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Xi Boötis, 37 Boötis, HD131156, HIP72659, HR5544

Primary Facts on Xi Boötis

  • Xi Boötis's star type is rotating main sequence dwarf star that can be located in the constellation of Bootes. The description is based on the spectral class.
  • Xi Boötis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G8V + K4V) of the star, the star's colour is white to yellow .
  • Xi Bootis is the Bayer name for the star. It was assigned this name by Johann Bayer in 1603. The closer to the start of the Greek Alphabet the name, the brighter the star is. Alpha stars tend to be the brightest in the constellation. A notable exception is Pollux (Beta Geminorum) which is the brighest star in the Gemini constellation.
  • 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 21.89 light years away from us.

Xi Bootis's Alternative Names

Xi Bootis (Ksi Boo) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5544. HIP72659 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD131156. The Gliese ID of the star is GL 566A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

Xi Bootis has alternative name(s) :- , ksi Boo.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 37 Bootis with it shortened to 37 Boo.

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+19 2870.

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

Location of Xi Boötis

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 Xi Boötis, the location is 14h 51m 23.28 and +19° 06` 02.3 .

Radial Velocity and Proper Motion of Xi Boötis

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 -66.43 ± 0.38 miliarcseconds/year towards the north and 154.98 ± 0.48 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 1.59 km/s with an error of about 0.30 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.

Xi Boötis 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 0.67 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Physical Properties (Colour, Temperature) of Xi Boötis

Xi Boötis has a spectral type of G8V + K4V. This means the star is a white to yellow main sequence dwarf star. The star is 7,397.00 Parsecs from the Galactic Centre or in terms of Light Years is 24,126.30 s. The star has a B-V Colour Index of 0.72 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,503 Kelvin.

Xi Boötis Radius has been calculated as being 0.85 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 591,746.49.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 0.85. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is -0.14 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

Xi Boötis Apparent and Absolute Magnitudes

Xi Boötis has an apparent magnitude of 4.54 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 5.41 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.41. 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 Xi Boötis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 149.26 which gave the calculated distance to Xi Boötis as 21.85 light years away from Earth or 6.70 parsecs. It would take a spaceship travelling at the speed of light, 21.85 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 148.98 which put Xi Boötis at a distance of 21.89 light years or 6.71 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 1,384,027.21 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 7,397.00 Parsecs or 24,126.30 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of Xi Boötis

The star is a rotating BY Draconis 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. Xi Boötis brightness ranges from a magnitude of 4.710 to a magnitude of 4.660 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.0 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 Xi Boötis Facts and Figures

Visual Facts


Primary / Proper / Traditional NameXi Bootis
Alternative NamesKsi Boo, HD 131156, HIP 72659, HR 5544, 37 Bootis, 37 Boo, BD+19 2870, Gliese 566A, ksi Boo
Spectral TypeG8V + K4V
Constellation's Main StarNo
Multiple Star SystemYes
Star Type main sequence Dwarf Star
Colour white to yellow
GalaxyMilky Way
ConstellationBootes
Absolute Magnitude 5.41 / 5.41
Visual / Apparent Magnitude4.54
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)14h 51m 23.28
Declination (Dec.)+19° 06` 02.3
Galactic Latitude61.36 degrees
Galactic Longitude23.09 degrees
1997 Distance from Earth149.26 Parallax (milliarcseconds)
 21.85 Light Years
 6.70 Parsecs
2007 Distance from Earth148.98 Parallax (milliarcseconds)
 21.89 Light Years
 6.71 Parsecs
 1,384,027.21 Astronomical Units
Galacto-Centric Distance24,126.30 Light Years / 7,397.00 Parsecs
Proper Motion Dec.-66.43 ± 0.38 milliarcseconds/year
Proper Motion RA.154.98 ± 0.48 milliarcseconds/year
B-V Index0.72
Radial Velocity1.59 ± 0.30 km/s
Iron Abundance-0.14 ± 9.99 Fe/H
Eccentricity0.19
Semi-Major Axis8778.00
Stellar Luminosity (Lsun)0.67

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassRotating
Variable Star TypeBY Draconis
Mean Variability Period in Days0.033
Variable Magnitude Range (Brighter - Dimmer)4.660 - 4.710

Estimated Facts


Calculated Effective Temperature5,503 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
131156+19 2870.0A4.80000126.00000-98.00000G5Yellow
B6.700001836
C12.600001953
D9.600001953

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