HD 21278
Binary star system in the constellation Perseus
title: "HD 21278" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["b-type-main-sequence-stars", "spectroscopic-binaries", "alpha-persei-cluster", "perseus-(constellation)", "durchmusterung-objects", "henry-draper-catalogue-objects", "hipparcos-objects", "bright-star-catalogue-objects"] description: "Binary star system in the constellation Perseus" topic_path: "science/astronomy" source: "https://en.wikipedia.org/wiki/HD_21278" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Binary star system in the constellation Perseus ::
| image = |image=Perseus constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=8|mark_link=HD 21278 |x=533|y=443 | caption = Location of HD 21278 (circled) | epoch = J2000 | constell = Perseus | ra = | dec = | appmag_v = 4.99 | type = Main sequence | class = B5V + B9V | b-v = −0.10 | u-b = −0.56 | variable = | radial_v = +1.20 | prop_mo_ra = +22.754 | prop_mo_dec = | pm_footnote = | parallax = 5.6775 | p_error = 0.1248 | parallax_footnote = | absmag_v = −1.49 | reference = | period_unitless = days | axis_unitless = | eccentricity = | inclination = | node = | periastron = mJD | periarg = | k1 = | k2 = | source = | component1 = A | radius = | mass = | gravity = | age_myr = | metal_fe = 0.00 | temperature = 16,750 | luminosity = 940 | rotational_velocity = 53 | component2 = B | mass2 = | temperature2 = 11,120 | age_myr2 = | names = | Simbad = HD+21278
HD 21278 is a binary star system in the constellation Perseus, located within the Alpha Persei Cluster. It has a blue-white hue and is visible to the naked eye with a combined apparent visual magnitude of 4.99. The system is located at a distance of approximately 570 light years from the Sun based on parallax, and it is drifting further away with a radial velocity of +1.20 km/s.
The binary nature of this star was announced in 1925 by Otto Struve. It is a double-lined spectroscopic binary with an orbital period of 21.685 days and an eccentricity of 0.138.
The primary component is a B-type main-sequence star with a stellar classification of B5V, indicating it is generating energy through core hydrogen fusion. The star is spinning with a projected rotational velocity of 53 km/s. It has 5.381 times the mass of the Sun and about 3.75 times the Sun's radius. HD 21278 A is radiating 940 times the luminosity of the Sun from its photosphere at an effective temperature of 16,410 K.
The secondary component is also a B-type main-sequence star, with a spectral class B9V. It has 3.353 times the mass of the Sun and an effective temperature of 11,120 K.
References
| title=XHIP: An extended hipparcos compilation | last1=Anderson | first1=E. | last2=Francis | first2=Ch. | journal=Astronomy Letters | volume=38 | issue=5 | pages=331 | year=2012 | bibcode=2012AstL...38..331A | arxiv=1108.4971 | doi=10.1134/S1063773712050015 | s2cid=119257644 }} Vizier catalog entry
| last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A. | title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets | journal=The Astrophysical Journal | volume=804 | issue=2 | pages=146 | year=2015 | bibcode=2015ApJ...804..146D | arxiv=1501.03154 | doi=10.1088/0004-637X/804/2/146 | s2cid=33401607 }}
| last1=Morrell | first1=Nidia | last2=Abt | first2=Helmut A. | title=Spectroscopic binaries in the Alpha Persei cluster | journal=Astrophysical Journal, Part 1 | volume=393 | issue=2 | date=July 10, 1992 | pages=666–673 | doi=10.1086/171534 | bibcode=1992ApJ...393..666M }}
| last1=Silaj | first1=J. | last2=Landstreet | first2=J. D. | title=Accurate age determinations of several nearby open clusters containing magnetic Ap stars | journal=Astronomy & Astrophysics | volume=566 | pages=A132 | year=2014 | bibcode=2014A&A...566A.132S | arxiv=1407.4531 | doi=10.1051/0004-6361/201321468 | s2cid=53370832 }}
| last1=Gontcharov | first1=G. A. | title=Dependence of kinematics on the age of stars in the solar neighborhood | journal=Astronomy Letters | volume=38 | issue=12 | pages=771–782 | year=2012 | bibcode=2012AstL...38..771G | arxiv=1606.08814 | doi=10.1134/S1063773712120031 | s2cid=118345778
| title=Twelve new spectroscopic binaries | last1=Struve | first1=O. | journal=Astrophysical Journal | volume=62 | pages=434 | date=December 1925 | doi=10.1086/142944 | bibcode=1925ApJ....62..434S }}
| bibcode=2014JAVSO..42..443M | title=Sloan Magnitudes for the Brightest Stars | journal=The Journal of the American Association of Variable Star Observers | volume=42 | pages=443 | last1=Mallama | first1=A. | year=2014 | issue=2
| bibcode=2004A&A...424..727P | doi=10.1051/0004-6361:20041213 | arxiv=astro-ph/0406573 | title=SB9: The ninth catalogue of spectroscopic binary orbits | journal=Astronomy and Astrophysics | volume=424 | issue=2 | pages=727–732 | year=2004 | display-authors=1 | last1=Pourbaix | first1=D. | last2=Tokovinin | first2=A. A. | last3=Batten | first3=A. H. | last4=Fekel | first4=F. C. | last5=Hartkopf | first5=W. I. | last6=Levato | first6=H. | last7=Morrell | first7=N. I. | author-link7=Nidia Morrell | last8=Torres | first8=G. | last9=Udry | first9=S. | s2cid=119387088 }}
References
- "HD 21278".
- {{Cite Gaia DR3. 441416161501150848
- (2025-06-09). "Precise Age For The Binary HD 21278 In The Young Alpha Persei Cluster". [[The Astrophysical Journal]].
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::