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HD 221525

Location of HD 221525 (circled)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cepheus
Right ascension	23 27 00.91338
Declination	87° 18′ 27.0304″
Apparent magnitude (V)	5.56
Characteristics
Spectral type	A8III or A7IV
B−V color index	0.250±0.004
Astrometry
Radial velocity (Rv)	−10.9±2.9 km/s
Proper motion (μ)	RA: +75.736 mas/yr Dec.: +16.724 mas/yr
Parallax (π)	10.3023 ± 0.0957 mas
Distance	317 ± 3 ly (97.1 ± 0.9 pc)
Absolute magnitude (MV)	0.52
Details
Mass	2.25? M☉
Radius	3.98+0.11 −0.13 R☉
Luminosity	44.3±0.5 L☉
Temperature	7466+217 −105 K
Rotational velocity (v sin i)	110 km/s
Age	~900 Myr
Other designations
BD+86°3444, HD 221525, HIP 115746, HR 8938, SAO 3916
Database references
SIMBAD	data

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

This object is an A-type star with a stellar classification of A7IV or A8III, 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. The star has four times the radius of the Sun and is radiating 44 times the Sun's luminosity from its photosphere at an effective temperature of 7,466 K.

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: ${\displaystyle ({\sqrt{100}})^{5.56-1.97}\approx 27.2}$

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

v t e Constellation of Cepheus
List of stars in Cepheus Cepheus in Chinese astronomy
Stars	Bayer α (Alderamin) β (Alfirk) γ (Errai) δ ε ζ η θ ι κ λ μ (Garnet Star) ν ξ (Kurhah) ο π ρ ρ Flamsteed 7 9 11 14 16 19 24 2 UMi Variable AR T V W RW VV VW WZ DH DO MY PV S SS ST U V354 V381 V419 HR 597 881 7955 8281 8442 8702 8748 8938 9038 HD 1 197911 204521 Other Gliese 809 WISE 0313+7807 WR 156 IRAS 23077+6707
Exoplanets γ Cephei Ab (Tadmor) TOI-1431 b
Star clusters	NGC 188 6939 7023 7129 7142 7160 7380 7419 7429 7510 Other Palomar 1
Nebulae	NGC NGC 40 NGC 7129 NGC 7139 NGC 7354 NGC 7538 NGC 7822 Other Seahorse Nebula Elephant's Trunk Nebula Ghost Nebula Gyulbudaghian's Nebula IC 1396 Iris Nebula L1157 S 155 SSTGFLS J222557+601148
Galaxies	NGC 2276 2300 6952 Other 3C 61.1 S5 0014+81 NVSS 2146+82 UGC 11861
Category

• A-type subgiants
• A-type giants
• Cepheus (constellation)
• Durchmusterung objects
• Henry Draper Catalogue objects
• Bright Star Catalogue objects
• Hipparcos objects