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AO Virginis, HIP70209

AO Virginis is a red pulsating variable star that can be located in the constellation of Virgo. The description is based on the spectral class. AO Virginis is not part of the constellation but is within the borders of the constellation.

The star can not be seen by the naked eye, you need a telescope to see it.

AO Virginis's Alternative Names

HIP70209 is the reference name for the star in the Hipparcos Star Catalogue.

AO Virginis has alternative name(s) :- , AO Vir.

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+04 2853.

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

Location of AO Virginis

The location of the 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 star is compared to the celestial equator and is expressed in degrees. For AO Virginis, the location is 14h 21m 51.53 and +03° 54` 33.9 .

Radial Velocity and Proper Motion of AO Virginis

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 43.33 ± 13.34 miliarcseconds/year towards the north and -79.99 ± 22.17 miliarcseconds/year east if we saw them in the horizon.

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -6.00 km/s with an error of about 7.40 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 (Colour, Temperature) of AO Virginis

AO Virginis has a spectral type of M2e-M4e. This means the star is a red variable star. The star has a B-V Colour Index of 1.5 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 4,014 Kelvin.

AO Virginis Radius has been calculated as being 1.44 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 1,005,027.21.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 0.95. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

AO Virginis Apparent and Absolute Magnitudes

AO Virginis has an apparent magnitude of 11.16 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 5.63 If you used the 2007 Parallax value, you would get an absolute magnitude of 6.54. 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 AO Virginis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.83 which gave the calculated distance to AO Virginis as 416.56 light years away from Earth or 127.71 parsecs. It would take a spaceship travelling at the speed of light, 416.56 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 11.89 which put AO Virginis at a distance of 274.32 light years or 84.10 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 17,346,749.33 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.

Variable Type of AO Virginis

The star is a pulsating Omicron Ceti variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. AO Virginis brightness ranges from a magnitude of 11.497 to a magnitude of 9.303 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 254.0 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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AO Virginis Facts

Visual Facts


Primary / Proper / Traditional NameAO Virginis
Alternative NamesHIP 70209, BD+04 2853, AO Vir
Spectral TypeM2e-M4e
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeVariable Star
Colour red
GalaxyMilky Way
ConstellationVirgo
Absolute Magnitude 5.63 / 6.54
Visual / Apparent Magnitude11.16
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)14h 21m 51.53
Declination (Dec.)+03° 54` 33.9
Galactic Latitude58.30 degrees
Galactic Longitude349.80 degrees
1997 Distance from Earth7.83 Parallax (milliarcseconds)
 416.56 Light Years
 127.71 Parsecs
2007 Distance from Earth11.89 Parallax (milliarcseconds)
 274.32 Light Years
 84.10 Parsecs
 17,346,749.33 Astronomical Units
Proper Motion Dec.43.33 ± 13.34 milliarcseconds/year
Proper Motion RA.-79.99 ± 22.17 milliarcseconds/year
B-V Index1.50
Radial Velocity-6.00 ± 7.40 km/s

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days254.000
Variable Magnitude Range (Brighter - Dimmer)9.303 - 11.497

Estimated Facts


Calculated Effective Temperature4,014 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
+04 2853.0A10.30000
B11.400001956

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