mu Hydrae
{{Short description|Star in the constellation Hydra}}
{{Starbox begin
| name = μ Hydrae
}}
{{Starbox observe
| epoch = J2000.0
| constell = Hydra
| dec = {{DEC|−14|19|56.2675}}
}}
{{Starbox character
| r-i =
}}
{{Starbox astrometry
| radial_v = {{Val|+40.81|0.36}}
| parallax = 13.93
| p_error = 0.18
}}
{{Starbox detail
| mass =
| radius = 45
| temperature = {{Val|3999|8|fmt=commas}}
| gravity = 1.5
| metal_fe = −0.12
| rotational_velocity = 6.0
| age_myr =
}}
{{Starbox catalog
| names = μ Hya, 42 Hydrae, BD−16°3052, FK5 389, HD 90432, HIP 51069, HR 4094, SAO 155980.
}}
{{Starbox reference
| Simbad = mu+Hya
}}
{{starbox end}}
μ Hydrae, Latinised as Mu Hydrae, is a solitary, orange-hued star in the equatorial constellation of Hydra. It is visible to the naked eye with an apparent visual magnitude of 3.83. Positioned just 1.8° to the south-southwest is the planetary nebula NGC 3242. Mu Hydrae has an annual parallax shift of 13.93 mas, which yields a distance estimate of 234 light years.
This is an evolved K-type giant star with a stellar classification of K4 III, having used up its core hydrogen and has expanded to around 45 times the radius of the Sun. It is a suspected variable star, with a brightness that varies about 0.03 in magnitude. The relatively cool outer atmosphere has an effective temperature of 3999 K.
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=. }}
| title=XHIP: An extended hipparcos compilation
| last1=Anderson | first1=E. | last2=Francis | first2=Ch.
| journal=Astronomy Letters
| volume=38 | issue=5 | pages=331 | year=2012
| bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
| arxiv=1108.4971 | s2cid=119257644 | postscript=. }}
| title=Herschel 400 Observing Guide
| first1=Steve | last1=O'Meara | postscript=.
| publisher=Cambridge University Press
| year=2007 | isbn=978-0521858939 | page=107
| url=https://books.google.com/books?id=Nyh9fAC_tpIC&pg=PA107 }}
| last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A.
| title=A catalogue of multiplicity among bright stellar systems
| journal=Monthly Notices of the Royal Astronomical Society
| volume=389 | issue=2 | pages=869–879 | date=September 2008
| doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E
| arxiv=0806.2878 | s2cid=14878976 | postscript=. }}
| 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 | display-authors=1 | 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
| year=1986 | publisher=SIMBAD | bibcode=1986EgUBV........0M
| postscript=. }}
| first1=N. |last1=Houk | first2=M. |last2=Smith-Moore
| title=University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Declinations -26°.0 to -12°.0
| publisher=Department of Astronomy, University of Michigan
| volume=4 | date=1988 | bibcode=1988mcts.book.....H | postscript=. }}
| title=General Catalogue of Variable Stars
| last1=Samus | first1=N. N. | last2=Durlevich | first2=O. V.
| journal=Vizier Online Data Catalog | display-authors=etal | date=2009 | volume=1
| bibcode=2009yCat....102025S | postscript=. }}
| title=* mu. Hya
| access-date=2017-01-06 }}
}}
{{Stars of Hydra|state=collapsed}}
{{DEFAULTSORT:Mu Hydrae}}
Category:Hydra (constellation)