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34 Boötis
	; The visual band light curve of W Boötes, adapted from Percy et al. (1997)
Observation data; Epoch J2000 Equinox J2000
Constellation	Boötes
Right ascension	14h 43m 25.36304s
Declination	+26° 31′ 40.2663″
Apparent magnitude (V)	4.80 (4.49 - 5.40)
Characteristics
Spectral type	M3− III
B−V color index	1.672±0.006
Variable type	Semi-regular
Astrometry
Radial velocity (Rv)	+5.60±0.49 km/s
Proper motion (μ)	RA: –13.57 mas/yr ; Dec.: −16.08 mas/yr
Parallax (π)	4.63 ± 0.28 mas
Distance	700 ± 40 ly ; (220 ± 10 pc)
Absolute magnitude (MV)	−1.86
Details
Mass	2.20±0.23 M☉
Radius	129.36+8.42; −7.49 R☉
Luminosity	2,802±367 L☉
Surface gravity (log g)	1.24 cgs
Temperature	3,691±50 K
Age	1.05±0.27 Gyr
Other designations
	34 Boo, W Boötis, BD+27°2413, FK5 1383, GC 19831, HD 129712, HIP 71995, HR 5490, SAO 83488
Database references
SIMBAD	data

34 Boötis is a single^[8] variable star^[4] in the northern constellation Boötes, located around 700 light years away from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction of 0.49±0.02 due to interstellar dust.^[6] It has the variable star designation W Boötis; 34 Boötis is the Flamsteed designation. This object is visible to the naked eye as a faint, red-hued star with a baseline apparent visual magnitude of 4.80.^[3] It is moving away from the Earth with a heliocentric radial velocity of +5.6 km/s.^[3]

This is an aging red giant star with a stellar classification of M3− III,^[5] which indicates it has exhausted the supply of hydrogen at its core and evolved off the main sequence branch. It is classified as a semiregular variable with a brightness that varies from magnitude +4.49 down to +5.4 with a period of 25 days,^[4] with some evidence of longer term variation and mode switching.^[1] The star is around a billion years old with 2.2 times the mass of the Sun and has expanded to 129 times the size of the Sun. It is radiating 2,802 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,691 K.^[6]

The parallax calculated in the new Hipparcos reduction is 4.63±0.28 mas,^[2] and in Gaia Data Release 2 the parallax is given as 6.3168±0.2900 max.^[9] Each has a margin of error of about 5%, but they differ from each other by far more than 5%.

References

^ ^a ^b Percy, John R.; et al. (April 1997), "Sorting Out W Bootis and Its Comparison Stars", Information Bulletin on Variable Stars, 4467: 1, Bibcode:1997IBVS.4467....1P.
^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b ^c ^d ^e ^f 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.
^ ^a ^b ^c ^d Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
^ ^a ^b Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins Catalog of Revised MK Types for the Cooler Stars", The Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373, S2CID 123149047.
^ ^a ^b ^c Baines, E.; et al. (2017), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal, 155 (1): 30, arXiv:1712.08109, Bibcode:2018AJ....155...30B, doi:10.3847/1538-3881/aa9d8b, S2CID 119427037.
^ "34 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 11, 2019.
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
^ 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.