HD 225218

HD 225218 is a quadruple star system in the northern constellation of Andromeda. The primary component, HD 225218 A, is a giant star with a stellar classification of B9III,^[4] an apparent magnitude of 6.16,^[2] and is a candidate Lambda Boötis star.^[9] It has a fainter, magnitude 9.65 companion, HD 225218 B, at an angular separation of 5.2″ along a position angle of 171°.^[2] The primary itself has been identified as a binary star system through interferometry, with the two components separated by 0.165″. The pair, HD 225218 Aa and Ab, orbit each other with a period of about 70 years and an eccentricity of 0.515.^[6] Component B is likewise a spectroscopic binary.^[9]

HD 225218

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Andromeda
HD 225218 A
Right ascension	00h 04m 36.58441s[1]
Declination	+42° 05′ 33.0865″[1]
Apparent magnitude (V)	6.16[2]
HD 225218 B
Right ascension	00h 04m 36.67195s[3]
Declination	+42° 05′ 27.8497″[3]
Apparent magnitude (V)	9.65[2]
Characteristics
Spectral type	B9III[4] + F0V:
U−B color index	0.14
B−V color index	0.15
Astrometry
HD 225218 A
Radial velocity (Rv)	−8.0[5] km/s
Proper motion (μ)	RA: −10.367±0.266[1] mas/yr Dec.: −14.491±0.222[1] mas/yr
Parallax (π)	3.0041 ± 0.3539 mas[1]
Distance	approx. 1,100 ly (approx. 330 pc)
HD 225218 B
Proper motion (μ)	RA: −12.314±0.015[3] mas/yr Dec.: −16.129±0.015[3] mas/yr
Parallax (π)	4.4324 ± 0.0208 mas[3]
Distance	736 ± 3 ly (226 ± 1 pc)
Orbit[6]
Period (P)	70.12 yr
Semi-major axis (a)	0.165″
Eccentricity (e)	0.515
Details
Luminosity	394[7] L☉
Temperature	7,611[7] K
Rotation	25[8]
Other designations
BD+41 4933, HD 225218, HIP 365, HR 9105, NSV 15012, SAO 36037, WDS J00046+4206.
Database references
SIMBAD	data
Database references
SIMBAD	data

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. Mason, Brian D.; et al. (December 2001), "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
3. 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.
4. Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819
5. Wilson, R. E. (1953), "General Catalogue of Stellar Radial Velocities", Carnegie Institute Washington D.C. Publication, Carnegie Institute of Washington, D.C., Bibcode:1953GCRV..C......0W
6. Malkov, O. Yu.; et al. (2012), "Dynamical Masses of a Selected Sample of Orbital Binaries", Astronomy & Astrophysics, 546: 5, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774, A69
7. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352
8. Abt, Helmut A.; et al. (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590
9. Faraggiana, Rosanna; Bonifacio, Piercarlo (September 1999), "How many lambda Bootis stars are binaries?", Astronomy and Astrophysics, 349: 521–531, arXiv:astro-ph/9906009, Bibcode:1999A&A...349..521F

External links

• Image HD 225218