A sub-Earth is a planet "substantially less massive" than Earth and Venus.[1] In the Solar System, this category includes Mercury and Mars. Sub-Earth exoplanets are among the most difficult type to detect because their small sizes and masses produce the weakest signal. Despite the difficulty, one of the first exoplanets found was a sub-Earth around a millisecond pulsarPSR B1257+12. The smallest known is WD 1145+017 b with a size of 0.15 Earth radii, or somewhat smaller than Pluto. However, WD 1145+017 b is not massive enough to qualify as a sub-Earth classical planet and is instead defined as a minor, or dwarf, planet.[2] It is orbiting within a thick cloud of dust and gas as chunks of itself continually break off to then spiral in towards the star, and within around 5,000 years it will have more-or-less disintegrated.[3]
The Kepler space telescope opened up a new realm of sub-Earth discoveries. On January 10, 2012, Kepler discovered the first three sub-Earths around an ordinary star, Kepler-42. As of June 2014, Kepler has 45 confirmed planets that are smaller than Earth, with 17 of them being smaller than 0.8 Rⴲ. In addition, there are over 310 planet candidates with an estimated radius of <1 Rⴲ, with 135 of them being smaller than 0.8 Rⴲ.[1][4]
There is suspected to be a sub-Earth orbiting Proxima Centauri, the closest star to the Sun.[5] The mass of Proxima d is believed to be between that of Mars and Venus.[6]
Sub-Earths commonly lack substantial atmospheres because of their low gravity and weak magnetic fields, allowing stellar radiation to wear away their atmospheres.[1] Due to their small sizes, and unless there are significant tidal forces when orbiting close to the parent star, sub-Earths also have short periods of geologic activity.
Referencesedit
^ abcSinukoff, E.; Fulton, B.; Scuderi, L.; Gaidos, E. (2013-08-28). "Below One Earth Mass: The Detection, Formation, and Properties of Subterrestrial Worlds". Space Science Reviews. 180 (1–4): 71–99. arXiv:1308.6308. Bibcode:2013SSRv..180...71S. doi:10.1007/s11214-013-0019-1. S2CID 255071638.
^Vanderburg, Andrew; John Asher Johnson; Rappaport, Saul; Bieryla, Allyson; et al. (2015). "A disintegrating minor planet transiting a white dwarf". Nature. 526 (7574): 546–549. arXiv:1510.06387. Bibcode:2015Natur.526..546V. doi:10.1038/nature15527. PMID 26490620. S2CID 4451207.
^Rappaport, S.; Gary, B. L.; Kaye, T.; Vanderburg, A.; Croll, B.; Benni, P.; Foote, J. (June 2016). "Drifting asteroid fragments around WD 1145+017". Monthly Notices of the Royal Astronomical Society. 458 (4): 3904–3917. arXiv:1602.00740. doi:10.1093/mnras/stw612.
^Faria, J. P.; Suárez Mascareño, A.; Figueira, P.; Silva, A.M.; et al. (February 2022). "A candidate short-period sub-Earth orbiting Proxima Centauri". Astronomy and Astrophysics. 658: A115. arXiv:2202.05188. Bibcode:2022A&A...658A.115F. doi:10.1051/0004-6361/202142337.
January 01, 1970
earth, earth, planet, substantially, less, massive, than, earth, venus, solar, system, this, category, includes, mercury, mars, exoplanets, among, most, difficult, type, detect, because, their, small, sizes, masses, produce, weakest, signal, despite, difficult. A sub Earth is a planet substantially less massive than Earth and Venus 1 In the Solar System this category includes Mercury and Mars Sub Earth exoplanets are among the most difficult type to detect because their small sizes and masses produce the weakest signal Despite the difficulty one of the first exoplanets found was a sub Earth around a millisecond pulsar PSR B1257 12 The smallest known is WD 1145 017 b with a size of 0 15 Earth radii or somewhat smaller than Pluto However WD 1145 017 b is not massive enough to qualify as a sub Earth classical planet and is instead defined as a minor or dwarf planet 2 It is orbiting within a thick cloud of dust and gas as chunks of itself continually break off to then spiral in towards the star and within around 5 000 years it will have more or less disintegrated 3 Comparing the size of Earth Mars and exoplanets of Kepler 20 and Kepler 42 The Kepler space telescope opened up a new realm of sub Earth discoveries On January 10 2012 Kepler discovered the first three sub Earths around an ordinary star Kepler 42 As of June 2014 Kepler has 45 confirmed planets that are smaller than Earth with 17 of them being smaller than 0 8 Rⴲ In addition there are over 310 planet candidates with an estimated radius of lt 1 Rⴲ with 135 of them being smaller than 0 8 Rⴲ 1 4 There is suspected to be a sub Earth orbiting Proxima Centauri the closest star to the Sun 5 The mass of Proxima d is believed to be between that of Mars and Venus 6 Sub Earths commonly lack substantial atmospheres because of their low gravity and weak magnetic fields allowing stellar radiation to wear away their atmospheres 1 Due to their small sizes and unless there are significant tidal forces when orbiting close to the parent star sub Earths also have short periods of geologic activity References edit a b c Sinukoff E Fulton B Scuderi L Gaidos E 2013 08 28 Below One Earth Mass The Detection Formation and Properties of Subterrestrial Worlds Space Science Reviews 180 1 4 71 99 arXiv 1308 6308 Bibcode 2013SSRv 180 71S doi 10 1007 s11214 013 0019 1 S2CID 255071638 Vanderburg Andrew John Asher Johnson Rappaport Saul Bieryla Allyson et al 2015 A disintegrating minor planet transiting a white dwarf Nature 526 7574 546 549 arXiv 1510 06387 Bibcode 2015Natur 526 546V doi 10 1038 nature15527 PMID 26490620 S2CID 4451207 Rappaport S Gary B L Kaye T Vanderburg A Croll B Benni P Foote J June 2016 Drifting asteroid fragments around WD 1145 017 Monthly Notices of the Royal Astronomical Society 458 4 3904 3917 arXiv 1602 00740 doi 10 1093 mnras stw612 NASA Exoplanet Archive Extrasolar Planets Encyclopaedia Faria J P Suarez Mascareno A Figueira P Silva A M et al February 2022 A candidate short period sub Earth orbiting Proxima Centauri Astronomy and Astrophysics 658 A115 arXiv 2202 05188 Bibcode 2022A amp A 658A 115F doi 10 1051 0004 6361 202142337 Retrieved from https en wikipedia org w index php title Sub Earth amp oldid 1215637118, wikipedia, wiki, book, books, library,
