K2-18b

K2-18b
Eksoplaneet
’n Kunstenaarsvoorstelling van K2-18b (regs) wat om die rooidwerg K2-18 (links) wentel. Die onbevestigde eksoplaneetkandidaat K2-18c is tussen hulle te sien.
Soort planeet	Eksoplaneet
Moederster	K2-18
Ster se eienskappe
Sterrebeeld	Leeu
Regte klimming	11h 30m 14.518s[1]
Deklinasie	+07° 35′ 18.26″[1]
Skynmagnitude (m)	13,5[2]
Afstand (ligjaar)	124 ligjare
Metaalinhoud	0,123±0,157[3]
Spektraaltipe	M2,8[4]
Planeet
Massa	8,63±1,35 M⊕[5]
Radius	2,71±0,07 R⊕[5]
Temperatuur	265 ± 5 K (-8 ± 5 °C)[5]
Wentelperiode	33 dae[6]
Ontdekking
Datum	2015[7]
Ontdekkers	Kepler-ruimteteleskoop
Metode	Oorgang
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K2-18b, ook bekend as EPIC 201912552 b, is ’n eksoplaneet wat om die rooidwerg K2-18 wentel, 124 ligjare van die Aarde af.^[5] Die planeet, wat aanvanklik met die Kepler-ruimteteleskoop ontdek is, het ’n massa van sowat agt keer die Aarde s’n en is dus ’n superaarde. Dit wentel elke 33 dae om sy moederster en is binne die bewoonbare sone. Dit is egter waarskynlik onbewoonbaar.

In 2019 het twee onafhanklike navorsingstudies, wat data van die ruimteteleskope Kepler, Spitzer en Hubble gekombineer het, bevind daar is aansienlike hoeveelhede waterdamp in die planeet se atmosfeer, wat ’n eerste vir ’n planeet in die bewoonbare sone is.^[8][9][10]

1. ↑ ^{1,0 1,1} Brown, A.G.A.; et al. (Gaia collaboration) (Augustus 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. {{cite journal}}: Cite has empty unknown parameter: |displayauthors= (hulp)
2. ↑ Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (2012). "VizieR Online Data Catalog: UCAC4 Catalogue (Zacharias+, 2012)". Vizier Online Data Catalog. Bibcode:2012yCat.1322....0Z.
3. ↑ Benneke, Björn; Werner, Michael; Petigura, Erik; Knutson, Heather; Dressing, Courtney; Crossfield, Ian J. M.; Schlieder, Joshua E.; Livingston, John; Beichman, Charles; Christiansen, Jessie; Krick, Jessica; Gorjian, Varoujan; Howard, Andrew W.; Sinukoff, Evan; Ciardi, David R.; Akeson, Rachel L. (2017). "Spitzerobservations Confirm And Rescue The Habitable-Zone Super-Earth K2-18b For Future Characterization". The Astrophysical Journal. 834 (2): 187. arXiv:1610.07249. Bibcode:2017ApJ...834..187B. doi:10.3847/1538-4357/834/2/187.
4. ↑ Montet, Benjamin T.; et al. (5 Augustus 2015). "Stellar and Planetary Properties of K2 Campaign 1 Candidates and Validation of 17 Planets, Including a Planet Receiving Earth-like Insolation". The Astrophysical Journal. 809 (1): 25. arXiv:1503.07866. Bibcode:2015ApJ...809...25M. doi:10.1088/0004-637X/809/1/25.
5. ↑ ^{5,0 5,1 5,2 5,3} Cloutier, R.; et al. (7 Januarie 2019). "Confirmation of the radial velocity super-Earth K2-18c with HARPS and CARMENES". Astronomy & Astrophysics. 621. A49. arXiv:1810.04731. Bibcode:2019A&A...621A..49C. doi:10.1051/0004-6361/201833995.
6. ↑ Sarkis, Paula; et al. (2018). "The CARMENES Search for Exoplanets around M Dwarfs: A Low-mass Planet in the Temperate Zone of the Nearby K2-18". The Astronomical Journal. 155 (6): 257. arXiv:1805.00830. Bibcode:2018AJ....155..257S. doi:10.3847/1538-3881/aac108.
7. ↑ Cloutier, R.; et al. (5 Desember 2017). "Characterization of the K2-18 multi-planetary system with HARPS. A habitable zone super-Earth and discovery of a second, warm super-Earth on a non-coplanar orbit". Astronomy & Astrophysics. 608 (35). A35. arXiv:1707.04292. Bibcode:2017A&A...608A..35C. doi:10.1051/0004-6361/201731558. Besoek op 11 September 2019.{{cite journal}}: CS1 maint: date and year (link)
8. ↑ Ghosh, Pallab (12 September 2019). "Water found for first time on 'potentially habitable' planet". BBC News (in Engels). Geargiveer vanaf die oorspronklike op 5 April 2020. Besoek op 13 September 2019.
9. ↑ Greshko, Michael (11 September 2019). "Water found on a potentially life-friendly alien planet". National Geographic (in Engels). Geargiveer vanaf die oorspronklike op 26 Februarie 2020. Besoek op 11 September 2019.
10. ↑ Tsiaras, Angelos; et al. (11 September 2019). "Water vapour in the atmosphere of the habitable-zone eight-Earth-mass planet K2-18 b". Nature Astronomy: 1–6. arXiv:1909.05218. Bibcode:2019arXiv190905218T. doi:10.1038/s41550-019-0878-9. Besoek op 11 September 2019.