GY Andromedae

GY Andromedae

A visual band light curve for GY Andromedae, adapted from Metlova et al. (2014)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 01h 38m 31.82552s[2]
Declination +45° 23′ 58.9357″[2]
Apparent magnitude (V) 6.36[3]
Characteristics
Spectral type B9 pe[4]
U−B color index -0.10[3]
B−V color index +0.04[3]
Variable type α2 CVn
Astrometry
Radial velocity (Rv)+3.0[5] km/s
Proper motion (μ) RA: −17.292(211)[2] mas/yr
Dec.: −1.386(150)[2] mas/yr
Parallax (π)7.1093 ± 0.1589 mas[2]
Distance460 ± 10 ly
(141 ± 3 pc)
Absolute magnitude (MV)+0.68[6]
Details
Mass2.47 ± 0.15[6] M☉
Radius2.6 ± 0.4[6] R☉
Luminosity52[6] L☉
Surface gravity (log g)4.01 ± 0.14[6] cgs
Temperature10,723[7] K
Metallicity [Fe/H]0.86[7] dex
Rotational velocity (v sin i)31[8] km/s
Orbit[9]
CompanionGY And B
Period (P)272.99 days
Semi-major axis (a)> 0.25 AU
Eccentricity (e)0.47
Argument of periastron (ω)
(secondary)		17.7°
Other designations
BD +44°341, HD 9996, HIP 7651, HR 465, SAO 37393, PPM 44258[4]
Database references
SIMBADdata

GY Andromedae (GY And) is an α2 Canum Venaticorum type binary variable star in the northern constellation Andromeda. Its brightness fluctuates in visual magnitude between 6.27m and 6.41m, making it a challenge to view with the naked eye even in good seeing conditions. The magnetic activity on this star shows an unusually long period of variability, cycling about once every 23 years.[10] Based upon parallax measurements, this star is located at a distance of about 460 light-years (140 parsecs) from the Earth.[2]

This is classified as an Ap/Bp star, with a peculiar spectrum[10] showing lines of chromium and europium that change in intensity over a period matching the variability cycle, although opposite in phase.[11] Its most striking characteristic is the presence of the unstable element promethium in its emission spectrum. All isotopes of this element are radioactive with half lives of 17.7 years or less. The promethium in the outer envelope may be generated by the spontaneous fission of higher mass transuranic elements.[12]

  1. ^ Cite error: The named reference Metlova2014 was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference Gaia EDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference aass34_1 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference gcrv1953 was invoked but never defined (see the help page).
  6. ^ a b c d e Cite error: The named reference aaa334_181 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference aaa19_248 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference aaa393_897 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference an299_2_81 was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference aaas114_79 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference apj160_1071 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference apj181_475 was invoked but never defined (see the help page).