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{{short description|Exoplanet orbiting HR 8799}} |
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__NOTOC__ |
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__NOTOC__ |
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{{Infobox planet |
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{{Planetbox begin |
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| name = ] 8799 c |
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| name = ] 8799 c |
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| image = Exoplanet Comparison HR 8799 c.png |
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| caption = Size comparison of HR 8799 c (gray) with Jupiter. |
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<!-- DISCOVERY --> |
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| discoverer = Marois et al. |
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| discovery_site = ] and ] in ] |
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| discovered = November 13, 2008 |
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| discovery_method = ] |
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<!-- ORBITAL --> |
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| apsis = astron |
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| semimajor = ~ 38 ] |
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| period = ~ 190<ref name="Marois2008" /><ref group="note" name="circular_orbit">Value given assuming the planet's orbit is circular and is being observed face-on.</ref> ] |
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| star = ] |
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<!-- PHYS CHARS --> |
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| mean_radius = 1.3<ref name="spectrum"/> {{Jupiter radius|link=y}} |
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| mass = 7{{±|3|2}}<ref>{{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 }}</ref> {{Jupiter mass|link=y}} |
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| density = {{val|4.702|u=g/cm3}}<ref>{{cite web |url=https://www.stellarcatalog.com/exoplanet.php?planetID=100841 |title=Exoplanet HR 8799 c |access-date=29 July 2024}}</ref> |
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| single_temperature = 1090{{±|10|90}}<ref name="Marois2008">{{cite journal |last1=Marois |first1=Christian |display-authors = 1 |date=November 2008 |title=Direct Imaging of Multiple Planets Orbiting the Star HR 8799 |journal=] |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 }}</ref> ] |
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<!-- NOTES --> |
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| note = below |
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'''HR 8799 c''' is an ] located approximately 129 ]s away in the ] of ], orbiting the 6th ] ] ]. This planet has a mass between 5 and 10 ]es and a radius from 20 to 30% larger than ]'s. It orbits at 38 ] 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 ] and the ] in ]. These planets were discovered using the ] technique.<ref name="Marois2008" /><ref>{{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}}</ref><ref>{{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}}</ref><ref>{{cite news|title=Scientists Publish First Direct Images of Extrasolar Planets|first=Joel|last=Achenbach|newspaper=]|date=2008-11-13|accessdate=2008-12-02|url=https://www.washingtonpost.com/wp-dyn/content/article/2008/11/13/AR2008111302267.html}}</ref><ref>{{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 }}</ref> In January 2010, HR 8799 c became the 9th exoplanet candidate to have a portion of its spectrum directly observed (following ], ], ], ], ], ], ] and ]), confirming the feasibility of direct spectrographic studies of exoplanets.<ref name="spectrum"/><ref>{{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.}}</ref> |
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{{Planetbox image |
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| image = Exoplanet Comparison HR 8799 c.png |
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| caption = Size comparison of HR 8799 c (gray) with Jupiter. |
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{{Planetbox star |
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| star = ] |
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| constell = ] |
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| RA = {{RA|23|07|28.7150}}<ref name="SIMBAD">{{SIMBAD link|HR+8799|V* V342 Peg -- Variable Star of gamma Dor type}}, entry, ]. Accessed on line November 14, 2008.</ref> |
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| DEC = {{DEC|+21|08|03.302}}<ref name="SIMBAD" /> |
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| app_mag = 5.964<ref name="SIMBAD" /> |
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| dist_ly = 129 ± 4<ref name="vanLeeuwen2007">{{cite web|url=http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/311/hip2&recno=113804|title=HIP 114189|work=Hipparcos, the New Reduction|author=van Leeuwen, F.|year=2007|accessdate=2008-10-13}}</ref><ref group="note" name="calculate_distance">Computed from parallax: <math>\scriptstyle \mathrm{distance\ in\ parsecs}=\frac{1000}{\mathrm{parallax\ in\ milliarcseconds}}</math></ref> |
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| dist_pc = 39 ± 1<ref name="vanLeeuwen2007" /><ref group="note" name="calculate_distance" /> |
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| class = kA5 hF0 mA5 V; λ Boo<ref name="Gray1999">{{cite journal|title=HR 8799: A Link between γ Doradus Variables and λ Bootis Stars|author=Gray, R.O. and Kaye, A.B.|year=1999|journal=]|volume=118|issue=6|pages=2993–2996|doi=10.1086/301134|bibcode=1999AJ....118.2993G}}</ref><ref name="Kaye1999">{{cite journal|title=Gamma Doradus Stars: Defining a New Class of Pulsating Variables|author=Kaye, A.B. et al.|year=1999|journal=]|volume=111|issue=761|pages=840–844|bibcode=1999PASP..111..840K|doi=10.1086/316399|arxiv = astro-ph/9905042 }}</ref> |
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{{Planetbox separation |
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| epoch = 2008-09-18 |
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| separation_mas = 964<ref name="Marois2008">{{cite journal |last=Marois |first=Christian |authorlink= |author2=et al. |date=November 2008 |title=Direct Imaging of Multiple Planets Orbiting the Star HR 8799 |journal=] |volume=322 |issue=5906 |pages=1348–1352 |doi=10.1126/science.1166585 |arxiv=0811.2606 |accessdate= |quote= |pmid=19008415 |bibcode = 2008Sci...322.1348M }}</ref><ref group="note" name="separation">Calculated from the separations in the East and North directions which are −0.657 and 0.706 ]s respectively.</ref> |
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| position_angle = 317.06<ref name="Marois2008" /><ref group="note" name="separation" /> |
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| separation = 38<ref name="Marois2008" /> |
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{{Planetbox orbit |
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| semimajor = ~ 38<ref name="Marois2008" /><ref group="note" name="circular_orbit">Value given assuming the planet's orbit is circular and is being observed face-on.</ref> |
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| semimajor_gm = ~ 5600 |
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| period_year = ~ 190<ref name="Marois2008" /><ref group="note" name="circular_orbit" /> |
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{{Planetbox character |
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| mass = 7{{±|3|2}}<ref>{{cite arxiv |eprint=1011.4918 |author1=Marois |author2=Zuckerman |author3=Konopacky |author4=Macintosh |author5=Barman |title=Images of a fourth planet orbiting HR 8799 |class=astro-ph.EP |year=2010}}</ref> |
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| radius = 1.3<ref name="spectrum"/> |
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| density = 3.2{{±|1.3|0.7}} |
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| temperature = 1090{{±|10|90}}<ref name="Marois2008" /> |
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{{Planetbox discovery |
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| discovery_date = November 13, 2008 |
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| discoverers = Marois ''et al.'' |
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| discovery_method = ] |
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| discovery_site = ] and ] in ] |
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| discovery_status = Published |
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{{Planetbox catalog |
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| names = ] 218396 c<ref>{{SIMBAD link|HD+218396c|HD 218396c -- Extra-solar Planet Candidate}}, entry, ]. Accessed on line December 6, 2008.</ref> |
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{{Planetbox reference |
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| star = HR+8799 |
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| planet = c |
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| simbad = HD+218396c |
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}} |
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{{Planetbox end}} |
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'''HR 8799 c''' is an ] located approximately 129 ]s away in the ] of ], orbiting the 6th ] ] ]. This planet has a mass between 5 and 10 ]es and a radius from 20 to 30% larger than ]'s. It orbits at 38 ] 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 ] and the ] in ]. These planets were discovered using the ] technique.<ref name="Marois2008" /><ref>{{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|accessdate=2008-12-02}}</ref><ref>{{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}}</ref><ref>{{cite news|title=Scientists Publish First Direct Images of Extrasolar Planets|first=Joel|last=Achenbach|work=]|publisher=]|date=2008-11-13|accessdate=2008-12-02|url=http://www.washingtonpost.com/wp-dyn/content/article/2008/11/13/AR2008111302267.html}}</ref><ref>{{cite journal |title=Stability of the directly imaged multiplanet system HR 8799: resonance and masses |author=Fabrycky et al. |date=1 December 2008|pages=1408–1421 |accessdate=2008-12-02 |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 }}</ref> 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.<ref name="spectrum"/><ref>{{cite journal|last=Janson|first=M.|date=13 January 2010|title=VLT Captures First Direct Spectrum of an Exoplanet|journal=ESO|location=La Silla Observatory|url=http://www.eso.org/public/news/eso1002/|accessdate=2010-01-13}}</ref> |
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==Spectra== |
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==Spectra== |
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]’s ].]] |
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]’s ].]] |
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Near infrared spectroscopy from 995 to 1769 nanometers made with the Palomar Observatory show evidence of ], perhaps some ] but neither ] nor substantial ].<ref name=Gilliland>{{Cite journal|author = B. R. Oppenheimer|title= Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy|publisher=]|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}}</ref> 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.<ref>{{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 }}</ref><ref>{{cite web |title=Giant Alien Planet in Supersized Solar System May Solve Mystery |date=2013-03-14 |website=] |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}}</ref> |
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Near infrared spectroscopy from 995 to 1769 nanometers made with the Palomar Obervatory show evidence of Ammonia, perhaps some Acetylene but neither Carbon Dioxide nor substantial Methane.<ref name=Gilliland>{{cite web|first = B. R. Oppenheimer|title= Reconnaissance of the HR 8799 Exosolar System I: Near IR Spectroscopy|url=http://arxiv.org/abs/1303.2627|publisher=Cornell University|accessdate=12 March 2013}}</ref> |
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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.<ref></ref><ref></ref> |
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Later, in November 2018, researchers confirmed the existence of ] and the absence of methane in the atmosphere of HR 8799c, using high-resolution spectroscopy and near-infrared adaptive optics (]) at the Keck Observatory.<ref name="EA-20181120">{{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=] |accessdate=21 November 2018 |author-link=W. M. Keck Observatory }}</ref><ref name="AJ-20181120">{{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=] |volume=156 |pages=272 |number=6 |doi=10.3847/1538-3881/aae47b |bibcode=2018AJ....156..272W |arxiv=1809.09080 |s2cid=119372301 |doi-access=free }}</ref> |
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==Notes== |
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{{clear left}} |
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<references group="note" /> |
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The detection of water and ] in the planetary atmosphere was announced in 2021.<ref>{{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 }}</ref> |
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==See also== |
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==See also== |
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* ] |
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* ] |
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==Notes== |
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<references group="note" /> |
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==References== |
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==References== |
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{{reflist|refs= |
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{{Reflist|refs= |
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<ref name="spectrum"> |
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<ref name="spectrum"> |
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{{cite journal |last=Jason |first=M. |author2=C. Bergfors |author3=M. Goto |author4=W. Brandner |author5=D. Lafrenière |year=2010 |title=Spatially resolved spectroscopy of the exoplanet HR 8799 c |journal=The Astrophysical Journal |volume= |issue= |pages= |url=http://www.eso.org/public/archives/releases/sciencepapers/eso1002/eso1002.pdf |doi= |accessdate=2010-01-13}}</ref> |
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{{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 }}</ref> |
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==External links== |
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==External links== |
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{{Commons category-inline}} |
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{{Commons category-inline}} |
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* {{cite web | url=http://media4.obspm.fr/exoplanets/base/planete.php?etoile=HR+8799&planete=c | title=HR 8799 c | work=Exoplanets}} |
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* {{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 }} |
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{{HR 8799}} |
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{{HR 8799}} |
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{{Sky|23|07|28.7150|+|21|08|03.302|129}} |
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{{Sky|23|07|28.7150|+|21|08|03.302|129}} |
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{{Pegasus (constellation)}} |
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{{DEFAULTSORT:Hr 8799 C}} |
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{{DEFAULTSORT:Hr 8799 C}} |
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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. 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.
Size comparison of HR 8799 c (gray) with Jupiter..jpg)
Media related to HR 8799 c at Wikimedia Commons
Category