HD 85945

HD 85945 (HR 3922) is a star in the constellation Ursa Major. It is a yellow giant star with a spectral type of G6III:Fe-0.5. Based on information from Gaia DR3, it is located 132.54 parsecs (432.3 ly) from Earth and is moving towards Earth at a velocity of 47 km/s. It has an apparent magnitude of 5.96, which makes it faintly visible to the naked eye.

HD 85945

Observation data Epoch J2000      Equinox J2000
Constellation	Ursa Major[1]
Right ascension	09h 57m 13.61s[2]
Declination	+57° 25′ 05.54″[2]
Apparent magnitude (V)	5.959±0.009[2]
Characteristics
Evolutionary stage	Horizontal branch[3]
Spectral type	G6III:Fe-0.5[2]
Apparent magnitude (B)	6.854±0.015[2]
Apparent magnitude (G)	5.733[2]
Apparent magnitude (J)	4.513±0.028[2]
Apparent magnitude (H)	4.141±0.036[2]
Apparent magnitude (K)	3.978±0.3[2]
B−V color index	0.895[4]
Astrometry
Radial velocity (Rv)	−46.55±0.12[5] km/s
Proper motion (μ)	RA: 31.347 mas/yr[5] Dec.: -61.766 mas/yr[5]
Parallax (π)	7.4137±0.024 mas[5]
Distance	432.08 ly (132.54 pc)[5]
Absolute magnitude (MV)	0.16[1]
Details
Mass	2.5[3] M☉
Radius	10.28±0.14[6] R☉
Luminosity	77.62[7][a] L☉
Surface gravity (log g)	2.6866[5] cgs
Temperature	5281±22[6] K
Metallicity [Fe/H]	–0.4[7] dex
Rotational velocity (v sin i)	7.53[4] km/s
Age	660.7[3][b] Myr
Other designations
BD+58 1224, Gaia DR2 1046383298937140864, Gaia DR3 1046383298937140864, HIP 48802, HR 3922, PPM 32387, TIC 377368616, TYC 3817-1649-1, GSC 03817-01649, IRAS 09537+5739
Database references
SIMBAD	data

Characteristics

It is an evolved G-type giant star, based on its spectral type of G6III:Fe-0.5, which also indicates that it has a [Fe/H] metallicity of -0.5.^[2] HD 85945 is 2.5 times more massive than the Sun and has expanded to 10.28 times the Sun's size.^[3][6] It is emitting 78 times the solar luminosity from its photosphere at an effective temperature of 5,281 K.^[7][6] Currently, the star is located in the horizontal branch stage of evolution.^[3] The age of HD 85945 is estimated at 660 million years,^[3] and it rotates under its axis at a speed of 7.53 km/s.^[4] It is slightly metal-poor compared to the Sun, with an abundance of iron equivalent to 40% of the solar abundance.^[7][c]

HD 85945 is located within the Ursa Major constellation. The distance to HD 85945 is of 132.54 parsecs (432.3 ly), based on spectra from Gaia DR3.^[5] The apparent magnitude of the star is of 5.96,^[2] which is brighter than the limiting magnitude for naked-eye vision (6.5^m), making it faintly visible to the naked eye.^[8] The absolute magnitude, i.e. the brightness of the star if it was seen at a distance of 10 parsecs (32.6 ly), is 0.32.^[9] At the current distance, its brightness is diminished by 0.03 magnitudes due to interstellar extinction between Earth and the star.^[6] HD 85945 is moving away from Earth at a velocity of 46.55 km/s.^[5] It has a high proper motion in the sky.^[6][2]

Notes

1. From a logarithm of 1.62.
2. from a logarithm of 8.82.
3. From a logarithm of -0.4