ET Andromedae is abinary star system star in the northern constellation of Andromeda.[14] It has anapparent 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 annualparallax shift of5.42 mas,[2] which yields a value of 602 light years.
In 1953, Sanford S. Provin announced that HD 219749 might be photometrically variable, based on observations made atYerkes Observatory.[17] Variability was confirmed fromLowell Observatory measurements published by Karl D. Rakos in 1962.[18]The star is anAlpha2 Canum Venaticorum variable with a period of 1.618875 days.[19]
^Blanco, C.; Catalano, F. A.; Strazzulla, G. (January 1980)."The light variations of the Ap Star HR 8861".Astronomy & Astrophysics Supplement Series.39:127–128. Retrieved8 October 2021.
^Cowley, A.; et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications".Astronomical Journal.74:375–406.Bibcode:1969AJ.....74..375C.doi:10.1086/110819.
^abOuhrabka, M.; Grygar, J. (May 1979). "Spectroscopic evidence for the binary nature of the Ap star".Information Bulletin on Variable Stars.1600: 1.Bibcode:1979IBVS.1600....1O.
^abAdelman, Saul J. (2002). "On the Periods of the Magnetic CP Stars".Baltic Astronomy.11:475–485.Bibcode:2002BaltA..11..475A.
^Kreidl, T. J. (October 1993), "A Null Detection of Rapid Oscillations in the Ap Star ET And",Information Bulletin on Variable Stars,3945: 1,Bibcode:1993IBVS.3945....1K
^abAdelman, Saul J. (May 2000). "UVBY photometry of the magnetic CP stars HD 36668, 36 Lyncis, HD 86592, and HR 8861".Astronomy and Astrophysics.357:548–552.Bibcode:2000A&A...357..548A.
