Universe Guide

BU Crucis

BU Crucis Facts

BU Crucis's Alternative Names

HIP62913 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD111934.

BU Crucis has alternative name(s) :- , BU Cru.

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

Location of BU Crucis

The location of the supergiant 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 BU Crucis, the location is 12h 53m 37.62 and -60° 21` 25.4 .

Radial Velocity and Proper Motion of BU Crucis

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 2.95 ± 2.06 milliarcseconds/year towards the north and -2.10 ± 3.09 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 -17.00 km/s with an error of about 10.00 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 BU Crucis

BU Crucis Colour and Temperature

BU Crucis has a spectral type of B3Ib:. This means the star is a blue supergiant star. The star has a B-V Colour Index of 0.18 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 7,564 Kelvin.

BU Crucis Apparent and Absolute Magnitudes

BU Crucis has an apparent magnitude of 6.91 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 If you used the 2007 Parallax value, you would get an absolute magnitude of 0.81. 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 BU Crucis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -1.82 which gave the calculated distance to BU Crucis as -1792.11 light years away from Earth or -549.45 parsecs. If you want that in miles, it is 3,179,748,464,355,009.24.

In 2007, Hipparcos data was revised with a new parallax of 6.03 which put BU Crucis at a distance of 540.90 light years or 165.84 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 34,206,717.11 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.

Time to Travel to BU Crucis

A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

If you were to drive there at about 120 m.p.h. in a car with an infinity engine so you didn't have to pull over for petrol, it would take you -87,792,860,979,467.18 hours or -10,022,016,093.55 years.

At the time of writing, the fastest probe so far created is the New Horizon probe which is travelling at a speed of 33,000 m.p.h. If the probe was travelling to BU Crucis then it would take -319,246,767,198.06 hours / -36,443,694.89 years to get there. Speed Ref: N.A.S.A.

It would to take a spaceship journey travelling at the speed of light, -1792.11 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

BU Crucis brightness ranges from a magnitude of 7.060 to a magnitude of 6.900 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.1 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 BU Crucis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameBU Crucis
Alternative NamesHD 111934, HIP 62913, BU Cru
Spectral TypeB3Ib:
Constellation's Main StarNo
Multiple Star SystemYes
Star Type very luminous Supergiant Star less luminour Supergiant Star
GalaxyMilky Way
Absolute Magnitude / 0.81
Visual / Apparent Magnitude6.91
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)12h 53m 37.62
Declination (Dec.)-60° 21` 25.4
Galactic Latitude2.51 degrees
Galactic Longitude303.20 degrees
1997 Distance from Earth-1.82 Parallax (milliarcseconds)
 -1792.11 Light Years
 -549.45 Parsecs
2007 Distance from Earth6.03 Parallax (milliarcseconds)
 540.90 Light Years
 165.84 Parsecs
 34,206,717.11 Astronomical Units
Proper Motion Dec.2.95 ± 2.06 milliarcseconds/year
Proper Motion RA.-2.10 ± 3.09 milliarcseconds/year
B-V Index0.18
Radial Velocity-17.00 ± 10.00 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Mean Variability Period in Days0.130
Variable Magnitude Range (Brighter - Dimmer)6.900 - 7.060

Estimated Calculated Facts

Effective Temperature7,564 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
111934-59 4543.4A7.00000-6.00000-1.00000B3Blue/White

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