Gliese 581 d: Difference between revisions
wikademia>Hiberniantears rv spelling change. "surmise" is correct: http://dictionary.reference.com/browse/surmise |
wikademia>Wikademia No edit summary |
||
| (124 intermediate revisions by 76 users not shown) | |||
| Line 1: | Line 1: | ||
'''Gliese 581 d''' 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. In late April | |||
2009 new observations by the original discovery team concluded that the planet is within the [[habitable zone]] where liquid water, and therefore, life, could exist. | |||
'''Gliese 581 d''' is an [[extrasolar planet]] | |||
== Discovery == | == Discovery == | ||
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]]. 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. | {{ntnes}} | ||
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]].<ref name=udry/> | |||
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. | 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 44 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 == | == Climate and habitability == | ||
{{Gliese 581}} | It was originally thought that Gliese 581 d orbits outside the theoretical [[habitable zone]] of its star. Further studies released in April of 2009 confirmed that the planet is within the habitable zone where liquid water could exist. According to Stephan Udry, "d could be covered by a 'large and deep ocean'; it is the first serious [[Ocean planet|waterworld]] candidate."<ref>http://www.google.com/hostednews/ap/article/ALeqM5g004fh_K-6Q4ebEceKWMDqEAiCagD97NCL9G0</ref> Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star."<ref>[http://www.space.com/scienceastronomy/070618_mm_gliese_581d.html SPACE.com - Hopes Dashed for Life on Distant Planet<!-- Bot generated title -->]</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|year=2007}}</ref> Scientists originally believed that Gliese 581 d would be too cold for [[liquid]] [[water]] to exist, and therefore could not support [[life]] in forms as existing on Earth. However, since Earth's temperature would be about -18°C<ref>{{cite web|url=http://lwf.ncdc.noaa.gov/oa/climate/globalwarming.html#q1 |title=Global Warming Frequently Asked Questions |publisher=Lwf.ncdc.noaa.gov |date=2008-05-08 |accessdate=2009-01-18}}</ref> 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.<ref>{{cite paper |last=von Bloh |first=W. |authorlink= |coauthors=''et al.'' |year=2008 |month= |title=Habitability of Super-Earths: Gliese 581c and 581d |journal= |volume= |issue= |pages= |id={{Arxiv|0712.3219v4}} |url= |accessdate= |quote= }}</ref><ref>{{cite web|url=http://www.centauri-dreams.org/?p=1625 |title=Centauri Dreams » Blog Archive » Gliese 581d: A Habitable World After All? |publisher=Centauri-dreams.org |date=2007-12-13 |accessdate=2009-01-18}}</ref><ref>{{cite web|author=Posted at 12:06 AM in Space Exploration |url=http://www.dailygalaxy.com/my_weblog/2007/06/another_super_e.html |title=New 'Super Earth 2' Discovered in Constellation Libra |publisher=Dailygalaxy.com |date=2007-06-15 |accessdate=2009-01-18}}</ref> | ||
[[ | On 21 April 2009, [[European Organisation for Astronomical Research in the Southern Hemisphere|ESO]] announced, together with the discovery of [[Gliese 581 e]], that they had refined the models of Gliese 581 d's orbit, discovering it lay well within the habitable zone.<ref>{{cite web|url=http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html|title=Lightest exoplanet yet discovered|publisher=eso.org|date=2009-04-21|accessdate=2009-04-21}}</ref><ref name="mayor">{{cite journal | url=http://obswww.unige.ch/~udry/Gl581_preprint.pdf|author=Mayor et al.|title=The HARPS search for southern extra-solar planets,XVIII. An Earth-mass planet in the GJ 581 planetary system |journal =[[Astronomy and Astrophysics]] |year=2009 }}</ref> | ||
[[ | [[Category:Planets]] | ||
Latest revision as of 05:18, 23 April 2009
Gliese 581 d is an extrasolar planet approximately 20 light-years away in the constellation of Libra. Because of its mass, the planet is classified as a super-Earth planet. In late April 2009 new observations by the original discovery team concluded that the planet is within the habitable zone where liquid water, and therefore, life, could exist.
Discovery
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.[1]
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 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.[2] For Gliese 581 d, the upper bound of its mass must be half that of 581 b; that is, 581 d's maximum is 44 Earth masses.[3] 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
It was originally thought that Gliese 581 d orbits outside the theoretical habitable zone of its star. Further studies released in April of 2009 confirmed that the planet is within the habitable zone where liquid water could exist. According to Stephan Udry, "d could be covered by a 'large and deep ocean'; it is the first serious waterworld candidate."[4] Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star."[5][6] Scientists originally believed that Gliese 581 d would be too cold for liquid water to exist, and therefore could not support life in forms as existing on Earth. However, since Earth's temperature would be about -18°C[7] 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 temperatures at which liquid water can exist, and therefore the planet may be capable of supporting life.[8][9][10]
On 21 April 2009, ESO announced, together with the discovery of Gliese 581 e, that they had refined the models of Gliese 581 d's orbit, discovering it lay well within the habitable zone.[11][12]
- ↑ Cite error: Invalid
<ref>tag; no text was provided for refs namedudry - ↑ Beust, H. et al. (2008). "Dynamical evolution of the Gliese 581 planetary system". Astronomy and Astrophysics 479 (1): 277–282. doi:. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2008A%26A...479..277B&db_key=AST&nosetcookie=1. Retrieved on 2008-08-20.
- ↑ Dividing the m sin i by "Sin(10/180 * PI)" on a radian-configured processor.
- ↑ http://www.google.com/hostednews/ap/article/ALeqM5g004fh_K-6Q4ebEceKWMDqEAiCagD97NCL9G0
- ↑ SPACE.com - Hopes Dashed for Life on Distant Planet
- ↑ von Bloh, W.; Bounama, C.; Cuntz, M.; Franck, S. (2007). "The Habitability of Super-Earths in Gliese 581". Astronomy & Astrophysics 476: 1365 – 1371. doi:. http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2007A%26A...476.1365V&db_key=AST&nosetcookie=1. Retrieved on 2008-08-18.
- ↑ "Global Warming Frequently Asked Questions". Lwf.ncdc.noaa.gov. 2008-05-08. http://lwf.ncdc.noaa.gov/oa/climate/globalwarming.html#q1. Retrieved on 2009-01-18.
- ↑ Template:Cite paper
- ↑ "Centauri Dreams » Blog Archive » Gliese 581d: A Habitable World After All?". Centauri-dreams.org. 2007-12-13. http://www.centauri-dreams.org/?p=1625. Retrieved on 2009-01-18.
- ↑ Posted at 12:06 AM in Space Exploration (2007-06-15). "New 'Super Earth 2' Discovered in Constellation Libra". Dailygalaxy.com. http://www.dailygalaxy.com/my_weblog/2007/06/another_super_e.html. Retrieved on 2009-01-18.
- ↑ "Lightest exoplanet yet discovered". eso.org. 2009-04-21. http://www.eso.org/public/outreach/press-rel/pr-2009/pr-15-09.html. Retrieved on 2009-04-21.
- ↑ Mayor et al. (2009). "The HARPS search for southern extra-solar planets,XVIII. An Earth-mass planet in the GJ 581 planetary system". Astronomy and Astrophysics. http://obswww.unige.ch/~udry/Gl581_preprint.pdf.