HD 5788 and HD 5789
Binary star system in the constellation Andromeda
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HD 5789 and HD 5788 is a pair of stars comprising a binary star[14] system in the northern constellation of Andromeda. Located approximately 151 parsecs (490 ly) away, the primary is a hot, massive blue star with an apparent magnitude of 6.06 while the secondary is slightly smaller and cooler, with an apparent magnitude of 6.76. Both stars are main-sequence stars, meaning that they are currently fusing hydrogen into helium in their cores. As of 2016, the pair had an angular separation of 7.90″ along a position angle of 195°.[15] While both have a similar proper motion and parallax, there's still no proof that the pair is gravitationally bound.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda[1] |
| HD 5789 | |
| Right ascension | 01h 00m 03.55767s[2] |
| Declination | +44° 42′ 47.6898″[2] |
| Apparent magnitude (V) | 6.06[3] |
| HD 5788 | |
| Right ascension | 01h 00m 03.38277s[4] |
| Declination | +44° 42′ 40.0515″[4] |
| Apparent magnitude (V) | 6.763[5] |
| Characteristics | |
| HD 5789 | |
| Evolutionary stage | main sequence[6] |
| Spectral type | B9.5Vnn (λ Boo)[7] |
| B−V color index | −0.031[8] |
| HD 5788 | |
| Evolutionary stage | main sequence[6] |
| Spectral type | A2 Vn[9] |
| B−V color index | −0.010[8] |
| Astrometry | |
| HD 5789 | |
| Radial velocity (Rv) | +4.4±3.3[10] km/s |
| Proper motion (μ) | RA: +13.85[2] mas/yr Dec.: −23.83[2] mas/yr |
| Parallax (π) | 6.6432±0.0809 mas[2] |
| Distance | 491 ± 6 ly (151 ± 2 pc) |
| HD 5788 | |
| Proper motion (μ) | RA: +11.582[4] mas/yr Dec.: −24.369[4] mas/yr |
| Parallax (π) | 6.5625±0.0688 mas[4] |
| Distance | 497 ± 5 ly (152 ± 2 pc) |
| Details | |
| HD 5789 | |
| Mass | 2.74±0.12[6] M☉ |
| Radius | 3.2[11] R☉ |
| Luminosity | 85.6+19.2 −15.6[6] L☉ |
| Surface gravity (log g) | 3.82[11] cgs |
| Temperature | 9,977[8] K |
| Rotational velocity (v sin i) | 249[6] km/s |
| HD 5788 | |
| Mass | 2.67±0.12[6] M☉ |
| Radius | 2.2[11] R☉ |
| Luminosity | 73.3+18.4 −14.7[6] L☉ |
| Surface gravity (log g) | 4.18[11] cgs |
| Temperature | 9,840[8] K |
| Rotational velocity (v sin i) | 270[6] km/s |
| Other designations | |
| BD+43°193, HIP 4675, ADS 824, WDS J01001+4443 | |
| HD 5789: HR 283, SAO 36833[12] | |
| HD 5788: HR 282, SAO 36832[13] | |
| Database references | |
| SIMBAD | HD 5789 |
| HD 5788 | |
The primary component is HD 5789, a B-type main-sequence star with a stellar classification of B9.5Vnn (λ Boo), where the 'n' indicates "nebulous" lines due to rapid rotation. Abt and Morrell (1995) listed it as a Lambda Boötis star,[7] although this is disputed.[16] It has 2.7 times the mass of the Sun and is spinning rapidly with a projected rotational velocity of 249 km/s.[6] The star is radiating 86[6] times the Sun's luminosity from its photosphere at an effective temperature of 9,977 K.[8]
The fainter secondary component is an A-type main-sequence star with a class of A2 Vn.[9] It shows a projected rotational velocity of 270 km/s and has 2.7 times the Sun's mass. The star shines with 73[6] times the Sun's luminosity at an effective temperature of 9,840 K.[8]