18 Delphini

Star in the constellation Delphinus 18 Delphini / Musica Delphinus constellation map.svg center 280 right Red circle.svg 10 18 Delphini 168 550 Location of 18 Delphini (circled in red) J2000 Delphinus 20 58 25.93353 +10 50 21.4309 5.506 red clump G6III 0.934 0.004 +4.17 0.12 −49.921 −34.509 13.3021 0.0652 1.15 2.35 0.07 7.19 0.38 5071 10 commas 33.9 6.9 5.7 3.00 0.04 0.10 0.02 690 50 1.60 0.45 Musica 18 Del +10°4425 199665 103527 8030 29266 106712 J20584+1050A *+18+Del A *+18+Del+B B 18 Del 18 Delphini, also named Musica ' m juː z I k @,musica is a binary star in the constellation of Delphinus of the low northern hemisphere. The primary has a Sun-like golden hue and is faintly visible to the naked eye with an apparent visual magnitude of 5.506. It has a red dwarf companion at a wide separation. The star is located at a distance of approximately 245 light-years from the Sun based on parallax, and it is drifting further away with a radial velocity of +4 km/s. An object believed to be an extrasolar planet (designated 18 Delphini b or Arion) orbits the primary star. Nomenclature 18 Delphini is the star's Flamsteed designation, abbreviated 18 Del. Following its discovery the planet was designated 18 Delphini b. As part of the NameExoWorlds program by the International Astronomical Union, in 2015 the name Musica, Latin for 'music', was selected for this star by Tokushima Prefectural Jonan High School Science Club of Japan. The planet was given the name Arion, after a genius of poetry and music in ancient Greece. According to legend, his life was saved at sea by dolphins after attracting their attention by the playing of his kithara. The constellation 'Delphinus' is Latin for 'dolphin'. Properties The stellar classification of 18 Delphini is G6III, which means it is an evolved star that has cooled and expanded off the main sequence. It is a suspected red clump giant that is generating energy from core helium fusion. A moderate level of X-ray emission has been detected from this star, which suggests it has a mildly active chromosphere. The star is 650 million years old with more than double the mass of the Sun, and has expanded to seven times the Sun's radius. It is radiating 34 times the luminosity of the Sun from its photosphere at an effective temperature of 5,071 K. The Washington Double Star Catalogue lists a pair of visual companions for this star. Component B is magnitude 9.88 and lies at an angular separation of 197.5 arcseconds along a position angle (PA) of 162° from the brighter star as of 2003. Component C has a magnitude of 12.77 with a separation of 129.3 arcseconds as of 2000. The proper motion of both stars are diverging significantly from 18 Delphini, so they can be ruled out as physical companions. However, a faint star located 29.2 arcsecond away appears to be a co-moving companion. This has a projected separation of 2199 AU commas and a mass estimated as 19% that of the Sun. It is a small red dwarf star with a class of M4–5. Planetary system On February 19, 2008, an extrasolar planet was found to be orbiting the star with a period of 993.3 days years out off and a mild eccentricity (ovalness) of 0.08. The mass of this exoplanet is greater than 10 times the mass of Jupiter. There is a long-period radial velocity trend, which might indicate the presence of a second substellar companion. b (Arion) 9.207 0.160 0.077 ≥ 2.476 0.002 982.85 1.06 0.92 0.024 0.007 0.018 References HD 199665 2021-01-10 1756741374681702784 1 Mason B. D. Wycoff G. L. Hartkopf W. I. Douglass G. G. Worley C. E. The Washington Visual Double Star Catalog 2014 122 6 3466–3471 The Astronomical Journal 10.1086/323920 free 2001AJ....122.3466M New wide stellar companions of exoplanet host stars 1 Mugrauer M. Ginski C. Seeliger M. Monthly Notices of the Royal Astronomical Society 439 1 1063–1070 March 2014 10.1093/mnras/stu044 2014MNRAS.439.1063M free Anderson E. Francis Ch. XHIP: An extended hipparcos compilation Astronomy Letters 38 5 331 2012 2012AstL...38..331A 1108.4971 10.1134/S1063773712050015 119257644 Stellar parameters and chemical abundances of 223 evolved stars with and without planets Jofré E. Petrucci R. Saffe C. Saker L. Artur de la Villarmois E. Chavero C. Gómez M. Mauas P. J. D. 1 Astronomy & Astrophysics 574 A50 2015 10.1051/0004-6361/201424474 1410.6422 2015A&A...574A..50J 53666931 Haakonsen Christian Bernt Rutledge Robert E. XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources The Astrophysical Journal Supplement 184 1 138–151 September 2009 2009ApJS..184..138H 0910.3229 10.1088/0067-0049/184/1/138 119267456 The spectrophotometric parallaxes of 42 visual binaries Opolski A. Arkiv för Astronomi 2 55 1957 1957ArA.....2...55O Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae and HD 81688 Sato Bun'ei Izumiura Hideyuki Toyota Eri Kambe Eiji Ikoma Masahiro Omiya Masashi Masuda Seiji Takeda Yoichi Murata Daisuke Itoh Yoichi Ando Hiroyasu Yoshida Michitoshi Kokubo Eiichiro Ida Shigeru 1 Publications of the Astronomical Society of Japan 60 3 539–550 2008 0802.2590 2008PASJ...60..539S 10.1093/pasj/60.3.539 18806627 The Tycho-2 catalogue of the 2.5 million brightest stars 1 Høg E. Fabricius C. Makarov V. V. Urban S. Corbin T. Wycoff G. Bastian U. Schwekendiek P. Wicenec A. Astronomy and Astrophysics 355 L27 2000 2000A&A...355L..27H Final Results of NameExoWorlds Public Vote Released IAU https://www.iau.org/news/pressreleases/detail/iau1514/ 2021-01-10 2018-06-17 https://web.archive.org/web/20180617192937/https://www.iau.org/news/pressreleases/detail/iau1514/ dead Final Results of NameExoWorlds Public Vote Announced IAU https://www.iau.org/news/pressreleases/detail/iau1514/ 2021-01-10 2018-06-17 https://web.archive.org/web/20180617192937/https://www.iau.org/news/pressreleases/detail/iau1514/ dead Naming Stars IAU iau.org https://www.iau.org/public/themes/naming_stars/ 28 July 2016 10 March 2025 https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/ dead Ryu Tsuguru Sato Bun'ei etal July 2016 High-contrast Imaging of Intermediate-mass Giants with Long-term Radial Velocity Trends The Astrophysical Journal 825 2 127 10.3847/0004-637X/825/2/127 32753766 7402361 free 1603.02017 2016ApJ...825..127R Teng Huan-Yu Sato Bun'ei etal August 2023 Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars Publications of the Astronomical Society of Japan 75 6 1030–1071 10.1093/pasj/psad056 2308.05343 2023PASJ...75.1030T External links Notes for star 18 Del Jean Schneider 2011 http://exoplanet.eu/star.php?st=18+Del https://web.archive.org/web/20080327170206/http://exoplanet.eu/star.php?st=18+Del dead March 27, 2008 Extrasolar Planets Encyclopaedia 30 September 2011 20 58 26 + 10 50 21 238 Category:G-type giants Category:Horizontal-branch stars Category:Binary stars Category:M-type main-sequence stars Category:Planetary systems with one confirmed planet Category:Delphinus BD+10 4425 Delphini, 18 199665 103527 8030 Musica Category:Population I stars