18 Delphini
| Observation data EpochJ2000.0EquinoxJ2000.0 | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h58m25.9336s[1] |
| Declination | +10° 50′ 21.4261″[1] |
| Apparent magnitude(V) | 5.506[2] |
| Characteristics | |
| Spectral type | G6III[3] |
| B−Vcolor index | 0.934±0.004[4] |
| Astrometry | |
| Radial velocity(Rv) | +4.35±0.15[1]km/s |
| Proper motion(μ) | RA:−50.034±0.147[1]mas/yr Dec.:−34.198±0.175[1]mas/yr |
| Parallax(π) | 13.0922 ± 0.1062mas[1] |
| Distance | 249 ± 2ly (76.4 ± 0.6pc) |
| Absolute magnitude(MV) | 1.15[5] |
| Details[6] | |
| Mass | 2.35±0.07M☉ |
| Radius | 7.19±0.38R☉ |
| Luminosity | 33.9+6.9 −5.7L☉ |
| Surface gravity(logg) | 3.00±0.04cgs |
| Temperature | 5,071±10K |
| Metallicity[Fe/H] | 0.10±0.02dex |
| Rotational velocity(vsini) | 1.60±0.45km/s |
| Age | 690±50Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
18 Delphini,also namedMusica/ˈmjuːzɪkə/,[8][9]is a single[10]starin theconstellationofDelphinusof the low northern hemisphere. It has a Sun-like golden hue and is faintly visible to the naked eye with anapparent visual magnitudeof 5.506.[2]The star is located at a distance of approximately 249light yearsfrom theSunbased onparallax,[1]and it is drifting further away with aradial velocityof +4 km/s.[1]An object believed to be anextrasolar planet(designated18 Delphini bor Arion) orbits the star.[5]
Nomenclature
[edit]18 Delphini is the star'sFlamsteed designation,abbreviated 18 Del. Following its discovery the planet was designated 18 Delphini b.[5]
As part of theNameExoWorldsprogram by theInternational Astronomical Union,in 2015 the name Musica,Latinfor 'music', was selected for this star by Tokushima Prefectural Jonan High School Science Club ofJapan.The planet was given the nameArion,[11]after a genius of poetry and music in ancient Greece. According to legend, his life was saved at sea bydolphinsafter attracting their attention by the playing of hiskithara.The constellation 'Delphinus' is Latin for 'dolphin'.[12][8]
Properties
[edit]Thestellar classificationof 18 Delphini is G6III,[3]which means it is anevolvedstar that has cooled and expanded off themain sequence.It is a suspectedred clumpgiant that is generating energy fromcorehelium fusion.[5]A moderate level ofX-ray emissionhas been detected from this star,[13]which suggests it has a mildlyactive chromosphere.[5]The star is 650 million years old with more than double themass of the Sun,and has expanded to seven times theSun's radius.It is radiating 34 times theluminosity of the Sunfrom itsphotosphereat aneffective temperatureof 5,071 K.[6]
TheWashington Double Star Cataloguelists a pair ofvisual companionsfor this star. Component B is magnitude 9.88 and lies at anangular separationof197.5arcsecondsalong aposition angle(PA) of 162° from the brighter star as of 2003. Component C has a magnitude of 12.77 with a separation of129.3 arcsecondsas of 2000.[14]Theproper motionof both stars are diverging significantly from 18 Delphini, so they can be ruled out as physical companions. However, a faint star located29.2″away appears to be a co-moving companion. This has aprojected separationof2,199AUand a mass estimated as 19% that of the Sun. It is a smallred dwarfstar with a class of M4–5.[15]
Planetary system
[edit]On February 19, 2008, anextrasolar planetwas found to be orbiting the star with a period of 2.720 years and a mild eccentricity (ovalness) of 0.08. The mass of this exoplanet is greater than 10 times themass of Jupiter.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b (Arion) | >10.3MJ | 2.6 | 993.3 ± 3.2 | 0.08 ± 0.01 | — | — |
References
[edit]- ^abcdefghBrown, A. G. A.;et al. (Gaia collaboration) (August 2018)."GaiaData 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 sourceatVizieR.
- ^abHøg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars".Astronomy and Astrophysics.355:L27.Bibcode:2000A&A...355L..27H.
- ^abOpolski, A. (1957). "The spectrophotometric parallaxes of 42 visual binaries".Arkiv för Astronomi.2:55.Bibcode:1957ArA.....2...55O.
- ^Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation".Astronomy Letters.38(5): 331.arXiv:1108.4971.Bibcode:2012AstL...38..331A.doi:10.1134/S1063773712050015.S2CID119257644.
- ^abcdefgSato, Bun'ei; et al. (2008). "Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae and HD 81688".Publications of the Astronomical Society of Japan.60(3): 539–550.arXiv:0802.2590.Bibcode:2008PASJ...60..539S.doi:10.1093/pasj/60.3.539.S2CID18806627.
- ^abJofré, E.; et al. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets".Astronomy & Astrophysics.574:A50.arXiv:1410.6422.Bibcode:2015A&A...574A..50J.doi:10.1051/0004-6361/201424474.S2CID53666931.
- ^"HD 199665".SIMBAD.Centre de données astronomiques de Strasbourg.Retrieved2021-01-10.
- ^ab"Naming Stars".iau.org.IAU.Retrieved28 July2016.
- ^"musica".Oxford English Dictionary(Online ed.).Oxford University Press.(Subscription orparticipating institution membershiprequired.)
- ^Eggleton, P. P.; Tokovinin, A. A. (September 2008)."A catalogue of multiplicity among bright stellar systems".Monthly Notices of the Royal Astronomical Society.389(2): 869–879.arXiv:0806.2878.Bibcode:2008MNRAS.389..869E.doi:10.1111/j.1365-2966.2008.13596.x.S2CID14878976.
- ^"Final Results of NameExoWorlds Public Vote Announced".IAU.Retrieved2021-01-10.
- ^"Final Results of NameExoWorlds Public Vote Released".IAU.Retrieved2021-01-10.
- ^Haakonsen, Christian Bernt; Rutledge, Robert E. (September 2009). "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.arXiv:0910.3229.Bibcode:2009ApJS..184..138H.doi:10.1088/0067-0049/184/1/138.S2CID119267456.
- ^Mason, B. D.; et al. (2014)."The Washington Visual Double Star Catalog".The Astronomical Journal.122(6): 3466–3471.Bibcode:2001AJ....122.3466M.doi:10.1086/323920.
- ^Mugrauer, M.; et al. (March 2014)."New wide stellar companions of exoplanet host stars".Monthly Notices of the Royal Astronomical Society.439(1): 1063–1070.Bibcode:2014MNRAS.439.1063M.doi:10.1093/mnras/stu044.
External links
[edit]- Schneider, Jean (2011)."Notes for star 18 Del".Extrasolar Planets Encyclopaedia.Archived fromthe originalon March 27, 2008.Retrieved30 September2011.
