HD 221525

HD 221525 is a single[7] star near the north celestial pole[5] in the constellation Cepheus. At an apparent magnitude of 5.56,[2] it can be seen with the naked eye under dark skies. It is about 30 times fainter than the nearby prominent star Polaris.[8] Based upon parallax measurements, HD 221525 is located at a distance of approximately 317 light years from the Sun,[1] but is drifting closer with a radial velocity of −11 km/s.[2]

HD 221525
Location of HD 221525 (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cepheus
Right ascension  23h 27m 00.91338s[1]
Declination 87° 18′ 27.0304″[1]
Apparent magnitude (V) 5.56[2]
Characteristics
Spectral type A8III[3] or A7IV[4]
B−V color index 0.250±0.004[2]
Astrometry
Radial velocity (Rv)−10.9±2.9[2] km/s
Proper motion (μ) RA: +75.736[1] mas/yr
Dec.: +16.724[1] mas/yr
Parallax (π)10.3023 ± 0.0957[1] mas
Distance317 ± 3 ly
(97.1 ± 0.9 pc)
Absolute magnitude (MV)0.52[2]
Details
Mass2.25?[5] M☉
Radius3.98+0.11
−0.13[1] R☉
Luminosity44.3±0.5[1] L☉
Temperature7466+217
−105[1] K
Rotational velocity (v sin i)110[4] km/s
Age~900[5] Myr
Other designations
BD+86°3444, HD 221525, HIP 115746, HR 8938, SAO 3916[6]
Database references
SIMBADdata

This object is an A-type star with a stellar classification of A7IV[4] or A8III,[3] suggesting it is an evolving star on the subgiant or giant branch, respectively. It has a relatively high rate of spin, showing a projected rotational velocity of 110 km/s.[4] The star has four[1] times the radius of the Sun and is radiating 44[1] times the Sun's luminosity from its photosphere at an effective temperature of 7,466 K.[1]

Progressive house music composer Deadmau5 has named a piece after this star.[9]

References
  1. 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.
  2. 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.
  3. Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
  4. Cowley, Anne; Fraquelli, Dorothy (1974). "MK Spectral Types for Some Bright F Stars". Publications of the Astronomical Society of the Pacific. 86: 70. Bibcode:1974PASP...86...70C. doi:10.1086/129562.
  5. Jim Kaler. "HR 306 and HR 8938". Stars.astro.illinois.edu. Retrieved 2012-02-29.
  6. "HD 221525". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-11-21.
  7. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  8. Calculation:
  9. "Deadmau5 – HR 8938 Cephei". Discogs. Retrieved 2018-10-16.
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