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70 Ophiuchi system

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70 Ophiuchi system is a conjectured planetary system orbiting both stars of the binary system. It is located 16.6 light-years away in the constellation Ophiuchus in the caelregio Tarandus.

Stars Edit

Both components are K-type stars that are smaller, cooler, and dimmer than our Sun. The components orbit around the center of mass in 83.4 days at a separation of 23.2 AU and varies from 11.4 to 34.8 AU.

Planetary system Edit

Class Semimajor axis (AU) Eccentricity Orbital period (yr) Radius Mass Density (g/cm3) Gravity (g) Rotation period (d) Surface temp (K)
Ab GNH 0.2896 0.24589 0.1627 0.3527 RJ 0.0485 MJ 1.466 1.029 44.5764 435
Ac GNC 0.5166 0.41267 −0.3878 0.3284 RJ 0.0359 MJ 1.344 0.879 14.1632 329
Ad GJcM 1.2887 0.28170 −1.5277 0.5480 RJ 0.1314 MJ 1.058 1.154 −0.7889 224
Ae GJcM 2.2145 0.78395 −3.4414 0.6653 RJ 0.1848 MJ 0.833 1.102 0.6864 177
Bb SiOEcH 0.3914 0.11694 0.2919 0.5417 R 0.1543 M 5.350 0.526 62.2018 291
Bc SiMtEbC 0.6290 0.04214 −0.5949 1.1965 R 1.5481 M 4.983 1.081 0.6606 488
Bd GJaM 1.9559 0.83776 −3.2616 2.2752 R 7.7169 M 3.613 1.491 1.9514 154
Be GNA 3.2175 0.61428 −6.8818 4.5728 R 20.1560 M 1.163 0.964 1.3002 115

Capt. W.S. Jacobs claimed to have found a probable planet orbiting around 70 Ophiuchi A in 1855 by studying the anomaly of binary orbit. This claim was later helped by other astronomers and then eventually retracted. This star system is speculated to have eight planets, four around each star. There are three terrestrial planets and five giant planets with masses ranging from 0.15 Earth masses to 0.18 Jupiter masses.

Gravitational effects of binary stars cause planet's eccentricities to be quite high, even as high as 0.84. The planetary system's average eccentricity is 0.41691, the highest of any planetary system containing at least four planets, both known and conjectured. Their orbital distances between these planets range from 0.29 AU to 3.22 AU and orbital periods ranging from about two months to nearly seven years. One unusual aspect of this planetary system is that all but one planet orbit in a retrograde paths, orbiting in the opposite direction to their parent star's rotation.

70 Ophiuchi Ab Edit

70 Ophiuchi Ab is the innermost planet of the primary star with an orbital period of 59.4 days. The planet is one-third the size of Jupiter but it masses just 5% that of Jupiter, classifying this as midplanet with a density slightly higher than Jupiter's at 1.47 g/cm3. Its gravitational field is very similar in strength to Earth's at 102.9%. It is a blue, featureless ice giant with no clouds with a visible albedo of 25%.

70 Ophiuchi Ac Edit

70 Ophiuchi Ac is a planet similar in size to Ab but its mass is a little bit lower. It takes 141.6 days to orbit once around the star at distances varying from 0.30 to 0.73 AU. The planet has temperatures suitable enough for water clouds and sulfur clouds to exist and this planet appears yellow-gray from space with a visible albedo of 0.66. The surface temp is 132°F.

70 Ophiuchi Ad Edit

70 Ophiuchi Ad is a sub-Saturn mass planet that takes a year and a half to revolve once around the star. The orbital distance varies from 0.93 AU (just inside Earth's orbit) to 1.65 AU (just beyond Mars' orbit). It rotates in a retrograde motion relative to orbit, taking 19 hours to complete one complete rotation. In addition, this planet is rotating on its side like Uranus, meaning that all of its hemisphere except for the equatorial region have day-night cycles lasting a planetary year instead of planetary day. This planet's upper clouds are made exclusively of water at a temp of 56 degrees below zero. This planet appears light gray from space with a visible albedo of 71%.

70 Ophiuchi Ae Edit

70 Ophiuchi Ae is a sub-Saturn mass planet taking 3.4 years to revolve once around the star and takes 1612 to rotate once in the same direction as its orbit. It has mass 0.185 MJ and radius 0.665 RJ. Like Jupiter and Saturn, clouds of 70 Oph Ae seen from space are made of ammonia, plus water.

70 Oph Ae orbits in a very eccentric path, varying in distances from 0.48 to 3.95 AU, a factor of 8.26. It orbits at an average distance of 2.215 AU and an eccentricity value of 0.784. 70 Oph Ae would cross the orbit of two planets, but there's no chance to collide with planet since this planet orbits in a different plane. The high eccentricity is caused by the gravitational tug of the binary star component.

70 Ophiuchi Bb Edit

70 Ophiuchi Bb is a Mercury-like planet in terms of size and orbit. However, this planet orbits in the habitable zone because the parent star is just 18 the Sun's luminosity. The surface is covered with 64% water surrounded by an atmosphere half the thickness of Earth's. The surface temperature is 65°F, nearly matching with Earth's 59°F.

70 Oph Bb orbits at 25 the Earth–Sun distance and takes 312 months to orbit once around the star. This is the only planet of the 70 Oph system that orbits in the same direction as the rotation of the star. The planet's rotation period is 5313 days, similar to 59 day rotation for Mercury. Planet's slow rotation is due to tidal forces of the star. Rotation is in a 1:2 tidal lock ratio to its orbital revolution.

The planet masses 0.154 M or about three Mercury masses and is about the size of Mars. 70 Oph Bb has an average density of 5.35 g/cm3, meaning the planet is made of about same materials which make up Earth. Its surface gravity is 0.53 g, meaning it is half the strength of Earth's. An average adult person would weigh 79 pounds on 70 Oph Bb.

70 Ophiuchi Bc Edit

70 Ophiuchi Bc is a planet bigger and more massive than Earth. 70 Oph Bc orbits at 0.63 AU with a circular orbit, revolving around the star once every seven months. Planet's rotation takes less than 16 hours to complete one 360° spin.

It masses 1.55 times that of Earth and has a diameter of 9484 miles, which is about 20% larger than Earth. The planet sports a density a shade under five and its surface gravity is slightly greater than Earth's. The planet's lower density than Earth would suggest that heavy metals are less common on this planet than on Earth, such as lead, silver and gold, but due to planet being a bit more massive than Earth, 70 Oph Bc would contain at least the same amount of heavy metals as Earth.

70 Ophiuchi Bd Edit

70 Ophiuchi Bd is a super-Earth 7.7 times more massive than Earth. Its density is lower than Earth's but its surface gravity is stronger than Earth's. It is a gas dwarf, meaning it is a small gaseous planet with no solid surface. There are ammonia clouds with heights between 10–50 miles. The surface temp is –182°F, slightly colder than on Jupiter. This planet can sometimes be called "mini-Jupiter" due to its similar appearance to Jupiter, albeit lot smaller. It sizes just one-quarter that of Jupiter's and masses 150 of that of Jupiter.

In addition to the so-called "mini-Jupiter", another interesting aspect is that planet orbits in a comet-like path around the star with an eccentricity of 0.84, due to combined gravitational tugs of the planet beyond this orbit and another star in the binary system. It orbits at an average distance of 1.956 AU and varies from 0.32 to 3.59 AU, meaning this planet crosses the orbits of all other siblings. It takes 314 years or just over 100 megaseconds to complete one oval orbit.

70 Ophiuchi Be Edit

70 Ophiuchi Be is the outermost planet in this system. It is a gaseous planet massing 20 Earth masses and sizing over 412 times that. It takes 31.2 days to complete one rotation, twice as long as Neptune's. It is the coldest planet of the 70 Ophiuchi system as the surface temperature is −269°F.

70 Oph Be orbits in a very eccentric path, but not as high as 70 Oph Bd, but it still crosses the orbit of that planet. It orbits at a semimajor axis of 3.22 AU and its periastron is at 1.24 AU, well inside the 70 Oph Bd's semimajor axis. Also the planet can sometimes be found as far as 5.19 AU, 29 the average separation between two stars. The planet takes 6.8 years to revolve once around the star in a retrograde path.

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