Universe Guide

44 Boötis

44 Boötis Facts

  • 44 Boötis is a eclipsing binary sys main sequence star that can be located in the constellation of Bootes. The description is based on the spectral class.
  • 44 Boötis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (G2V + G2V) of the star, the star's colour is yellow .
  • 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 15.00 Billion of Years but could be as young as 13.70 to 16.10 according to Hipparcos.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 40.80 light years away from us. Distance

44 Bootis's Alternative Names

The Id of the star in the Yale Bright Star Catalogue is HR5618. HIP73695 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD133640. The Gliese ID of the star is GL 575A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names

44 Bootis has alternative name(s) :- , i Boo.

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 44 Bootis. The Flamsteed name can be shortened to 44 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+48 2259.

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

Location of 44 Boötis

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 44 Boötis, the location is 15h 03m 47.68 and +47° 39` 14.5 .

Radial Velocity and Proper Motion of 44 Boötis

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 19.86 ± 1.34 milliarcseconds/year towards the north and -445.84 ± 1.56 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 -17.89000 km/s with an error of about 0.40 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 of 44 Boötis

44 Bootis Colour and Temperature

Based on the star's spectral type of G2V + G2V , 44 Bootis's colour and type is yellow main sequence star. The star has a B-V Colour Index of 0.64 which means the star's temperature is about 5,755 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

44 Bootis 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 1.76 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

44 Bootis Radius

44 Bootis estimated radius has been calculated as being 1.30 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 902,100.57.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 1.2728292348004666061189560000. 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.

44 Bootis Iron Abundance

44 Bootis Iron Abundance is -0.29 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.

44 Bootis Estimated Age

The stars age according to Hipparcos data files put the star at an age of about 15.00 Billion years old but could be between 13.70 and 16.10 Billion years old. In comparison, the Sun's age is about 4.6 Billion Years Old. The reported age is older than the widely recognised age of the Universe so a little scepticism about the age is warranted.

44 Boötis Apparent and Absolute Magnitudes

44 Boötis has an apparent magnitude of 4.83 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 4.30 If you used the 2007 Parallax value, you would get an absolute magnitude of 4.34. 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 44 Boötis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 78.39000 which gave the calculated distance to 44 Boötis as 41.61 light years away from Earth or 12.76 parsecs. If you want that in miles, it is about 244,609,601,778,170.01, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 79.95000 which put 44 Boötis at a distance of 40.80 light years or 12.51 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 2,580,354.75 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 7,399.00 Parsecs or 24,132.83 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 44 Bootis

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 A38073637,175,487.04
Speed of Sound (Mach 1)767.26935,660,450.85
Concorde (Mach 2)1,534.5417,830,202.19
New Horizons Probe33,000829,126.01
Speed of Light670,616,629.0040.80

Variable Type of 44 Boötis

The star is a eclipsing binary sys W Ursae Majoris 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. 44 Boötis brightness ranges from a magnitude of 5.000 to a magnitude of 4.834 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.3 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 44 Boötis Facts and Figures

Visual Facts

Primary / Proper / Traditional Name44 Bootis
Alternative NamesI Boo, HD 133640, HIP 73695, HR 5618, 44 Boo, BD+48 2259, Gliese 575A, i Boo
Spectral TypeG2V + G2V
Constellation's Main StarNo
Multiple Star SystemYes
Star Type Main Sequence Dwarf Star
GalaxyMilky Way
Age15.00 Billion Years Old
Age Range13.70 - 16.10 Billion Years Old
Absolute Magnitude 4.30 / 4.34
Visual / Apparent Magnitude4.83
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)15h 03m 47.68
Declination (Dec.)+47° 39` 14.5
Galactic Latitude57.06506524 degrees
Galactic Longitude80.36871634 degrees
1997 Distance from Earth78.39000 Parallax (milliarcseconds)
 41.61 Light Years
 12.76 Parsecs
2007 Distance from Earth79.95000 Parallax (milliarcseconds)
 40.80 Light Years
 12.51 Parsecs
 2,580,354.75 Astronomical Units
Galacto-Centric Distance24,132.83 Light Years / 7,399.00 Parsecs
Proper Motion Dec.19.86000 ± 1.34000 milliarcseconds/year
Proper Motion RA.-445.84000 ± 1.56000 milliarcseconds/year
B-V Index0.64
Radial Velocity-17.89000 ± 0.40 km/s
Iron Abundance-0.2900 ± 9.99 Fe/H
Semi-Major Axis6593.0000000
Stellar Luminosity (Lsun)1.7600000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEclipsing binary sys
Variable Star TypeW Ursae Majoris
Mean Variability Period in Days0.268
Variable Magnitude Range (Brighter - Dimmer)4.834 - 5.000

Estimated Calculated Facts

Radius (x the Sun)1.27
Effective Temperature5,755 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
133640+48 2259.0A5.30000-394.0000026.00000G0Yellow

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