Delta Horologii

Delta Horologii (δ Horologii) is a binary star^[3] system in the constellation Horologium. It is visible to the naked eye with a combined apparent visual magnitude of 4.93.^[2] As of 2014, the pair had an angular separation of 0.20 arc seconds along a position angle of 24°.^[9] Based upon an annual parallax shift of 18.24 mas as seen from Earth,^[1] it is located 179 ± 4 light years from the Sun.

Delta Horologii

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Horologium
Right ascension	04h 10m 50.58927s[1]
Declination	−41° 59′ 36.8537″[1]
Apparent magnitude (V)	4.93[2] (5.15 + 7.29)[3]
Characteristics
Spectral type	A9 V[3]
U−B color index	+0.084[2]
B−V color index	+0.338[2]
Astrometry
Radial velocity (Rv)	+38.3±2.6[4] km/s
Proper motion (μ)	RA: +199.08[1] mas/yr Dec.: +70.18[1] mas/yr
Parallax (π)	18.24±0.41 mas[1]
Distance	179 ± 4 ly (55 ± 1 pc)
Absolute magnitude (MV)	1.50[5]
Details
δ Hor A
Mass	1.41[6] M☉
Surface gravity (log g)	3.71±0.14[6] cgs
Temperature	7,033±239[6] K
Metallicity [Fe/H]	−0.32[7] dex
Rotational velocity (v sin i)	220.1±11.0[5] km/s
Age	768[6] Myr
δ Hor B
Rotational velocity (v sin i)	51.7±2.6[5] km/s
Other designations
δ Hor, CD−42°1400, HD 26612, HIP 19515, HR 1302, SAO 216682, WDS J04108-4200AB[8]
Database references
SIMBAD	data

The primary, component A, is a magnitude 5.15 A-type main sequence star with a stellar classification of A9 V.^[3] At the estimated age of 768 million years,^[6] it is spinning rapidly with a projected rotational velocity of 220 km/s,^[5] giving the star an oblate shape with an equatorial bulge that is 15% larger than the polar radius.^[10] The star has 1.4^[6] times the mass of the Sun.

The secondary has an apparent magnitude of 7.29.^[3]