HD 44120
Binary star system in the constellation Pictor
From Wikipedia, the free encyclopedia
HD 44120 is a wide binary star system in the southern constellation of Pictor. Although visible to the naked eye, it is a challenge to view having an apparent visual magnitude of 6.44.[1] The system is located at a distance of 118 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −2 km/s.[7] It has an absolute magnitude of 3.57.[1]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pictor[1] |
| A | |
| Right ascension | 06h 16m 18.786s[2] |
| Declination | −59° 12′ 48.61″[2] |
| Apparent magnitude (V) | 6.44[1] |
| B | |
| Right ascension | 06h 16m 14.257s[3] |
| Declination | −59° 12′ 27.41″[3] |
| Apparent magnitude (V) | 14.03[4] |
| Characteristics | |
| A | |
| Evolutionary stage | subgiant[2] |
| Spectral type | F9.5V[5] |
| B−V color index | 0.593±0.015[1] |
| B | |
| Evolutionary stage | white dwarf[6] |
| Spectral type | DB3.2[4] |
| Astrometry | |
| A | |
| Radial velocity (Rv) | −2.125±0.0003[7] km/s |
| Proper motion (μ) | RA: −45.187 mas/yr[2] Dec.: −316.389 mas/yr[2] |
| Parallax (π) | 27.7563±0.0172 mas[2] |
| Distance | 117.51 ± 0.07 ly (36.03 ± 0.02 pc) |
| Absolute magnitude (MV) | 3.57[1] |
| B | |
| Radial velocity (Rv) | 40[8] km/s |
| Proper motion (μ) | RA: −48.359 mas/yr[3] Dec.: −312.181 mas/yr[3] |
| Parallax (π) | 27.7297±0.0203 mas[3] |
| Distance | 117.62 ± 0.09 ly (36.06 ± 0.03 pc) |
| Details | |
| A | |
| Mass | 1.214±0.040[9] M☉ |
| Radius | 1.56[10] R☉ |
| Luminosity | 2.93[10] L☉ |
| Surface gravity (log g) | 4.10±0.03[11] cgs |
| Temperature | 6,005±70[11] K |
| Metallicity [Fe/H] | 0.09±0.06[11] dex |
| Rotational velocity (v sin i) | 3.39[12] km/s |
| Age | 4.105±0.755[9] Gyr |
| C | |
| Mass | 0.67±0.10[13] M☉ |
| Radius | 0.0130±0.0003[13] R☉ |
| Surface gravity (log g) | 8.04±0.06[13] cgs |
| Temperature | 15,746±238[13] K |
| Other designations | |
| GJ 9209, WDS J06163-5913[14] | |
| A: CD−59°1275, HD 44120, HIP 29788, HR 2274, SAO 234418 | |
| C: L 182-61, WD 0615-591[4] | |
| Database references | |
| SIMBAD | A |
| C | |
The primary member, designated component A of this system, is an F-type main-sequence star with a stellar classification of F9.5V.[5] It is a Sun-like star and has been considered a "hot" solar analog with a shallower convection zone than the Sun.[15] The estimated age of this star is about four billion years,[9] and it is spinning with a projected rotational velocity of 3.4 km/s.[12] It is chromospherically inactive.[16] The star has 1.2 times the mass of the Sun[9] and 1.6 times the Sun's radius.[10] It is radiating nearly three times the luminosity of the Sun[10] from its photosphere at an effective temperature of 6,005 K.[11]
The faint secondary companion, component C, is a magnitude 14.03 white dwarf star with a class of DB3.2,[4] indicating a helium-rich atmosphere. The object has an effective temperature of ~15,700 K with 67% of the Sun's mass but only 1.3% of the Sun's radius.[13] It has taken 155±16 Myr for the white dwarf to have cooled to the current temperature. Prior to leaving the main sequence, this star is estimated to have had 1.45+0.20
−0.16 M☉ and thus was the system primary.[6] It has an angular separation of 40.98″ along a position angle of 301.6° from the current primary. The projected separation of this co-moving pair is 1,533.9 AU. Their estimated orbit has a semimajor axis of 1,702.6 AU and an orbital period of 51,100 years.[4]
A magnitude 7.61 visual companion, HD 44105, or component B, lies at an angular separation of 32.50″ along a position angle of 234° from component A, as of 2015. It was discovered as a double star by the Scottish astronomer James Dunlop and announced in 1829.[17] The parallax for this star indicates a distance of approximately 214 ly (66 pc) from the Sun.[18]