56 Ursae Majoris

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56 Ursae Majoris
Observation data
Epoch J2000        Equinox J2000
Constellation Ursa Major
Right ascension 11h 22m 49.58373s [1]
Declination +43° 28′ 57.7267″ [1]
Apparent magnitude  (V)5.03 [2]
Characteristics
Spectral type G7IIIBa0.3 [3]
U−B color index +0.82 [4]
B−V color index +1.02 [4]
Astrometry
Radial velocity (Rv)1.01±0.05 [5] km/s
Proper motion (μ)RA: −35.561 mas/yr [6]
Dec.: −10.651 mas/yr [6]
Parallax (π)5.8813±0.0930  mas [6]
Distance 555 ± 9  ly
(170 ± 3  pc)
Orbit [7]
Period (P)16,911+438
−401 days
Semi-major axis (a)22.9+1.0
−1.1 AU
Eccentricity (e)0.562+0.012
−0.012
Inclination (i)68+3.6
−3.4°
Longitude of the node (Ω)60+3
−3°
Periastron epoch (T)2468401+432
−385
Argument of periastron (ω)
(secondary)		286+2.3
−2.3°
Details [7]
56 UMa A
Mass 4.3±0.2  M☉
Radius 21.16±0.86 [8]   R☉
Surface gravity (log g)2.30 [8]   cgs
Temperature 4,917±34 [8]   K
Metallicity [Fe/H]0.05  dex
56 UMa B
Mass 1.31+0.11
−0.12  M☉
Other designations
BD+44°2083, FK5 2908, HD 98839, HIP 55560, HR 4392, SAO 43719
Database references
SIMBAD data

56 Ursae Majoris (56 UMa) is a binary star in the constellation Ursa Major. At an apparent magnitude of 5.03, it is a faint star but visible to the naked eye depending on factors such as light pollution and eyesight. Parallax measurements derive a distance of 555 light-years.

It is a single-lined spectroscopic binary with an orbital period of about 45 years. [5] The primary is an evolved giant star with a spectral class G7IIIBa0.3, a Barium star. [3] The companion star is likely a heavy neutron star born by a supernova that exploded around 100,000 years ago. [7]

References

  1. 1 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.
  2. ↑ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. 1 2 Lu, Phillip K. (1991). "Taxonomy of barium stars". Astronomical Journal. 101: 2229–2254. Bibcode:1991AJ....101.2229L. doi: 10.1086/115845 .
  4. 1 2 Fernie, J. D. (1983). "New UBVRI photometry for 900 supergiants". Astrophysical Journal Supplement Series. 52 (7–22): 7. Bibcode:1983ApJS...52....7F. doi: 10.1086/190856 .
  5. 1 2 Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv: astro-ph/0406573 . Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213. S2CID   119387088.
  6. 1 2 3 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  7. 1 2 3 Escorza, A.; Karinkuzhi, D.; Jorissen, A.; Van Eck, S.; Schmelz, J. T.; Verschuur, G. L.; Boffin, H. M. J.; De Rosa, R. J.; Van Winckel, H. (2023). "A neutron star candidate in the long-period binary 56 UMa". Astronomy and Astrophysics. 670: L14. arXiv: 2301.06531 . Bibcode:2023A&A...670L..14E. doi:10.1051/0004-6361/202245796. S2CID   255941814.
  8. 1 2 3 Baines, Ellyn K.; Clark, James H.; Kingsley, Bradley I.; Schmitt, Henrique R.; Stone, Jordan M. (2025-05-07). "Vintage NPOI: New and Updated Angular Diameters for 145 Stars". The Astronomical Journal. 169 (6): 293. arXiv: 2506.02912 . doi: 10.3847/1538-3881/adc930 . ISSN   1538-3881.


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