18 Delphini
{{Short description|Star in the constellation Delphinus}}
{{Starbox begin|name=18 Delphini / Musica}}
{{Starbox observe
| epoch = J2000.0
| constell = Delphinus
| dec = {{DEC|+10|50|21.4309}}
}}
{{Starbox character
| type = red clump
| variable =
}}
{{Starbox astrometry
| radial_v = {{val|+4.17|0.12}}
| prop_mo_ra = {{val|−49.921}}
| prop_mo_dec = {{val|−34.509}}
| parallax = 13.3021
| p_error = 0.0652
}}
{{Starbox detail
| mass = {{val|2.35|0.07}}
| radius = {{val|7.19|0.38}}
| temperature = {{val|5071|10|fmt=commas}}
| luminosity = {{val|33.9|6.9|5.7}}
| gravity = {{val|3.00|0.04}}
| metal_fe = {{val|0.10|0.02}}
| age_myr = {{val|690|50}}
| rotational_velocity = {{val|1.60|0.45}}
}}
{{Starbox catalogue
| names = {{odlist | name=Musica | F=18 Del | BD=+10°4425 | HD=199665 | HIP=103527 | HR=8030 | GC=29266 | SAO=106712 | WDS=J20584+1050A }}
}}
{{Starbox reference
| Simbad = HD+199665
| NSTED = 18%20Del
}}
{{Starbox end}}
18 Delphini, also named Musica {{IPAc-en|'|m|juː|z|I|k|@}},{{OED|musica}} is a single star in the constellation of Delphinus of the low northern hemisphere. It has a Sun-like golden hue and is faintly visible to the naked eye with an apparent visual magnitude of 5.506. 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 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 {{val|197.5|ul=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 {{val|129.3|u=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 {{val|29.2|u=arcsecond}} away appears to be a co-moving companion. This has a projected separation of {{val|2199|ul=AU|fmt=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 {{convert|993.3|days|years|disp=out|abbr=off}} and a mild eccentricity (ovalness) of 0.08. The mass of this exoplanet is greater than 10 times the mass of Jupiter.
{{OrbitboxPlanet begin
}}
{{OrbitboxPlanet
| exoplanet = b (Arion)
| mass = >10.3
| semimajor = 2.6
| period = 993.3 ± 3.2
| eccentricity = 0.08 ± 0.01
}}
{{Orbitbox end}}
References
{{reflist|refs=
| title=HD 199665 | access-date=2021-01-10 }}
{{Cite Gaia DR3|1756741374681702784}}
| display-authors=1 | last1=Mason | first1=B. D.
| last2=Wycoff | first2=G. L. | last3=Hartkopf | first3=W. I.
| last4=Douglass | first4=G. G. | last5=Worley | first5=C. E.
| title=The Washington Visual Double Star Catalog
| year=2014 | volume=122 | issue=6 | pages=3466–3471
| journal=The Astronomical Journal
| doi=10.1086/323920 | doi-access=free
| bibcode=2001AJ....122.3466M }}
| title=New wide stellar companions of exoplanet host stars
| display-authors=1 | last1=Mugrauer | first1=M.
| last2=Ginski | first2=C. | last3=Seeliger | first3=M.
| journal=Monthly Notices of the Royal Astronomical Society
| volume=439 | issue=1 | pages=1063–1070 | date=March 2014
| doi=10.1093/mnras/stu044 | bibcode=2014MNRAS.439.1063M | doi-access=free }}
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| title=XHIP: An extended hipparcos compilation
| journal=Astronomy Letters
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | arxiv=1108.4971
| doi=10.1134/S1063773712050015 | s2cid=119257644 }}
| title=Stellar parameters and chemical abundances of 223 evolved stars with and without planets
| last1=Jofré | first1=E. | last2=Petrucci | first2=R.
| last3=Saffe | first3=C. | last4=Saker | first4=L.
| last5=Artur de la Villarmois | first5=E. | last6=Chavero | first6=C.
| last7=Gómez | first7=M. | last8=Mauas | first8=P. J. D.
| display-authors=1 | journal=Astronomy & Astrophysics
| volume=574 | pages=A50 | year=2015
| doi=10.1051/0004-6361/201424474 | arxiv=1410.6422
| bibcode=2015A&A...574A..50J | s2cid=53666931 }}
| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
| title=A catalogue of multiplicity among bright stellar systems
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389 | issue=2 | pages=869–879 | date=September 2008
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | arxiv=0806.2878
| bibcode=2008MNRAS.389..869E | s2cid=14878976 }}
| last1=Haakonsen | first1=Christian Bernt | last2=Rutledge | first2=Robert E.
| title=XID II: Statistical Cross-Association of ROSAT Bright Source Catalog X-ray Sources with 2MASS Point Source Catalog Near-Infrared Sources
| journal=The Astrophysical Journal Supplement
| volume=184 | issue=1 | pages=138–151 | date=September 2009
| bibcode=2009ApJS..184..138H | arxiv=0910.3229
| doi=10.1088/0067-0049/184/1/138 | s2cid=119267456 }}
| title=The spectrophotometric parallaxes of 42 visual binaries
| last=Opolski | first=A.
| journal=Arkiv för Astronomi
| volume=2 | pages=55 | year= 1957
| bibcode=1957ArA.....2...55O }}
| title=Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae and HD 81688
| last1=Sato | first1=Bun'ei | last2=Izumiura | first2=Hideyuki
| last3=Toyota | first3=Eri | last4=Kambe | first4=Eiji
| last5=Ikoma | first5=Masahiro | last6=Omiya | first6=Masashi
| last7=Masuda | first7=Seiji | last8=Takeda | first8=Yoichi
| last9=Murata | first9=Daisuke | last10=Itoh | first10=Yoichi
| last11=Ando | first11=Hiroyasu | last12=Yoshida | first12=Michitoshi
| last13=Kokubo | first13=Eiichiro | last14=Ida | first14=Shigeru
| display-authors=1 | journal=Publications of the Astronomical Society of Japan
| volume=60 | issue=3 | pages=539–550 | year=2008
| arxiv=0802.2590 | bibcode=2008PASJ...60..539S
| doi=10.1093/pasj/60.3.539| s2cid=18806627 }}
| title=The Tycho-2 catalogue of the 2.5 million brightest stars
| display-authors=1 | last1=Høg | first1=E.
| last2=Fabricius | first2=C. | last3=Makarov | first3=V. V.
| last4=Urban | first4=S. | last5=Corbin | first5=T.
| last6=Wycoff | first6=G. | last7=Bastian | first7=U.
| last8=Schwekendiek | first8=P. | last9=Wicenec | first9=A.
| journal=Astronomy and Astrophysics
| volume=355 | pages=L27 | year=2000
| bibcode=2000A&A...355L..27H }}
| title=Final Results of NameExoWorlds Public Vote Released | publisher=IAU
| url=https://www.iau.org/news/pressreleases/detail/iau1514/
| access-date=2021-01-10 }}
| title=Final Results of NameExoWorlds Public Vote Announced
| publisher=IAU
| url=https://www.iau.org/news/pressreleases/detail/iau1514/
| access-date=2021-01-10 }}
| title=Naming Stars
| publisher=IAU | website=iau.org
| url=https://www.iau.org/public/themes/naming_stars/
| accessdate=28 July 2016 }}
}}
External links
- {{cite encyclopedia | title=Notes for star 18 Del | first=Jean | last=Schneider | year=2011 | url=http://exoplanet.eu/star.php?st=18+Del | archive-url=https://web.archive.org/web/20080327170206/http://exoplanet.eu/star.php?st=18+Del | url-status=dead | archive-date=March 27, 2008 | encyclopedia=Extrasolar Planets Encyclopaedia | access-date=30 September 2011 }}
{{Sky|20|58|26|+|10|50|21|238}}
{{Stars of Delphinus}}
{{Authority control}}
{{DEFAULTSORT:18 Delphini}}
Category:Horizontal-branch stars