Mu Leonis
{{Short description|Star in the constellation Leo}}
{{Starbox begin
| name=Mu Leonis
}}
{{Starbox observe
| constell = Leo
| dec = {{DEC|+26|00|25.0319}}
}}
{{Starbox character
| type = Red giant branch
| class = {{nowrap|K2 IIIb CN1 Ca1}}
| variable =
}}
{{Starbox astrometry
| radial_v = {{Val|14.03|0.19}}
| parallax = 26.28
| p_error = 0.16
}}
{{Starbox detail
| temperature = {{val|4519|23|fmt=commas}}
| metal_fe = {{val|0.27|0.03}}
| rotation =
| age_gyr = {{Val|3.35|0.70}}, ~5.0
}}
{{Starbox catalog
| names = Rasalas, Alshemali, μ Leo, 24 Leonis, BD+26°2019, HD 85503, HIP 48455, HR 3905, SAO 81064
}}
{{Starbox reference
|Simbad=mu+Leo
}}
{{Starbox end}}
Mu Leonis (μ Leonis, abbreviated Mu Leo, μ Leo), also named Rasalas {{IPAc-en|'|r|æ|s|@|l|æ|s}},{{cite journal
|title=Star Name Pronunciation
|last=Rumrill |first=H. B.
|journal=Publications of the Astronomical Society of the Pacific
|volume=48
|number=283
|date=June 1936
|page=139 |location = San Francisco, California
|doi=10.1086/124681
|bibcode=1936PASP...48..139R |s2cid=120743052 |doi-access=free
}}{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=16 December 2017}} is a star in the constellation of Leo. The apparent visual magnitude of this star is 3.88, 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, this system is {{Convert|38.1|pc|ly|abbr=off|lk=on|disp=flip}} 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. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN){{citation
| url=https://www.iau.org/science/scientific_bodies/working_groups/280/
| title=IAU Working Group on Star Names (WGSN)
| publisher=International Astronomical Union
| accessdate=22 May 2016 | postscript=. }} 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.
Properties
Mu Leonis is an evolved K-type red giant star with a stellar classification of {{nowrap|K2 IIIb CN1 Ca1}}. It is believed to be on the red giant branch, where it is fusing hydrogen into helium in a shell surrounding an inert helium core.{{Cite journal |last1=Howes |first1=Louise M. |last2=Lindegren |first2=Lennart |last3=Feltzing |first3=Sofia |last4=Church |first4=Ross P. |last5=Bensby |first5=Thomas |date=2019-02-01 |title=Estimating stellar ages and metallicities from parallaxes and broadband photometry: successes and shortcomings |url=https://www.aanda.org/articles/aa/abs/2019/02/aa33280-18/aa33280-18.html |journal=Astronomy & Astrophysics |language=en |volume=622 |pages=A27 |doi=10.1051/0004-6361/201833280 |issn=0004-6361|arxiv=1804.08321 |bibcode=2019A&A...622A..27H }} 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. It has around 1.5 times the Sun's mass and is estimated to be 5 billion years old, older than the Sun's age of 4.6 billion years. Using interferometry with the Navy Precision Optical Interferometer, its diameter was determined to be 11.8 times that of the Sun. Mu Leonis shines with 57 times the luminosity of the Sun from an outer atmosphere that has an effective temperature of 4,606 K.
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.
Later in 2024, a study using astrometry from the Gaia spacecraft find a mass of {{jupiter mass|12.6}}, which the authors interpret as a likely upper limit, as the large level of RUWE in the astrometric solution{{emdash}}which could be caused by a companion around the star{{emdash}}might be just the result of systematic calibration errors. This indicate that Mu Leonis b lies in the planetary-mass regime and is not a brown dwarf.
{{OrbitboxOnePlanet
| mass = ≥{{Val|2.4|0.4}} and ≤12.6
| semimajor = {{Val|1.1|0.1}}
| period = {{Val|357.8|1.2}}
| eccentricity = {{Val|0.09|0.06}}
| year = 2014
}}
References
{{reflist|refs=
{{Citation |last1=Soubiran |first1=C. |last2=Creevey |first2=O. L. |last3=Lagarde |first3=N. |last4=Brouillet |first4=N. |last5=Jofré |first5=P. |last6=Casamiquela |first6=L. |last7=Heiter |first7=U. |last8=Aguilera-Gómez |first8=C. |last9=Vitali |first9=S. |last10=Worley |first10=C. |last11=de Brito Silva |first11=D. |date=2024-02-01 |title=Gaia FGK benchmark stars: Fundamental Teff and log g of the third version |bibcode=2024A&A...682A.145S |journal=Astronomy and Astrophysics |volume=682 |pages=A145 |doi=10.1051/0004-6361/202347136 |issn=0004-6361}} [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/A%2BA/682/A145&HIP=HIP48455 Mu Leonis' database entry] at VizieR.
| title=Validation of the new Hipparcos reduction
| last1=van Leeuwen | first1=F.
| journal=Astronomy and Astrophysics
| volume=474 | issue=2 | pages=653–664 | date=2007
| arxiv=0708.1752 | bibcode=2007A&A...474..653V
| doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}
| title=Mg II chromospheric radiative loss rates in cool active and quiet stars
| last1=Cardini | first1=D. | postscript=.
| journal=Astronomy and Astrophysics
| volume=430 | pages=303–311 | date=January 2005
| doi=10.1051/0004-6361:20041440 | bibcode=2005A&A...430..303C |arxiv = astro-ph/0409683 | s2cid=12136256 }}
| title=Star-names and Their Meanings
| first1=Richard Hinckley | last1=Allen
| publisher=G. E. Stechert | year=1899
| url=https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA263
| accessdate=2016-09-28 | postscript=. }}
| title=Planetary Companions in K giants β Cancri, μ Leonis, and β Ursae Minoris
| display-authors=1
| last1=Lee | first1=B.-C. | last2=Han | first2=I.
| last3=Park | first3=M.-G. | last4=Mkrtichian | first4=D.E.
| last5=Hatzes | first5=A.P. | last6=Kim | first6=K.-M.
| journal=Astronomy & Astrophysics
| volume=566 | id=A67 | pages=7 | year=2014
| doi=10.1051/0004-6361/201322608 | bibcode=2014A&A...566A..67L
| arxiv=1405.2127 | s2cid=118631934
}}
| first1=P. | last1=Keenan | first2=R. | last2=McNeil
| title = The Perkins catalog of revised MK types for the cooler stars
| journal=Astrophysical Journal Supplement Series
| volume=71 | pages=245–266 | date=October 1989
| bibcode=1989ApJS...71..245K | doi=10.1086/191373
| postscript=. }}
| display-authors=1
| last1=Massarotti | first1=Alessandro | last2=Latham | first2=David W.
| last3=Stefanik | first3=Robert P. | last4=Fogel | first4=Jeffrey
| title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity
| journal=The Astronomical Journal
| volume=135 | issue=1 | pages=209–231 | date=January 2008
| doi=10.1088/0004-6256/135/1/209 | bibcode=2008AJ....135..209M
| s2cid=121883397 | postscript=. | doi-access=free }}
| title=Spectral types and their uses
| last1=Keenan | first1=Philip C.
| journal=Publications of the Astronomical Society of the Pacific
| volume=99 | pages=713–723 | date=August 1987
| doi=10.1086/132036 | bibcode=1987PASP...99..713K
| postscript=. | doi-access=free}}
| last1=Mermilliod | first1=J.-C.
| title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)
| journal=Catalogue of Eggen's UBV Data
| publisher=SIMBAD | date=1986
| bibcode=1986EgUBV........0M | postscript=. }}
| title=* mu. Leo
| access-date=2016-09-28 | postscript=. }}
}}
External links
- {{citation
| first1=James B. | last1=Kaler |
title=Rasalas| work=Stars
| publisher=University of Illinois
| url=http://stars.astro.illinois.edu/sow/rasalas.html
| accessdate=19 August 2014 | postscript=. }}
{{Stars of Leo|state=collapsed}}
{{DEFAULTSORT:Mu Leonis}}