HD 221776

HD 221776 is a double star in the northern constellation of Andromeda. With an apparent visual magnitude of 6.18,[2], it is viewable by the naked eye user very favourable conditions. The most luminous component has a spectral classification K5III, meaning that it's an orange giant star that has evolved off the main sequence. An infrared excess has been detected around this star, indicating the star is associated with a cloud of dust particles.[5]

HD 221776
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension  23h 34m 46.7420s[1]
Declination +38° 01′ 26.4016″[1]
Apparent magnitude (V) 6.18[2]
Characteristics
Spectral type K5III[2]
U−B color index +1.97[3]
B−V color index +1.586[2]
Astrometry
Radial velocity (Rv)−13.74±0.11[4] km/s
Proper motion (μ) RA: 10.272±0.114[1] mas/yr
Dec.: 11.738±0.106[1] mas/yr
Parallax (π)4.0297 ± 0.0838[1] mas
Distance810 ± 20 ly
(248 ± 5 pc)
Absolute magnitude (MV)−0.68[2]
Details
Radius3.43×107[5] km
Luminosity451[5] L☉
Temperature3,800[5] K
Other designations
BD+37° 4866, HD 221776, HIP 116365, HR 8950, SAO 73351.
Database references
SIMBADdata
Database references
SIMBADdata

There is a magnitude 11.8 companion at angular separation of 19.8″ along a position angle of 329°, as of 2002;[6] however, its distance measured by parallax yields a much greater distance than the primary star.[7]

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. Jasniewicz, G.; et al. (February 1999), "Late-type giants with infrared excess. I. Lithium abundances", Astronomy and Astrophysics, 342: 831–838, Bibcode:1999A&A...342..831J
  3. Guetter, H. H.; Hewitt, A. V. (June 1984), "Photoelectric UBV photometry for 317 PZT and VZT stars", Publications of the Astronomical Society of the Pacific, 96: 441–443, Bibcode:1984PASP...96..441G, doi:10.1086/131362
  4. Famaey, B.; et al. (2005). "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters". Astronomy and Astrophysics. 430: 165–186. arXiv:astro-ph/0409579. Bibcode:2005A&A...430..165F. doi:10.1051/0004-6361:20041272.
  5. Kim, Sungsoo S.; et al. (April 2001), "Extent of Excess Far-Infrared Emission around Luminosity Class III Stars", The Astrophysical Journal, 550 (2): 1000–1006, arXiv:astro-ph/0012001, Bibcode:2001ApJ...550.1000K, doi:10.1086/319803
  6. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  7. 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.


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