 A visual band light curve for UX Lyncis. The top panel shows the variation over a period of years, and the lower plot shows the variation over a period of months. Adapted from Percy and Wilson (2001)[1] | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx |
| Right ascension | 09h 03m 47.10789s[2] |
| Declination | +38° 44′ 31.6542″[2] |
| Apparent magnitude (V) | 6.6 - 6.78[3] |
| Characteristics | |
| Evolutionary stage | AGB[4] |
| Spectral type | M3III[5] or M6III[6] |
| B−V color index | 1.356±0.011[7] |
| Variable type | SRb:[4] |
| Astrometry | |
| Radial velocity (Rv) | +38.60±0.64[7] km/s |
| Proper motion (μ) | RA: −17.176[2] mas/yr Dec.: −20.823[2] mas/yr |
| Parallax (π) | 3.6035±0.4422 mas[2] |
| Distance | approx. 900 ly (approx. 280 pc) |
| Absolute bolometric magnitude (Mbol) | −0.15[7] |
| Details | |
| Radius | 128.38+0.92 −9.89[2] R☉ |
| Luminosity | 1,766±242[2] L☉ |
| Temperature | 3302+135 −11[2] K |
| Other designations | |
| UX Lyn, BD+39°2193, HD 77443, HIP 44481, SAO 61226, IRAS 09005+3856[8] | |
| Database references | |
| SIMBAD | data |
UX Lyncis is a variable star in the faint northern constellation of Lynx, positioned about 3° to the south of the 4th magnitude star 10 Ursae Majoris.[9] This is a red-hued star near the lower threshold of visibility to the naked eye, having an apparent visual magnitude that fluctuates around 6.70.[7] It is located at a distance of approximately 900 light years from the Sun based on parallax,[2] and is drifting further away with a radial velocity of +39 km/s.[7]
The stellar classification of this star is M3III,[5] while the infrared spectrum matches a class of M6III.[6] It is an aging red giant on the asymptotic giant branch that has exhausted the supply of both hydrogen and helium in its core, then cooled and expanded. At present it has 128[2] times the radius of the Sun, which is equivalent to 0.60 AU or 60% of the distance from the Sun to the Earth. On average, it radiates a luminosity approximately 1,766 times that of the Sun from its swollen photosphere at an effective temperature of 3,302 K.[2] Infrared observations show little or no evidence for an oxygen-rich dusty shell around the star.[4]
The variability of this star was reported by R. L. Walker in 1970 from the U.S. Naval Observatory.[10] It was given its variable star designation in 1973.[11] UX Lyncis has been classified as a semiregular variable ranging from magnitude 6.6 down to 6.78.[3] Its changes in brightness are complex, with a shorter period of 37.3 days due to the star's pulsations, and a longer period of 420 days possibly due to the star's rotation or convectively induced oscillatory thermal (COT) mode.[1] There is some evidence for an additional weak variability with a 29 day period.[12]
