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ET Andromedae

ET Andromedae

The visual band light curve of ET Andromedae, adapted from Blanco et al. (1980)[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension 23h 17m 56.011185s[2]
Declination +45° 29′ 20.1197″[2]
Apparent magnitude (V) 6.48[3]
Characteristics
Spectral type A0 Vp SiSr[4] or B9p SI[5]
B−V color index −0.037±0.006[3]
Variable type α2 CVn
Astrometry
Radial velocity (Rv)−0.30±4.10[3] km/s
Proper motion (μ) RA: +24.740[2] mas/yr
Dec.: −11.038[2] mas/yr
Parallax (π)5.4200 ± 0.0572 mas[2]
Distance602 ± 6 ly
(185 ± 2 pc)
Absolute magnitude (MV)0.58[6]
Orbit[7]
Period (P)48.304±0.007 d
Eccentricity (e)0.50±0.05
Periastron epoch (T)2443720.11±0.64 JD
Argument of periastron (ω)
(secondary)		49.8±6.0°
Semi-amplitude (K1)
(primary)		25.7±2.0 km/s
Details
Mass3.25[8] M☉
Radius2.7[9] R☉
Luminosity91.06[3] L☉
Surface gravity (log g)3.81[10] cgs
Temperature11,444[10] K
Rotation1.62 d[11]
Rotational velocity (v sin i)65[12] km/s
Age284[6] Myr
Other designations
AG+45° 2124, BD+44° 4373, HD 219749, HIP 115036, HR 8861, SAO 52876, PPM 64037, TYC 3636-2562-1, GSC 03636-02562, 2MASS J23175600+4529201[13]
Database references
SIMBADdata

ET Andromedae is a binary star system star in the northern constellation of Andromeda.[14] It has an apparent visual magnitude of 6.48,[3] placing it at the nominal limit for visibility with the naked eye. The distance to this system can be estimated from its annual parallax shift of 5.42 mas,[2] which yields a value of 602 light years.

Variations in the radial velocity of this star suggest it is a single-lined spectroscopic binary system. This yields orbital elements with a period of 48.3 days and an eccentricity of 0.50. The a sin i value for the primary is 14.8 Gm (0.099 AU), where a is the semimajor axis and i is the (unknown) orbital inclination.[7]

The visible component is a well-studied magnetic chemically peculiar star[15] with a stellar classification of A0 Vp SiSr.[4] The SiSr notation indicates unusual abundances of silicon and strontium in the spectrum. It has a magnetic field with an average surface value of 3.2 kT.[16] The abundance of silicon varies depending on the viewing angle.[15]

In 1953, Sanford S. Provin announced that HD 219749 might be photometrically variable, based on observations made at Yerkes Observatory.[17] Variability was confirmed from Lowell Observatory measurements published by Karl D. Rakos in 1962.[18] The star is an Alpha2 Canum Venaticorum variable with a period of 1.618875 days.[19]

  1. ^ Cite error: The named reference blanco was invoked but never defined (see the help page).
  2. ^ a b c d e f Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference abt1995 was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Ouhrabka1979 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference ducati2011 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference CADARS was invoked but never defined (see the help page).
  10. ^ a b Cite error: The named reference Adelman2002 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Kreidl1993 was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Strom2005 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  14. ^ Cite error: The named reference AAVSOET was invoked but never defined (see the help page).
  15. ^ a b Cite error: The named reference Adelman2000 was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference Glagolevskij2007 was invoked but never defined (see the help page).
  17. ^ Cite error: The named reference Provin was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference Rakos was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference gcvs was invoked but never defined (see the help page).
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