KELT-9b

Last updated
KELT-9b
Artist's impression of KELT-9b orbiting KELT-9.jpg
Artist's impression of KELT-9b and its parent star
Orbital characteristics
0.03462+0.00110
−0.00093 AU
1.4811235±0.0000011 [1] d
Inclination 86.79±0.25 [1]
Star HD 195689
Physical characteristics
1.891+0.061
−0.053 [1] RJ
Mass 2.17±0.56 [2] MJ
Mean density
0.53000 ± 0.00015 g/cm3[ citation needed ]
Albedo <0.14 [3]
Temperature 4050±180 [1] K

    KELT-9b is an exoplanet and ultra-hot Jupiter that orbits the late B-type/early A-type star KELT-9, [4] located about 670 light-years from Earth. [4] Detected using the Kilodegree Extremely Little Telescope, the discovery of KELT-9b was announced in 2016. [5] [1] As of June 2017, it is the hottest known exoplanet. [6]

    Contents

    Host star

    The host star, KELT-9, is 2 to 3 times larger and 2 to 3 times more massive than the sun. The surface temperature is 10,170  K (9,897  °C ; 17,846  °F ), unusually hot for a star with a transiting planet. Prior to the discovery of KELT-9b, only six A-type stars were known to have planets, of which the warmest, WASP-33, is significantly cooler at 7,430 K (7,157 °C; 12,914 °F); no B-type stars were previously known to host planets. KELT-9, classified as B9.5-A0 [1] [7] could be the first B-type star known to have a planet. KELT-9b occupies a circular but strongly inclined orbit a mere 0.03462 AU from KELT-9 with an orbital period of less than 1.5 days. [8] [9]

    Physical properties

    Exoplanet KELT-9b orbits host star KELT-9 PIA21472 - Hottest Hot Jupiter Animation (Artist's Concept).gif
    Exoplanet KELT-9b orbits host star KELT-9

    KELT-9b is a relatively large giant planet at about 2.8 times the mass of Jupiter; however given that its radius is nearly twice that of Jupiter, its density is less than half that of it. Like many hot Jupiters, KELT-9b is tidally locked with its host star. [9] The outer boundary of its atmosphere nearly reaches its Roche lobe, implying that the planet is experiencing rapid atmospheric escape [10] driven by the extreme amount of radiation it receives from its host star. [9] [8] In 2020, atmospheric loss rate was measured to be equal to 18 - 68 Earth masses per billion years. [11]

    The planet's elemental abundances remain largely unknown as of 2022, but a low carbon-to-oxygen ratio is strongly suspected. [12]

    This graph shows the average temperature and mass relative to Jupiter (Mj) of known exoplanets as of 2022 Temperature vs Mass of known exoplanets.png
    This graph shows the average temperature and mass relative to Jupiter (Mj) of known exoplanets as of 2022

    As of 2022, KELT-9b is the hottest known exoplanet, with dayside temperatures approaching 4,600 K (4,327 °C; 7,820 °F) — warmer than some K-type stars. [1] [4] Molecules on the day side are broken into their component atoms, so that normally sequestered refractory elements can exist as atomic species, including neutral oxygen, [13] neutral and singly ionized atomic iron [14] (Fe and Fe+) and singly ionized titanium (Ti+), [15] only to temporarily reform once they reach the cooler night side, [4] which is indirectly confirmed by measured enhanced heat transfer efficiency of 0.3 between dayside and nightside, likely diven by the latent heat of dissociation and recombination of the molecular hydrogen. [3] Surprisingly, spectra taken in 2021 have unambiguously indicated a presence of metal oxides and hydrides in the planetary atmosphere, [16] although higher resolution spectra taken in 2021 have not found any molecular emissions from the planetary dayside. [17]

    The thermosphere layer of KELT-9b is expected to heat up to 10,000–11,000 K (9,727–10,727 °C; 17,540–19,340 °F), driven by ionization of heavy metals atoms like iron. [18]

    Size comparison
    JupiterKELT-9b
    Small Jupiter.jpg Exoplanet sphere.jpg

    See also

    Related Research Articles

    <span class="mw-page-title-main">HD 189733 b</span> Hot Jupiter exoplanet in the constellation Vulpecula

    HD 189733 b is an exoplanet in the constellation of Vulpecula approximately 64.5 light-years away from the Solar System. Astronomers in France discovered the planet orbiting the star HD 189733 on October 5, 2005, by observing its transit across the star's face. With a mass 11.2% higher than that of Jupiter and a radius 11.4% greater, HD 189733 b orbits its host star once every 2.2 days at an orbital speed of 152.0 kilometers per second, making it a hot Jupiter with poor prospects for extraterrestrial life.

    WASP-33b is an extrasolar planet orbiting the star HD 15082. It was the first planet discovered to orbit a Delta Scuti variable star. With a semimajor axis of 0.026 AU and a mass likely greater than Jupiter's, it belongs to the hot Jupiter class of planets.

    <span class="mw-page-title-main">WASP-43b</span> Extrasolar planet in the constellation Sextans

    WASP-43b, formally named Astrolábos, is a transiting planet in orbit around the young, active, and low-mass star WASP-43 in the constellation Sextans. The planet is a hot Jupiter with a mass twice that of Jupiter, but with a roughly equal radius. WASP-43b was flagged as a candidate by the SuperWASP program, before they conducted follow-ups using instruments at La Silla Observatory in Chile, which confirmed its existence and provided orbital and physical characteristics. The planet's discovery was published on April 14, 2011.

    <span class="mw-page-title-main">WASP-121b</span> Hot Jupiter exoplanet orbiting WASP-121

    WASP-121b, formally named Tylos, is an exoplanet orbiting the star WASP-121. WASP-121b is the first exoplanet found to contain water in an extrasolar planetary stratosphere. WASP-121b is in the constellation Puppis, and is about 858 light-years from Earth.

    <span class="mw-page-title-main">MASCARA</span>

    MASCARA is an exoplanet experiment by Leiden University. It has two stations, one in each hemisphere, each of which use cameras to make short exposure photographs of most of the visible sky to observe stars to a magnitude of 8.4. The Northern Hemisphere station at Roque de los Muchachos Observatory, La Palma, started observations in February 2015. The Southern Hemisphere station at La Silla Observatory, Chile, saw first light in July 2017.

    WASP-34, also named Amansinaya, is a sunlike star of spectral type G5V that has 1.01 ± 0.07 times the mass and 0.93 ± 0.12 times the diameter of the Sun. It rotates on its axis every 34 ± 15 days, indicating it is around 6.7 billion years old.

    WASP-49 is a binary star system about 636 light-years away in the constellation Lepus. The two stars are separated by 443 AU. The primary is a G-type main-sequence star, with a surface temperature of 5,600 K. WASP-49 is depleted of heavy elements relative to the Sun. It has a metallicity Fe/H index of –0.23, meaning it has 59% the iron level of the Sun.

    WASP-189 b is an extrasolar planet that has an orbital period around its host star, WASP-189, of less than three earth days, and is about 322 light-years away in the Libra constellation. It was first discovered in 2018, and was observed in 2020 by CHEOPS.

    WASP-69, also named Wouri, is a K-type main-sequence star 164 light-years away. Its surface temperature is 4782±15 K. WASP-69 is slightly enriched in heavy elements compared to the Sun, with a metallicity Fe/H index of 0.10±0.01, and is much younger than the Sun at 2 billion years. The data regarding starspot activity of WASP-69 are inconclusive, but spot coverage of the photosphere may be very high.

    KELT-1 is a F-type main-sequence star. Its surface temperature is 6518±50 K. It is similar to the Sun in its concentration of heavy elements, with a metallicity Fe/H index of 0.008±0.073, but is much younger at an age of 1.75±0.25 billion years. The star is rotating very rapidly.

    <span class="mw-page-title-main">KELT-6b</span> Exoplanet orbiting KELT-6

    KELT-6b is an exoplanet orbiting the F-type subgiant KELT-6 approximately 791 light years away in the northern constellation Coma Berenices. It was discovered in 2013 using the transit method, and was announced in 2014.

    <span class="mw-page-title-main">KELT-20b</span> Exoplanet orbiting KELT-20

    KELT-20b, also known as MASCARA-2b, was an exoplanet announced in 2017. It is an Ultra-hot Jupiter orbiting an A-type star. The carbon monoxide, steam and neutral iron detection in the atmosphere of KELT-20b was announced in 2022.

    KELT-20, also known as MASCARA-2, is an A2 main sequence star in the constellation of Cygnus, about 447 light years away.

    WASP-178b, also known as KELT-26b and HD 134004 b, is an ultra-hot Jupiter exoplanet discovered in 2019 orbiting WASP-178, a hot A-type star located about 1,350 light-years away in the constellation of Lupus. At over 1.8 times the radius of Jupiter, it is among the largest exoplanets. The planet is tidally locked, heating up one side of the planet to such a degree that silicate rock and metal evaporate. Supersonic winds blow constantly towards the dark, cooler nighttime side, where the vaporized minerals condense and fall as rain.

    <span class="mw-page-title-main">WASP-178</span>

    WASP-178, also known as KELT-26 and HD 134004, is a star located about 1,350 light-years away in the southern constellation of Lupus. It is a hot A-type main sequence star or subgiant, a likely Am star, and a possible Delta Scuti variable, about twice as massive as the Sun and twenty times as luminous. In late 2019, the star was discovered to be orbited by an ultra-hot Jupiter planet, WASP-178b, making it one of the hottest stars known to host a hot Jupiter.

    References

    1. 1 2 3 4 5 6 7 Gaudi, B. Scott; et al. (5 June 2017). "A giant planet undergoing extreme-ultraviolet irradiation by its hot massive-star host" (pdf). Nature. 546 (7659): 514–518. arXiv: 1706.06723 . Bibcode:2017Natur.546..514G. doi:10.1038/nature22392. ISSN   1476-4687. PMID   28582774. S2CID   205256410 . Retrieved 2017-06-06.
    2. ↑ Asnodkar, Anusha Pai; et al. (4 January 2022). "KELT-9 as an Eclipsing Double-lined Spectroscopic Binary: A Unique and Self-consistent Solution to the System". The Astronomical Journal. 163 (2). 40. arXiv: 2110.15275 . Bibcode:2022AJ....163...40P. doi: 10.3847/1538-3881/ac32c7 .
    3. 1 2 Jones, K.; et al. (2022), "The stable climate of KELT-9b", Astronomy & Astrophysics, 666: A118, arXiv: 2208.04818 , Bibcode:2022A&A...666A.118J, doi:10.1051/0004-6361/202243823, S2CID   251442580
    4. 1 2 3 4 Brennan, Pat; Cofield, Calia (24 January 2020). "For Hottest Planet, a Major Meltdown, Study Shows". NASA . Retrieved 24 January 2020.
    5. ↑ Collins, Karen A.; Stassun, Keivan; Gaudi, B. Scott; Beatty, Thomas G.; Zhou, George; Latham, David W.; Bieryla, Allyson; Eastman, Jason D.; Siverd, Robert; Crepp, Justin R.; Pepper, Joshua (2016). "KELT-9b: A Case Study in Dynamical Planet Ingestion by a Hot Host Star". American Astronomical Society. 47: 204.03. Bibcode:2016DDA....4720403C.
    6. ↑ Tribur, Melissa (2017-06-05). "Meet KELT-9b, the Hottest Exoplanet Ever Discovered". Eos. Retrieved 2022-10-28.
    7. ↑ Jensen, K. S. (1981). "Spectral Classification in the MK System of 167 Northern HD Stars". Astronomy and Astrophysics Supplement. 45: 455. Bibcode:1981A&AS...45..455J.
    8. 1 2 KELT-9 b Exoplanet Exploration Program 2017
    9. 1 2 3 NASA JPL, Pasadena CA (5 June 2017) Astronomers Find Planet Hotter Than Most Stars
    10. ↑ Yan, Fei; Henning, Thomas (2 July 2018). "An extended hydrogen envelope of the extremely hot giant exoplanet KELT-9b". Nature Astronomy. 2 (9): 714–718. arXiv: 1807.00869 . Bibcode:2018NatAs...2..714Y. doi:10.1038/s41550-018-0503-3. ISSN   2397-3366. S2CID   119405172 . Retrieved 18 August 2018.
    11. ↑ Wyttenbach, A.; Mollière, P.; Ehrenreich, D.; Cegla, H. M.; Bourrier, V.; Lovis, C.; Pino, L.; Allart, R.; Seidel, J. V.; Hoeijmakers, H. J.; Nielsen, L. D.; Lavie, B.; Pepe, F.; Bonfils, X.; Snellen, I. A. G. (2020). "Mass loss rate and local thermodynamic state of KELT-9 b thermosphere from the hydrogen Balmer series". Astronomy & Astrophysics. 638: A87. arXiv: 2004.13733 . Bibcode:2020A&A...638A..87W. doi:10.1051/0004-6361/201937316. S2CID   216641961.
    12. ↑ Jacobs, Bob; Désert, Jean-Michel; Pino, Lorenzo; Line, Michael R.; Bean, Jacob L.; Khorshid, Niloofar; Schlawin, Everett; Arcangeli, Jacob; Barat, Saugata; Jens Hoeijmakers, H.; Komacek, Thaddeus D.; Mansfield, Megan; Parmentier, Vivien; Thorngren, Daniel (2022), "A strong H− opacity signal in the near-infrared emission spectrum of the ultra-hot Jupiter KELT-9b", Astronomy & Astrophysics, 668: L1, arXiv: 2211.10297 , Bibcode:2022A&A...668L...1J, doi:10.1051/0004-6361/202244533, S2CID   253708097
    13. ↑ Borsa, Francesco; Fossati, Luca; Koskinen, Tommi; Young, Mitchell E.; Shulyak, Denis (2022), "High-resolution detection of neutral oxygen and non-LTE effects in the atmosphere of KELT-9b", Nature Astronomy, 6 (2): 226–231, arXiv: 2112.12059 , doi:10.1038/s41550-021-01544-4, S2CID   245385802
    14. ↑ Pino, L.; Désert, J. M.; Brogi, M.; Malavolta, L.; Wyttenbach, A.; Line, M.; Hoeijmakers, J.; Fossati, L.; Bonomo, A. S.; Nascimbeni, V.; Panwar, V.; Affer, L.; Benatti, S.; Biazzo, K.; Bignamini, A.; Borsa, F.; Carleo, I.; Claudi, R.; Cosentino, R.; Covino, E.; Damasso, M.; Desidera, S.; Giacobbe, P.; Harutyunyan, A.; Lanza, A. F.; Leto, G.; Maggio, A.; Maldonado, J.; Mancini, L.; et al. (2020). "Neutral Iron Emission Lines from the Day-side of KELT-9b -- the GAPS Programme with HARPS-N at TNG XX". The Astrophysical Journal. 894 (2): L27. arXiv: 2004.11335 . Bibcode:2020ApJ...894L..27P. doi: 10.3847/2041-8213/ab8c44 . S2CID   216080480.
    15. ↑ Hoeijmakers, H. Jens; Ehrenreich, David; Heng, Kevin; Kitzmann, Daniel; Grimm, Simon L.; Allart, Romain; Deitrick, Russell; Wyttenbach, Aurélien; Oreshenko, Maria; Pino, Lorenzo; Rimmer, Paul B.; Molinari, Emilio; Di Fabrizio, Luca (15 August 2018). "Atomic iron and titanium in the atmosphere of the exoplanet KELT-9b". Nature. 560 (7719): 453–455. arXiv: 1808.05653 . Bibcode:2018Natur.560..453H. doi:10.1038/s41586-018-0401-y. ISSN   1476-4687. PMC   6322651 . PMID   30111838.
    16. ↑ Changeat, Quentin; Edwards, Billy (2021), "The Hubble WFC3 Emission Spectrum of the Extremely Hot Jupiter KELT-9b", The Astrophysical Journal Letters, 907 (1): L22, arXiv: 2101.00469 , Bibcode:2021ApJ...907L..22C, doi: 10.3847/2041-8213/abd84f , S2CID   230435556
    17. ↑ Kasper, David; Bean, Jacob L.; Line, Michael R.; Seifahrt, Andreas; Stürmer, Julian; Pino, Lorenzo; Désert, Jean-Michel; Brogi, Matteo (2021), "Confirmation of Iron Emission Lines and Nondetection of TiO on the Dayside of KELT-9b with MAROON-X", The Astrophysical Journal Letters, 921 (1): L18, arXiv: 2108.08389 , Bibcode:2021ApJ...921L..18K, doi: 10.3847/2041-8213/ac30e1 , S2CID   239024467
    18. ↑ Fossati, L.; Shulyak, D.; Sreejith, A. G.; Koskinen, T.; Young, M. E.; Cubillos, P. E.; Lara, L. M.; France, K.; Rengel, M.; Cauley, P. W.; Turner, J. D.; Wyttenbach, A.; Yan, F. (2020), "A data-driven approach to constraining the atmospheric temperature structure of the ultra-hot Jupiter KELT-9b", Astronomy & Astrophysics, 643: A131, arXiv: 2010.00997 , Bibcode:2020A&A...643A.131F, doi:10.1051/0004-6361/202039061, S2CID   225127226
    This page is based on this Wikipedia article
    Text is available under the CC BY-SA 4.0 license; additional terms may apply.
    Images, videos and audio are available under their respective licenses.