Astronomy:RR Ursae Minoris
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 14h 57m 35.01625s[2] |
| Declination | +65° 55′ 56.9143″[2] |
| Apparent magnitude (V) | 4.44 - 4.85[3] |
| Characteristics | |
| Spectral type | M4.55 III[4] |
| B−V color index | 1.590±0.017[5] |
| Variable type | SRb[6] |
| Astrometry | |
| Radial velocity (Rv) | 6.21±0.30[7] km/s |
| Proper motion (μ) | RA: −82.191[2] mas/yr Dec.: +26.981[2] mas/yr |
| Parallax (π) | 10.0206 ± 0.6341[2] mas |
| Distance | 330 ± 20 ly (100 ± 6 pc) |
| Absolute magnitude (MV) | −1.11[5] |
| Orbit[8] | |
| Period (P) | 748.9 d |
| Eccentricity (e) | 0.13±0.05 |
| Inclination (i) | 79.6±2.4[9]° |
| Longitude of the node (Ω) | 48.0±2.5[9]° |
| Periastron epoch (T) | 2,444,419±46 JD |
| Argument of periastron (ω) (secondary) | 212±22° |
| Semi-amplitude (K1) (primary) | 8.3±0.3 km/s |
| Details | |
| Mass | 1.15±0.1[10] M☉ |
| Radius | 59.8+15.1 −3.6[2] R☉ |
| Luminosity | 756.7±54.4[2] L☉ |
| Surface gravity (log g) | 0.00[11] cgs |
| Temperature | 3,464[12] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
RR Ursae Minoris, abbreviated RR UMi, is a binary star[11] system in the northern circumpolar constellation of Ursa Minor. It can be viewed with the naked eye, typically having an apparent visual magnitude of around 4.710.[9] Based upon an annual parallax shift of 10.0 mas[2] as seen from Earth's orbit, it is located 330 light years away. The system is moving further from the Sun with a heliocentric radial velocity of +6 km/s.[7]
This star was found to have a variable radial velocity by J. H. Moore in 1910. It is a single-lined spectroscopic binary system with an orbital period of 2.05 years and an eccentricity (ovalness) of 0.13. The a sin i value is 84 Gm (0.56 astronomical unit|AU),[8] where a is the semimajor axis and i is the orbital inclination to the line of sight from the Earth. This gives a lower bound on the physical size of the orbit. The system is a source for X-ray and far-UV emission, with the latter most likely coming from the companion.[11]
The visible component is an aging red giant star on the asymptotic giant branch[11] with a stellar classification of M4.5 III.[4] It was found to be a variable star by J. Ashbrook in 1946,[14] and is catalogued as a semiregular variable of subtype SRb[6] that ranges from magnitude 4.44 to 4.85 over a period of 43.3 days.[3] However, variations in the period have been observed on a time scale of 30–60 days.[15] The star has 1.15[10] times the mass of the Sun and has expanded to 60 times the Sun's radius.[2] It is radiating 757[2] times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 3,464 K.[12]
References
- ↑ "Hipparcos Tools Interactive Data Access". ESA. https://www.cosmos.esa.int/web/hipparcos/interactive-data-access.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G. Gaia DR2 record for this source at VizieR.
- ↑ 3.0 3.1 Otero, Sebastian Alberto (16 November 2009). "RR Ursae Minoris". AAVSO Website. American Association of Variable Star Observers. http://www.aavso.org/vsx/index.php?view=detail.top&oid=37384. Retrieved 18 May 2014.
- ↑ 4.0 4.1 Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". Astrophysical Journal Supplement Series 71: 245. doi:10.1086/191373. Bibcode: 1989ApJS...71..245K.
- ↑ 5.0 5.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Samus', N. N; Kazarovets, E. V; Durlevich, O. V; Kireeva, N. N; Pastukhova, E. N (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 7.0 7.1 de Bruijne, J. H. J.; Eilers, A.-C. (October 2012). "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project". Astronomy & Astrophysics 546: 14. doi:10.1051/0004-6361/201219219. A61. Bibcode: 2012A&A...546A..61D.
- ↑ 8.0 8.1 Batten, A. H.; Fletcher, J. M. (July 1986). "A revised spectroscopic orbit for RR Ursae Minoris". Publications of the Astronomical Society of the Pacific 98: 647–650. doi:10.1086/131808. Bibcode: 1986PASP...98..647B.
- ↑ 9.0 9.1 9.2 Ren, Shulin; Fu, Yanning (March 2013). "Hipparcos Photocentric Orbits of 72 Single-lined Spectroscopic Binaries". The Astronomical Journal 145 (3): 7. doi:10.1088/0004-6256/145/3/81. 81. Bibcode: 2013AJ....145...81R.
- ↑ 10.0 10.1 Halabi, Ghina M.; Eid, Mounib El (2015). "Exploring masses and CNO surface abundances of red giant stars". Monthly Notices of the Royal Astronomical Society 451 (3): 2957. doi:10.1093/mnras/stv1141. Bibcode: 2015MNRAS.451.2957H.
- ↑ 11.0 11.1 11.2 11.3 Ortiz, Roberto; Guerrero, Martín A. (2016). "Ultraviolet emission from main-sequence companions of AGB stars". Monthly Notices of the Royal Astronomical Society 461 (3): 3036. doi:10.1093/mnras/stw1547. Bibcode: 2016MNRAS.461.3036O.
- ↑ 12.0 12.1 Soubiran, Caroline et al. (2016). "The PASTEL catalogue: 2016 version". Astronomy & Astrophysics 591: A118. doi:10.1051/0004-6361/201628497. Bibcode: 2016A&A...591A.118S.
- ↑ "RR UMi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=RR+UMi.
- ↑ Dettmar, R. -J.; Gieseking, F. (December 1983). "The intrinsically variable spectroscopic binary RR UMi". Astronomy and Astrophysics, Supplemental Series 54: 541–543. Bibcode: 1983A&AS...54..541D.
- ↑ Lloyd, C.; West, K. W. (May 1996). "Observations of Low-amplitude Late-Type Variables". Information Bulletin on Variable Stars 4335: 1. Bibcode: 1996IBVS.4335....1L.
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