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 Gaia spacecraft put it at a distance of about 218 light-years (67 parsecs).^[1]

ζ Delphini

Location of ζ Delphini (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Delphinus
Right ascension	20h 35m 18.53621s[1]
Declination	+14° 40′ 27.1739″[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)	−27.68±0.37[1] km/s
Proper motion (μ)	RA: 45.504 mas/yr[1] Dec.: 11.510 mas/yr[1]
Parallax (π)	14.9441±0.1284 mas[1]
Distance	218 ± 2 ly (66.9 ± 0.6 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)	3.60±0.12[5] cgs
Temperature	8236±124[5] K
Metallicity [Fe/H]	−0.05 dex
Rotational velocity (v sin i)	108.0±3.6[5] km/s
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
ζ Del, 4 Del, 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]

A 2021 study identified Zeta Delphini as a Lambda Boötis star, a type of star with peculiar chemical abundances. It is the first known Lambda Boötis star orbited by a brown dwarf.^[5]