4 Vulpeculae

4 Vulpeculae is a single,^[8] orange-hued star in the northern constellation of Vulpecula. It forms part of the asterism, formerly thought to be an open cluster, called the coathanger or Brocchi's Cluster.^[9][10] The star is faintly visible to the naked eye with an apparent visual magnitude of 5.16.^[2] The distance to this star, based upon an annual parallax shift of 12.5320±0.1008 mas,^[1] is around 260 light years.

4 Vulpeculae

Observation data Epoch J2000      Equinox J2000
Constellation	Vulpecula
Right ascension	19h 25m 28.6030389750s[1]
Declination	+19° 47′ 54.059820728″[1]
Apparent magnitude (V)	5.16[2]
Characteristics
Evolutionary stage	red clump[3]
Spectral type	K0 III[2]
B−V color index	+0.980[2]
Astrometry
Radial velocity (Rv)	+0.95 ± 0.12[1] km/s
Proper motion (μ)	RA: +87.392 ± 0.137[1] mas/yr Dec.: -73.038 ± 0.152[1] mas/yr
Parallax (π)	12.5320±0.1008 mas[1]
Distance	260 ± 2 ly (79.8 ± 0.6 pc)
Absolute magnitude (MV)	+0.54[4]
Details
Mass	1.72[2] M☉
Radius	11.42[1] R☉
Luminosity	67.6[2] L☉
Surface gravity (log g)	3.01[5] cgs
Temperature	4,763±26[2] K
Metallicity [Fe/H]	−0.20[5] dex
Rotational velocity (v sin i)	2.9[6] km/s
Age	2.63[2] Gyr
Other designations
4 Vul, BD+19°4010, Gaia DR2 4515855716012824704, HD 182762, HIP 95498, HR 7385, SAO 104818, WDS J19255+1948A[7]
Database references
SIMBAD	data

At the age of about 2.6 billion years old,^[2] this is an aging giant star with a stellar classification of K0 III,^[2] having exhausted the supply of hydrogen at its core and evolved off the main sequence. It is now a red clump giant, indicating that it is on the horizontal branch and is generating energy through the fusion of helium at its core.^[3] The star has an estimated 1.72^[2] times the mass of the Sun and has expanded to 11.42^[1] times the Sun's radius. It is radiating 67.6^[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,763 K.^[2]