KELT-21b is an extrasolar planet discovered in 2017. It is a hot Jupiter with radius of about 1.586 MJ.[1]
| Discovery | |
|---|---|
| Discovered by | Marshall Johnson et al.[1] |
| Discovery site | KELT |
| Discovery date | 2018 |
| Transit method | |
| Orbital characteristics | |
| 0.05224 AU (7,815,000 km) | |
| 3.6127647[1] d | |
| Inclination | 86.46[1] |
| Star | KELT-21 A (HD 332124) |
| Physical characteristics | |
Mean radius | 1.586[1] RJ |
| Mass | <3.91[1] MJ |
Mean density | <1.24 g cm−3 |
| Temperature | 2051[1] |
Host star
KELT-21b orbits KELT-21 A (HD 332124). It orbits the primary star in a triple star system, with the other two stars located 1.2 arcseconds away. These two stars, designated KELT-21 B and C, have masses of 0.13 M☉ and 0.11 M☉, respectively.[1] The primary star is heavy at 1.458±0.029M☉, extremely hot at 8210±771 K and rapidly rotating (equatorial velocity equal to 141 km/s).[2] The planetary orbit is well aligned with the equatorial plane of the host star, with misalignment equal to −5.6+1.7
−1.9°[3]
Transmission planetary spectroscopy was performed in 2021, based on a single transit observation in 2019. High planetary gravity and relatively low planetary temperature made detection of an atmosphere impossible that time.[4]