Zeta Delphini

Zeta Delphini (ζ Delphini) is a star in the constellation of Delphinus. With an apparent magnitude of about 4.6,^[2] it is faintly visible to the naked eye. Parallax measurements of the system made by the Hipparcos spacecraft put it at a distance of about 220 light-years, or 67 parsecs.^[1]

ζ Delphini

Location of ζ Delphini (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Delphinus
Right ascension	20h 35m 18.53563s[1]
Declination	+14° 40′ 27.1675″[1]
Apparent magnitude (V)	+4.647[2]
Characteristics
Spectral type	A3Va / L5[3]
U−B color index	+0.14[4]
B−V color index	+0.105[4]
Astrometry
Radial velocity (Rv)	−25 ± 2[5] km/s
Proper motion (μ)	RA: 45.52[1] mas/yr Dec.: 11.74[1] mas/yr
Parallax (π)	14.82 ± 0.23 mas[1]
Distance	220 ± 3 ly (67 ± 1 pc)
Absolute bolometric magnitude (Mbol)	0.523 / 14.59[3]
Details[3]
ζ Del A
Mass	2.5 ± 0.2 M☉
Luminosity	48.63 ± 1.66 L☉
Surface gravity (log g)	3.72 cgs
Temperature	8336 K
Metallicity [Fe/H]	−0.05 dex
Age	525 ± 125 Myr
ζ Del B
Mass	55 ± 10 MJup
Luminosity	0.00012 ± 0.00001 L☉
Surface gravity (log g)	5.0+0.5 −1.0 cgs
Temperature	1550+250 −100 K
Age	525 ± 125 Myr
Other designations
4 Delphini, BD+14°4353, HD 196180, HIP 101589, HR 7871, SAO 106274[6]
Database references
SIMBAD	ζ Del
	ζ Del B

Zeta Delphini has a spectral type of A3V, implying it is an A-type main-sequence star.^[3] These types of stars are bluish-white colored, and have effective temperatures between 7100 and 11500 K:^[7] Zeta Delphini has a temperature of 8336 K.^[3] Its age is estimated to be around 500 million years, considerably younger than the Sun.^[3]

In 2014, the discovery of a brown dwarf around Zeta Delphini was announced. Zeta Delphini B is a brown dwarf with a spectral type of L5 (but may be from L3 to L7), and has a mass of about 55 Jupiters. At over 13 arcseconds away, this brown dwarf is separated at least 910 AU from Zeta Delphini.^[3]

References

1. van Leeuwen, F.; et al. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
2. Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H.
3. De Rosa, R. J.; Patience, J.; Ward-Duong, K.; Vigan, A.; Marois, C.; Song, I.; MacIntosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Lai, O.; McCarthy, D. W.; Kulesa, C. (2014). "The VAST Survey - IV. A wide brown dwarf companion to the A3V star ζ Delphini". Monthly Notices of the Royal Astronomical Society. 445 (4): 3694. arXiv:1410.0005. Bibcode:2014MNRAS.445.3694D. doi:10.1093/mnras/stu2018. S2CID 34066734.
4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
5. Wilson, Ralph Elmer (1953). "General catalogue of stellar radial velocities". Washington. Bibcode:1953GCRV..C......0W.
6. "zet+Del". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 5 March 2017.
7. Adelman, Saul J. (2004). "The physical properties of normal A stars". Proceedings of the International Astronomical Union. 2004: 1–11. Bibcode:2004IAUS..224....1A. doi:10.1017/S1743921304004314.

External links

• Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789.