KELT-20

	KELT-20
Observationsdata; Epok: J2000.0
Stjärnbild	Svanen
Rektascension	19t 38m 38,735s
Deklination	+31° 31′ 09,22″
Skenbar magnitud ()	7,58
Stjärntyp
Spektraltyp	A2 V
Variabeltyp	planetpassage
Astrometri
Radialhastighet ()	-26,78 ± 0,71 km/s
Egenrörelse (µ)	RA: +3,251 +0,030−0,008 mas/år; Dek.: -6,01 ± 0,03 mas/år
Parallax ()	7,3015 ± 0,0433
Avstånd	447 ± 3 lå (137,0 ± 0,8 pc)
Absolut magnitud ()	+2,30
Detaljer
Massa	2,3 M☉
Radie	1,6 R☉
Luminositet	15,7 L☉
Temperatur	9 032 K
Metallicitet	-0,02 ± 0,07 dex
Ålder	58 ± 5 miljoner år
Andra beteckningar
	HD 185603, MASCARA-2, KELT-20, AG+31 1846, BD+30 3673, GSC 02655-03344, HIC 96618, HIP 96618, LF 2 +31 176, 2MASS J19383872+3113091, PPM 83273, SAO 68614, TD1 25169, TYC 2655-3344-1, uvby98 100185603, Gaia DR3 2033123654092592384, Gaia DR2 2033123654092592384, Gaia DR1 2033123649761760384

KELT-20, även känd som MASCARA-2, är en stjärna av spektraltyp A2 i huvudserien, belägen i stjärnbilden Svanen på ett avstånd av ca 447 ljusår från solsystemet.

En följeslagare i form av en brun dvärgstjärna hittades år 2026, med hjälp av radialhastighetsmätning och astrometri, i omlopp kring stjärnan.^[6] Den antas ha en massa motsvarande 34 ⁺²⁹₋₁₁ jupitermassor.^[6]

Nomenklatur

KELT-20 är stjärnans KELT-beteckning. Den har också beteckningen MASCARA-2, vilket betyder att den är den andra stjärnan som observerats inom MASCARA-programmet för exoplanetsökning. Dess Henry Draper-katalogbeteckning är HD 185603 och dess Hipparcos-beteckning är HIP 96618.

Planetsystem

År 2017 tillkännagavs upptäckten av planeten KELT-20b.^[10]^[11]^[12]

KELT-20 solsystem^[11]
Planet	Massa	Halv storaxel (AE)	Siderisk omloppstid (d)	Excentricitet	Inklination	Radie
b	3,382 M_J	0,05	3,6127647	-	86,12°	1,741 R_J

Referenser

Den här artikeln är helt eller delvis baserad på material från engelskspråkiga Wikipedia, KELT-20, 18 augusti 2026.

Noter

1 2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
1 2 3 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
↑ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 978-0333750889.
↑ Lund, Michael B.; et al. (2017). "KELT-20b: A Giant Planet with a Period of P ∼ 3.5 days Transiting the V ∼ 7.6 Early a Star HD 185603". The Astronomical Journal. 154 (5): 194. arXiv:1707.01518. Bibcode:2017AJ....154..194L. doi:10.3847/1538-3881/aa8f95.
1 2 https://simbad.cds.unistra.fr/simbad/sim-id?Ident=HD+185603. Hämtad 2020-09-08.
1 2 3 4 Yang, Eritas; Lu, Tiger; Yahalomi, Daniel A.; Winn, Joshua N. (2026-06-01). "A Massive Hot-Jupiter Companion that Disfavors Giant Planet Formation Beyond the Water-Ice Line". The Astrophysical Journal Letters. arXiv:2606.02705.
1 2 3 4 Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.
↑ Talens, G. J. J.; Justesen, A. B.; Albrecht, S.; McCormac, J.; Van Eylen, V.; Otten, G. P. P. L.; Murgas, F.; Palle, E.; Pollacco, D.; Stuik, R.; Spronck, J. F. P.; Lesage, A. -L.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Snellen, I. A. G. (2018). "MASCARA-2 b. A hot Jupiter transiting the mV = 7.6 A-star HD 185603". Astronomy and Astrophysics. 612. arXiv:1707.01500. Bibcode:2018A&A...612A..57T. doi:10.1051/0004-6361/201731512. S2CID 119422884.
↑ Distler, Adam; Soares-Furtado, Melinda; Mann, Andrew W.; Kraus, Adam L.; Gagné, Jonathan; Becker, Juliette; Narayan, Ritvik Sai; Clark, Max; Vanderburg, Andrew (2026-03-01). "TESS Hunt for Young and Maturing Exoplanets (THYME) XIV: A Comoving-Based Age Constraint for KELT-20". The Astronomical Journal. arXiv:2603.01313.
↑ Yan, F.; Reiners, A.; Pallé, E.; Shulyak, D.; Stangret, M.; Molaverdikhani, K.; Nortmann, L.; Mollière, P.; Henning, Th.; Casasayas-Barris, N.; Cont, D.; Chen, G.; Czesla, S.; Sánchez-López, A.; López-Puertas, M.; Ribas, I.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Galadí-Enríquez, D.; Khalafinejad, S.; Lara, L. M.; Montes, D.; Morello, G.; Nagel, E.; Sedaghati, E.; Zapatero Osorio, M. R.; Zechmeister, M. (2022), "Detection of iron emission lines and a temperature inversion on the dayside of the ultra-hot Jupiter KELT-20b", Astronomy & Astrophysics, 659: A7, arXiv:2201.08759, Bibcode:2022A&A...659A...7Y, doi:10.1051/0004-6361/202142395, S2CID 246210387
1 2 Fu, Guangwei; Sing, David K.; Lothringer, Joshua D.; Deming, Drake; Ih, Jegug; Kempton, Eliza M. -R.; Malik, Matej; Komacek, Thaddeus D.; Mansfield, Megan; Bean, Jacob L. (2022), "Strong H2O and CO Emission Features in the Spectrum of KELT-20b Driven by Stellar UV Irradiation", The Astrophysical Journal Letters, 925 (1): L3, arXiv:2201.02261, Bibcode:2022ApJ...925L...3F, doi:10.3847/2041-8213/ac4968
↑ Kasper, David; Bean, Jacob L.; Line, Michael R.; Seifahrt, Andreas; Brady, Madison T.; Lothringer, Joshua; Pino, Lorenzo; Fu, Guangwei; Pelletier, Stefan; Stürmer, Julian; Benneke, Björn; Brogi, Matteo; Désert, Jean-Michel (2023), "Unifying High- and Low-resolution Observations to Constrain the Dayside Atmosphere of KELT-20b/MASCARA-2b", The Astronomical Journal, 165 (1): 7, arXiv:2208.04759, Bibcode:2023AJ....165....7K, doi:10.3847/1538-3881/ac9f40

[A-1] 1 2 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.

[B-2] 1 2 3 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.

[C-3] Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862. ISBN 978-0333750889.

[D-4] Lund, Michael B.; et al. (2017). "KELT-20b: A Giant Planet with a Period of P ∼ 3.5 days Transiting the V ∼ 7.6 Early a Star HD 185603". The Astronomical Journal. 154 (5): 194. arXiv:1707.01518. Bibcode:2017AJ....154..194L. doi:10.3847/1538-3881/aa8f95.

[SIMBAD-5] 1 2 https://simbad.cds.unistra.fr/simbad/sim-id?Ident=HD+185603. Hämtad 2020-09-08.

[E-6] 1 2 3 4 Yang, Eritas; Lu, Tiger; Yahalomi, Daniel A.; Winn, Joshua N. (2026-06-01). "A Massive Hot-Jupiter Companion that Disfavors Giant Planet Formation Beyond the Water-Ice Line". The Astrophysical Journal Letters. arXiv:2606.02705.

[F-7] 1 2 3 4 Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. eISSN 1538-3881.

[G-8] Talens, G. J. J.; Justesen, A. B.; Albrecht, S.; McCormac, J.; Van Eylen, V.; Otten, G. P. P. L.; Murgas, F.; Palle, E.; Pollacco, D.; Stuik, R.; Spronck, J. F. P.; Lesage, A. -L.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Snellen, I. A. G. (2018). "MASCARA-2 b. A hot Jupiter transiting the mV = 7.6 A-star HD 185603". Astronomy and Astrophysics. 612. arXiv:1707.01500. Bibcode:2018A&A...612A..57T. doi:10.1051/0004-6361/201731512. S2CID 119422884.

[H-9] Distler, Adam; Soares-Furtado, Melinda; Mann, Andrew W.; Kraus, Adam L.; Gagné, Jonathan; Becker, Juliette; Narayan, Ritvik Sai; Clark, Max; Vanderburg, Andrew (2026-03-01). "TESS Hunt for Young and Maturing Exoplanets (THYME) XIV: A Comoving-Based Age Constraint for KELT-20". The Astronomical Journal. arXiv:2603.01313.

[I-10] Yan, F.; Reiners, A.; Pallé, E.; Shulyak, D.; Stangret, M.; Molaverdikhani, K.; Nortmann, L.; Mollière, P.; Henning, Th.; Casasayas-Barris, N.; Cont, D.; Chen, G.; Czesla, S.; Sánchez-López, A.; López-Puertas, M.; Ribas, I.; Quirrenbach, A.; Caballero, J. A.; Amado, P. J.; Galadí-Enríquez, D.; Khalafinejad, S.; Lara, L. M.; Montes, D.; Morello, G.; Nagel, E.; Sedaghati, E.; Zapatero Osorio, M. R.; Zechmeister, M. (2022), "Detection of iron emission lines and a temperature inversion on the dayside of the ultra-hot Jupiter KELT-20b", Astronomy & Astrophysics, 659: A7, arXiv:2201.08759, Bibcode:2022A&A...659A...7Y, doi:10.1051/0004-6361/202142395, S2CID 246210387

[J-11] 1 2 Fu, Guangwei; Sing, David K.; Lothringer, Joshua D.; Deming, Drake; Ih, Jegug; Kempton, Eliza M. -R.; Malik, Matej; Komacek, Thaddeus D.; Mansfield, Megan; Bean, Jacob L. (2022), "Strong H2O and CO Emission Features in the Spectrum of KELT-20b Driven by Stellar UV Irradiation", The Astrophysical Journal Letters, 925 (1): L3, arXiv:2201.02261, Bibcode:2022ApJ...925L...3F, doi:10.3847/2041-8213/ac4968

[K-12] Kasper, David; Bean, Jacob L.; Line, Michael R.; Seifahrt, Andreas; Brady, Madison T.; Lothringer, Joshua; Pino, Lorenzo; Fu, Guangwei; Pelletier, Stefan; Stürmer, Julian; Benneke, Björn; Brogi, Matteo; Désert, Jean-Michel (2023), "Unifying High- and Low-resolution Observations to Constrain the Dayside Atmosphere of KELT-20b/MASCARA-2b", The Astronomical Journal, 165 (1): 7, arXiv:2208.04759, Bibcode:2023AJ....165....7K, doi:10.3847/1538-3881/ac9f40

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Observationsdata Epok: J2000.0
KELT-20

Stjärnbild	Svanen^[1]
Rektascension	19^t 38^m 38,735^s^[2]
Deklination	+31° 31′ 09,22″^[2]
Skenbar magnitud ( $V$ )	7,58^[3]
Stjärntyp
Spektraltyp	A2 V^[4]
Variabeltyp	planetpassage
Astrometri
Radialhastighet ( $R_{v}$ )	-26,78 ± 0,71^[5] km/s
Egenrörelse (µ)	RA: +3,251 ^+0,030_−0,008^[6] mas/år Dek.: -6,01 ± 0,03^[6] mas/år
Parallax ( $\pi$ )	7,3015 ± 0,0433^[2]
Avstånd	447 ± 3 lå (137,0 ± 0,8 pc)
Absolut magnitud ( $M_{V}$ )	+2,30^[1]
Detaljer
Massa	2,3^[7] M_☉
Radie	1,6^[7] R_☉
Luminositet	15,7^[7] L_☉
Temperatur	9 032^[7] K
Metallicitet	-0,02 ± 0,07^[8] dex
Ålder	58 ± 5^[9] miljoner år
Andra beteckningar
HD 185603, MASCARA-2, KELT-20, AG+31 1846, BD+30 3673, GSC 02655-03344, HIC 96618, HIP 96618, LF 2 +31 176, 2MASS J19383872+3113091, PPM 83273, SAO 68614, TD1 25169, TYC 2655-3344-1, uvby98 100185603, Gaia DR3 2033123654092592384, Gaia DR2 2033123654092592384, Gaia DR1 2033123649761760384^[5]