{{short description|Star in the constellation Hydra}} {{Starbox begin |name=λ Hydrae }} {{Starbox image | image= {{Location mark |image=Hydra constellation map.svg|alt=|float=center|width=320 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=λ Hya |x=657|y=254 }} |caption=Location of λ Hydrae (circled) }} {{Starbox observe |constell=[[Hydra (constellation)|Hydra]] |epoch=[[J2000]] | ra = {{RA|10|10|35.27667}}<ref name="vanLeeuwen2007">{{cite journal | first=F. | last=van Leeuwen | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | date=November 2007 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752| s2cid=18759600 }}</ref> | dec = {{DEC|-12|21|14.6938}}<ref name="vanLeeuwen2007"/> |appmag_v=3.61<ref name="Ducati2002">{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|pages=0|last1=Ducati|first1=J. R.|year=2002}}</ref> }} {{Starbox character |type = [[red clump]]<ref name=alves/> |class= K0IIIbCN0.5<ref name=perkins>{{cite journal|bibcode= 1989ApJS...71..245K |title= The Perkins Catalog of Revised MK Types for the Cooler Stars |journal= The Astrophysical Journal Supplement Series |volume= 71 |pages= 245 |last1= Keenan |first1= Philip C. |last2= McNeil |first2= Raymond C. |year= 1989 |doi=10.1086/191373}}</ref> |b-v=+1.00<ref name=UBV>{{cite journal|title=A new photometric metal abundance and luminosity calibration for field G and K giants|author1=Jennens, P. A.|journal=Monthly Notices of the Royal Astronomical Society|volume=172|issue=3|pages=667–679|date=1975|bibcode=1975MNRAS.172..667J|doi=10.1093/mnras/172.3.667|doi-access=free}}</ref> |u-b=+0.92<ref name=UBV/> }} {{Starbox astrometry |radial_v=19.4<ref name=rv>{{cite journal|bibcode=1953GCRV..C......0W|title=General catalogue of stellar radial velocities|journal=Carnegie Institute Washington D.C. Publication|pages=0|last1=Wilson|first1=Ralph Elmer|year=1953}}</ref> |prop_mo_ra=−201.27<ref name="vanLeeuwen2007"/> |prop_mo_dec=−99.63<ref name="vanLeeuwen2007"/> |parallax=30.0232 |p_error=0.6973 |parallax_footnote=<ref name=dr2>{{cite DR2|3765867289804452608}}</ref> |absmag_v=+0.92<ref name=Anderson2012>{{citation | 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=. }}</ref> }} {{Starbox orbit |reference=<ref>{{cite journal|title=The Hipparcos and Tycho Catalogues|author=ESA|journal=VizieR On-line Data Catalog|date=1997|bibcode=1997yCat.1239....0E}}</ref> |primary= |name= |period_unitless=1585.8 days |axis_unitless=16.79 mas |inclination=79.49 |node=249.62 |periastron=2448664.3906 |eccentricity=0.138 |periarg=238.9 }} {{Starbox detail | source = | component1 = λ Hya A | mass = 1-2<ref name=cruzabeles>{{cite journal|bibcode=2013MNRAS.432.1658C|title=SPIDAST: A new modular software to process spectrointerferometric measurements|journal=Monthly Notices of the Royal Astronomical Society|volume=432|issue=2|pages=1658|last1=Cruzalèbes|first1=P.|last2=Rabbia|first2=Y.|last3=Jorissen|first3=A.|last4=Spang|first4=A.|last5=Sacuto|first5=S.|last6=Pasquato|first6=E.|last7=Chiavassa|first7=A.|last8=Chesneau|first8=O.|last9=Fréville|first9=P.|year=2013|doi=10.1093/mnras/stt593|arxiv=1304.1666|doi-access=free}}</ref> | radius = {{Val|8.62|0.22|0.23}}<ref name=Baines2025>{{Cite journal |last1=Baines |first1=Ellyn K. |last2=Clark |first2=James H. |last3=Kingsley |first3=Bradley I. |last4=Schmitt |first4=Henrique R. |last5=Stone |first5=Jordan M. |date=2025-05-07 |title=Vintage NPOI: New and Updated Angular Diameters for 145 Stars |journal=The Astronomical Journal |language=en |volume=169 |issue=6 |pages=293 |doi=10.3847/1538-3881/adc930 |doi-access=free |bibcode=2025AJ....169..293B |arxiv=2506.02912 |issn=1538-3881}}</ref> | luminosity = 39.8<ref name=cruzabeles/> | temperature = 4,656<ref name=cruzabeles/> | gravity = 2.64<ref name=cruzabeles/> | metal_fe = +0.25<ref name=hypatia>{{cite journal|bibcode=2014AJ....148...54H|title=Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog|journal=The Astronomical Journal|volume=148|issue=3|pages=54|last1=Hinkel|first1=Natalie R.|last2=Timmes|first2=F. X.|last3=Young|first3=Patrick A.|last4=Pagano|first4=Michael D.|last5=Turnbull|first5=Margaret C.|year=2014|doi=10.1088/0004-6256/148/3/54|arxiv=1405.6719|s2cid=119221402}}</ref> | rotational_velocity = 1.9<ref>{{cite journal|bibcode=2002ApJ...578..943D|title=The Rotation of Binary Systems with Evolved Components|journal=The Astrophysical Journal|volume=578|issue=2|pages=943–950|last1=De Medeiros|first1=J. R.|last2=Da Silva|first2=J. R. P.|last3=Maia|first3=M. R. G.|year=2002|doi=10.1086/342613|arxiv=astro-ph/0207288|doi-access=free}}</ref> | age_myr = }} {{Starbox catalog |names=[[Bayer designation|λ]] Hya, [[Flamsteed designation|41]] Hydrae, [[Bonner Durchmusterung|BD]]−11°2820, [[Henry Draper Catalogue|HD]] 88284, [[Hipparcos catalogue|HIP]] 49841, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 155785, [[Bright Star Catalogue|HR]] 3994, [[Boss General Catalogue|GC]] 13982, [[Tycho-2 Catalogue|TYC]] 5485-1310-1 }} {{Starbox reference |Simbad=HD+88284 }} {{Starbox end}} '''λ Hydrae''', Latinised as '''Lambda Hydrae''', is a [[spectroscopic binary]]<ref name="Eggleton2008">{{cite journal | 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 }}</ref> [[star]] in the [[constellation]] [[Hydra (constellation)|Hydra]]. Its apparent magnitude is 3.61 Located around {{convert|33.3|pc|ly}} distant. The [[spiral galaxy]] [[NGC 3145]] is only {{val|7.8|ul='}} away to the southwest.
The primary is an [[orange giant]] of spectral type K0IIICN+1,<ref name="Gray2006">{{cite journal | display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=[[The Astronomical Journal]] | volume=132 | issue=1 | pages=161–170 | date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770 | s2cid=119476992 }}</ref> a star that has used up its core [[hydrogen]], left the [[main sequence]], and expanded into a [[giant star|giant]]. It is considered to be a [[red clump]] giant, a cool [[horizontal branch]] star that is burning helium in its core.<ref name=alves>{{cite journal|bibcode=2000ApJ...539..732A|title=K-Band Calibration of the Red Clump Luminosity|journal=The Astrophysical Journal|volume=539|issue=2|pages=732–741|last1=Alves|first1=David R.|year=2000|doi=10.1086/309278|arxiv=astro-ph/0003329|doi-access=free}}</ref>
λ Hydrae has two visual companions, components B and C, 11th and 13th magnitude stars respectively {{val|71|ul="}} and {{val|111|u="}} away.<ref name=wds>{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}}</ref>
==References== {{reflist}}
{{Stars of Hydra}}
[[Category:K-type giants]] [[Category:Horizontal-branch stars]] [[Category:Spectroscopic binaries]] [[Category:Hydra (constellation)]] [[Category:Bayer objects|Hydrae, Lambda]] [[Category:Durchmusterung objects]] [[Category:Flamsteed objects|Hydrae, 41]] [[Category:Henry Draper Catalogue objects|088284]] [[Category:Hipparcos objects|049841]] [[Category:Bright Star Catalogue objects|3994]]