K2-18b: Perbedaan antara revisi

{{Infobox planet|extrasolarplanet=yes|name=K2-18b|image=File:Esa-hubble-k2-18a impression.jpg|caption=Gambaran dariIlustrasi K2-18b (kanan) yang mengorbit bintang katai merah K2-18 (kiri). Kandidat eksoplanet yang belum dikonfirmasi K2-18c ditampilkanada di bagian tengah.

<!-- DISCOVERY -->|discovery_ref=<ref>{{Cite namejournal|last="Cloutier2017"Cloutier|first=R.|last2=Astudillo-Defru|first2=N.|last3=Doyon|first3=R.|last4=Bonfils|first4=X.|last5=Almenara|first5=J.-M.|last6=Benneke|first6=B.|last7=Bouchy|first7=F.|last8=Delfosse|first8=X.|last9=Ehrenreich|first9=D.|date=2017-12|year=|title=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|url=http://www.aanda.org/10.1051/0004-6361/201731558|journal=Astronomy & Astrophysics|volume=608|issue=|pages=A35|arxiv=1707.04292|bibcode=2017A&A...608A..35C|doi=10.1051/0004-6361/201731558|issn=0004-6361}}</ref>|discovery_site=[[Kepler (wahana antariksa)|Observatorium Luar Angkasa Kepler]]|discovered=2015|discovery_method=[[Transit (astronomi)|Transit]]

'''K2-18b''', juga dikenal sebagai '''EPICEMPIC 201912552 b''' adalah sebuah planet ekstrasurya yang mengorbit bintang katai merah [[K2-18]] setiap 33 hari sekali. Planet ini berjarak sekitar 111 [[tahun cahaya]] dari [[Bumi]],<ref name=":0">{{Cite journal|last=Wünsche|first=A.|last2=Udry|first2=S.|last3=Santos|first3=N. C.|last4=Pepe|first4=F.|last5=Murgas|first5=F.|last6=Menou|first6=K.|last7=Mayor|first7=M.|last8=Lovis|first8=C.|last9=Forveille|first9=T.|date=2018-10-10|year=|title=Confirmation of the radial velocity super-Earth K2-18c with HARPS and CARMENES|url=https://arxiv.org/abs/1810.04731v1|journal=|language=en|volume=|issue=|pages=|arxiv=1810.04731|bibcode=2019A&A...621A..49C|doi=10.1051/0004-6361/201833995}}</ref> dan mengandung air cair di atmosfernya.{{Sky|11|30|14.518|+|07|35|18.257|124}} Eksoplanet ini memiliki massa sekitar 8 kali massa bumi dan diklasifikasikan sebagai [[Bumi super]].

K2-18b mengorbit K2-18 pada jarak sekitar 0,1429 AU (21,38 juta km).<ref>{{Cite journal|last=Yurchenko|first=Sergey N.|last2=Tennyson|first2=Jonathan|last3=Tinetti|first3=Giovanna|last4=Waldmann|first4=Ingo P.|last5=Tsiaras|first5=Angelos|date=2019-09-11|year=|title=Water vapour in the atmosphere of the habitable-zone eight Earth-mass planet K2-18 b|url=https://arxiv.org/abs/1909.05218v1|journal=|language=en|volume=|issue=|pages=|arxiv=1909.05218|bibcode=2019arXiv190905218T|doi=10.1038/s41550-019-0878-9}}</ref> Eksoplanet ini memiliki periode orbit 33 hari.<ref>{{Cite web|url=https://www.space.com/alien-planet-k2-18b-water-vapor-not-earth-twin.html|title=The Water Vapor Find on 'Habitable' Exoplanet K2-18 b Is Exciting — But It's No Earth Twin|last=Life|first=Mike Wall 2019-09-11T17:43:05Z Search for|website=Space.com|language=en|access-date=2019-09-14}}</ref><ref>{{Cite journal|last=Benneke|first=Björn|last2=Werner|first2=Michael|last3=Petigura|first3=Erik|last4=Knutson|first4=Heather|last5=Dressing|first5=Courtney|last6=Crossfield|first6=Ian J. M.|last7=Schlieder|first7=Joshua E.|last8=Livingston|first8=John|last9=Beichman|first9=Charles|date=2017-01-12|year=|title=SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION|url=http://stacks.iop.org/0004-637X/834/i=2/a=187?key=crossref.4113758b730f2803a70374cfb05d99cd|journal=The Astrophysical Journal|volume=834|issue=2|pages=187|arxiv=1610.07249|bibcode=2017ApJ...834..187B|doi=10.3847/1538-4357/834/2/187|issn=1538-4357}}</ref> Suhu permukaan eksoplanet ini diperkirakan sekitar 265 ± 5 K (−8 ± 5 &nbsp;° C).<ref name=":0" /> K2-18b diperkirakan memiliki radius 2,71 ± 0,07 ''R''_⊕ dan massa 8,63 ± 1,35 M_⊕, berdasarkan analisis menggunakan HARPS dan CARMENES.<ref name=":0" />