Gliese 581 d

2008-09-22T22:24:37Z

68.215.54.120:

{{Planetbox begin
| name = Gliese 581 d
}}
{{Planetbox image
| image = Gliese 581 d-v1.jpg
| caption = An artist's impression of Gliese 581 d and speculative moons.
}}
{{Planetbox star
| star = [[Gliese 581]]
| constell = [[Libra (constellation)|Libra]]
| RA = {{RA|15|19|26}}
| DEC = {{DEC|−07|43|20}}
| dist_ly = 19.9
| dist_pc = 6.12
| class = M2.5V
}}
{{Planetbox orbit
| period = 83.22730 ± 0.65845<ref name=udry>{{cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007A%26A...469L..43U&db_key=AST&nosetcookie=1|title=The HARPS search for southern extra-solar planets. XI. Super-Earths (5 and 8 M<sub>⊕</sub>) in a 3-planet system|author=Udry, S.; Bonfils, X.; Delfosse, X.; Forveille, T.; Mayor, M.; Perrier, C.; Bouchy, F.; Lovis, C.; Pepe, F.; Queloz, D.; Bertaux, J.-L.|journal=[[Astronomy and Astrophysics]]|volume=469|issue=3|year=2007|pages=L43 – L47|doi=10.1051/0004-6361:20077612|accessdate=2008-08-18}}</ref>
| semimajor = 0.2525 ± 0.013<ref name=udry />
| eccentricity = 0.12118 ± 0.12034<ref name=udry />
}}
{{Planetbox character
| mass_earth = >7.804 ± 0.69<ref name=udry />
}}
{{Planetbox discovery
| discovery_date = [[24 April]] [[2007]]
| discoverers = [[Stéphane Udry|Udry]] et al.
| discovery_method = [[Radial velocity]]
| discovery_site = {{flag|Switzerland}}
| discovery_status = Published<ref name=udry />
}}
{{Planetbox end}}

'''Gliese 581 d''' ({{pronEng|ˈgliːzə}}) is an [[extrasolar planet]] approximately 20 [[light-year]]s away in the [[constellation]] of [[Libra (constellation)|Libra]]. Because of its mass, the planet is classified as a [[super-Earth]] planet. Because the planet orbits in the outer edge of its parent star's [[habitable zone]], it is thought that the planet may be similar to [[Earth]].

== Discovery ==

BABY CATS. The planet was discovered by the team of [[Stéphane Udry]] of the [[Geneva Observatory]] in [[Switzerland]] using the [[HARPS]] instrument on the [[European Southern Observatory]] 3.6 [[meter]] [[telescope]] in [[La Silla]], [[Chile]] on 24 [[April 2007]]. Udry's team employed the [[radial velocity]] technique, in which the size and [[mass]] of a [[planet]] are determined based on the small perturbations it induces in its parent star’s [[orbit]] via [[gravity]].

The team is confident that the planet exists but recognizes that unlikely events could mimic its existence. They believe the issue will be settled by upcoming studies.

Dynamical simulations of the Gliese 581 system assuming that the orbits of the three planets are [[coplanarity|coplanar]] show that the system becomes unstable if its component masses are so high as to correspond to an overall inclination angle of 10° or less.<ref>{{cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2008A%26A...479..277B&db_key=AST&nosetcookie=1|author=Beust, H. et al.|title=Dynamical evolution of the Gliese 581 planetary system|journal=[[Astronomy and Astrophysics]]|volume=479|issue=1|year=2008|pages=277–282|doi=10.1051/0004-6361:20078794|accessdate=2008-08-20}}</ref> For Gliese 581 d, the upper bound of its mass must be half that of 581 b; that is, 581 d's maximum is 45 Earth masses.<ref>Dividing the m sin i by "Sin(10/180 * PI)" on a radian-configured processor.</ref> At this mass it must be held together with a central heavy-element core like Saturn and maybe even [[HD 149026 b]].

== Climate and habitability ==

Although Gliese 581 d orbits outside the theoretical [[habitable zone]] of its star, scientists surmise that conditions on the planet may be conducive to supporting life.<ref>[http://www.space.com/scienceastronomy/070618_mm_gliese_581d.html SPACE.com - Hopes Dashed for Life on Distant Planet]</ref><ref>{{cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007A%26A...476.1365V&db_key=AST&nosetcookie=1|title=The Habitability of Super-Earths in Gliese 581|author=von Bloh, W.; Bounama, C.; Cuntz, M.; Franck, S.|journal=[[Astronomy & Astrophysics]]|volume=476|pages=1365 – 1371|doi=10.1051/0004-6361:20077939|accessdate=2008-08-18}}</ref> Scientists originally believed that Gliese 581 d would in fact be too cold for [[liquid]] [[water]] to exist, and therefore could not support [[life]] as we understand it. However, since it is calculated that the Earth's temperature would be about minus nineteen degrees celsius without any greenhouse gases, and due to a theorized [[greenhouse effect]] of Gliese 581 d, research now suggests that [[atmospheric]] conditions on the planet could create [[temperature]]s at which liquid water can exist, and therefore the planet may be capable of supporting life.

== References ==
{{reflist|2}}

== External links ==

{{commonscat|Gliese 581}}

* {{cite web |url=http://exoplanet.eu/planet.php?p1=Gl+581&p2=d |title=Notes for planet Gl 581 d |accessdate=2008-07-15 |work=The Extrasolar Planets Encyclopaedia |publisher= |date= }}

[[Category:Extrasolar planets]]
[[Category:Libra constellation]]
[[Category:Super-Earths]]

[[de:Gliese 581 d]]
[[es:Gliese 581 d]]
[[fr:Gliese 581 d]]
[[ko:글리제 581 d]]
[[it:Gliese 581 d]]
[[ja:グリーゼ581d]]
[[lt:Gliese 581 d]]
[[nl:Gliese 581 d]]
[[pl:Gliese 581 d]]
[[ru:Глизе 581 d]]
[[fi:Gliese 581 d]]
[[sv:Gliese 581 d]]

IdeaWazaWiki - User contributions [en]

Gliese 581 d