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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 [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 (Rv) | −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 (Rv) | 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 (Rv) | −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, LV) | 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, 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 | |
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.
In the beliefs of the Kamilaroi and Euahlayi Aboriginal peoples in New South Wales, Australia, the star is called Guniibuu that represents the robin red-breast bird (Petroica boodang). In 2016, the IAU organized a Working Group on Star Names (WGSN) [11] 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. [12]
The McDonald Observatory team has set limits to the presence of one or more planets [8] around 36 Ophiuchi A with masses between 0.13 and 5.4 Jupiter masses and average separations spanning between 0.05 and 5.2 astronomical units (AU), although beyond 1.5 AU orbits are inherently unstable around either 36 Ophiuchi A or 36 Ophiuchi B. [13]
The star C (or namely HD 156026) is among five nearby paradigms as K-type stars 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 NASA's Goddard Space Flight Center. [14]
In the Dune franchise, the fictional planet Giedi Prime, homeworld of the antagonistic House Harkonnen, orbits 36 Ophiuchi B.
70 Ophiuchi is a binary star system located 16.6 light years away from the Earth. It is in the constellation Ophiuchus. At magnitude 4 it appears as a dim star visible to the unaided eye away from city lights.
Cor Caroli is a binary star designated Alpha Canum Venaticorum or α Canum Venaticorum. The International Astronomical Union uses the name "Cor Caroli" specifically for the brighter star of the binary. Alpha Canum Venaticorum is the brightest point of light in the northern constellation of Canes Venatici.
HR 7703 is a binary star system in the constellation of Sagittarius. The brighter component has an apparent visual magnitude of 5.31, which means it is visible from suburban skies at night. The two stars are separated by an angle of 7.10″, which corresponds to an estimated semimajor axis of 56.30 AU for their orbit.
Theta Eridani, Latinized from θ Eridani, is a binary system in the constellation of Eridanus with a combined apparent magnitude of 2.88. Its two components are designated θ1 Eridani, formally named Acamar, and θ2 Eridani. The system's distance from the Sun based on parallax measurements is approximately 165 light-years.
Epsilon Ophiuchi or ε Ophiuchi, formally named Yed Posterior, is a red giant star in the constellation of Ophiuchus. Located less than five degrees south of the celestial equator in the eastern part of the constellation, it forms a naked eye optical double with Delta Ophiuchi. With an apparent visual magnitude of 3.220, the star can be seen with the naked eye from most of the Earth under suitably dark skies. Parallax measurements yield an estimated distance of 106.4 light-years from the Sun.
Lambda Herculis, formally named Maasym, is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the Sun.
Gliese 105 is a triple star system in the constellation of Cetus. It is located relatively near the Sun at a distance of 23.6 light-years. Despite this, even the brightest component is barely visible with the unaided eye (see Bortle scale). No planets have yet been detected around any of the stars in this system.
N Centauri is a binary star in the southern constellation of Centaurus. The brighter star is dimly visible to the naked eye with an apparent visual magnitude of 5.26, and it is approximately 304 light years away based on parallax. It has an absolute magnitude of +0.76 and is drifting further away from the Sun with a radial velocity of +27 km/s. It is a candidate member of the Sco OB2 moving group.
HD 223229 is a suspected variable star in the northern constellation of Andromeda. It is a double star consisting of a magnitude 6.11 primary and a magnitude 8.73 companion. The pair have an angular separation of 0.80″ along a position angle of 250°, as of 2009. The primary is a B-type subgiant star with a stellar classification of B3IV. It has an estimated 6.3 times the mass of the Sun, with an effective temperature of 17,900 K.
HD 225218 is a quadruple star system in the northern constellation of Andromeda. The primary component, HD 225218 A, is a giant star with a stellar classification of B9III, an apparent magnitude of 6.16, and is a candidate Lambda Boötis star. It has a fainter, magnitude 9.65 companion, HD 225218 B, at an angular separation of 5.2″ along a position angle of 171°. The primary itself has been identified as a binary star system through interferometry, with the two components separated by 0.165″. The pair, HD 225218 Aa and Ab, orbit each other with a period of about 70 years and an eccentricity of 0.515. Component B is likewise a spectroscopic binary.
HD 130458 is a double star in the southern circumpolar constellation of Apus. The pair has a combined apparent magnitude of 5.8, making it faintly visible to the naked eye under ideal conditions. Parallax measurements place the system 310-24 light years away and it is receding with a heliocentric radial velocity of 31.4 km/s.
4 Camelopardalis is a probable multiple star in the northern constellation of Camelopardalis, located 177 light years away from the Sun, based upon parallax. With a combined apparent visual magnitude of 5.29, it is visible to the naked eye as a faint, white-hued star. The pair have a relatively high proper motion, traversing the celestial sphere at an angular rate of 0.158″ per year. The system's proper motion makes it a candidate for membership in the IC 2391 supercluster. They are moving away from the Earth with a heliocentric radial velocity of 22.5 km/s.
1 Camelopardalis is a double star system in the constellation Camelopardalis. Its combined apparent magnitude is 5.56 and it is approximately 800 parsecs (2,600 ly) away.
27 Vulpeculae is a single, blue-white star in the northern constellation of Vulpecula. It is a dim star, visible to the naked eye, with an apparent visual magnitude of 5.59. An annual parallax shift of 10.6692±0.0483 mas provides a distance estimate of about 306 light-years. It is moving closer with a heliocentric radial velocity of −22 km/s, and will make perihelion passage at a distance of around 119 ly (36.56 pc) in 3.75 million years.
HD 85951, formally named Felis, is a solitary orange hued star in the constellation Hydra. It has an apparent magnitude of 4.94, making it faintly visible to the naked eye under ideal conditions. Based on parallax measurements, the object is about 570 light-years away from the Sun and is receding with a heliocentric radial velocity of 50 km/s.
ADS 9731 is a star system that consists of six stars, located in the constellation of Corona Borealis. Four of the stars are visually separate in the sky, forming a visual star system, which was resolved using adaptive optics in 1995. Two of these stars were themselves found to be spectroscopic binaries in 1998, resulting in a total of six known stars in the system. It is one of very few multiple star systems known to have at least six members.
1 Delphini is the Flamsteed designation for a close binary star in the equatorial constellation Delphinus. With a combined apparent magnitude of 6.08, it is barely visible to the naked eye, even under ideal conditions. Parallax measurements put the components at a distance 703 and 780 light years respectively. However, its approaching the Solar System with a radial velocity of 15 km/s.
BP Tauri is a young T Tauri star in the constellation of Taurus about 416 light years away, belonging to the Taurus Molecular Cloud.
11 Sagittae is a blue in the constellation Sagitta with a spectral type of B9III.
'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.