Phi Leonis
{{Short description|Star in the constellation Leo}}
{{Starbox begin
| name=φ Leonis
}}
{{Starbox observe
| constell = Leo
| dec = {{DEC|−03|39|05.7770}}
}}
{{Starbox character
| variable =
}}
{{Starbox astrometry
| parallax = 17.71
| p_error = 0.25
}}
{{Starbox detail
| temperature = {{Val|7680|261|fmt=commas}}
| metal_fe =
}}
{{Starbox catalog
| names = φ Leo, 74 Leo, BD−02°3315, FK5 1292, HD 98058, HIP 55084, HR 4368, SAO 138102
}}
{{Starbox reference
| Simbad = phi+Leo
}}
{{Starbox end}}
Phi Leonis (φ Leo) is a single star in the constellation Leo. It is bright enough to be seen with the naked eye, having an apparent visual magnitude of 4.46. Based upon parallax measurements, the distance to Phi Leo is around 184 light years.
The spectrum of this star fits a stellar classification of A7IVn, which suggests it is an A-type subgiant star that has left the main sequence and is evolving into a giant star. It is being viewed with the plane of the star's equator lying close the line of sight from the Earth, and shows a high rotation rate with a projected rotational velocity of 254 km/s. This rapid spin is giving the star an oblate shape with an equatorial bulge that is 29% larger than the polar radius.
Phi Leonis has been mentioned as a shell star—indicating that there is a circumstellar disk of gas around the star's equator—and may display a slight variability. Sporadic variation of the spectra on the time scale of minutes up to months in duration suggests that solid, cometary bodies are in orbit around the star, with objects approaching close enough for refractory materials to sublimate. Most exocomet hosts do have a circumstellar disk, which can act as an exocomet reservoir. Cold dust around Phi Leonis was not detected, and the star is not associated with a warm debris disk.{{Cite journal|last1=Cataldi|first1=Gianni|last2=Moór|first2=Attila|last3=Ohashi|first3=Nagayoshi|last4=Eiroa|first4=Carlos|last5=Grady|first5=Carol|last6=Rebollido|first6=Isabel|date=2019-02-22|title=No Detection of Cold Dust around the Potential Exocomet Host ϕ Leo|journal=Research Notes of the AAS|language=en|volume=3|issue=2|pages=39|doi=10.3847/2515-5172/ab082b|bibcode=2019RNAAS...3...39C |s2cid=127680980 |issn=2515-5172 |doi-access=free }}
References
{{reflist|refs=
| 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=. }}
| display-authors=1 | last1=Royer | first1=F.
| last2=Zorec | first2=J. | last3=Gómez | first3=A. E.
| title=Rotational velocities of A-type stars. III. Velocity distributions
| journal=Astronomy and Astrophysics
| volume=463 | issue=2 | pages=671–682 | date=February 2007
| doi=10.1051/0004-6361:20065224 | bibcode=2007A&A...463..671R
| arxiv=astro-ph/0610785 | s2cid=18475298 | postscript=. }}
| title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic Fundamental Stars with Direct Solutions
| journal=Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg
| volume=35
| display-authors=1
| last1=Wielen | first1=R. | last2=Schwan | first2=H.
| last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H.
| last5=Jahreiß | first5=H. | last6=Jährling | first6=R.
| publisher=Astronomisches Rechen-Institut Heidelberg
| issue=35 | pages=1
| date=1999
| bibcode=1999VeARI..35....1W | postscript=. }}
| last1=David | first1=Trevor J.
| last2=Hillenbrand | first2=Lynne A.
| title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets
| journal=The Astrophysical Journal
| volume=804 | issue=2 | pages=146 | year=2015
| bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146
| arxiv=1501.03154 | s2cid=33401607
| postscript=. }}
| last1=van Belle, Gerard T. | first1=Gerard T.
| title=Interferometric observations of rapidly rotating stars
| journal=The Astronomy and Astrophysics Review
| volume=20 | issue=1 | page=51 |date=March 2012
| doi=10.1007/s00159-012-0051-2 | bibcode=2012A&ARv..20...51V
| arxiv=1204.2572 | s2cid=119273474
| postscript=. }}
| display-authors=1 | last1=Pasinetti Fracassini | first1=L. E.
| last2=Pastori | first2=L. | last3=Covino | first3=S.
| last4=Pozzi | first4=A.
| title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
| journal=Astronomy & Astrophysics
| volume=367 | issue=2 | pages=521–24 | date=2001
| bibcode=2001A&A...367..521P | doi=10.1051/0004-6361:20000451
| arxiv=astro-ph/0012289 | s2cid=425754 | postscript=. }}
| last1=Hauck | first1=B. | last2=Jaschek | first2=C.
| title=A-shell stars in the Geneva system
| journal=Astronomy and Astrophysics
| volume=354 | pages=157–162 | date=February 2000
| bibcode=2000A&A...354..157H | postscript=. }}
| display-authors=1 | last1=McDonald | first1=I.
| last2=Zijlstra | first2=A. A. | last3=Boyer | first3=M. L.
| title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars
| journal=Monthly Notices of the Royal Astronomical Society
| volume=427 | issue=1 | pages=343–57 | date=2012
| bibcode=2012MNRAS.427..343M | arxiv=1208.2037
| doi=10.1111/j.1365-2966.2012.21873.x | doi-access=free | s2cid=118665352 | postscript=. }}
| title=Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars | year=2021
| last1=Hutter | first1=D. J. | last2=Tycner | first2=C.
| last3=Zavala | first3=R. T. | last4=Benson | first4=J. A.
| last5=Hummel | first5=C. A. | last6=Zirm | first6=H.
| journal=The Astrophysical Journal Supplement Series
| volume=257 | issue=2 | page=69
| doi=10.3847/1538-4365/ac23cb | arxiv=2109.06839
| bibcode=2021ApJS..257...69H | s2cid=237503492 | 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=. }}
| display-authors=4
| first1=C. | last1=Eiroa | first2=I. | last2=Rebollido
| first3=B. | last3=Montesinos | first4=E. | last4=Villaver
| first5=O. | last5=Absil | first6=Th. | last6=Henning
| first7=A. | last7=Bayo | first8=H. | last8=Canovas
| first9=A. | last9=Carmona | first10=Ch. | last10=Chen
| first11=S. | last11=Ertel | first12=D. P. | last12=Iglesias
| first13=R. | last13=Launhardt | first14=J. | last14=Maldonado
| first15=G. | last15=Meeus | first16=A. | last16=Moór
| first17=A. | last17=Mora | first18=A. J. | last18=Mustill
| first19=J. | last19=Olofsson | first20=G. | last20=Rauw
| first21=P. | last21=Riviere-Marichalar
| first22=A. | last22=Roberge
| title=Exocomet signatures around the A-shell star Φ Leo?
| journal=Astronomy & Astrophysics | volume=L1 | pages=594 | date=September 14, 2016
| arxiv=1609.04263 | postscript=. |doi = 10.1051/0004-6361/201629514 |bibcode = 2016A&A...594L...1E | s2cid=41231308 | url=http://orbi.ulg.ac.be/bitstream/2268/204875/1/aa29514-16.pdf}}
| title=ups Leo
| accessdate=2016-09-29 | postscript=. }}
}}
{{Stars of Leo|state=collapsed}}
{{DEFAULTSORT:Phi Leonis}}