Astronomy:KELT-18b

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Short description: Giant exoplanet in the constellation Ursa Major
KELT-18b
Discovery[1]
Discovery siteWiner Observatory in Sonoita, Arizona Arizona (KELTNorth)
Discovery dateFebruary 6, 2017
Transit
Orbital characteristics
0.0455 ± 0.00069 AU (6,807,000 ± 103,000 km)[1]
Eccentricity0[1]
Orbital period2.87±0.00 d[2]
Inclination82.90°+0.62°
−0.54°
[2]
astron|astron|helion}}2,457,542.53±0.00 JD[2]
Semi-amplitude127±11 m/s[1]
StarKELT-18
Physical characteristics
Mean radius1.57±0.04 RJ[1]
Mass1.18±0.11 Jupiter mass[1]
Mean density380 ± 40 kg/m3 (641 ± 67 lb/cu yd)[1]
Physics2,085+39
−38
 K
[1]


KELT-18b is a hot Jupiter orbiting the F-type main sequence star KELT-18 approximately 1,058 light years away in the northern circumpolar constellation Ursa Major.[3] The planet was discovered using the transit method, and was announced in June 2017.

Discovery

KELT-18b was discovered in 2017 by scientists using the KELTNorth telescope at the Winer Observatory. The paper states that this planet is the most "inflated" of its type due to its low mass, density, and high radius.

Properties

KELT-18b has 1.18 times Jupiter's mass, and is 57% larger than Jupiter. Despite the high mass, its density is lower than Saturn's, and has a high equilibrium temperature of 2,085 K due to orbiting close to a hot star. The planet orbits at a distance 10 times closer than Mercury's in almost 3 days.

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 McLeod, Kim K.; Rodriguez, Joseph E.; Oelkers, Ryan J.; Collins, Karen A.; Bieryla, Allyson; Fulton, Benjamin J.; Stassun, Keivan G.; Gaudi, B. Scott et al. (1 June 2017). "KELT-18b: Puffy Planet, Hot Host, Probably Perturbed". The Astronomical Journal 153 (6): 263. doi:10.3847/1538-3881/aa6d5d. ISSN 0004-6256. Bibcode2017AJ....153..263M. 
  2. 2.0 2.1 2.2 Maciejewski, G. (1 September 2020). "Search for Planets in Hot Jupiter Systems with Multi-Sector TESS Photometry. I. No Companions in Planetary Systems KELT-18, KELT-23, KELT-24, Qatar-8, WASP-62, WASP-100, WASP-119, and WASP-126". Acta Astronomica 70 (3): 181–202. doi:10.32023/0001-5237/70.3.2. ISSN 0001-5237. Bibcode2020AcA....70..181M. https://ui.adsabs.harvard.edu/abs/2020AcA....70..181M/abstract. 
  3. Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.