Location of 36 Ophiuchi in the constellation Ophiuchus | |
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 [1] |
Declination | A: −26° 36′ 09.04″ B: −26° 36′ 10.18″ C: −26° 32′ 46.129″ [1] |
Apparent magnitude (V) | 5.08/5.03/6.34 [1] |
Characteristics | |
Spectral type | K2 V/K1 V/K5 V [1] |
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 [1] km/s |
Proper motion (μ) | RA: −498.600 mas/yr [2] Dec.: −1,149.158 mas/yr [2] |
Parallax (π) | 168.0031 ± 0.1343 mas [2] |
Distance | 19.41 ± 0.02 ly (5.952 ± 0.005 pc) |
36 Oph B | |
Radial velocity (Rv) | 0.0 [1] km/s |
Proper motion (μ) | RA: −465.861 mas/yr [3] Dec.: −1,141.168 mas/yr [3] |
Parallax (π) | 168.1303 ± 0.1081 mas [3] |
Distance | 19.40 ± 0.01 ly (5.948 ± 0.004 pc) |
36 Oph C | |
Radial velocity (Rv) | −0.04±0.22 [4] km/s |
Proper motion (μ) | RA: −479.573 mas/yr [4] Dec.: −1,124.332 mas/yr [4] |
Parallax (π) | 167.9617 ± 0.0311 mas [4] |
Distance | 19.418 ± 0.004 ly (5.954 ± 0.001 pc) |
Orbit [5] | |
Companion | 36 Ophiuchi B |
Period (P) | 470.9 yr |
Semi-major axis (a) | 13″ |
Eccentricity (e) | 0.916 |
Inclination (i) | 99.8° |
Details | |
36 Oph A | |
Mass | 0.75+0.02 −0.04 [6] M☉ |
Radius | 0.817±0.016 [7] R☉ |
Luminosity | 0.326±0.084 [8] L☉ |
Temperature | 5,103±29 [6] K |
Metallicity [Fe/H] | −0.23 [6] dex |
Age | 4.86+0.50 −0.22 [6] Gyr |
36 Oph B | |
Mass | 0.76+0.03 −0.06 [9] M☉ |
Radius | 0.709 [9] [a] R☉ |
Luminosity | 0.32 [9] L☉ |
Surface gravity (log g) | 4.61 [9] cgs |
Temperature | 5,171±71 [9] K |
Metallicity [Fe/H] | −0.22 [9] dex |
Age | 5.26+5.04 −2.94 [9] Gyr |
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 Ophiuchi (or Guniibuu for component A) is a triple star system 19.5 light-years from Earth 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) [12] 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. [13]
The McDonald Observatory team has set limits to the presence of one or more planets [14] 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. [15]
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. [16]
Atlas, designation 27 Tauri, is a triple star system in the constellation of Taurus. It is a member of the Pleiades, an open star cluster (M45). It is 431 light-years away, and is 3.92 degrees north of the ecliptic.
Eta Cassiopeiae is a binary star system in the northern constellation of Cassiopeia. Its binary nature was first discovered by William Herschel in August 1779. Based upon parallax measurements, the distance to this system is 19.42 light-years from the Sun. The two components are designated Eta Cassiopeiae A and B.
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.
Beta Ophiuchi or β Ophiuchi, also named Cebalrai, is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude of this star is 2.7, which is readily visible to the naked eye even from urban skies. The distance to this star can be estimated using parallax measurements, yielding a value of 83.4 light-years from the Sun.
Merope, designated 23 Tauri, is a star in the constellation of Taurus and a member of the Pleiades star cluster. It is approximately 440 light-years (135 pc) away.
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 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.
Gliese 445 is an M-type main sequence star in the northern part of the constellation Camelopardalis.
V1054 Ophiuchi, together with the star Gliese 643, is a nearby quintuple star system. In the constellation Ophiuchus at a distance of 21.19 light-years. It consists of five stars, all of which are red dwarfs. The alternative designation of Wolf 630 forms the namesake of a moving group of stars that share a similar motion through space.
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.
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.
HD 74423 is a heartbeat binary star and one component pulsates on only one hemisphere. This is caused by tidal interaction with its partner. The star is located in the Volans constellation.
BP Tauri is a young T Tauri star in the constellation of Taurus about 416 light years away, belonging to the Taurus Molecular Cloud.
HD 203949 is a K-type giant star 257 light-years away in the constellation of Microscopium. Its surface temperature is 4618±113 K. It is either on the red giant branch fusing hydrogen in a shell around a helium core, or more likely a red clump star currently fusing helium in its core. HD 203949 is enriched in heavy elements relative to the Sun, with a metallicity ([Fe/H]) of 0.17±0.07 dex. As is common for red giants, HD 203949 has an enhanced concentration of sodium and aluminium compared to iron.
CG Cygni is a ternary star system composed of main-sequence stars in the constellation of Cygnus about 320 light years away.
11 Sagittae is a blue in the constellation Sagitta with a spectral type of B9III.
HD 64307, also known as HR 3075, is a solitary, orange hued star located in the northern circumpolar constellation Camelopardalis. It has an apparent magnitude of 5.35, allowing it to be faintly seen with the naked eye. Based on parallax measurements from the Gaia spacecraft, The object is estimated to be 690 light years distant. It appears to be receding from the Sun, having a heliocentric radial velocity of 34 km/s.
HD 193472 is a solitary star in the equatorial constellation Delphinus. It has an apparent magnitude of 5.94, making it visible with the naked eye if viewed under ideal conditions. Parallax measurements put it at a distance of 282 light years and has a radial velocity of −8 km/s, indicating that the object drifting towards the Solar System.
HD 208741, also known as HR 8380, is a yellowish-white hued star located in the southern circumpolar constellation Octans. It has an apparent magnitude of 5.91, making it faintly visible to the naked eye. Parallax measurements place it at a distance of 211 light years, and it is currently receding with a heliocentric radial velocity of 8 km/s.
'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.