Astronomy:K2-38b
Discovery[1] | |
---|---|
Discovery site | Kepler Space Observatory |
Discovery date | 2016 |
Transit | |
Orbital characteristics | |
0.04994+0.00048−0.00049 AU | |
Eccentricity | 0.197+0.067−0.060[2] |
Orbital period | 4.01593 (± 0.0005)[3] d |
Inclination | 88.36 +0.17−0.15[2] |
Star | K2-38 |
Physical characteristics | |
Mass | 7.3+1.1−1.0[2] M⊕ |
Mean density | 11.0+5.8−3.7 g cm−3 |
3.08+1.2−0.74 g | |
Physics | 1,266 K (993 °C; 1,819 °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 (nearly 20,000 km wide) but about 12 times more massive (around 7.2*10^25 kg, a bit less than Uranus) indicating a composition rich in iron and an extremely high surface gravity. The planet is within K2 Campaign 2, in the constellation Scorpius.
Characteristics
Mass, radius, and temperature
K2-38b is a massive rocky exoplanet significantly larger and more massive than Earth. It has a radius of 1.55 R⊕,[3] close to the 1.6 R⊕ 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. Initially it was believed planet is made almost entirely of iron,[1] with a mass of about 12.0 M⊕ and a density of about 17.5 g/cm3.[3] This made it one of the densest exoplanets ever discovered. Measurement in 2020 have resulted in lower mass of 7.3+1.1−1.0[2] M⊕, and less extreme constraints on composition though.
Orbit
K2-38b 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 0.05 AU. For comparison, Mercury orbits every 88 days at 0.38 AU from the Sun. The eccentricity of K2-38's orbit is slightly larger than that of Mars.[2]
Host star
The parent star K2-38 is a G2 main-sequence star, similar to our own Sun. It is 1.10 R☉ and 1.07 M☉, 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.[3]
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.[1]
See also
References
- ↑ 1.0 1.1 1.2 Sinukoff, Evan et al. (2016). "Eleven Multiplanet Systems from K2 Campaigns 1 and 2 and the Masses of Two Hot Super-Earths". The Astrophysical Journal 827 (1): 78. doi:10.3847/0004-637X/827/1/78. Bibcode: 2016ApJ...827...78S.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Cite error: Invalid
<ref>
tag; no text was provided for refs namedToledo2020
- ↑ 3.0 3.1 3.2 3.3 "K2-38 b CONFIRMED PLANET OVERVIEW PAGE". NASA Exoplanet Archive. https://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=K2-38+b&type=CONFIRMED_PLANET. Retrieved 2018-01-20.
![]() | Original source: https://en.wikipedia.org/wiki/K2-38b.
Read more |