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 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

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

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

На других языках

[es] HR 8938