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HD 1976

Location of HD 1976 (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Cassiopeia
Right ascension	00 24 15.65400
Declination	+52° 01′ 11.7032″
Apparent magnitude (V)	5.580 (combined)
Characteristics
Spectral type	(B5IV + unknown) + ~B5-6IV
U−B color index	-0.619
B−V color index	-0.121
J−H color index	-0.102
J−K color index	-0.106
Variable type	Slowly pulsating B-type star (A; disputed)
Astrometry
Radial velocity (Rv)	−9.70 ± 0.49 km/s
Proper motion (μ)	RA: 15.504 mas/yr Dec.: -4.061 mas/yr
Parallax (π)	2.4621 ± 0.33 mas
Distance	approx. 1,300 ly (approx. 410 pc)
Orbit
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
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
HD 1976 Aa
Mass	4.71+0.17 −0.16, 6.45±0.17, 6.348 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 Myr
HD 1976 Ab
Mass	1.31, 1.87, 4.0±0.7 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
V746 Cassiopeiae, AG+51°39, BD+51°62, Gaia DR3 418916648901801728, GC 476, HD 1976, HIP 1921, HR 91, SAO 21366, PPM 25297, WDS J00243+5201AB, TIC 202418751, TYC 3260-2342-1, GSC 03260-02342, 2MASS J00241564+5201119,
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 B-type subgiant and a less massive unknown-type star, which is distantly orbited by another B-type subgiant. 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.

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_☉). In 2022, however, a far higher mass of 4.0±0.7 M_☉ was reported, which resembles that of a late B-type main-sequence star.

HD 1976 B

• magnetism

See also

• HD 25558

Footnotes

1. In comparison, a typical B7V star has a mass of about 3.92 M_☉.

References

1. ^ 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. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
2. ^ 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. ^ Neiner, C.; Tkachenko, A.; MiMeS collaboration (2014). "Discovery of a magnetic field in the B pulsating system HD 1976". Astronomy & Astrophysics. 563. EDP Sciences: L7. doi:10.1051/0004-6361/201423595. ISSN 0004-6361.
4. ^ Harmanec, P.; Brož, M.; Mayer, P.; et al. (22 December 2017). "Improved model of the triple system V746 Cassiopeiae that has a bipolar magnetic field associated with the tertiary". Astronomy & Astrophysics. 609. EDP Sciences: A5. doi:10.1051/0004-6361/201628363. ISSN 0004-6361.
5. ^ "HD 1976". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 10 November 2024.
6. ^ Gardner, Tyler; Monnier, John D.; Fekel, Francis C.; et al. (1 November 2022). "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.
7. Mamajek, Eric (16 April 2022). "A Modern Mean Dwarf Stellar Color and Effective Temperature Sequence". Retrieved 11 November 2024.

• 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. 60. American Astronomical Society: 945. doi:10.1086/191106. ISSN 0067-0049.

v t e Variable stars
Pulsating	Cepheids and cepheid-like Type I (Classical cepheids, Delta Scuti) Type II (BL Herculis, W Virginis, RV Tauri) RR Lyrae Rapidly oscillating Ap SX Phoenicis Blue-white with early spectra Alpha Cygni Beta Cephei Slowly pulsating B-type PV Telescopii Blue large-amplitude pulsator Long-period Mira Semiregular Slow irregular Other Gamma Doradus Solar-like oscillations White dwarf
Eruptive	Protostar and PMS Herbig Ae/Be Orion FU Orionis T Tauri Giants and supergiants Luminous blue variable R Coronae Borealis (DY Persei) Yellow hypergiant Eruptive binary Double periodic FS Canis Majoris RS Canum Venaticorum Other Flare Gamma Cassiopeiae Lambda Eridani Wolf–Rayet
Cataclysmic	AM Canum Venaticorum Dwarf nova Luminous red nova Nova Polar Intermediate Supernova Hypernova SW Sextantis Symbiotic Symbiotic nova Z Andromedae
Rotating	Non-spherical Rotating ellipsoidal Stellar spots BY Draconis FK Comae Berenices Magnetic fields α Canum Venaticorum Pulsar SX Arietis
Eclipsing	Algol Beta Lyrae Planetary transit W Ursae Majoris
Star portal * List

v t e Constellation of Cassiopeia
List of stars in Cassiopeia Cassiopeia in Chinese astronomy
Stars	Bayer α (Schedar) β (Caph) γ (Navi/Tsih) δ (Ruchbah) ε (Segin) ζ (Fulu) η (Achird) θ (Marfak) ι κ λ μ ν ξ ο π ρ σ τ υ υ (Castula) φ χ ψ ω Flamsteed 1 2 4 6 9 10 12 42 47 48 (A) 49 50 54 Variable R S TZ WZ YZ (21) AO AR PZ V373 V509 V547 V669 V705 V762 V863 V773 V987 V1022 V1405 HR 5 91 144 196 244 273 297 743 932 8832 8853 8881 HD 861 7924 7977 15558 17156 (Nushagak) 240210 240237 240429 240430 Other BD+60°2522 Gliese 49 IRAS 23304+6147 LS I +61 303 PSR J0205+6449 Tycho G 4U 0142+61 WR 2 WR 3
Exoplanets HD 7924 b HD 17156 b HD 219134 b c d e (h) f g HD 240210 b HD 240237 b
Star clusters Messier 52 Messier 103 NGC 103 NGC 110 NGC 129 NGC 133 NGC 136 NGC 146 NGC 189 NGC 225 NGC 358 NGC 366 NGC 381 NGC 433 NGC 436 NGC 457 NGC 559 NGC 637 NGC 654 NGC 659 NGC 663 NGC 1027 NGC 7789 NGC 7790 Trumpler 3
Nebulae	NGC 281 7635 Other 3C 58 Cassiopeia A Heart Nebula IC 289 IC 1805 KjPn 8 LBN 114.55+00.22 Sh 2-185 Westerhout 5
Galaxies	NGC 147 185 278 Other Andromeda VII 3C 20 3C 35 Dwingeloo 1 Dwingeloo 2 MB 3 IC 10 Maffei 1 Maffei 2 QSO B0153+744
Astronomical events SN 1181 SN 1572 (B)
Category