HD 221525

HD 221525

Location of HD 221525 (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cepheus
Right ascension	23^h 27^m 00.91338^s[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 mas[1]
Distance	317 ± 3 ly (97.1 ± 0.9 pc)
Absolute magnitude (MV)	0.52[2]
Details
Mass	2.25?[5] M☉
Radius	3.98+0.11 −0.13[1] R☉
Luminosity	44.3±0.5[1] L☉
Temperature	7466+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
SIMBAD	data

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]

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]

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. S2CID 119257644.
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 (509): 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. S2CID 14878976.
8. Calculation: ${\displaystyle ({\sqrt[{5}]{100}})^{5.56-1.97}\approx 27.2}$

External links

• Jim Kaler. "The Polar Project". University of Illinois. Retrieved 2012-05-02.
• HD 221525 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images