Universe Guide

BM Scorpii

BM Scorpii Facts

  • BM Scorpii is a pulsating giant star that can be located in the constellation of Scorpius. The description is based on the spectral class.
  • BM Scorpii is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (K3III + (G)) of the star, the star's colour is orange to red .
  • 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 787.83 light years away from us. Distance

BM Scorpii's Alternative Names

HIP86527 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD160371.

BM Scorpii has alternative name(s) :- , BM Sco.

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

Location of BM Scorpii

The location of the giant 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 BM Scorpii, the location is 17h 40m 58.55 and -32° 12` 52.0 .

Radial Velocity and Proper Motion of BM Scorpii

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 -6.51 ± 0.23 milliarcseconds/year towards the north and -2.01 ± 0.36 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 -7.99000 km/s with an error of about 0.20 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 BM Scorpii

BM Scorpii Colour and Temperature

Based on the star's spectral type of K3III + (G) , BM Scorpii's colour and type is orange to red giant star. The star has a B-V Colour Index of 1.67 which means the star's temperature is about 3,575 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

BM Scorpii Radius

BM Scorpii estimated radius has been calculated as being 71.84 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 49,987,199.82.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 37.013507970850656665235322094. 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.

BM Scorpii Apparent and Absolute Magnitudes

BM Scorpii has an apparent magnitude of 6.01 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 -2.35 If you used the 2007 Parallax value, you would get an absolute magnitude of -0.91. 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 BM Scorpii

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 2.13000 which gave the calculated distance to BM Scorpii as 1531.28 light years away from Earth or 469.48 parsecs. If you want that in miles, it is about 9,001,821,461,448,598.32, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 4.14000 which put BM Scorpii at a distance of 787.83 light years or 241.55 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 49,822,916.78 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 7,082.00 Parsecs or 23,098.89 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 BM Scorpii

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 A380736717,842,253.84
Speed of Sound (Mach 1)767.269688,587,573.36
Concorde (Mach 2)1,534.54344,293,337.95
New Horizons Probe33,00016,010,057.54
Speed of Light670,616,629.00787.83

Variable Type of BM Scorpii

The star is a pulsating Semiregular giants 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. BM Scorpii brightness ranges from a magnitude of 6.212 to a magnitude of 6.067 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.2 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 BM Scorpii Facts and Figures

Visual Facts

Primary / Proper / Traditional NameBM Scorpii
Alternative NamesHD 160371, HIP 86527, BM Sco
Spectral TypeK3III + (G)
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeGiant Star
ColourOrange to Red
GalaxyMilky Way
Absolute Magnitude -2.35 / -0.91
Visual / Apparent Magnitude6.01
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)17h 40m 58.55
Declination (Dec.)-32° 12` 52.0
Galactic Latitude-0.87130308 degrees
Galactic Longitude356.68527136 degrees
1997 Distance from Earth2.13000 Parallax (milliarcseconds)
 1531.28 Light Years
 469.48 Parsecs
2007 Distance from Earth4.14000 Parallax (milliarcseconds)
 787.83 Light Years
 241.55 Parsecs
 49,822,916.78 Astronomical Units
Galacto-Centric Distance23,098.89 Light Years / 7,082.00 Parsecs
Proper Motion Dec.-6.51000 ± 0.23000 milliarcseconds/year
Proper Motion RA.-2.01000 ± 0.36000 milliarcseconds/year
B-V Index1.67
Radial Velocity-7.99000 ± 0.20 km/s
Semi-Major Axis7122.0000000

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassPulsating
Variable Star TypeSemiregular giants
Mean Variability Period in Days0.212
Variable Magnitude Range (Brighter - Dimmer)6.067 - 6.212

Estimated Calculated Facts

Radius (x the Sun)37.01
Effective Temperature3,575 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

Comments and Questions

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