Y Lyncis

Y Lyncis is a semiregular variable star in the constellation Lynx. It is an asymptotic giant branch star of spectral type M6S, with a luminosity class of Ib, indicating a supergiant luminosity. It is around 1,160 light years away. Y Lyncis ranges in brightness from magnitude 6.2 to 8.9. When it is at its brightest, it very faintly visible to the naked eye under excellent observing conditions.

Y Lyncis

A visual band light curve for Y Lyncis, adapted from Percy et al. (2001).[1] The top panel shows the brightness variation over a period of several years, and the lower panel shows shorter time scale variations.
Observation data Epoch J2000      Equinox J2000
Constellation	Lynx
Right ascension	07h 28m 11.61657s[2]
Declination	+45° 59′ 26.2295″[2]
Apparent magnitude (V)	6.2 - 8.9[3]
Characteristics
Evolutionary stage	AGB[4]
Spectral type	M6S Ib[5]
Variable type	SRc[5]
Astrometry
Radial velocity (Rv)	5.50±0.6[6] km/s
Proper motion (μ)	RA: −1.278[2] mas/yr Dec.: −4.067[2] mas/yr
Parallax (π)	2.8068±0.1138 mas[2]
Distance	1,160 ± 50 ly (360 ± 10 pc)
Details
Mass	1.5 - 2.0[3] M☉
Radius	580[3] R☉
Luminosity	10,765[7] L☉
Surface gravity (log g)	0.0[8] cgs
Temperature	3,200[8] K
Metallicity [Fe/H]	−0.19[8] dex
Other designations
Y Lyn, HD 58521, BD+46°1271, HIP 36288, SAO 41784
Database references
SIMBAD	data

In 1901 it was announced that Williamina Fleming had discovered that the star, then known as BD +46°1271, is a variable star.^[9] It was given its variable star designation, Y Lyncis, in 1912.^[10] The changes in brightness of this star are complex, with at least two different periods showing. The General Catalogue of Variable Stars lists a period of 110 days.^[11] More recent studies show a primary pulsation period of 133 days, with and a long secondary period with an amplitude of 0.2 magnitudes and duration 1,300 days. The long secondary period variations are possibly caused by long-lived convection cells.^[12]

Y Lyncis has a mass around 1.5-2.0 M_☉ and a luminosity around 10,000 L_☉. It is a thermally pulsing asymptotic giant branch star, an evolved star with a carbon-oxygen core that is fusing helium in a shell and hydrogen in a separate shell.^[4] It is also an S-type star, where third dredge-ups have brought some carbon to the surface, but not enough to create a carbon star.^[7]