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Muphrid, Eta Bootis, 8 Bootis, HD121370, HIP67927, HR5235

Muphrid (Eta Bootis) is a white to yellow subgiant star that can be located in the constellation of Bootes. Muphrid is the brightest star in Bootes based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it. The star has an estimated age of 1.90 Billion of Years but could be as young as 1.80 to 2.00 according to Hipparcos.

Eta Bootis is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR5235. HIP67927 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD121370. The Gliese ID of the star is Gliese GL534. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Ref : Star Names.

Muphrid has alternative name(s), Mufrid , . In Arabic, it is known as Al-Mufrid.

Location of Muphrid

The location of the star in the galaxy 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 Muphrid, the location is 13h 54m 41.12 and +18d23`54.9 .

Proper Motion of Muphrid

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 -356.29 ± 0.66 miliarcseconds/year towards the north and -60.95 ± 1.24 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Age, Radius) of Muphrid

Muphrid has a spectral type of G0IV. This means the star is a white to yellow subgiant star. The star is 7397.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24126.3025556800000000s. The star has a B-V Colour Index of 0.58 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,968 Kelvin.

Muphrid Radius has been calculated as being 2.88 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 2,003,118.03.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 2.89. 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 0.25 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.

The stars age according to Hipparcos data files put the star at an age of about 1.90 Billion years old but could be between 1.80 and 2.00 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old.

Muphrid Apparent and Absolute Magnitudes

Muphrid has an apparent magnitude of 2.68 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 2.41 If you used the 2007 Parallax value, you would get an absolute magnitude of 2.40. 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 Muphrid

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 88.17 which gave the calculated distance to Muphrid as 36.99 light years away from Earth or 11.34 parsecs. It would take a spaceship travelling at the speed of light, 36.99 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 87.75 which put Muphrid at a distance of 37.17 light years or 11.40 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.

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*.

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.

Muphrid Facts

Alternative Names

Traditional/Proper NameMuphrid
Flamsteed Name8 Bootis
Flamsteed Short Name8 Boo
Arabic NameAl-Mufrid
English MeaningThe solitary one
Bayer DesignationEta Bootis
Alternative Name(s)Mufrid
Hipparcos Library I.D.67927
Yale Bright Star Catalogue (HR) Id5235
Bonner DurchmusterungBD+19 2725
Gliese ID534
Henry Draper Designation121370

Visual Facts

Star Typesubgiant star
Age1.90 Billion Years Old
Age Range1.80 - 2.00 Billion Years Old
Absolute Magnitude2.41 / 2.40
Visual / Apparent Magnitude2.68
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)13h 54m 41.12
Declination (Dec.)+18d23`54.9
Galactic Latitude73.03 degrees
Galactic Longitude5.29 degrees
1997 Distance from Earth88.17 Parallax (milliarcseconds)
 36.99 Light Years
 11.34 Parsecs
2007 Revised Distance from Earth87.75 Parallax (milliarcseconds)
 37.17 Light Years
 11.40 Parsecs
Galacto-Centric Distance24,126.30 Light Years / 7,397.00 Parsecs
Proper Motion Dec.-356.29 ± 0.66 milliarcseconds/year
Proper Motion RA.-60.95 ± 1.24 milliarcseconds/year
B-V Index0.58
Radial Velocity0.70 ± 0.60 km/s
Iron Abundance0.25 ± 9.99 Fe/H
Eccentricity0.26
Inclination116.57
Semi-Major Axis35.41
Orbital Period (Days)494.17
Argument Of Periastron326.33
Spectral TypeG0IV
Colour(G) White to Yellow

Estimated Facts

Calculated Effective Temperature5,968 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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
121370+19 2725.0A2.80000-64.00000-363.00000G0Yellow
+19 2726.0B8.80000-42.0000012.000001925

Location of Muphrid in Bootes


Muphrid (Eta Bootis) Location in Bootes

The map was generated using Night Vision, an awesome free application by Brian Simpson.


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