang, Jason J. et al. (2021), "Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy", The Astronomical Journal 162 (4): 148, doi:10.3847/1538-3881/ac1349, Bibcode: 2021AJ....162..148W 

Template:HR 8799 Coordinates: Sky map 23h 07m 28.7150s, +21° 08′ 03.302″



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