Location of 70 Ophiuchi in the constellation Ophiuchus | |
Observation data Epoch J2000 Equinox | |
---|---|
Constellation | Ophiuchus |
70 Ophiuchi | |
Right ascension | 18h 05m 27.285s [1] |
Declination | +02° 29′ 00.36″ [1] |
Apparent magnitude (V) | 4.00 - 4.03 [2] |
A | |
Right ascension | 18h 05m 27.371s [3] |
Declination | +02° 29′ 59.32″ [3] |
Apparent magnitude (V) | 4.13 [3] |
B | |
Right ascension | 18h 05m 27.462s [4] |
Declination | +02° 29′ 56.22″ [4] |
Apparent magnitude (V) | 6.07 [3] |
Characteristics | |
Spectral type | K0V + K4V [5] |
Apparent magnitude (B) | 4.97/7.26 [3] |
Apparent magnitude (R) | 3.6/5.6 [3] |
U−B color index | +0.69 [6] |
B−V color index | +0.84/+1.19 [3] |
Variable type | BY Dra [7] or RS CVn [2] |
Astrometry | |
70 Oph A | |
Radial velocity (Rv) | −6.87 [8] km/s |
Proper motion (μ) | RA: 206.525±0.246 [9] mas/yr Dec.: −1107.492±0.164 [9] mas/yr |
Parallax (π) | 195.5674 ± 0.1964 mas [9] |
Distance | 16.68 ± 0.02 ly (5.113 ± 0.005 pc) |
Absolute magnitude (MV) | +5.49 [10] |
70 Oph B | |
Proper motion (μ) | RA: 333.292±0.264 [11] mas/yr Dec.: −1068.354±0.215 [11] mas/yr |
Parallax (π) | 195.2166 ± 0.1012 mas [12] |
Distance | 16.707 ± 0.009 ly (5.123 ± 0.003 pc) |
Orbit [8] | |
Period (P) | 88.38±0.017 yr |
Semi-major axis (a) | 4.554±0.0052″ |
Eccentricity (e) | 0.4992±0.00039 |
Inclination (i) | 121.16±0.078° |
Longitude of the node (Ω) | 302.12±0.097° |
Periastron epoch (T) | 1895.94 |
Argument of periastron (ω) (secondary) | 14.0±0.14° |
Details | |
70 Oph A | |
Mass | 0.90 ± 0.04 [13] M☉ |
Radius | 0.91 ± 0.03 [14] R☉ |
Luminosity (bolometric) | 0.59 ± 0.02 [14] L☉ |
Surface gravity (log g) | 4.5 [15] cgs |
Temperature | 5,300 [15] K |
Metallicity [Fe/H] | +0.04 [16] dex |
Rotation | 19.7 days [16] |
Age | 1.9 [17] Gyr |
70 Oph B | |
Mass | 0.70 ± 0.07 [13] M☉ |
Luminosity (bolometric) | 0.13 ± 0.03 [13] L☉ |
Temperature | 4,350 ± 150 [13] K |
Other designations | |
70 Oph A: LHS 458 | |
70 Oph B: LHS 459 | |
Database references | |
SIMBAD | The system |
A | |
B | |
Exoplanet Archive | data |
ARICNS | data |
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.
In Ptolemy's 2nd-century Almagest star catalogue this star system is listed as a 4th magnitude star, the 28th (or 4th outside the constellation figure) in Ophiuchus. It is star No. 261 in this catalogue. [18]
This star system was first catalogued as a binary star by William Herschel in the late 18th century in his study of binary stars. Herschel proved that this system is a gravitationally bound binary system where the two stars orbit around a common center of mass. This was an important contribution to the proof that Newton's law of universal gravitation applied to objects beyond the Solar System.
This star was once considered part of the obsolete constellation Taurus Poniatovii, but after the International Astronomical Union officially recognized constellations, it was placed in Ophiuchus. [19]
70 Ophiuchi is a variable star with a magnitude range for the two stars combined of 4.00 to 4.03. [2] The type of variability is uncertain and it is not clear which of the two components causes the variations. It has been suspected of being either a BY Draconis variable [7] or an RS Canum Venaticorum variable, and a period of 1.92396 days has been measured. [2]
The primary star is a yellow-orange main sequence dwarf of spectral type K0, while the secondary is an orange dwarf of spectral type K4. [5] The two stars orbit each other at an average distance of 23.2 AU. But since the orbit is highly elliptical (at e=0.499), the separation between the two varies from 11.4 to 34.8 AU, [21] with one orbit taking 88.38 years to complete. [8]
In 1855, William Stephen Jacob of the Madras Observatory claimed that the orbit of the binary showed an anomaly, and it was "highly probable" that there was a "planetary body in connection with this system". [22] This is the first known attempt to use astrometric methods to detect an exoplanet, although Friedrich Bessel had applied similar methods 10 years earlier to deduce the existence of Sirius B. [23]
T. J. J. See made a stronger claim for the existence of a dark companion in this system in 1899, [24] but Forest Ray Moulton soon published a paper proving that a three-body system with the specified orbital parameters would be highly unstable. [25] The claims by Jacob and See have both been shown to be erroneous. [26]
Discovery of a "third dark companion" was announced by Louis Berman in 1932. This "dark body" around 70 Oph A was thought to have an 18-year period and a mass of 0.1 to 0.2 the Sun's mass. [27] A claim of a planetary system was again made, this time by Dirk Reuyl and Erik Holberg in 1943. The companion was estimated to have a mass 0.008 to 0.012 that of the Sun and a 17-year period. [28] This caused quite a sensation at the time but later observations have gradually discredited this claim. [26] [29] [30]
The negative results of past studies does not completely rule out the possibility of planets. In 2006 a McDonald Observatory team set limits to the presence of one or more planets around 70 Ophiuchi with masses between 0.46 and 12.8 Jupiter masses and average separations spanning between 0.05 and 5.2 AU. [31]
36 Ophiuchi is a triple star system 19.5 light-years from Earth. It is in the constellation Ophiuchus.
Xi Boötis, Latinised from ξ Boötis, is a binary star system located at a distance of 22 light-years away from Earth. It is the nearest visible star in the constellation Boötes. The brighter, primary component of the pair has a visual magnitude of 4.70, making it visible to the naked eye.
Delta Serpentis, Latinized from δ Serpentis, is a binary star system in the constellation Serpens, in its head. The light from the two stars in the system give a combined apparent magnitude of +3.80, which is bright enough to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 230 light years from the Sun. The system is moving closer with a radial velocity of ~42 km/s, and may come to within 115 light-years in 1.2 million years.
9 Aurigae is a star system in Auriga (constellation). It has an apparent magnitude of about 5, making it visible to the naked eye in many suburban skies. Parallax estimates made by the Hipparcos spacecraft put it at about 86 light-years from the solar system, although individual Gaia Data Release 3 parallaxes place all three components at 88 light years.
λ Ophiuchi, Latinized as Lambda Ophiuchi, is a triple star system in the equatorial constellation of Ophiuchus. It has the traditional name Marfik, which now applies exclusively to the primary component. The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of 3.82. It is located approximately 173 light-years from the Sun, based on its parallax, but is drifting closer with a radial velocity of –16 km/s.
Nu Ophiuchi is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude is +3.3, making it one of the brighter members of this constellation. Based upon parallax measurements made by the Gaia spacecraft, this star is located about 142 light-years from Earth.
Gliese 412 is a pair of stars that share a common proper motion through space and are thought to form a binary star system. The pair have an angular separation of 31.4″ at a position angle of 126.1°. They are located 15.8 light-years distant from the Sun in the constellation Ursa Major. Both components are relatively dim red dwarf stars.
HD 178911 is a triple star system with an exoplanetary companion in the northern constellation of Lyra. With a combined apparent visual magnitude of 6.70, it is a challenge to view with the naked eye. The system is located at a distance of approximately 161 light years from the Sun based on parallax measurements, but is drifting closer with a radial velocity of −38 km/s.
HD 115404 is a binary star system located in the constellation Coma Berenices. Parallax measurements made by Hipparcos put the system at 36 light-years, or 11 parsecs, away. The combined apparent magnitude of the system is 6.52, with the magnitudes of the components being 6.66 and 9.50.
HD 224635 and HD 224636 is a pair of stars comprising a binary star system in the constellation Andromeda. They are located approximately 94 light years away and they orbit each other every 717 years.
HD 6114 is a visual binary star system in the northern constellation of Andromeda. With a combined apparent magnitude of 6.46, the star can only be seen with the naked eye by keen-eyed observers even on the best of nights. Based upon an annual parallax shift of 10.4 mas as seen from Earth's orbit, the system is located approximately 108 parsecs (350 ly) distant.
Chi Ophiuchi, Latinized from χ Ophiuchi, is a variable star in the equatorial constellation of Ophiuchus. It has a blue-white hue and is faintly visible to the naked eye with an apparent visual magnitude that fluctuates around 4.22. The distance to this object, as determined from parallax measurements, is approximately 500 light years, but it is moving closer to the Sun with a radial velocity of −19 km/s. This star is a proper motion member of the Upper Scorpius sub-group in the Scorpius–Centaurus OB association; the nearest such co-moving association of massive stars to the Sun.
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.
ξ Oph, Latinized as Xi Ophiuchi, is a visual binary star system in the equatorial constellation of Ophiuchus. It has a yellow-white hue and is faintly visible to the naked eye with a combined apparent visual magnitude of 4.39. The system is located approximately 57.1 light-years away from the Sun based on parallax, but is drifting closer with a radial velocity of -9 km/s.
41 Ophiuchi is a binary star system in the zodiac constellation of Ophiuchus, and is positioned less than half a degree to the south of the celestial equator. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.72. The distance to this system is approximately 202 light years based on parallax.
Tau Ophiuchi is a multiple star in the constellation Ophiuchus, approximately 167 light years away based on parallax. Its two main components are two yellow-white main sequence stars, A, of magnitude 5.24 and class F2V, and B, of magnitude 5.94 and class F5V, orbiting each other with a period of 257 years and eccentricity around 0.77. A is reported as a spectroscopic binary with a smaller star of 0.29 solar masses orbiting it every 186 days. An additional component, C, has a separation of 100.8" and magnitude 11.28.
53 Ophiuchi is a multiple star system in the equatorial constellation of Ophiuchus. It is visible to the naked eye as a faint star with a combined apparent visual magnitude of 5.80. Located around 370 light years distant from the Sun based on parallax, it is moving closer to the Earth with a heliocentric radial velocity of −14 km/s. As of 2011, the visible components had an angular separation of 41.28″ along a position angle of 190°. The primary may itself be a close binary system with a separation of 0.3692″ and a magnitude difference of 3.97 at an infrared wavelength of 562 nm.
EQ Pegasi is a nearby binary system of two red dwarfs. Both components are flare stars, with spectral types of M4Ve and M6Ve respectively, and a current separation between the components of 5.8 arcseconds. The system is at a distance of 20.4 light-years, and is 950 million years old. The primary star is orbited by one known exoplanet.
HD 44120 is a wide binary star system in the southern constellation of Pictor. Although visible to the naked eye, it is a challenge to view having an apparent visual magnitude of 6.44. The system is located at a distance of 118 light years from the Sun based on parallax, but it is drifting closer with a radial velocity of −2 km/s. It has an absolute magnitude of 3.57.
HD 72945 and HD 72946 form a co-moving star system in the northern constellation of Cancer. HD 72945 is a binary star that is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.91. At an angular separation of 10.10″ is the fainter companion star HD 72946 at magnitude 7.25. It is being orbited by a brown dwarf. The system as a whole is located at a distance of approximately 84 light years from the Sun based on parallax measurements.