Universe Guide

70 Ophiuchi

70 Ophiuchi Facts

  • 70 Ophiuchi is a main sequence star that can be located in the constellation of Ophiuchus. The description is based on the spectral class.
  • 70 Ophiuchi is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K0V SB) of the star, the star's colour is orange to red .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 16.58 light years away from us. Distance

70 Ophiuchi's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR6752. HIP88601 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD165341. The Gliese ID of the star is GL 702A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

70 Ophiuchi has alternative name(s) :- V2391 Oph, V2391 Oph.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 70 Ophiuchi. The Flamsteed name can be shortened to 70 Oph.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 197 G. Ophiuchi. There are no stars with a Gould designation in Ursa Major for example.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD+02 3482.

More details on objects' alternative names can be found at Star Names .

Location of 70 Ophiuchi

The location of the main sequence star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For 70 Ophiuchi, the location is 18h 05m 27.21 and +02° 30` 08.8 .

Radial Velocity and Proper Motion of 70 Ophiuchi

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -962.82 ± 0.58 milliarcseconds/year towards the north and 124.16 ± 0.83 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -6.87000 km/s with an error of about 0.08 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of 70 Ophiuchi

70 Ophiuchi Temperature and Colour

Based on the star's spectral type of K0V SB , 70 Ophiuchi's colour and type is orange to red main sequence star. The star's effective temperature is 5,019 Kelvin which is cooler than our own Sun's effective Temperature which is 5,777 Kelvin

70 Ophiuchi Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 0.68 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

70 Ophiuchi Radius

70 Ophiuchi estimated radius has been calculated as being 0.93 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 650,487.01.km. If you need the diameter of the star, you just need to multiple the radius by 2. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.9348764108632991073595061507. The figure is derived at by using the formula from SDSS rather than peer reviewed papers. It has been known to produce widely incorrect figures.

70 Ophiuchi Iron Abundance

70 Ophiuchi Iron Abundance is 0.03 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context. The value comes from the Hipparcos Extended Catalog.

70 Ophiuchi Apparent and Absolute Magnitudes

70 Ophiuchi has an apparent magnitude of 4.03 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 5.50 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.50. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to 70 Ophiuchi

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 196.62000 which gave the calculated distance to 70 Ophiuchi as 16.59 light years away from Earth or 5.09 parsecs. If you want that in miles, it is about 97,526,394,941,116.09, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 196.72000 which put 70 Ophiuchi at a distance of 16.58 light years or 5.08 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 1,047,817.91 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,396.00 Parsecs or 24,123.04 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to 70 Ophiuchi

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Airbus A38073615,107,097.43
Speed of Sound (Mach 1)767.26914,491,428.31
Concorde (Mach 2)1,534.547,245,704.71
New Horizons Probe33,000336,934.05
Speed of Light670,616,629.0016.58
70 Ophiuchi brightness ranges from a magnitude of 4.166 to a magnitude of 4.143 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 2.0 days (variability).

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional 70 Ophiuchi Facts and Figures

Visual Facts

Primary / Proper / Traditional Name70 Ophiuchi
Alternative NamesP Oph, V2391 Oph, HD 165341, HIP 88601, HR 6752, 197 G. Ophiuchi, 70 Oph, BD+02 3482, Gliese 702A, V2391 Oph
Spectral TypeK0V SB
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 5.50 / 5.50
Visual / Apparent Magnitude4.03
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)18h 05m 27.21
Declination (Dec.)+02° 30` 08.8
Galactic Latitude11.36833776 degrees
Galactic Longitude29.89541929 degrees
1997 Distance from Earth196.62000 Parallax (milliarcseconds)
 16.59 Light Years
 5.09 Parsecs
2007 Distance from Earth196.72000 Parallax (milliarcseconds)
 16.58 Light Years
 5.08 Parsecs
 1,047,817.91 Astronomical Units
Galacto-Centric Distance24,123.04 Light Years / 7,396.00 Parsecs
Proper Motion Dec.-962.82000 ± 0.58000 milliarcseconds/year
Proper Motion RA.124.16000 ± 0.83000 milliarcseconds/year
B-V Index0.86
Radial Velocity-6.87000 ± 0.08 km/s
Iron Abundance0.0300 ± 9.99 Fe/H
Semi-Major Axis7135.0000000
Stellar Luminosity (Lsun)0.6800000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Mean Variability Period in Days1.964
Variable Magnitude Range (Brighter - Dimmer)4.143 - 4.166

Estimated Calculated Facts

Radius (x the Sun)0.93
Effective Temperature5,141 Kelvin

Sources and Links

SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.

Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
165341+02 3482.0A4.30000261.00000-1100.00000K1Orange

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