Astronomy:4 Ursae Minoris
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Ursa Minor |
| Right ascension | 14h 08m 50.92654s[1] |
| Declination | +77° 32′ 51.0466″[1] |
| Apparent magnitude (V) | 4.80[2] |
| Characteristics | |
| Spectral type | K3-IIIb Fe-0.5[3] |
| B−V color index | 1.368[4] |
| Astrometry | |
| Radial velocity (Rv) | +5.86±0.10[5] km/s |
| Proper motion (μ) | RA: −30.45[1] mas/yr Dec.: +32.85[1] mas/yr |
| Parallax (π) | 7.14 ± 0.42[1] mas |
| Distance | 460 ± 30 ly (140 ± 8 pc) |
| Absolute magnitude (MV) | −1.06[4] |
| Orbit[6] | |
| Period (P) | 605.8 d |
| Semi-major axis (a) | 6.5 mas[7] |
| Eccentricity (e) | 0.137±0.012 |
| Inclination (i) | 136.0±5.1[7]° |
| Longitude of the node (Ω) | 325.5±2.8° |
| Periastron epoch (T) | 2,438,901.7±8.5 JD |
| Argument of periastron (ω) (secondary) | 311.8±5.2° |
| Semi-amplitude (K1) (primary) | 12.65±0.16 km/s |
| Details | |
| 4 UMi A | |
| Radius | 28[8] R☉ |
| Luminosity | 436.72[2] L☉ |
| Surface gravity (log g) | 1.73±0.45[9] cgs |
| Temperature | 4,165±48[9] K |
| Metallicity [Fe/H] | −0.19±0.11[9] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
4 Ursae Minoris is a binary star[6] system in the northern circumpolar constellation Ursa Minor. It is faintly visible to the naked eye with an apparent visual magnitude of 4.80.[2] Based upon an annual parallax shift of 7.14±0.42 mas[1] as seen from Earth's orbit, it is located roughly 460 light years from the Sun. It is moving further away with a heliocentric radial velocity of +5.9 km/s.[5]
This is a single-lined spectroscopic binary star system with an orbital period of 1.66 years and an eccentricity of 0.14.[7][6] The primary is a red giant of spectral type K3-IIIb Fe-0.5,[3] a star that has used up its core hydrogen and is expanding. The suffix notation indicates the spectrum displays a mild underabundance of iron for a star of its type. It has expanded to around 28[8] times the Sun's radius and is radiating 437[2] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,165 K.[9]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 3.0 3.1 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.
- ↑ 4.0 4.1 Ryon, Jenna et al. (August 2009), "Comparing the Ca ii H and K Emission Lines in Red Giant Stars", Publications of the Astronomical Society of the Pacific 121 (882): 842, doi:10.1086/605456, Bibcode: 2009PASP..121..842R.
- ↑ 5.0 5.1 De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics 546: A61, doi:10.1051/0004-6361/201219219, Bibcode: 2012A&A...546A..61D.
- ↑ 6.0 6.1 6.2 Scarfe, C. D. (1971), "A Revised Orbit for 4 Ursae Minoris", Publications of the Astronomical Society of the Pacific 83 (496): 807, doi:10.1086/129218, Bibcode: 1971PASP...83..807S.
- ↑ 7.0 7.1 7.2 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.
- ↑ 8.0 8.1 Pasinetti Fracassini, L. E. et al. (February 2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS)", Astronomy and Astrophysics 367 (2): 521–524, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P.
- ↑ 9.0 9.1 9.2 9.3 Koleva, M.; Vazdekis, A. (February 2012), "Stellar population models in the UV. I. Characterisation of the New Generation Stellar Library", Astronomy & Astrophysics 538: 13, doi:10.1051/0004-6361/201118065, A143, Bibcode: 2012A&A...538A.143K.
- ↑ "4 UMi". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=4+UMi.
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