HD 21278

Binary star system in the constellation Perseus

HD 21278
Observation data Epoch J2000 Equinox J2000
Location of HD 21278 (circled)
Constellation	Perseus
Right ascension	03^h 28^m 03.07229^s^[1]
Declination	49° 03′ 46.3315″^[1]
Apparent magnitude (V)	4.99^[2]
Characteristics
Spectral type	B5V^[3]
U−B color index	−0.56^[4]
B−V color index	−0.10^[4]
Astrometry

Radial velocity (R_v)	+1.20^[5] km/s
Proper motion (μ)	RA: +21.784^[1] mas/yr Dec.: −26.036^[1] mas/yr
Parallax (π)	5.6334 ± 0.2298 mas^[1]
Distance	580 ± 20 ly (178 ± 7 pc)
Absolute magnitude (M_V)	−1.49^[6]

Orbit^[7]
Period (P)	21.695±0.004 d
Semi-major axis (a)	≥6.72 Gm
Eccentricity (e)	0.12±0.04
Periastron epoch (T)	24,446,714.5±0.2
Argument of periastron (ω) (secondary)	109±3°
Semi-amplitude (K₁) (primary)	22.7±0.9 km/s
Semi-amplitude (K₂) (secondary)	49±3 km/s
Details
A
Mass	4.597^[8] `M`_☉
Radius	3.9^[9] `R`_☉
Luminosity	940^[6] `L`_☉
Surface gravity (log g)	4.152±0.113^[10] cgs
Temperature	15,274±244^[10] K
Metallicity [Fe/H]	0.00^[11] dex
Rotational velocity (v sin i)	75^[10] km/s
Age	187^[11] or 60^[6] Myr

Other designations
BD+48°920, GC 4108, HD 21278, HIP 16147, HR 1034, SAO 38849^[12]
Database references
SIMBAD	data

HD 21278 is a binary star^[7] system in the constellation Perseus, located within the 60±7^[6] million year old Alpha Persei Cluster.^[7] It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of 4.99.^[2] The system is located at a distance of approximately 580 light years from the Sun based on parallax,^[1] and it is drifting further away with a radial velocity of +1.20 km/s.^[5]

The binary nature of this star was announced in 1925 by Otto Struve.^[13] It is a double-lined spectroscopic binary with an orbital period of 21.7 days and an eccentricity of 0.12.^[7]

The primary component is a B-type main-sequence star with a stellar classification of B5V,^[3] indicating it is generating energy through core hydrogen fusion. The star is spinning with a projected rotational velocity of 75 km/s.^[10] It has 4.6^[8] times the mass of the Sun and about 3.9^[9] times the Sun's radius. HD 21278 is radiating 940^[6] times the luminosity of the Sun from its photosphere at an effective temperature of 15,274 K.^[10]

References

^ ^a ^b ^c ^d ^e ^f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
^ ^a ^b Zuckerman, B.; et al. (June 2012). "Stellar Membership and Dusty Debris Disks in the α Persei Cluster". The Astrophysical Journal. 752 (1): 12. arXiv:1204.3950. Bibcode:2012ApJ...752...58Z. doi:10.1088/0004-637X/752/1/58. S2CID 119207634. 58.
^ ^a ^b Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
^ ^a ^b Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID 119387088.
^ ^a ^b ^c ^d ^e Silaj, J.; Landstreet, J. D. (2014). "Accurate age determinations of several nearby open clusters containing magnetic Ap stars". Astronomy & Astrophysics. 566: A132. arXiv:1407.4531. Bibcode:2014A&A...566A.132S. doi:10.1051/0004-6361/201321468. S2CID 53370832.
^ ^a ^b ^c ^d Morrell, Nidia; Abt, Helmut A. (July 10, 1992). "Spectroscopic binaries in the Alpha Persei cluster". Astrophysical Journal, Part 1. 393 (2): 666–673. Bibcode:1992ApJ...393..666M. doi:10.1086/171534.
^ ^a ^b Sheikhi, Najmeh; et al. (March 2016). "The binary fraction and mass segregation in Alpha Persei open cluster". Monthly Notices of the Royal Astronomical Society. 457 (1): 1028–1036. arXiv:1601.02186. Bibcode:2016MNRAS.457.1028S. doi:10.1093/mnras/stw059.
^ ^a ^b Pasinetti Fracassini, L. E.; et al. (2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)". Astronomy & Astrophysics. 367 (2) (Third ed.): 521–24. arXiv:astro-ph/0012289. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451. S2CID 425754.
^ ^a ^b ^c ^d ^e David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607.
^ ^a ^b Gontcharov, G. A. (2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters. 38 (12): 771–782. arXiv:1606.08814. Bibcode:2012AstL...38..771G. doi:10.1134/S1063773712120031. S2CID 118345778.
^ "HD 21278". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-12-16.
^ Struve, O. (December 1925). "Twelve new spectroscopic binaries". Astrophysical Journal. 62: 434. Bibcode:1925ApJ....62..434S. doi:10.1086/142944.

Constellation of Perseus

Stars

Bayer	α (Mirfak) β (Algol) γ δ ε ζ η (Miram) θ ι κ (Misam) λ μ ν ξ (Menkib) ο (Atik) π (Gorgonea Secunda) ρ (Gorgonea Tertia) σ τ φ ψ ω (Gorgonea Quarta) b
Flamsteed	1 2 3 4 (g) 5 7 8 9 (i) 10 11 12 14 16 17 20 21 24 29 30 31 32 (l) 34 36 40 (o) 42 (n) 43 (A) 48 (c) 49 50 52 (f) 53 (d) 54 55 56 57 (m) 58 (e) 59 1 Aur
Variable	S T U V X Z RS RT RV RW RY ST SU SV TZ UV UX UY VX XX XY XZ YZ AB AG AR AS AW AX BM DM DY FO GK IK IP IQ IU IW IX IZ KP KS KT KW LX V351 V356 V357 V361 V376 V380 V386 V392 V396 V400 V423 V432 V440 V459 V461 V471 V472 V473 V480 V490 V492 V505 V509 V518 V520 (61 And) V521 V545 V551 V572 V573 V575 V576 V621 V718 V1024
HR	470 526 529 538 540 621 641 787 792 810 820 831 842 846 849 864 865 876 885 886 890 894 918 (k) 920 923 930 949 950 956 964 966 969 973 975 979 986 991 1001 1019 1034 1037 1041 1047 1051 1056 1059 1074 1097 1113 1127 1130 1133 1141 1160 1164 1176 1191 1197 1198 1207 1215 1226 1234 1286 1301 1330 1333 1337 1344 1371 1390 1419 1424 1482 1489 1493 1500 1514
HD	13519 14433 14434 16691 16760 17092 17245 17605 21684 22781 23301 23596 25329 26702 29587
Other	BD+31 643 BD+48 740 G 38-29 G 95-57 GD 61 HAT-P-15 (Berehynia) HAT-P-29 (Muspelheim) IRAS 04296+3429 L1448-IRS2E LkHα 101 LRLL 54361 NGC 1333 13 NGC 1333 IRAS 2A NGC 1333 IRAS 4A NGC 1333 IRAS 4B NGC 1624-2 PSR B0355+54 PSR J0357+3205 WR 4

Exoplanets	WASP-11b/HAT-P-10b

Star
clusters

NGC	869 (h) 884 (χ) 957 1039 1220 1285 1342 1444 1513 1528 1545 1624
Other	Alpha Persei Cluster IC 348 Trumpler 2

Nebulae

NGC	650 (Little Dumbbell Nebula) 1333 1491 1499 (California Nebula) 1579
Other	Barnard 203 Wreath Nebula

Galaxies

NGC	1003 1023 1058 1077 1160 1161 1167 1169 1250 1259 1260 1264 1265 1267 1268 1270 1271 1272 1273 1274 1275 1277 1278 1279 1281 1282 1283 1293 1294 1334
Other	IC 310 UGC 2885 (Godzilla galaxy) 4C +37.11