KELT-21b
Discovery
Discovered byMarshall Johnson et al.[1]
Discovery siteKELT
Discovery date2018
Transit method
Orbital characteristics
0.05224 AU (7,815,000 km)
3.6127647[1] d
Inclination86.46[1]
StarKELT-21 A
(HD 332124)
Physical characteristics
Mean radius
1.586[1] RJ
Mass<3.91[1] MJ
Mean density
<1.24 g cm−3
Temperature2051[1]

    KELT-21b is an extrasolar planet discovered in 2017. It is a hot Jupiter with radius of about 1.586 MJ.[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]

    References

    1. 1 2 3 4 5 6 7 8 Johnson, Marshall C; Rodriguez, Joseph E; Zhou, George; Gonzales, Erica J; Cargile, Phillip A; Crepp, Justin R; Penev, Kaloyan; Stassun, Keivan G; Gaudi, B. Scott; Colón, Knicole D; Stevens, Daniel J; Strassmeier, Klaus G; Ilyin, Ilya; Collins, Karen A; Kielkopf, John F; Oberst, Thomas E; Maritch, Luke; Reed, Phillip A; Gregorio, Joao; Bozza, Valerio; Novati, Sebastiano Calchi; d'Ago, Giuseppe; Scarpetta, Gaetano; Zambelli, Roberto; Latham, David W; Bieryla, Allyson; Cochran, William D; Endl, Michael; Tayar, Jamie; et al. (2018). "KELT-21b: A Hot Jupiter Transiting the Rapidly Rotating Metal-poor Late-A Primary of a Likely Hierarchical Triple System". The Astronomical Journal. 155 (2): 100. arXiv:1712.03241. Bibcode:2018AJ....155..100J. doi:10.3847/1538-3881/aaa5af. S2CID 73559090.
    2. ↑ Garai, Z.; Pribulla, T.; Kovács, J.; Szabó, Gy M.; Claret, A.; Komžík, R.; Kundra, E. (2022), "Rapidly rotating stars and their transiting planets: KELT-17b, KELT-19Ab, and KELT-21b in the CHEOPS and TESS era", Monthly Notices of the Royal Astronomical Society, 513 (2): 2822–2840, arXiv:2204.09077, doi:10.1093/mnras/stac1095
    3. ↑ Rice, Malena; Wang, Songhu; Wang, Xian-Yu; Stefánsson, Guđmundur; Isaacson, Howard; Howard, Andrew W.; Logsdon, Sarah E.; Schweiker, Heidi; Dai, Fei; Brinkman, Casey; Giacalone, Steven; Holcomb, Rae (2022), "A Tendency Toward Alignment in Single-star Warm-Jupiter Systems", The Astronomical Journal, 164 (3): 104, arXiv:2207.06511, Bibcode:2022AJ....164..104R, doi:10.3847/1538-3881/ac8153, S2CID 250526491
    4. ↑ Stangret, M.; Casasayas-Barris, N.; Pallé, E.; Orell-Miquel, J.; Morello, G.; Luque, R.; Nowak, G.; Yan, F. (2022), "High-resolution transmission spectroscopy study of ultra-hot Jupiters HAT-P-57b, KELT-17b, KELT-21b, KELT-7b, MASCARA-1b, and WASP-189b", Astronomy & Astrophysics, 662: A101, arXiv:2111.13064, Bibcode:2022A&A...662A.101S, doi:10.1051/0004-6361/202141799, S2CID 244709777


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