Astronomy:R Ursae Majoris
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Major[1] |
| Right ascension | 10h 44m 38.472s[2] |
| Declination | +68° 46′ 32.68″[2] |
| Apparent magnitude (V) | 6.5 – 13.7[1] |
| Characteristics | |
| Evolutionary stage | AGB[3] |
| Spectral type | M3e-M9e[1] |
| Variable type | Mira variable[1] |
| Astrometry | |
| Radial velocity (Rv) | +40.49[4] km/s |
| Proper motion (μ) | RA: −40.665[2] mas/yr Dec.: −24.566[2] mas/yr |
| Parallax (π) | 1.97 ± 0.05[4] mas |
| Distance | 1,657 ± 42 ly (508±13 pc) |
| Details | |
| Mass | 2.8[5] M☉ |
| Radius | 230[lower-alpha 1] R☉ |
| Luminosity | 5,000±900[3] L☉ |
| Surface gravity (log g) | 1.75[5] cgs |
| Temperature | 3,200+100 −400[3] K |
| Metallicity [Fe/H] | −0.54[5] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
R Ursae Majoris is a Mira variable star in the constellation Ursa Major. Parallax measurements give a distance of 1,660 light-years (508 parsecs) light-years.[4]
Characteristics
R Ursae Majoris is a Mira variable with a pulsation period of 301.45 days. The star's apparent magnitude varies from +6.5 and +13.7, which is too faint to be visible to the naked eye, and its spectral type varies from M3e to M9e, with the 'e' indicating emission lines in the spectrum. It was discovered to be a variable star in 1853 by Norman Pogson.[1]
This is an evolved star, currently in the asymptotic giant branch stage of evolution. It is roughly 5,000 times as luminous as the Sun, having a size 230 times that of the Sun[lower-alpha 1] and a cool effective temperature of 3,200 K,[3] giving it a red hue typical of M-type stars.[7] The high luminosity and pulsations induce stellar mass loss, forming a circumstellar envelope made up of gas and dust. The dust shell is modelled to have an inner radius of 3,700 solar radii (17 astronomical units) and an outer radius of 37,000 R☉ (170 au). At the inner edge of the shell, the dust's temperature is of 760 K.[3]
R Ursae Majoris may have a companion. It displays an excess of ultraviolet radiation, which might be coming from a hotter star. This star is estimated to have an effective temperature of 9,200+1,100
−300 K and a luminosity 0.85+0.40
−0.20 times solar (L☉), although the luminosity seems far too low for a main sequence star of the expected temperature.[8]
Notes
- ↑ 1.0 1.1 Calculated, using the Stefan-Boltzmann law and the star's effective temperature and luminosity, with respect to the solar nominal effective temperature of 5,772 K:
References
- ↑ 1.0 1.1 1.2 1.3 1.4 "VSX : Detail for R UMa". https://vsx.aavso.org/index.php?view=detail.top&oid=37105.
- ↑ 2.0 2.1 2.2 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940 Gaia DR3 record for this source at VizieR.
- ↑ 3.0 3.1 3.2 3.3 3.4 Alonso-Hernández, J.; Sánchez Contreras, C.; Sahai, R.; Sanz-Forcada, J. (2026-04-13). "The dusty envelopes of asymptotic giant branch stars with ultraviolet excesses". Astronomy & Astrophysics. doi:10.1051/0004-6361/202659537. ISSN 0004-6361.
- ↑ 4.0 4.1 4.2 Nakagawa, Akiharu; Kurayama, Tomoharu; Matsui, Makoto; Omodaka, Toshihiro; Honma, Mareki; Shibata, Katsunori M.; Sato, Katsuhisa; Jike, Takaaki (October 2016). "Parallax of a Mira variable R Ursae Majoris studied with astrometric VLBI" (in en). Publications of the Astronomical Society of Japan 68 (5): 78. doi:10.1093/pasj/psw069. ISSN 0004-6264. Bibcode: 2016PASJ...68...78N.
- ↑ 5.0 5.1 5.2 Khalatyan, A.; Anders, F.; Chiappini, C.; Queiroz, A. B. A.; Nepal, S.; Dal Ponte, M.; Jordi, C.; Guiglion, G. et al. (2024). "Transferring spectroscopic stellar labels to 217 million Gaia DR3 XP stars with SHBoost". Astronomy and Astrophysics 691: A98. doi:10.1051/0004-6361/202451427. Bibcode: 2024A&A...691A..98K.
- ↑ "R UMa". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=R+UMa.
- ↑ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html. Retrieved 2012-01-16.
- ↑ Sahai, R.; Findeisen, K.; de Paz, A. Gil; Sánchez Contreras, C. (2008-12-20). "Binarity in Cool Asymptotic Giant Branch Stars: AGALEXSearch for Ultraviolet Excesses". The Astrophysical Journal 689 (2): 1274–1278. doi:10.1086/592559. ISSN 0004-637X.
Coordinates: 
10h 44m 38.472s, +68° 46′ 32.68″
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