View source for Astronomy:36 Ophiuchi

{{short description|Triple star system in the constellation Ophiuchus}}
{{Sky|17|15|20.851|-|26|36|09.04|19.418}}
{{Starbox begin |
   name=36 Ophiuchi A/B/C }}
{{Starbox image
| image = [[Image:V2215OphLightCurve.png|350px]]
| caption = A [[Astronomy:Photometric system#Photometric letters|visual band]] [[Astronomy:Light curve|light curve]] for 36 Ophiuchi C (V2215 Ophiuchi), plotted from ''[[Astronomy:All Sky Automated Survey for SuperNovae|ASAS-SN]]'' data<ref name="ASAS-SN"/>
}}
{{Starbox observe |
  epoch=J2000 |
  constell=[[Astronomy:Ophiuchus|Ophiuchus]] |
  ra=A:&nbsp;{{RA|17|15|20.851}}<br/>B:&nbsp;{{RA|17|15|20.978}}<br/>C:&nbsp;{{RA|17|16|13.3624}}<ref name="SIMBAD">{{cite web
 | url=http://simbad.u-strasbg.fr/
 | title=SIMBAD Astronomical Database
 | publisher=Centre de Données astronomiques de Strasbourg
 | access-date=2013-08-23
}}<br/>
* A: [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD%20155886 LHS 437 -- High proper-motion Star]
* B: [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD%20155885 LHS 438 -- High proper-motion Star ]
* C: [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HD%20156026 V* V2215 Oph -- Variable of RS CVn type]</ref>
 |
 dec=A:&nbsp;{{DEC| -26|36|09.04}}<br/>B:&nbsp;{{DEC| -26|36|10.18}}<br/>C:&nbsp;{{DEC| -26|32|46.129}}<ref name="SIMBAD"/> |
 appmag_v=5.08/5.03/6.34<ref name="SIMBAD"/> }}
{{Starbox character |
 class=K2&nbsp;V/K1&nbsp;V/K5&nbsp;V<ref name="SIMBAD"/> |
 b-v=0.85(AB)/1.16 |
 u-b=0.51(AB)/1.04 |
 variable=C: [[Astronomy:RS Canum Venaticorum variable|RS CVn]] }}
{{Starbox astrometry
| component1 = 36 Oph A
| radial_v=−0.6<ref name="SIMBAD"/>
| prop_mo_ra={{val|-498.600|0.123}}<ref name="GaiaEDR3a"/>
| prop_mo_dec={{val|-1149.158|0.086}}<ref name="GaiaEDR3a"/>
| parallax=168.0031
| p_error=0.1343
| parallax_footnote=<ref name="GaiaEDR3a">{{Cite Gaia EDR3|4109030160308320128}}</ref>
| absmag_v=
| component2 = 36 Oph B
| radial_v2=0.0<ref name="SIMBAD"/>
| prop_mo_ra2={{val|-465.861|0.111}}<ref name="GaiaEDR3b"/>
| prop_mo_dec2={{val|-1141.168|0.073}}<ref name="GaiaEDR3b"/>
| parallax2=168.1303
| p_error2=0.1081
| parallax_footnote2=<ref name="GaiaEDR3b">{{Cite Gaia EDR3|4109030160308317312}}</ref>
| absmag_v2=
}}
{{Starbox astrometry|no_heading=y
| component1 = 36 Oph C
| radial_v={{val|-0.04|0.22}}<ref name="GaiaEDR3c"/>
| prop_mo_ra={{val|-479.573|0.031}}<ref name="GaiaEDR3c"/>
| prop_mo_dec={{val|-1124.332|0.020}}<ref name="GaiaEDR3c"/>
| parallax=167.9617
| p_error=0.0311
| parallax_footnote=<ref name="GaiaEDR3c">{{Cite Gaia EDR3|4109034455276324608}}</ref>
| absmag_v=
}}
{{Starbox visbin
| name=36 Ophiuchi B
| period=568.9
| axis=14.7
| eccentricity=0.922
| inclination=99.6
| node=−83.6
| periastron=1,763.39
}}
{{Starbox detail
| component1 = 36 Oph A/B
| age_gyr = 0.6-1.8<ref name="search"/><ref name="MH08"/>
| metal = B: {{nowrap|–0.31 ± 0.042<ref name=apjs161_2_444T/> dex}}
| metal_fe = A: –0.20<ref name=aaa505_1_205/>
| mass     = 0.85/0.85
| radius   = {{nowrap|0.817 ± 0.016}}<ref name=aaa505_1_205/>/0.81
| rotation =
| luminosity_bolometric = 0.33/0.36<ref name="lumbol" group="note">From ''L''=4π''R''<sup>2</sup>σ''T''<sub>eff</sub><sup>4</sup>, where ''L'' is the luminosity, ''R'' is the radius, ''T''<sub>eff</sub> is the effective surface temperature and ''σ'' is the [[Physics:Stefan–Boltzmann constant|Stefan–Boltzmann constant]].</ref>
| luminosity_visual = 0.28/0.30
| temperature = {{nowrap|4,843 ± 134}}<ref name=aaa505_1_205/>/{{nowrap|4,985 ± 20}}<ref name=apjs161_2_444T/>
| component2 = 36 Oph C
| metal2   = 46–100% Sun
| mass2    = 0.71
| radius2  = 0.72
| luminosity_bolometric2 = 0.20<ref name="lumbol" group="note"/>
| luminosity_visual2 = 0.09
| temperature2 = 4,550
}}
{{Starbox catalog 
| names=36 Oph, [[Astronomy:Washington Double Star Catalog|WDS]]&nbsp;J17153-2636
| component1 = AB
| names1=[[Astronomy:Gliese Catalogue of Nearby Stars|GJ]]&nbsp;663, CD−26°12026, GCTP&nbsp;3908.00, HIP&nbsp;84405
| component2 = A
| names2=Guniibuu, [[Astronomy:Bright Star Catalogue|HR]]&nbsp;6402, HD&nbsp;155886, LHS&nbsp;437, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;185198
| component3 = B
| names3=[[Astronomy:Bright Star Catalogue|HR]]&nbsp;6401, HD&nbsp;155885, LHS&nbsp;438, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;185199
| component4 = C
| names4=[[Astronomy:Variable star designation|V2215]]&nbsp;Ophiuchi, [[Astronomy:Gliese Catalogue of Nearby Stars|GJ]]&nbsp;664, CD−26°12036, HD&nbsp;156026, GCTP&nbsp;3913.00, LHS&nbsp;439, [[Astronomy:Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;185213, HIP&nbsp;84478

}}
{{Starbox reference
| Simbad = *+36+Oph|sn=AB
| Simbad2 = HD+155886|sn2=A
| Simbad3 = HD+155885|sn3=B
| Simbad4 = HD+156026|sn4=C
| NSTED = GJ+663A|nn=A
| NSTED2 = GJ+663B|nn2=B
| NSTED3 = GJ+664|nn3=C
| ARICNS = 01379|an=A
| ARICNS2 = 01380|an2=B
| ARICNS3 = 01381|an3=C
}}
{{Starbox image
|image={{Location map|100x100|AlternativeMap=Ophiuchus_constellation_map.svg
|alt=36 Ophiuchi is located in the constellation Ophiuchus
|caption=Location of 36 Ophiuchi in the constellation [[Astronomy:Ophiuchus|Ophiuchus]]|border=infobox|mark=Red_circle.svg|width=350
|label=36
|position=top
|lat=17.5
|long=51.3
}}|caption=
}}
{{Starbox end}}

'''36 Ophiuchi''' (or '''Guniibuu''' for component A) is a triple [[Astronomy:Star system|star system]] 19.5 [[Astronomy:Light-year|light-year]]s from [[Astronomy:Earth|Earth]]. It is in the [[Astronomy:Constellation|constellation]] [[Astronomy:Ophiuchus|Ophiuchus]].

The primary and secondary stars (also known as HD 155886) are nearly identical orange main-sequence dwarfs of spectral type K2/K1. This binary is unusual because its eruptions do not seem to conform to the Waldmeier effect; that is, the strongest eruptions of HD 155886 are not the ones characterized by the fast eruption onset.<ref>{{citation|arxiv=1909.12148|year=2019|title=Waldmeier Effect in Stellar Cycles|doi=10.3847/1538-4357/ab4a17|last1=Garg|first1=Suyog|last2=Karak|first2=Bidya Binay|last3=Egeland|first3=Ricky|last4=Soon|first4=Willie|last5=Baliunas|first5=Sallie|journal=The Astrophysical Journal|volume=886|issue=2|page=132|bibcode=2019ApJ...886..132G|s2cid=202888617 |doi-access=free }}</ref> The tertiary star is an orange main-sequence dwarf of spectral type K5.

Star C is separated from the A-B pair by 700 arcseconds, compared to a minimum of 4.6 arcseconds for A-B, so its effect on the movements of the A-B pair is small. A and B have active [[Astronomy:Chromosphere|chromosphere]]s.
At present the distance between the stars forming the AB-pair is 5.1 arcseconds and the position angle is 139 degrees, while star C is 731.6 arcseconds away from the A-component and situated at a position angle of 74 degrees.

==Nomenclature==

In the beliefs of the Kamilaroi and Euahlayi Aboriginal peoples in New South Wales, Australia, the star A is called ''Guniibuu'' that represents the robin red-breast bird ([[Biology:Scarlet robin|''Petroica boodang'']]). In 2016, the IAU organized a Working Group on Star Names (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=17 September 2018}}</ref> to catalog and standardize proper names for stars. The WGSN approved the name ''Guniibuu'' for the star A on 10 August 2018 and it is now so included in the List of IAU-approved Star Names.<ref name="IAU-CSN">{{Cite web
 |url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt
 |title=IAU Catalog of Star Names
 |publisher=[[Organization:International Astronomical Union|International Astronomical Union]]
 |access-date=2018-09-17}}</ref>

==Hunt for substellar objects==
The McDonald Observatory team has set limits to the presence of one or more planets<ref name="search"/> around 36 Ophiuchi A with masses between 0.13 and 5.4 [[Astronomy:Jupiter mass|Jupiter mass]]es and average separations spanning between 0.05 and 5.2 [[Astronomy:Astronomical unit|astronomical unit]]s (AU), although beyond 1.5 AU orbits are inherently unstable around either 36 Ophiuchi A or 36 Ophiuchi B.<ref name="Irwin">Irwin ''et al.'' (1996).</ref>

The star C (or namely HD 156026) is among five nearby paradigms as [[Astronomy:K-type star|K-type star]]s of a type in a 'sweet spot’ between Sun-analog stars and M stars for the likelihood of evolved life, per analysis of Giada Arney from [[Organization:NASA|NASA]]'s [[Organization:Goddard Space Flight Center|Goddard Space Flight Center]].<ref name=Nasa2019-03-07/>

==Notes==
{{reflist|group=note}}

==References==

<ref name="ASAS-SN">{{cite web |url=https://asas-sn.osu.edu/variables/lookup |website=ASAS-SN Variable Stars Database|title=ASAS-SN Variable Stars Database|publisher=ASAS-SN |access-date=6 January 2022}}</ref>

{{Reflist|refs=
<ref name=Nasa2019-03-07>
{{cite news     
| url         = https://www.nasa.gov/feature/goddard/2019/k-star-advantage
| title       = "Goldilocks" Stars May Be "Just Right" for Finding Habitable Worlds
| work        = [[Organization:NASA|NASA]]
| author      = Bill Steigerwald
| date        = 2019-03-07
| access-date  = 2020-05-12
| quote       = {{'}}I find that certain nearby K stars like 61 Cyg A/B, Epsilon Indi, Groombridge 1618, and HD 156026 may be particularly good targets for future biosignature searches,{{'}} said Arney.
}}
</ref>

<ref name=aaa505_1_205>{{cite journal
 | title=Mass-radius relation of low and very low-mass stars revisited with the VLTI
 | journal=Astronomy and Astrophysics | volume=505 | issue=1
 | date=October 2009 | pages=205–215
 | doi=10.1051/0004-6361/200911976
 | bibcode=2009A&A...505..205D |arxiv = 0906.0602
 |last1=Demory |first1=Brice-Olivier
 |last2=Ségransan |first2=Damien
 |last3=Forveille |first3=Thierry
 |last4=Queloz |first4=Didier
 |last5=Beuzit |first5=Jean-Luc
 |last6=Delfosse |first6=Xavier
 |last7=Di Folco |first7=Emmanuel
 |last8=Kervella |first8=Pierre
 |last9=Le Bouquin |first9=Jean-Baptiste
 |last10=Perrier |first10=Christian
 |last11=Benisty |first11=Myriam
 |last12=Duvert |first12=Gilles
 |last13=Hofmann |first13=Karl-Heinz
 |last14=Lopez |first14=Bruno
 |last15=Petrov |first15=Romain
 |s2cid=14786643
 }}</ref>

<ref name=apjs161_2_444T>{{citation | last=Taylor | first=B. J. |date=December 2005 |  title=Statistical Cataloging of Archival Data for Luminosity Class IV-V Stars. III. The Epoch 2004 [Fe/H] and Temperature Catalogs | journal=[[Astronomy:The Astrophysical Journal|The Astrophysical Journal Supplement Series]] | volume=161 | issue=2 | pages=444–455 | doi=10.1086/496885 | bibcode=2005ApJS..161..444T |postscript=. | doi-access=free }}[http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-ref=VIZ52d212351f95&-out.add=.&-source=J/ApJS/161/444/catalog&recno=857 Vizier catalog entry]</ref>
 
<ref name="search">Wittenmeyer ''et al.'' (2006).</ref>

<ref name="MH08">{{Citation | last1=Mamajek | first1=Eric E. | last2=Hillenbrand | first2=Lynne A. | title=Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics | journal=The Astrophysical Journal | volume=687 | issue=2 | pages=1264–1293 | doi=10.1086/591785 | bibcode=2008ApJ...687.1264M |arxiv = 0807.1686 |date=November 2008| s2cid=27151456 }}</ref>

}}

==Further reading==
*{{Citation |last1=Irwin |first1=Alan W. |last2=Yang |first2=Stephenson L. S. |last3=Walker |first3=Gordon A. H. |name-list-style=amp |date=1996 |title=36 Ophiuchi AB: Incompatibility of the Orbit and Precise Radial Velocities |journal=Publications of the Astronomical Society of the Pacific |volume=108 |pages=580 |doi=10.1086/133768 |bibcode=1996PASP..108..580I|doi-access=free }}
*{{Citation |last1=Cayrel de Strobel |first1=G. |last2=Lebreton |first2=Y. |last3=Perrin |first3=M.-N. |last4=Cayrel |first4=R. |name-list-style=amp |date=1989 |title=A thorough spectroscopic study of the very nearby triple system - 36 Ophiuchi |journal=Astronomy and Astrophysics |volume=225 |issue=2 |pages=369–380 |bibcode = 1989A&A...225..369C }}
*{{Citation |last1=Wittenmeyer |first1=R. A. |last2=Endl |first2=Michael |last3=Cochran |first3=William D. |last4=Hatzes |first4=Artie P. |last5=Walker |first5=G. A. H. |last6=Yang |first6=S. L. S. |last7=Paulson |first7=Diane B. |name-list-style=amp |date=2006 |title=Detection Limits from the McDonald Observatory Planet Search Program |journal=Astronomical Journal |volume=132 |issue=1 |pages=177–188 |doi=10.1086/504942 |bibcode=2006AJ....132..177W|arxiv = astro-ph/0604171 |s2cid=16755455 }}
*{{Citation |last=Barnes |first=Sydney A. |date=2007 |title=Ages for Illustrative Field Stars Using Gyrochronology: Viability, Limitations, and Errors |journal=The Astrophysical Journal |volume=669 |issue=2 |pages=1167–1189 |doi=10.1086/519295 |bibcode=2007ApJ...669.1167B|arxiv = 0704.3068 |s2cid=14614725 }}

==External links==
* {{cite web |
 title=36 Ophiuchi | 
 work=SolStation |
 url=http://www.solstation.com/stars/36ophiu3.htm |
 access-date=3 November 2005 }}
* https://arxiv.org/abs/astro-ph/0604171
{{Nearest systems|4}}
{{Stars of Ophiuchus}}

{{DEFAULTSORT:36 Ophiuchi}}
[[Category:Triple star systems]]
[[Category:Flamsteed objects|Ophiuchi, 36]]
[[Category:K-type main-sequence stars]]
[[Category:Solar-type stars|Ophiuchi, 36]]
[[Category:Bright Star Catalogue objects|6401 2]]
[[Category:Henry Draper Catalogue objects|155885 5886 6026]]
[[Category:Hipparcos objects|084405 78]]
[[Category:Durchmusterung objects|CD-26 12026]]
[[Category:Bayer objects|Ophiuchi, A]]
[[Category:RS Canum Venaticorum variables]]
[[Category:Gliese and GJ objects|0663 4]]
[[Category:Objects with variable star designations|Ophiuchi, V2215]]

{{Sourceattribution|36 Ophiuchi}}