36 Ophiuchi

36 Ophiuchi A/B/C
	; A visual band light curve for 36 Ophiuchi C (V2215 Ophiuchi), plotted from ASAS-SN data
Observation data; Epoch J2000 Equinox J2000
Constellation	Ophiuchus
Right ascension	A: 17h 15m 20.851s; B: 17h 15m 20.978s; C: 17h 16m 13.3624s
Declination	A: −26° 36′ 09.04″; B: −26° 36′ 10.18″; C: −26° 32′ 46.129″
Apparent magnitude (V)	5.08/5.03/6.34
Characteristics
Spectral type	K2 V/K1 V/K5 V
U−B color index	0.51(AB)/1.04
B−V color index	0.85(AB)/1.16
Variable type	C: RS CVn
Astrometry
36 Oph A
Radial velocity (Rv)	−0.6 km/s
Proper motion (μ)	RA: −498.600±0.123 mas/yr ; Dec.: −1149.158±0.086 mas/yr
Parallax (π)	168.0031 ± 0.1343 mas
Distance	19.41 ± 0.02 ly ; (5.952 ± 0.005 pc)
36 Oph B
Radial velocity (Rv)	0.0 km/s
Proper motion (μ)	RA: −465.861±0.111 mas/yr ; Dec.: −1141.168±0.073 mas/yr
Parallax (π)	168.1303 ± 0.1081 mas
Distance	19.40 ± 0.01 ly ; (5.948 ± 0.004 pc)
36 Oph C
Radial velocity (Rv)	−0.04±0.22 km/s
Proper motion (μ)	RA: −479.573±0.031 mas/yr ; Dec.: −1124.332±0.020 mas/yr
Parallax (π)	167.9617 ± 0.0311 mas
Distance	19.418 ± 0.004 ly ; (5.954 ± 0.001 pc)
Orbit
Companion	36 Ophiuchi B
Period (P)	568.9 yr
Semi-major axis (a)	14.7″
Eccentricity (e)	0.922
Inclination (i)	99.6°
Longitude of the node (Ω)	−83.6°
Periastron epoch (T)	1,763.39
Details
36 Oph A/B
Mass	0.85/0.85 M☉
Radius	0.817 ± 0.016/0.81 R☉
Luminosity (bolometric)	0.33/0.36 L☉
Luminosity (visual, LV)	0.28/0.30 L☉
Temperature	4,843 ± 134/4,985 ± 20 K
Metallicity	B: –0.31 ± 0.042 dex
Metallicity [Fe/H]	A: –0.20 dex
Age	0.6-1.8 Gyr
36 Oph C
Mass	0.71 M☉
Radius	0.72 R☉
Luminosity (bolometric)	0.20 L☉
Luminosity (visual, LV)	0.09 L☉
Temperature	4,550 K
Metallicity	46–100% Sun
Other designations
	36 Oph, WDS J17153-2636
	AB: GJ 663, CD−26°12026, GCTP 3908.00, HIP 84405
	A: Guniibuu, HR 6402, HD 155886, LHS 437, SAO 185198
	B: HR 6401, HD 155885, LHS 438, SAO 185199
	C: V2215 Ophiuchi, GJ 664, CD−26°12036, HD 156026, GCTP 3913.00, LHS 439, SAO 185213, HIP 84478
Database references
SIMBAD	AB
	A
	B
	C
Exoplanet Archive	A
	B
	C
ARICNS	A
	B
	C
	36 Location of 36 Ophiuchi in the constellation Ophiuchus;

36 Ophiuchi (or Guniibuu for component A) is a triple star system 19.5 light-years from Earth. It is in the constellation 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.^[10] 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 chromospheres. 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.

^ Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f
"SIMBAD Astronomical Database". Centre de Données astronomiques de Strasbourg. Retrieved 2013-08-23.
^ ^a ^b ^c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c ^d Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
^ ^a ^b ^c Cite error: The named reference aaa505_1_205 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference apjs161_2_444T was invoked but never defined (see the help page).
^ Cite error: The named reference search was invoked but never defined (see the help page).
^ Cite error: The named reference MH08 was invoked but never defined (see the help page).
^ Garg, Suyog; Karak, Bidya Binay; Egeland, Ricky; Soon, Willie; Baliunas, Sallie (2019), "Waldmeier Effect in Stellar Cycles", The Astrophysical Journal, 886 (2): 132, arXiv:1909.12148, Bibcode:2019ApJ...886..132G, doi:10.3847/1538-4357/ab4a17, S2CID 202888617

Cite error: There are <ref group=note> tags on this page, but the references will not show without a {{reflist|group=note}} template (see the help page).

[ASAS-SN-1] Cite error: The named reference ASAS-SN was invoked but never defined (see the help page).

[SIMBAD-2] ^ ^a ^b ^c ^d ^e ^f "SIMBAD Astronomical Database". Centre de Données astronomiques de Strasbourg. Retrieved 2013-08-23.

A: LHS 437 -- High proper-motion Star

B: LHS 438 -- High proper-motion Star

C: V* V2215 Oph -- Variable of RS CVn type

[3] A: LHS 437 -- High proper-motion Star

[4] B: LHS 438 -- High proper-motion Star

[5] C: V* V2215 Oph -- Variable of RS CVn type

[GaiaEDR3a-3] Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[GaiaEDR3b-4] Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[GaiaEDR3c-5] Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.

[aaa505_1_205-6] Cite error: The named reference aaa505_1_205 was invoked but never defined (see the help page).

[apjs161_2_444T-8] Cite error: The named reference apjs161_2_444T was invoked but never defined (see the help page).

[search-9] Cite error: The named reference search was invoked but never defined (see the help page).

[MH08-10] Cite error: The named reference MH08 was invoked but never defined (see the help page).

[11] Garg, Suyog; Karak, Bidya Binay; Egeland, Ricky; Soon, Willie; Baliunas, Sallie (2019), "Waldmeier Effect in Stellar Cycles", The Astrophysical Journal, 886 (2): 132, arXiv:1909.12148, Bibcode:2019ApJ...886..132G, doi:10.3847/1538-4357/ab4a17, S2CID 202888617

[1]

[2]

[3]

[4]

[5]

[6]

[note 1]

[7]

[8]

[9]

[10]

Observation data Epoch J2000 Equinox J2000
A visual band light curve for 36 Ophiuchi C (V2215 Ophiuchi), plotted from ASAS-SN data^[1]
Constellation	Ophiuchus
Right ascension	A: 17^h 15^m 20.851^s B: 17^h 15^m 20.978^s C: 17^h 16^m 13.3624^s^[2]
Declination	A: −26° 36′ 09.04″ B: −26° 36′ 10.18″ C: −26° 32′ 46.129″^[2]
Apparent magnitude (V)	5.08/5.03/6.34^[2]
Characteristics
Spectral type	K2 V/K1 V/K5 V^[2]
U−B color index	0.51(AB)/1.04
B−V color index	0.85(AB)/1.16
Variable type	C: RS CVn
Astrometry
36 Oph A
Radial velocity (R_v)	−0.6^[2] km/s
Proper motion (μ)	RA: −498.600±0.123^[3] mas/yr Dec.: −1149.158±0.086^[3] mas/yr
Parallax (π)	168.0031 ± 0.1343 mas^[3]
Distance	19.41 ± 0.02 ly (5.952 ± 0.005 pc)
36 Oph B
Radial velocity (R_v)	0.0^[2] km/s
Proper motion (μ)	RA: −465.861±0.111^[4] mas/yr Dec.: −1141.168±0.073^[4] mas/yr
Parallax (π)	168.1303 ± 0.1081 mas^[4]
Distance	19.40 ± 0.01 ly (5.948 ± 0.004 pc)

36 Oph C
Radial velocity (R_v)	−0.04±0.22^[5] km/s
Proper motion (μ)	RA: −479.573±0.031^[5] mas/yr Dec.: −1124.332±0.020^[5] mas/yr
Parallax (π)	167.9617 ± 0.0311 mas^[5]
Distance	19.418 ± 0.004 ly (5.954 ± 0.001 pc)

Orbit
Companion	36 Ophiuchi B
Period (P)	568.9 yr
Semi-major axis (a)	14.7″
Eccentricity (e)	0.922
Inclination (i)	99.6°
Longitude of the node (Ω)	−83.6°
Periastron epoch (T)	1,763.39
Details
36 Oph A/B
Mass	0.85/0.85 `M`_☉
Radius	0.817 ± 0.016^[6]/0.81 `R`_☉
Luminosity (bolometric)	0.33/0.36^{[note 1]} `L`_☉
Luminosity (visual, L_V)	0.28/0.30 `L`_☉
Temperature	4,843 ± 134^[6]/4,985 ± 20^[7] K
Metallicity	B: –0.31 ± 0.042^[7] dex
Metallicity [Fe/H]	A: –0.20^[6] dex
Age	0.6-1.8^[8]^[9] Gyr
36 Oph C
Mass	0.71 `M`_☉
Radius	0.72 `R`_☉
Luminosity (bolometric)	0.20^{[note 1]} `L`_☉
Luminosity (visual, L_V)	0.09 `L`_☉
Temperature	4,550 K
Metallicity	46–100% Sun
Other designations
36 Oph, WDS J17153-2636
AB: GJ 663, CD−26°12026, GCTP 3908.00, HIP 84405
A: Guniibuu, HR 6402, HD 155886, LHS 437, SAO 185198
B: HR 6401, HD 155885, LHS 438, SAO 185199
C: V2215 Ophiuchi, GJ 664, CD−26°12036, HD 156026, GCTP 3913.00, LHS 439, SAO 185213, HIP 84478
Database references
SIMBAD	AB
	A
	B
	C
Exoplanet Archive	A
	B
	C
ARICNS	A
	B
	C
36 Location of 36 Ophiuchi in the constellation Ophiuchus