Universe Guide

FN Boötis

FN Boötis Facts

  • FN Boötis is a variable star that can be located in the constellation of Bootes. The description is based on the spectral class.
  • FN Boötis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K6) of the star, the star's colour is orange to red .
  • The star can not be seen by the naked eye, you need a telescope to see it.
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 99.38 light years away from us. Distance

FN Bootis's Alternative Names

HIP76042 is the reference name for the star in the Hipparcos Star Catalogue.

FN Bootis has alternative name(s) :- , FN 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+47 2239.

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

Location of FN Boötis

The location of the variable 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 FN Boötis, the location is 15h 31m 46.68 and +47° 03` 27.2 .

Proper Motion of FN 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 -298.04 ± 1.03 milliarcseconds/year towards the north and 155.10 ± 1.12 milliarcseconds/year east if we saw them in the horizon. . 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 FN Boötis

FN Bootis Colour and Temperature

Based on the star's spectral type of K6 , FN Bootis's colour and type is orange to red variable star. The star has a B-V Colour Index of 1.58 which means the star's temperature is about 3,828 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

FN 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 0.19 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

FN Bootis Radius

FN Bootis estimated radius has been calculated as being 0.53 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 367,591.31.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 0.5115406179279701589491113243. 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.

FN Boötis Apparent and Absolute Magnitudes

FN Boötis has an apparent magnitude of 10.51 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 8.02 If you used the 2007 Parallax value, you would get an absolute magnitude of 8.09. 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 FN Boötis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 31.79000 which gave the calculated distance to FN Boötis as 102.60 light years away from Earth or 31.46 parsecs. If you want that in miles, it is about 603,146,963,288,638.39, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 32.82000 which put FN Boötis at a distance of 99.38 light years or 30.47 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 6,284,844.85 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 FN 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 A38073690,551,468.19
Speed of Sound (Mach 1)767.26986,861,166.80
Concorde (Mach 2)1,534.5443,430,526.80
New Horizons Probe33,0002,019,572.14
Speed of Light670,616,629.0099.38
FN Boötis brightness ranges from a magnitude of 10.764 to a magnitude of 10.470 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 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 FN Boötis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameFN Bootis
Alternative NamesHIP 76042, BD+47 2239, FN Boo
Spectral TypeK6
Constellation's Main StarNo
Multiple Star SystemYes
Star TypeVariable Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude 8.02 / 8.09
Visual / Apparent Magnitude10.51
Naked Eye VisibleRequires a 4.5 - 6 Inch Telescope - Magnitudes
Right Ascension (R.A.)15h 31m 46.68
Declination (Dec.)+47° 03` 27.2
Galactic Latitude52.90949645 degrees
Galactic Longitude76.26245271 degrees
1997 Distance from Earth31.79000 Parallax (milliarcseconds)
 102.60 Light Years
 31.46 Parsecs
2007 Distance from Earth32.82000 Parallax (milliarcseconds)
 99.38 Light Years
 30.47 Parsecs
 6,284,844.85 Astronomical Units
Galacto-Centric Distance24,123.04 Light Years / 7,396.00 Parsecs
Proper Motion Dec.-298.04000 ± 1.03000 milliarcseconds/year
Proper Motion RA. 155.10000 ± 1.12000 milliarcseconds/year
B-V Index1.58
Stellar Luminosity (Lsun)0.1900000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Mean Variability Period in Days0.530
Variable Magnitude Range (Brighter - Dimmer)10.470 - 10.764

Estimated Calculated Facts

Radius (x the Sun)0.51
Effective Temperature3,828 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
+47 2239.0A12.10000226.00000-331.00000

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