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BM Eridani

BM Eridani Facts

  • BM Eridani is a pulsating giant star that can be located in the constellation of Eridanus. The description is based on the spectral class.
  • BM Eridani is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (M6III) of the star, the star's colour is 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 2938.41 light years away from us. Distance

BM Eridani's Alternative Names

HIP19717 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD26750.

BM Eridani has alternative name(s) :- , BM Eri.

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-10 863.

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

Location of BM Eridani

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 Eridani, the location is 04h 13m 29.62 and -10° 23` 13.5 .

Proper Motion of BM Eridani

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 -31.10 ± 0.66 milliarcseconds/year towards the north and -1.99 ± 1.03 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 BM Eridani

BM Eridani Colour and Temperature

Based on the star's spectral type of M6III , BM Eridani's colour and type is red giant star. The star has a B-V Colour Index of 1.52 which means the star's temperature is about 3,952 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

BM Eridani Radius

BM Eridani estimated radius has been calculated as being 21.25 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 14,782,753.42.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 64.164449193963638313162218909. 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 Eridani Apparent and Absolute Magnitudes

BM Eridani has an apparent magnitude of 7.23 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 -0.14 If you used the 2007 Parallax value, you would get an absolute magnitude of -2.54. 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 Eridani

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 3.35000 which gave the calculated distance to BM Eridani as 973.62 light years away from Earth or 298.51 parsecs. If you want that in miles, it is about 5,723,547,235,839,026.37, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 1.11000 which put BM Eridani at a distance of 2938.41 light years or 900.90 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 185,822,669.12 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.

Travel Time to BM Eridani

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)
Walking4492,636,652,204.97
Car12016,421,221,740.17
Airbus A3807362,677,373,109.81
Speed of Sound (Mach 1)767.2692,568,260,426.03
Concorde (Mach 2)1,534.541,284,128,539.38
New Horizons Probe33,00059,713,533.60
Speed of Light670,616,629.002,938.41

Variable Type of BM Eridani

The star is a pulsating Semi-Regular Star w 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 Eridani brightness ranges from a magnitude of 7.660 to a magnitude of 6.739 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.8 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 Eridani Facts and Figures

Visual Facts


Primary / Proper / Traditional NameBM Eridani
Alternative NamesHD 26750, HIP 19717, BD-10 863, BM Eri
Spectral TypeM6III
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star TypeGiant Star
ColourRed
GalaxyMilky Way
ConstellationEridanus
Absolute Magnitude -0.14 / -2.54
Visual / Apparent Magnitude7.23
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)04h 13m 29.62
Declination (Dec.)-10° 23` 13.5
Galactic Latitude-39.70783275 degrees
Galactic Longitude203.60040195 degrees
1997 Distance from Earth3.35000 Parallax (milliarcseconds)
 973.62 Light Years
 298.51 Parsecs
2007 Distance from Earth1.11000 Parallax (milliarcseconds)
 2938.41 Light Years
 900.90 Parsecs
 185,822,669.12 Astronomical Units
Proper Motion Dec.-31.10000 ± 0.66000 milliarcseconds/year
Proper Motion RA.-1.99000 ± 1.03000 milliarcseconds/year
B-V Index1.52

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeSemi-Regular Star w
Mean Variability Period in Days0.842
Variable Magnitude Range (Brighter - Dimmer)6.739 - 7.660

Estimated Calculated Facts


Radius (x the Sun)64.16
Effective Temperature3,952 Kelvin

Sources and Links


SIMBAD SourceLink

Related Stars


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