Article · Wikipedia archive · Last revised Jul 16, 2026

34 Boötis

34 Boötis, also named Alrumh, is a single variable star 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. 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 an apparent visual magnitude of around five. It is moving away from the Earth with a heliocentric radial velocity of +5.6 km/s.

Last revised
Jul 16, 2026
Read time
≈ 3 min
Length
680 w
Citations
28
Source
Wikipedia ↗
34 Boötis
Location of 34 Boötis (circled in red)
Observation data
Epoch J2000      Equinox ICRS
Constellation Boötes1
Right ascension 14h 43m 25.36304s2
Declination +26° 31′ 40.2663″2
Apparent magnitude (V) 4.49 - 5.403
Characteristics
Evolutionary stage AGB4
Spectral type M3− III5
B−V color index 1.672±0.0061
Variable type Semi-regular3
Astrometry
Radial velocity (Rv)+5.60±0.491 km/s
Proper motion (μ) RA: −13.572 mas/yr
Dec.: −16.082 mas/yr
Parallax (π)4.63±0.28 mas2
Distance700 ± 40 ly
(220 ± 10 pc)
Absolute magnitude (MV)−1.861
Details6
Mass2.20±0.23 M☉
Radius129.36+8.42
−7.49 R☉
Luminosity2,802±367 L☉
Surface gravity (log g)1.24 cgs
Temperature3,691±50 K
Age1.05±0.27 Gyr
Other designations
Alrumh, 34 Boo, W Boötis, BD+27°2413, FK5 1383, GC 19831, HD 129712, HIP 71995, HR 5490, SAO 834887
Database references
SIMBADdata

34 Boötis, also named Alrumh,8 is a single9 variable star3 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 an apparent visual magnitude of around five. It is moving away from the Earth with a heliocentric radial velocity of +5.6 km/s.1

The visual band light curve of W Boötis, adapted from Percy et al. (1997)10 source ↗

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,3 with some evidence of longer term variation and mode switching.10 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.11 Each has a margin of error of about 5%, but they differ from each other by far more than 5%.

Al-Rumḥ (الرُّمْح), the Lance, is an Arabic asterism in the area of ε Boötis (Izar), η Boötis (Muphrid), σ Boötis (Genghe), and υ Boötis. 34 Boötis is a star in this area near the otherwise-named ε Boötis. The IAU Working Group on Star Names approved the name Alrumh for this star on 15 April 2026.8

References

References

  1. 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. XHIP record for this object at VizieR.
  2. 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.
  3. 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.
  4. Eggen, Olin J. (1992). "Asymptotic Giant Branch Stars Near the Sun". The Astronomical Journal. 104: 275. Bibcode:1992AJ....104..275E. doi:10.1086/116239.
  5. 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.
  6. 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.
  7. "34 Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved May 11, 2019.
  8. "IAU Catalog of Star Names". Retrieved 20 April 2026.
  9. 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.
  10. 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.
  11. 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.