HD 1976
  | |
| Observation data Epoch J2000[1] Equinox J2000[1] | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 00h 24m 15.65400s |
| Declination | +52° 01′ 11.7032″ |
| Apparent magnitude (V) | 5.580 (combined)[2] |
| Characteristics | |
| Spectral type | (B5IV[3] + unknown) + ~B5-6IV[4] |
| U−B color index | -0.619[5] |
| B−V color index | -0.121[2] |
| J−H color index | -0.102[5] |
| J−K color index | -0.106[5] |
| Variable type | Slowly pulsating B-type star (A) |
| Astrometry | |
| Radial velocity (Rv) | −9.70 ± 0.49[1] km/s |
| Proper motion (μ) | RA: 15.504[1] mas/yr Dec.: -4.061[1] mas/yr |
| Parallax (π) | 2.4621 ± 0.33[1] mas |
| Distance | approx. 1,300 ly (approx. 410 pc) |
| Orbit[6] | |
| Primary | HD 1976 Aa |
| Companion | HD 1976 Ab |
| Period (P) | 25.4163±0.0008 d |
| Semi-major axis (a) | 0.42±0.05 mas |
| Eccentricity (e) | 0.05±0.03 |
| Inclination (i) | 100.7±1.2° |
| Longitude of the node (Ω) | 339.9±1.1° |
| Periastron epoch (T) | 59477±5 |
| Argument of periastron (ω) (secondary) | 61±52° |
| Orbit[6] | |
| Primary | HD 1976 A |
| Companion | HD 1976 B |
| Period (P) | 171±3 yr |
| Semi-major axis (a) | 208.0±2.7 mas |
| Eccentricity (e) | 0.162±0.008 |
| Inclination (i) | 62.8±0.4° |
| Longitude of the node (Ω) | 27.8±0.4° |
| Periastron epoch (T) | 33710±679 |
| Argument of periastron (ω) (secondary) | 306.0±4° |
| Details[4] | |
| HD 1976 Aa | |
| Mass | 4.71+0.17 −0.16, 6.45±0.17, 6.348[6] M☉ |
| Radius | 5.74+0.18 −0.16, 5.24+0.14 −0.10 R☉ |
| Surface gravity (log g) | 3.59±0.01, 3.81±0.01 cgs |
| Temperature | 15534±69, 16526+100 −82 K |
| Rotational velocity (v sin i) | 178±6, 170±4 km/s |
| Age | ~60[3] Myr |
| HD 1976 Ab | |
| Mass | 1.31, 1.87, 4.0±0.7[6] M☉ |
| Radius | 1.40, 1.82 R☉ |
| Surface gravity (log g) | 4.27, 4.18 cgs |
| Temperature | 6385+565 −657, 8071+266 −352 K |
| Rotational velocity (v sin i) | 165 km/s |
| HD 1976 B | |
| Mass | 2.65±0.25, 6.10+0.27 −0.26 M☉ |
| Radius | 3.40+0.29 −0.26, 4.48±0.20 R☉ |
| Surface gravity (log g) | 3.80±0.03. 3.92±0.02 cgs |
| Temperature | 14750±66, 13620+154 −144 K |
| Rotational velocity (v sin i) | 63+9 −8, 73+6 −5 km/s |
| Other designations | |
| Database references | |
| SIMBAD | HD 1976 |
HD 1976 is a hierarchical triple system in the deep northern constellation of Cassiopeia, approximately 1,100 light-years (340 parsecs) from Earth. It has the variable-star designation V746 Cassiopeiae (abbreviated to V746 Cas). The system is faintly visible to the naked eye under dark skies, having an apparent magnitude of 5.580. It consists of an inner pair between a slowly pulsating B-type star and a less massive star, which is distantly orbited by another B-type star. It is currently moving closer towards the Solar System at a heliocentric radial velocity of −9.70 km/s.
Stellar properties
- uncertain distance
HD 1976 Aa
- large discrepancy
- pulsations
- magnetism
HD 1976 Ab
The only component whose spectrum cannot be directly observed, HD 1976 Ab is in a nearly circular (eccentricity 0.05) 25-day orbit with Aa.[4]
As is the case with the other two stars, its physical properties are very uncertain. A 2017 study presented two sets of possible characteristics, each corresponding to an A-type (1.87 M☉) and F-type main-sequence star (1.31 M☉).[4] In 2022, however, a far higher mass of 4.0±0.7 M☉ was reported,[6] which resembles that of a late B-type main-sequence star.[lower-alpha 1]
HD 1976 B
- magnetism
See also
Footnotes
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. Unknown parameter
|s2cid=ignored (help) Gaia EDR3 record for this source at VizieR. - ↑ 2.0 2.1 Høg, E.; et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27–L30. Bibcode:2000A&A...355L..27H.
- ↑ 3.0 3.1 Neiner, C.; Tkachenko, A.; MiMeS collaboration (2014). "Discovery of a magnetic field in the B pulsating system HD 1976". Astronomy & Astrophysics. EDP Sciences. 563: L7. doi:10.1051/0004-6361/201423595. ISSN 0004-6361.
- ↑ 4.0 4.1 4.2 4.3 Harmanec, P.; Brož, M.; Mayer, P.; et al. (2017-12-22). "Improved model of the triple system V746 Cassiopeiae that has a bipolar magnetic field associated with the tertiary". Astronomy & Astrophysics. EDP Sciences. 609: A5. doi:10.1051/0004-6361/201628363. ISSN 0004-6361.
- ↑ 5.0 5.1 5.2 5.3 "HD 1976". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2024-11-10.
- ↑ 6.0 6.1 6.2 6.3 6.4 Gardner, Tyler; Monnier, John D.; Fekel, Francis C.; et al. (2022-11-01). "ARMADA. II. Further Detections of Inner Companions to Intermediate-mass Binaries with Microarcsecond Astrometry at CHARA and VLTI". The Astronomical Journal. 164 (5): 184. doi:10.3847/1538-3881/ac8eae. ISSN 0004-6256.
- ↑ Mamajek, Eric (2022-04-16). "A Modern Mean Dwarf Stellar Color and Effective Temperature Sequence". Retrieved 2024-11-11.
- Docobo, J. A.; Costa, J. M. (1986). "First orbits for the visual double stars ADS 328, ADS 9043, and ADS 13048". The Astrophysical Journal Supplement Series. American Astronomical Society. 60: 945. doi:10.1086/191106. ISSN 0004-6256.
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