| Revision as of 07:57, 18 September 2015 editRfassbind (talk | contribs)Autopatrolled, Extended confirmed users, Rollbackers186,689 edits →top: WP:LEADPARAGRAPH added earth mass of Neptune and Uranus to provide context. Added {{Better source}} to lead-paragraph. Removed boldface on gas dwarf→different article and different definition← Previous edit | Revision as of 08:54, 10 October 2015 edit undo85.155.148.64 (talk)No edit summaryNext edit → | ||
| Line 1: | Line 1: | ||
| A '''mini-Neptune''' (sometimes known as a ] or '''transitional planet''') is a planet of |
A '''mini-Neptune''' (sometimes known as a ] or '''transitional planet''') is a planet of up to 10 ]es ({{earth mass}}), smaller than ] and ], which have about 14.5 {{earth mass}} and 17 {{earth mass}}, respectively. Mini-Neputnes have thick ]–] atmospheres, probably with deep layers of ice, rock or liquid oceans (made of ], ], a mixture of both, or heavier volatiles). These planets have small cores made of low-density volatiles.<ref name="galactica">{{cite web |url=http://www.orionsarm.com/eg-article/4e393001bf7fb |title=Gas Dwarf |work=Orion's Arm |publisher=Encyclopedia Galactica}}</ref>{{Better source|reason=Term mini-Neptune missing. Website does not refer to other sources. Volatiles and oceans not mentioned, only helium atmosphere and low-density core. Overall questionable terminology: Neptune is an ice giant (not gas giant), a mini-Neptune would therefore rather be called ice-dwarf. Term gas dwarf links to different article with a mass-definition that contradicts this article|date=September 2015}} | ||
| Theoretical studies of such planets are loosely based on knowledge about Uranus and Neptune. Without a thick atmosphere, it would be classified as an ] instead.<ref>, E.J.W. de Mooij (1), M. Brogi (1), R.J. de Kok (2), J. Koppenhoefer (3,4), S.V. Nefs (1), I.A.G. Snellen (1), J. Greiner (4), J. Hanse (1), R.C. Heinsbroek (1), C.H. Lee (3), P.P. van der Werf (1),</ref> An estimated dividing line between a rocky planet and a gaseous planet is around two Earth radii.<ref>, Daniel C. Fabrycky, Jack J. Lissauer, Darin Ragozzine, Jason F. Rowe, Eric Agol, Thomas Barclay, Natalie Batalha, William Borucki, David R. Ciardi, Eric B. Ford, John C. Geary, Matthew J. Holman, Jon M. Jenkins, Jie Li, Robert C. Morehead, Avi Shporer, Jeffrey C. Smith, Jason H. Steffen, Martin Still</ref><ref>, blogs.scientificamerican.com, 20 June 2012</ref> In fact, empirical observations are showing that planets larger than approximately 1.6 Earth-radius (more massive than approximately 6 Earth-masses) contain significant amounts of volatiles or H–He gas (such planets appear to have a diversity of compositions that is not well-explained by a single mass–radius relation as that found in rocky planets).<ref>Courtney D. Dressing et al. ""</ref><ref>Leslie A. Rogers ""</ref> Similar results are confirmed by other studies.<ref>Lauren M. Weiss, and Geoffrey W. Marcy. ""</ref><ref>Geoffrey W. Marcy, Lauren M. Weiss, Erik A. Petigura, Howard Isaacson, Andrew W. Howard and Lars A. Buchhave. ""</ref><ref>Geoffrey W. Marcy et al. ""</ref> As for mass, the lower limit can vary widely for different planets depending on their compositions; the dividing mass can vary from as low as one to as high as 20 {{earth mass}}. | Theoretical studies of such planets are loosely based on knowledge about Uranus and Neptune. Without a thick atmosphere, it would be classified as an ] instead.<ref>, E.J.W. de Mooij (1), M. Brogi (1), R.J. de Kok (2), J. Koppenhoefer (3,4), S.V. Nefs (1), I.A.G. Snellen (1), J. Greiner (4), J. Hanse (1), R.C. Heinsbroek (1), C.H. Lee (3), P.P. van der Werf (1),</ref> An estimated dividing line between a rocky planet and a gaseous planet is around two Earth radii.<ref>, Daniel C. Fabrycky, Jack J. Lissauer, Darin Ragozzine, Jason F. Rowe, Eric Agol, Thomas Barclay, Natalie Batalha, William Borucki, David R. Ciardi, Eric B. Ford, John C. Geary, Matthew J. Holman, Jon M. Jenkins, Jie Li, Robert C. Morehead, Avi Shporer, Jeffrey C. Smith, Jason H. Steffen, Martin Still</ref><ref>, blogs.scientificamerican.com, 20 June 2012</ref> In fact, empirical observations are showing that planets larger than approximately 1.6 Earth-radius (more massive than approximately 6 Earth-masses) contain significant amounts of volatiles or H–He gas (such planets appear to have a diversity of compositions that is not well-explained by a single mass–radius relation as that found in rocky planets).<ref>Courtney D. Dressing et al. ""</ref><ref>Leslie A. Rogers ""</ref> Similar results are confirmed by other studies.<ref>Lauren M. Weiss, and Geoffrey W. Marcy. ""</ref><ref>Geoffrey W. Marcy, Lauren M. Weiss, Erik A. Petigura, Howard Isaacson, Andrew W. Howard and Lars A. Buchhave. ""</ref><ref>Geoffrey W. Marcy et al. ""</ref> As for mass, the lower limit can vary widely for different planets depending on their compositions; the dividing mass can vary from as low as one to as high as 20 {{earth mass}}. | ||
Revision as of 08:54, 10 October 2015
A mini-Neptune (sometimes known as a gas dwarf or transitional planet) is a planet of up to 10 Earth masses (ME), smaller than Uranus and Neptune, which have about 14.5 ME and 17 ME, respectively. Mini-Neputnes have thick hydrogen–helium atmospheres, probably with deep layers of ice, rock or liquid oceans (made of water, ammonia, a mixture of both, or heavier volatiles). These planets have small cores made of low-density volatiles.
Theoretical studies of such planets are loosely based on knowledge about Uranus and Neptune. Without a thick atmosphere, it would be classified as an ocean planet instead. An estimated dividing line between a rocky planet and a gaseous planet is around two Earth radii. In fact, empirical observations are showing that planets larger than approximately 1.6 Earth-radius (more massive than approximately 6 Earth-masses) contain significant amounts of volatiles or H–He gas (such planets appear to have a diversity of compositions that is not well-explained by a single mass–radius relation as that found in rocky planets). Similar results are confirmed by other studies. As for mass, the lower limit can vary widely for different planets depending on their compositions; the dividing mass can vary from as low as one to as high as 20 ME.
Several exoplanets have been discovered that are possibly gas dwarfs, based on known masses and densities. For example, Kepler-11f has a mass of 2.3 ME, yet its density is the same as that of Saturn, implying that it is a gas dwarf with a liquid ocean surrounded by a thick hydrogen–helium atmosphere and only a small rocky core. The even smaller Kepler-138d, having only roughly Earth's mass, is also a suspected gas planet due to its relatively large diameter (~ 20500 km) and its consequently low density. Such planets don't orbit too close to their parent stars, otherwise their thick atmospheres would be evaporated by heat or blown away by stellar winds. It is demonstrated that the inner planets of the Kepler-11 system have higher densities than planets farther away.
See also
References
- ^ "Gas Dwarf". Orion's Arm. Encyclopedia Galactica.
- Optical to near-infrared transit observations of super-Earth GJ1214b: water-world or mini-Neptune?, E.J.W. de Mooij (1), M. Brogi (1), R.J. de Kok (2), J. Koppenhoefer (3,4), S.V. Nefs (1), I.A.G. Snellen (1), J. Greiner (4), J. Hanse (1), R.C. Heinsbroek (1), C.H. Lee (3), P.P. van der Werf (1),
- Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates, Daniel C. Fabrycky, Jack J. Lissauer, Darin Ragozzine, Jason F. Rowe, Eric Agol, Thomas Barclay, Natalie Batalha, William Borucki, David R. Ciardi, Eric B. Ford, John C. Geary, Matthew J. Holman, Jon M. Jenkins, Jie Li, Robert C. Morehead, Avi Shporer, Jeffrey C. Smith, Jason H. Steffen, Martin Still
- When Does an Exoplanet’s Surface Become Earth-Like?, blogs.scientificamerican.com, 20 June 2012
- Courtney D. Dressing et al. "The Mass of Kepler-93b and The Composition of Terrestrial Planets"
- Leslie A. Rogers "Most 1.6 Earth-Radius Planets are not Rocky"
- Lauren M. Weiss, and Geoffrey W. Marcy. "The mass-radius relation for 65 exoplanets smaller than 4 Earth radii"
- Geoffrey W. Marcy, Lauren M. Weiss, Erik A. Petigura, Howard Isaacson, Andrew W. Howard and Lars A. Buchhave. "Occurrence and core-envelope structure of 1-4x Earth-size planets around Sun-like stars"
- Geoffrey W. Marcy et al. "Masses, Radii, and Orbits of Small Kepler Planets: The Transition from Gaseous to Rocky Planets"
- Cowen, Ron (6 January 2014). "Earth-mass exoplanet is no Earth twin : Nature News & Comment". Nature. doi:10.1038/nature.2014.14477.
- Six New Planets: Mini-Neptunes Found Around Sunlike Star, Victoria Jaggard, National Geographic News, Published February 2, 2011
- Barnes, Rory; Jackson, Brian; Raymond, Sean N.; West, Andrew A.; Greenberg, Richard (January 13, 2009). "The HD 40307 Planetary System: Super-Earths or Mini-Neptunes?". The Astrophysical Journal. 695 (2): 1006. arXiv:0901.1698. Bibcode:2009ApJ...695.1006B. doi:10.1088/0004-637X/695/2/1006.
