HR 8799 c
{{short description|Exoplanet orbiting HR 8799}}
__NOTOC__
{{Infobox planet
| name = HR 8799 c
| image = Exoplanet Comparison HR 8799 c.png
| caption = Size comparison of HR 8799 c (gray) with Jupiter.
| discoverer = Marois et al.
| discovery_site = Keck and Gemini
observatories in Hawaii
| discovered = November 13, 2008
| discovery_method = Direct imaging
| apsis = astron
| semimajor = ~ 38 AU
| period = ~ 190Value given assuming the planet's orbit is circular and is being observed face-on. y
| star = HR 8799
| mean_radius = 1.3 {{Jupiter radius|link=y}}
| mass = 7{{±|3|2}}{{cite journal |arxiv=1011.4918 |author1=Marois |author2=Zuckerman |author3=Konopacky |author4=Macintosh |author5=Barman |title=Images of a fourth planet orbiting HR 8799 |date=2010 |doi=10.1038/nature09684 |pmid=21150902 |volume=468 |issue=7327 |journal=Nature |pages=1080–1083|bibcode = 2010Natur.468.1080M |s2cid=4425891 }} {{Jupiter mass|link=y}}
| density = {{val|4.702|u=g/cm3}}{{cite web |url=https://www.stellarcatalog.com/exoplanet.php?planetID=100841 |title=Exoplanet HR 8799 c |access-date=29 July 2024}}
| single_temperature = 1090{{±|10|90}}{{cite journal |last1=Marois |first1=Christian |display-authors = 1 |date=November 2008 |title=Direct Imaging of Multiple Planets Orbiting the Star HR 8799 |journal=Science |volume=322 |issue=5906 |pages=1348–1352 |doi=10.1126/science.1166585 |arxiv=0811.2606 |pmid=19008415 |bibcode = 2008Sci...322.1348M |last2=Barman |first2=Travis |last3=Zuckerman |first3=B. |last4=Song |first4=Inseok |last5=Patience |first5=Jennifer |last6=Lafrenière |first6=David |last7=Doyon |first7=René |s2cid=206516630 }} K
| note = below
}}
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.{{cite press release|url=http://www.keckobservatory.org/article.php?id=231|title=Astronomers capture first images of newly-discovered solar system|publisher=W. M. Keck Observatory|date=2008-11-13|access-date=2008-12-02|url-status=dead|archive-url=https://web.archive.org/web/20131126160805/http://www.keckobservatory.org/article.php?id=231|archive-date=2013-11-26}}{{cite press release|url=http://www.gemini.edu/node/11151|title=Gemini Releases Historic Discovery Image of Planetary First Family|publisher=Gemini Observatory|date=2008-11-13|accessdate=2008-12-02}}{{cite news|title=Scientists Publish First Direct Images of Extrasolar Planets|first=Joel|last=Achenbach|newspaper=The Washington Post|date=2008-11-13|accessdate=2008-12-02|url=https://www.washingtonpost.com/wp-dyn/content/article/2008/11/13/AR2008111302267.html}}{{cite journal |title=Stability of the directly imaged multiplanet system HR 8799: resonance and masses |year=2010|pages=1408–1421 |issue=2 |volume=710 |author2=Murray-Clay |doi=10.1088/0004-637X/710/2/1408 |journal=Astrophys. J. |arxiv=0812.0011|bibcode = 2010ApJ...710.1408F |author=Fabrycky |s2cid=11760422|display-authors=1 }} 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.{{cite journal|last=Janson|first=M.|date=13 January 2010|title=VLT Captures First Direct Spectrum of an Exoplanet|journal=ESO|pages=2|location=La Silla Observatory|url=https://www.eso.org/public/news/eso1002/|accessdate=2010-01-13|bibcode=2010eso..pres....2.}}
Spectra
File:Spectrum of planet around HR 8799 (annotated).jpg’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.{{Cite journal|author = B. R. Oppenheimer|title= Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy|publisher=Cornell University|arxiv= 1303.2627|bibcode = 2013ApJ...768...24O |doi = 10.1088/0004-637X/768/1/24|volume=768|issue= 1|journal=The Astrophysical Journal|page=24|year= 2013|s2cid= 7173368}} 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.{{Cite web |url=http://www.salon.com/2013/03/14/alien_planets_atmosphere_contains_water_and_carbon_monoxide/ |title=Alien planet's atmosphere contains water and carbon monoxide |access-date=2013-03-14 |archive-date=2019-03-30 |archive-url=https://web.archive.org/web/20190330223032/https://www.salon.com/2013/03/14/alien_planets_atmosphere_contains_water_and_carbon_monoxide/ |url-status=dead }}{{cite web |title=Giant Alien Planet in Supersized Solar System May Solve Mystery |date=2013-03-14 |website=Space.com |archive-url=https://web.archive.org/web/20230607031148/https://www.space.com/20230-giant-planet-atmosphere-solar-system.html |archive-date=2023-06-07 |url-status=live |url=http://www.space.com/20230-giant-planet-atmosphere-solar-system.html}}
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.{{cite news |author=W. M. Keck Observatory |title=Exoplanet stepping stones - Researchers are perfecting technology to one day look for signs of alien life |url=https://www.eurekalert.org/pub_releases/2018-11/wmko-ess112018.php |date=20 November 2018 |work=EurekAlert! |accessdate=21 November 2018 |author-link=W. M. Keck Observatory }}{{cite journal |author=Wang, Ji|display-authors=etal |title=Detecting Water in the Atmosphere of HR 8799 c with L-band High-dispersion Spectroscopy Aided by Adaptive Optics |date=20 November 2018 |journal=The Astronomical Journal |volume=156 |pages=272 |number=6 |doi=10.3847/1538-3881/aae47b |bibcode=2018AJ....156..272W |arxiv=1809.09080 |s2cid=119372301 |doi-access=free }}
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The detection of water and carbon monoxide in the planetary atmosphere was announced in 2021.{{citation|arxiv=2107.06949|year=2021|title=Detection and Bulk Properties of the HR 8799 Planets with High-resolution Spectroscopy|doi=10.3847/1538-3881/ac1349 |last1=Wang |first1=Jason J. |last2=Ruffio |first2=Jean-Baptiste |last3=Morris |first3=Evan |last4=Delorme |first4=Jacques-Robert |last5=Jovanovic |first5=Nemanja |last6=Pezzato |first6=Jacklyn |last7=Echeverri |first7=Daniel |last8=Finnerty |first8=Luke |last9=Hood |first9=Callie |last10=Zanazzi |first10=J. J. |last11=Bryan |first11=Marta L. |last12=Bond |first12=Charlotte Z. |last13=Cetre |first13=Sylvain |last14=Martin |first14=Emily C. |last15=Mawet |first15=Dimitri |last16=Skemer |first16=Andy |last17=Baker |first17=Ashley |last18=Xuan |first18=Jerry W. |last19=Wallace |first19=J. Kent |last20=Wang |first20=Ji |last21=Bartos |first21=Randall |last22=Blake |first22=Geoffrey A. |last23=Boden |first23=Andy |last24=Buzard |first24=Cam |last25=Calvin |first25=Benjamin |last26=Chun |first26=Mark |last27=Doppmann |first27=Greg |last28=Dupuy |first28=Trent J. |last29=Duchêne |first29=Gaspard |last30=Feng |first30=Y. Katherina |journal=The Astronomical Journal |volume=162 |issue=4 |page=148 |bibcode=2021AJ....162..148W |s2cid=235898867 |display-authors=1 |doi-access=free }}
See also
Notes
References
{{Reflist|refs=
{{cite journal |last=Jason |first=M. |author2=C. Bergfors |author3=M. Goto |author4=W. Brandner |author5=D. Lafrenière |date=2010 |title=Spatially resolved spectroscopy of the exoplanet HR 8799 c |journal=The Astrophysical Journal |volume= 710|issue= 1|pages= L35–L38|url=http://www.eso.org/public/archives/releases/sciencepapers/eso1002/eso1002.pdf |doi= 10.1088/2041-8205/710/1/l35 |accessdate=2010-01-13|arxiv = 1001.2017 |bibcode = 2010ApJ...710L..35J |s2cid=9159181 }}
}}
External links
{{Commons category-inline}}
- {{cite web | url=http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HR+8799&planete=c | title=HR 8799 c | work=Exoplanets | access-date=2008-12-02 | archive-url=https://web.archive.org/web/20120304131137/http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HR+8799&planete=c | archive-date=2012-03-04 | url-status=dead }}
{{HR 8799}}
{{Sky|23|07|28.7150|+|21|08|03.302|129}}
{{Pegasus (constellation)}}
{{DEFAULTSORT:Hr 8799 C}}
Category:Exoplanets discovered in 2008