20 Ophiuchi

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20 Ophiuchi
Ophiuchus constellation map.svg
Red circle.svg
Location of 20 Ophiuchi (circled)
Observation data
Epoch J2000       Equinox J2000
Constellation Ophiuchus
Right ascension 16h 49m 50.01604s [1]
Declination −10° 46 58.7775 [1]
Apparent magnitude  (V)4.64 [2]
Characteristics
Spectral type F6IV [3]
U−B color index +0.07 [4]
B−V color index +0.47 [4]
Astrometry
Radial velocity (Rv)-1.60 [5]  km/s
Proper motion (μ)RA: +72.33 [1]   mas/yr
Dec.: -78.80 [1]   mas/yr
Parallax (π)31.27 ± 2.16  mas [1]
Distance 104 ± 7  ly
(32 ± 2  pc)
Absolute magnitude  (MV)2.13 [2]
Orbit [6]
Period (P)35.5 ± 1.5 yr
Semi-major axis (a)0.460 ± 0.030″
Eccentricity (e)0.8 ± 0.2
Inclination (i)74 ± 11°
Longitude of the node (Ω)118 ± 9°
Periastron epoch (T)1981.2 ± 1.7
Argument of periastron (ω)
(secondary)
34 ± 26°
Details
20 Oph A
Mass 1.70 [7]   M
Radius 3.0 [7]   R
Luminosity 12.06 [2]   L
Surface gravity (log g)3.89 [8]   cgs
Temperature 6,417 [8]   K
Metallicity [Fe/H]+0.13 [8]   dex
Rotational velocity (v sin i)11.3 [9]  km/s
20 Oph B
Mass 0.8 ± 0.2 [6]   M
Other designations
BD-10°4394, FK5  1438, GC  22643, HIP  82369, HR  6243, HD  151769, SAO  160118
Database references
SIMBAD data

20 Ophiuchi is a class F6IV [3] (yellow-white subgiant) star in the constellation Ophiuchus. Its apparent magnitude is 4.64 [2] and it is approximately 104 light years away based on parallax. [1] It lies near the star Zeta Ophiuchi.

20 Ophiuchi is an astrometric binary. The primary star is a late F-type subgiant star. It has a mass 1.72 times that of the Sun. [6] The companion star regularly perturbs the primary star, causing it to wobble around the barycenter. From this, an orbital period of 35.5 years has been calculated. The secondary star is 0.8 times the mass of the Sun, and it may be a white dwarf or red dwarf. [6]

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<span class="mw-page-title-main">45 Ophiuchi</span> Star in the constellation Ophiuchus

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<span class="mw-page-title-main">16 Puppis</span> Star in the constellation Puppis

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<span class="mw-page-title-main">31 Persei</span> Star in the constellation Perseus

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Gamma<sup>1</sup> Octantis Yellow-hued giant star in the constellation Octans

Gamma1 Octantis, Latinized from γ1 Octantis, is a single, yellow-hued star in the constellation which includes the southern celestial pole, Octans. Its apparent visual magnitude is 5.10, meaning that in good conditions it is bright enough to be faintly visible to the naked eye.

References

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