Astronomy:Mu Leonis
| Observation data Epoch J2000.0 Equinox (celestial coordinates) | |
|---|---|
| Constellation | Leo |
| Right ascension | 09h 52m 45.81654s[1] |
| Declination | +26° 00′ 25.0319″[1] |
| Apparent magnitude (V) | 3.88[2] |
| Characteristics | |
| Spectral type | K2 IIIb CN1 Ca1[3] |
| U−B color index | +1.38[2] |
| B−V color index | +1.23[2] |
| Astrometry | |
| Radial velocity (Rv) | 14.03±0.19[4] km/s |
| Proper motion (μ) | RA: −217.31[1] mas/yr Dec.: −54.26[1] mas/yr |
| Parallax (π) | 26.28 ± 0.16[1] mas |
| Distance | 124.1 ± 0.8 ly (38.1 ± 0.2 pc) |
| Absolute magnitude (MV) | +0.83[5] |
| Details | |
| Mass | 1.5±0.1[6] M☉ |
| Radius | 14[4] R☉ |
| Luminosity | 63[4] L☉ |
| Surface gravity (log g) | 2.5[4] cgs |
| Temperature | 4,436[4] K |
| Metallicity [Fe/H] | +0.17[4] dex |
| Rotational velocity (v sin i) | 4.5[4] km/s |
| Age | 3.35±0.70[6] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Mu Leonis (μ Leonis, abbreviated Mu Leo, μ Leo), also named Rasalas /ˈræsəlæs/,[8][9] is a star in the constellation of Leo. The apparent visual magnitude of this star is 3.88,[2] which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 0.02628 arc seconds as measured by the Hipparcos satellite,[1] this system is 124 light-years (38.1 parsecs) from the Sun. In 2014, an exoplanet was discovered to be orbiting the star.
Nomenclature
μ Leonis (Latinised to Mu Leonis) is the star's Bayer designation.
It bore the traditional names Rasalas and Alshemali, both abbreviations of Ras al Asad al Shamaliyy.[10] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[11] to catalogue and standardize proper names for stars. The WGSN approved the name Rasalas for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.[9]
Properties
Mu Leonis is an evolved K-type giant star with a stellar classification of K2 IIIb CN1 Ca1.[3] The trailing notation indicates that, for a star of its type, it has stronger than normal absorption lines of cyanogen and calcium in its spectrum.[12] It has around 1.5 times the Sun's mass, but has expanded to around 14 times the Sun's radius. Mu Leonis shines with 63 times the luminosity of the Sun from an outer atmosphere that has an effective temperature of 4,436 K. It is around 3.35 billion years old.[4]
Planetary system
In 2014 it was announced that Mu Leonis has a planetary companion that is at least 2.4 times as massive as Jupiter and orbits with a period of 358 days. This planet was detected by measuring radial velocity variations caused by gravitational displacement from the orbiting body.[6]
| Companion | Mass | Semimajor axis (AU) | Orbital period | Eccentricity | Discovery year |
| b | ≤2.4±0.4 MJ | 1.1±0.1 | 357.8±1.2 days | 0.09±0.06 | 2014 |
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 Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data (SIMBAD), Bibcode: 1986EgUBV........0M.
- ↑ 3.0 3.1 Keenan, P.; McNeil, R. (October 1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series 71: 245–266, doi:10.1086/191373, Bibcode: 1989ApJS...71..245K.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M.
- ↑ Cardini, D. (January 2005), "Mg II chromospheric radiative loss rates in cool active and quiet stars", Astronomy and Astrophysics 430: 303–311, doi:10.1051/0004-6361:20041440, Bibcode: 2005A&A...430..303C.
- ↑ 6.0 6.1 6.2 Lee, B.-C. et al. (2014). "Planetary Companions in K giants β Cancri, μ Leonis, and β Ursae Minoris". Astronomy & Astrophysics 566: 7. doi:10.1051/0004-6361/201322608. A67. Bibcode: 2014A&A...566A..67L.
- ↑ "* mu. Leo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+mu.+Leo.
- ↑ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific (San Francisco, California) 48 (283): 139. doi:10.1086/124681. Bibcode: 1936PASP...48..139R.
- ↑ 9.0 9.1 "Naming Stars". IAU.org. https://www.iau.org/public/themes/naming_stars/. Retrieved 16 December 2017.
- ↑ Allen, Richard Hinckley (1899), Star-names and Their Meanings, G. E. Stechert, https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA263, retrieved 2016-09-28.
- ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016.
- ↑ Keenan, Philip C. (August 1987), "Spectral types and their uses", Publications of the Astronomical Society of the Pacific 99: 713–723, doi:10.1086/132036, Bibcode: 1987PASP...99..713K.
External links
- Kaler, James B., "Rasalas", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/rasalas.html, retrieved 19 August 2014.
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