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UX Lyncis
	; 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)
Observation data; Epoch J2000 Equinox J2000
Constellation	Lynx
Right ascension	09h 03m 47.10789s
Declination	+38° 44′ 31.6542″
Apparent magnitude (V)	6.6 - 6.78
Characteristics
Evolutionary stage	AGB
Spectral type	M3III or M6III
B−V color index	1.356±0.011
Variable type	SRb:
Astrometry
Radial velocity (Rv)	+38.60±0.64 km/s
Proper motion (μ)	RA: −17.176 mas/yr ; Dec.: −20.823 mas/yr
Parallax (π)	3.6035 ± 0.4422 mas
Distance	approx. 900 ly ; (approx. 280 pc)
Absolute bolometric; magnitude (Mbol)	−0.15
Details
Radius	128.38+0.92; −9.89 R☉
Luminosity	1,766±242 L☉
Temperature	3302+135; −11 K
Other designations
	UX Lyn, BD+39°2193, HD 77443, HIP 44481, SAO 61226, IRAS 09005+3856
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]

References

^ ^a ^b Percy, John R.; et al. (2001). "Long-Term VRI Photometry of Small-Amplitude Red Variables. I. Light Curves and Periods". The Publications of the Astronomical Society of the Pacific. 113 (786): 983–96. Bibcode:2001PASP..113..983P. doi:10.1086/322153.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ ^a ^b Watson, Christopher (4 January 2010). "UX Lyncis". AAVSO Website. American Association of Variable Star Observers. Retrieved 10 March 2016.
^ ^a ^b ^c Sloan, G. C.; Price, S. D. (December 1998). "The Infrared Spectral Classification of Oxygen-rich Dust Shells". The Astrophysical Journal Supplement Series. 119 (2): 141–158. Bibcode:1998ApJS..119..141S. doi:10.1086/313156.
^ ^a ^b Sato, K.; Kuji, S. (November 1990). "MK classification and photometry of stars used for time and latitude observations at Mizusawa and Washington". Astronomy & Astrophysics Supplement Series. 85: 1069. Bibcode:1990A&AS...85.1069S.
^ ^a ^b Lebzelter, T.; Hron, J. (December 2003). "Technetium and the third dredge up in AGB stars. I. Field stars". Astronomy and Astrophysics. 411 (3): 533–542. arXiv:astro-ph/0310018. Bibcode:2003A&A...411..533L. doi:10.1051/0004-6361:20031458. S2CID 18879265.
^ ^a ^b ^c ^d ^e Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
^ "UX Lyn". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-22.
^ Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 2. Sky Publishing Corporation and the European Space Agency. p. 620. ISBN 0-933346-83-2.
^ Walker, R. L. (July 1970). "Light Variations of BD+39°2193". Information Bulletin on Variable Stars. 447: 1. Bibcode:1970IBVS..447....1W.
^ Kukarkin, B. V.; Kholopov, P. N.; Kukarkina, N. P.; Perova, N. B. (October 1973). "59th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 834. Bibcode:1973IBVS..834....1K. Retrieved 21 December 2024.
^ Percy, John R.; et al. (April 2003). "Multiperiodicity in Five Small-Amplitude Pulsating Red Giants". The Publications of the Astronomical Society of the Pacific. 115 (806): 479–483. Bibcode:2003PASP..115..479P. doi:10.1086/374199. S2CID 120018973.