KELT-18b

Last updated
KELT-18b
Discovery [1]
Discovery site Winer Observatory in Sonoita, Arizona Flag of Arizona.svg (KELTNorth)
Discovery dateFebruary 6, 2017
Transit
Orbital characteristics
0.0455 ± 0.00069 AU (6,807,000 ± 103,000 km) [1]
Eccentricity 0 [1]
2.87±0.00  d [2]
Inclination 82.90° +0.62°
−0.54°
[2]
2,457,542.53±0.00  JD [2]
Semi-amplitude 127±11  m/s [1]
Star KELT-18
Physical characteristics
Mean radius
1.57±0.04  RJ [1]
Mass 1.18±0.11  MJ [1]
Mean density
380 ± 40  kg/m3 (641 ± 67  lb/cu yd) [1]
Temperature 2,085+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.

    Contents

    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.

    Related Research Articles

    WASP-18 is a magnitude 9 star located in the Phoenix constellation of the southern hemisphere. It has a mass of 1.25 solar masses.

    WASP-43 is a K-type star in the Sextans constellation. It is about half the size of the Sun, and has approximately half the mass. WASP-43 has one known planet in orbit, a Hot Jupiter called WASP-43b. At the time of publishing of WASP-43b's discovery on April 15, 2011, the planet was the most closely orbiting Hot Jupiter discovered. The small orbit of WASP-43b is thought to be caused by WASP-43's unusually low mass. WASP-43 was first observed between January and May 2009 by the SuperWASP project, and was found to be cooler and slightly richer in metals than the Sun. WASP-43 has also been found to be an active star that rotates at a high velocity.

    WASP-44 is a G-type star in the constellation Cetus that is orbited by the Jupiter-size planet WASP-44b. The star is slightly less massive and slightly smaller than the Sun; it is also slightly cooler, but is more metal-rich. The star was observed by SuperWASP, an organization searching for exoplanets, starting in 2009; manual follow-up observations used WASP-44's spectrum and measurements of its radial velocity led to the discovery of the transiting planet WASP-44b. The planet and its star were presented along with WASP-45b and WASP-46b on May 17, 2011 by a team of scientists testing the idea that hot Jupiters tend to have circular orbits, an assumption that is made when the orbital eccentricity of such planets are not well-constrained.

    Kepler-41 or KOI-196 is a star in the constellation Cygnus. It is a G-type main-sequence star, like the Sun, and it is located about 3,68 light-years away. It is fairly similar to the Sun, with 115% of its mass, a radius of 129% times that of the Sun, and a surface temperature of 5,750 K. Search for stellar companions to Kepler-41 in 2013-2014 has yielded inconclusive results, compatible with Kepler-41 being the single star.

    WASP-47 is a star similar in size and brightness to the Sun about 870 light-years away in the constellation Aquarius. It lies within the Kepler K2 campaign field 3. It was first noticed to have a hot Jupiter exoplanet orbiting every 4 days in 2012 by the Wide Angle Search for Planets (WASP) team. While it was thought to be a typical hot Jupiter system, three more planets were found in 2015: an outer gas giant within the habitable zone, a hot Neptune exterior to the hot Jupiter's orbit and a super-Earth interior to the hot Jupiter's orbit. WASP-47 is the only planetary system known to have both planets near the hot Jupiter and another planet much further out.

    HD 146389, is a star with a yellow-white hue in the northern constellation of Hercules. The star was given the formal name Irena by the International Astronomical Union in January 2020. It is invisible to the naked eye with an apparent visual magnitude of 9.4 The star is located at a distance of approximately 446 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −9 km/s. The star is known to host one exoplanet, designated WASP-38b or formally named 'Iztok'.

    HAT-P-23 is a G-type main-sequence star about 1200 light-years away. It has a rapid rotation for its advanced age of 4 billion years, and exhibits a strong starspot activity. The star may be in the process of being spun up by the giant planet on close orbit. The star is enriched in heavy elements, having about 140% amount of metals compared to solar abundance.

    HD 233731, or HAT-P-22, is a suspected multiple star system in the northern circumpolar constellation of Ursa Major. It is invisible to the naked eye, having an apparent visual magnitude of 9.732. This system is located at a distance of 267 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +13 km/s.

    Qatar-2 is a K-type main-sequence star about 595 light-years away. The star is much older than Sun, and has a concentration of heavy elements similar to solar abundance. The star features a numerous and long-lived starspots, and belongs to a peculiar variety of inflated K-dwarfs with strong magnetic activity inhibiting internal convection.

    BD-07 436, also known as WASP-77 since 2012, is a binary star system about 344 light-years away. The star's components appears to have a different age, with the secondary older than 9 billion years, while the primary's age is 5 billion years. The BD-07 436 system's concentration of heavy elements is similar to the Sun. Its stars display moderate chromospheric activity, including x-ray flares.

    WASP-61 is a single F-type main-sequence star about 1560 light-years away. The star age is much likely younger than the Sun's at approximately 3.8+1.8
    −0.9
    billion years. WASP-61 is depleted in heavy elements, having just 40% of the solar abundance of iron.

    WASP-57 is a single G-type main-sequence star about 1310 light-years away. WASP-57 is depleted in heavy elements, having 55% of the solar abundance of iron. WASP-57 is much younger than the Sun at 0.957±0.518 billion years.

    WASP-54, also known as BD+00 3088, is a binary star system about 825 light-years away. The primary, WASP-54A, is a F-type main-sequence star, accompanied by the red dwarf WASP-54B on a wide orbit. WASP-54 is depleted in heavy elements, having 55% of the solar abundance of iron. The age of WASP-54 is slightly older than the Sun's at 6.9+1.0
    −1.9
    billion years.

    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.

    Qatar-3 is a faint 12th magnitude star located in the northern constellation Andromeda. It is host to a transiting planet. With a radial velocity of 10.99 km/s, it is currently drifting away from the Solar System, and is currently located 2,400 light years away based on parallax.

    <span class="mw-page-title-main">KELT-3b</span> Exoplanet orbiting KELT-3

    KELT-3b is an extrasolar planet orbiting the F-type main-sequence star KELT-3 690 light years in the zodiac constellation Leo. It was discovered in 2013 by KELT's telescope in Arizona.

    Qatar-8 is a faint solar analog located in the northern circumpolar constellation Ursa Major. With an apparent magnitude of 11.71, it is impossible to detect with the naked eye, but can be located with a powerful telescope. Qatar-8 is currently 924 light-years away from the Solar System, but is drifting further away, with a radial velocity of 5.06 km/s.

    KELT-6, also known as BD+31 2447, is a star in the constellation Coma Berenices. With an apparent magnitude of 10.34, it is impossible to see with the unaided eye, but can be seen with a powerful telescope. The star is located 791 light years away from the Solar System based on parallax, but is drifting away with a radial velocity of 1.62 km/s.

    <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.

    CD−34°8618, also known as KELT-13 or WASP-167, is a yellowish-white hued star located in the southern constellation of Centaurus. It has an apparent magnitude of 10.52, making it readily visible in medium sized telescopes, but not to the naked eye. Based on parallax measurements from the Gaia spacecraft, the object is estimated to be approximately 1,350 light years away from the Solar System. It appears to be drifting closer to it, having a radial velocity of −0.53 km/s.

    References

    1. 1 2 3 4 5 6 7 8 McLeod, Kim K.; Rodriguez, Joseph E.; Oelkers, Ryan J.; Collins, Karen A.; Bieryla, Allyson; Fulton, Benjamin J.; Stassun, Keivan G.; Gaudi, B. Scott; Penev, Kaloyan; Stevens, Daniel J.; et al. (1 June 2017). "KELT-18b: Puffy Planet, Hot Host, Probably Perturbed". The Astronomical Journal. 153 (6): 263. arXiv: 1702.01657 . Bibcode:2017AJ....153..263M. doi:10.3847/1538-3881/aa6d5d. ISSN   0004-6256. S2CID   54667386.
    2. 1 2 3 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. arXiv: 2010.11977 . Bibcode:2020AcA....70..181M. doi:10.32023/0001-5237/70.3.2. ISSN   0001-5237. S2CID   225061977.
    3. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics . 616. A1. arXiv: 1804.09365 . Bibcode: 2018A&A...616A...1G . doi: 10.1051/0004-6361/201833051 . Gaia DR2 record for this source at VizieR.