HD 3346, also known as V428 Andromedae, is a binary star system in the northern constellation of Andromeda. It is a dim star but visible to the naked eye under suitable viewing conditions, having an apparent visual magnitude of 5.14. The distance to HD 3346 can be determined from its annual parallax shift of 4.72mas. This yields a range of about 690 light-years (210 parsecs). At that distance the brightness of the system is diminished by an extinction of 0.16magnitude due to interstellar dust. It is moving closer to the Earth with a heliocentric radial velocity of −33km/s.
The visible component is a red giant star and has been defined as a standard star for the stellar classification of K6IIIa. Prior to that there had been no spectral standard for K6 giants and HD 3346 had been classified between K5 III and M0 III.
In 1996 it was announced that the variations in radial velocity of this star were larger than expected. Two orbiting companions were proposed to explain this variation, the one known since 1985 with a period of about 650 days and a minimum mass of about 60MJ, and a second one with a period of about 14-40 days and a minimum mass of about 10MJ. The existence of this second, possibly planetary companion was never confirmed.
Variability
In 1982, HD 3346 was listed as a suspected variable star (NSV 15135) in Pavel Nikolaevich Kholopov's catalog of suspected variable stars. Gregory W. Henry et al. confirmed that the star is variable in year 2000. It was given its variable star designation, V428 Andromedae, in 2003.
It is a short-period semi-regular variable (type SRS), also called an ultra-small-amplitude pulsating red giant. It has an amplitude of only 0.065 magnitudes. The main pulsation period is 11.5 days, but other periods of 11, 15, and 22 days have been detected.
12Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
↑Kholopov, P. N. (1982). New catalogue of stars suspected of variability containing data on 14810 variable stars which have not received definite nomenclature until 1980. Moskva: Nauka. p.359. Bibcode:1982ncss.book.....K.
123Percy, John R.; etal. (December 2001), "Periods of Eleven K5-M0 Pulsating Red Giants", Information Bulletin on Variable Stars, 5209: 1, Bibcode:2001IBVS.5209....1P