HD 32518

HD 32518 (HR 1636) is a solitary star in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 6.42,[2] placing it near the max naked eye visibility. Located about 400 light years away,[1] it is receding with a heliocentric radial velocity of −7.02 km/s.[6]

HD 32518 / Mago
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Camelopardalis
Right ascension 05h 09m 36.7201s[1]
Declination +69° 38′ 21.8551″[1]
Apparent magnitude (V) 6.42±0.01[2]
Characteristics
Evolutionary stage Horizontal branch[3]
Spectral type K1 III[4]
U−B color index +1.03[5]
B−V color index +1.11[5]
Astrometry
Radial velocity (Rv)–7.02±0.35[6] km/s
Proper motion (μ) RA: +61.133[1] mas/yr
Dec.: −62.406[1] mas/yr
Parallax (π)8.1601 ± 0.0204 mas[1]
Distance399.7 ± 1.0 ly
(122.5 ± 0.3 pc)
Absolute magnitude (MV)+1.04[7]
Details
Mass1.2 ± 0.1[8] M☉
Radius10.8 ± 0.3[8] R☉
Luminosity46.4 ± 0.9[8] L☉
Surface gravity (log g)2.48[3] cgs
Temperature4,731[3] K
Metallicity [Fe/H]+0.04[3] dex
Rotational velocity (v sin i)1.2±2[9] km/s
Age6.4 ± 1.5[8] Gyr
Other designations
Mago, AG+69°241, BD+69°302, GC 6245, HD 32518, HIP 24003, HR 1636, SAO 13382
Database references
SIMBADdata
Exoplanet Archivedata
Extrasolar Planets
Encyclopaedia		data

HD 32518 has a stellar classification of K1 III,[4] indicating that it is an orange giant star. Located in the cool end in the red clump, the object is currently on the horizontal branch.[3] At present it has 1.2 the mass of the Sun[8] but has expanded to a radius of 10.8 R☉.[8] It shines at 46.4 times the luminosity of the Sun[8] from its enlarged photosphere at an effective temperature of 4,731 K,[3] giving it an yellowish orange glow. HD 32518 is older than the Sun with an age of 6.4 billion years[8] and spins slowly with a projected rotational velocity of 1.2 km/s−1.[9] However, this amount is poorly constrained. As for its metallicity, studies place it around solar level.[3]

Planetary System

In August 2009, a group of astrometers discovered a gas giant orbiting the giant star using doppler spectroscopy.[10]

For the 100th anniversary of the IAU HD 32518 and the planet HD 32518b were selected NameExoWorlds campaigns for Germany. The approved name of the star HD 32518 is Mago, named after Mago National Park in Ethiopia, which is noted for its giraffes. The name was suggested by pupils of a physics course at the Max-Born-Gymnasium in Neckargemünd.[11][12][13]

The HD 32518 planetary system[10]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b (Neri) ≥3.04 ± 0.69 MJ 0.59 ± 0.03 157.54 ± 0.38 0.01 ± 0.03 — —

See also

References
  1. 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.
  2. Oja, T. (August 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89: 415. Bibcode:1991A&AS...89..415O. ISSN 0365-0138.
  3. Ting, Yuan-Sen; Hawkins, Keith; Rix, Hans-Walter (3 May 2018). "A Large and Pristine Sample of Standard Candles across the Milky Way: ~100,000 Red Clump Stars with 3% Contamination". The Astrophysical Journal. 858 (1): L7. arXiv:1803.06650. Bibcode:2018ApJ...858L...7T. doi:10.3847/2041-8213/aabf8e. ISSN 0004-637X.
  4. Halliday, Ian (September 1955). "Luminosity Function and Space Motions of G8-K1 Stars Derived from Spectroscopic Parallaxes". The Astrophysical Journal. 122: 222. Bibcode:1955ApJ...122..222H. doi:10.1086/146080. ISSN 0004-637X.
  5. Oja, T. (April 1983). "UVB photometry of FK4 and FK4 Supplement stars". Astronomy and Astrophysics Supplement Series. 52: 131–134. Bibcode:1983A&AS...52..131O. ISSN 0365-0138.
  6. Famaey, B.; Jorissen, A.; Luri, X.; Mayor, M.; Udry, S.; Dejonghe, H.; Turon, C. (January 2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data: Revisiting the concept of superclusters". Astronomy & Astrophysics. 430 (1): 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272. ISSN 0004-6361.
  7. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 255204555.
  8. Bonfanti, A.; et al. (2015). "Revising the ages of planet-hosting stars". Astronomy and Astrophysics. 575. A18. arXiv:1411.4302. Bibcode:2015A&A...575A..18B. doi:10.1051/0004-6361/201424951. S2CID 54555839.
  9. de Medeiros, J. R.; Mayor, M. (November 1999). "A catalog of rotational and radial velocities for evolved stars". Astronomy and Astrophysics Supplement Series. 139 (3): 433–460. Bibcode:1999A&AS..139..433D. doi:10.1051/aas:1999401. ISSN 0365-0138.
  10. Döllinger, M.; et al. (2009). "Planetary companions around the K giant stars 11 Ursae Minoris and HD 32518". Astronomy and Astrophysics. 505 (3): 1311–1317. arXiv:0908.1753. Bibcode:2009A&A...505.1311D. doi:10.1051/0004-6361/200911702. S2CID 9686080.
  11. "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  12. "Approved names". NameExoworlds. Retrieved 2020-01-02.
  13. "Abstimmung über Exoplaneten-Namen: Planet Neri umkreist Stern Mago". www.haus-der-astronomie.de. Retrieved 2020-01-02.
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