| 词条 | K2-38b |
| 释义 |
| name = K2-38b | discovery_site = Kepler Space Observatory | discovered = 2016 | discovery_method = Transit | apsis = astron | semimajor = 0.0506 (± 0.0008)[1] AU | eccentricity = null[1] | period = 4.01593 (± 0.0005)[1] d | inclination = 87.28 {{±|1.88|3.08}}[1] | star = K2-38 | mean_radius = 1.55 (± 0.16)[1] {{Earth radius|link=y}} | mass = 12.0 (± 2.9)[1] {{Earth mass|link=y}} | density = {{val|17.5|+8.5|-6.2}} g cm−3 | surface_grav = {{val|4.99|+2.72|-1.88}} g | single_temperature = {{convert|1184|K|C F}}[2] }} K2-38b, also designated EPIC 204221263 b, is a massive rocky exoplanet closely orbiting a Sun-like star and is one of the densest planets ever found. Discovered in 2016 by Crossfield et al. and later characterized by Sinukoff et al., K2-38b is a rocky Super-Earth about 55% larger than Earth but about 12 times more massive, indicating a composition rich in iron and an extremely high surface gravity. The planet is within K2 Campaign 2, in the constellation Scorpius. CharacteristicsMass, radius, and temperatureK2-38b is a massive rocky exoplanet significantly larger and more massive than Earth. It has a radius of 1.55 {{Earth_radius}},[1] close to the 1.6 {{Earth_radius}} limit where planets would begin to accumulate thick hydrogen-helium atmospheres and become something similar to a Mini-Neptune. However, K2-38b is instead a very dense terrestrial planet made almost entirely of iron,[2] with a mass of about 12.0 {{Earth_mass}} and a density of about 17.5 g/cm3.[1] This makes it one of the densest exoplanets ever discovered. The planet has a surface gravity around 5 times that of Earth, about twice that of the planet Jupiter. K2-38b is also very hot, with an equilibrium temperature of {{convert|1184|K|C F}}, hot enough to melt some types of metals.[2] OrbitK2-38b has a very tight orbit around its host star. The planet takes just 4 days to complete a single orbit at a distance of about 0.0506 AU. For comparison, Mercury orbits every 88 days at 0.38 AU from the Sun. The eccentricity of K2-38's orbit is unknown.[1] Host starThe parent star K2-38 is a G2 V main-sequence star, similar to our own Sun. It is 1.10 {{Solar_radius}} and 1.07 {{Solar_mass}}, with a temperature of 5757 K and an unknown age. For comparison, the Sun has a temperature of 5778 K and is about 4.5 billion years old.[1] The visual magnitude of K2-38, or how bright it appears to the human eye, is 11.39. Therefore, it is far too dim to be seen without a telescope.[2] See also
References1. ^1 2 3 4 5 6 7 8 9 {{cite web | url=https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=K2-38+b&type=CONFIRMED_PLANET | title=K2-38 b CONFIRMED PLANET OVERVIEW PAGE | work=NASA Exoplanet Archive | accessdate=2018-01-20}} 2. ^1 2 3 {{cite arxiv |title=Eleven Multi-planet Systems from K2 Campaigns 1 & 2 and the Masses of Two Hot Super-Earths|eprint=1511.09213 |class=astro-ph.EP |first1=Evan |last1=Sinukoff |first2=Andrew W. |last2=Howard |first3=Erik A. |last3=Petigura |first4=Joshua E. |last4=Schlieder |first5=Ian J. M. |last5=Crossfield |first6=David R. |last6=Ciardi |first7=Benjamin J. |last7=Fulton |first8=Howard |last8=Issacson |first9=Kimberly M. |last9=Aller |first10=Christoph |last10=Baranec |first11=Charles A. |last11=Beichman |first12=Brad M. S. |last12=Hansen |first13=Heather A. |last13=Knutson |first14=Nicholas M. |last14=Law |first15=Michael C. |last15=Liu |first16=Reed |last16=Riddle |first17=Courtney D. |last17=Dressing |date=21 June 2016}} 2 : Exoplanets discovered by K2|Transiting exoplanets |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。