Universe Guide

ER Orionis

ER Orionis Facts

  • ER Orionis is a eclipsing main sequence star that can be located in the constellation of Orion. The description is based on the spectral class.
  • ER Orionis is not part of the constellation outline but is within the borders of the constellation.
  • Based on the spectral type (F8V) of the star, the star's colour is yellow to white .
  • 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 1336.74 light years away from us. Distance

ER Orionis's Alternative Names

HIP24156 is the reference name for the star in the Hipparcos Star Catalogue.

ER Orionis has alternative name(s) :- ER Ori, ER Ori.

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-08 1050.

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

Location of ER Orionis

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 ER Orionis, the location is 05h 11m 14.50 and -08° 33` 24.4 .

Radial Velocity and Proper Motion of ER Orionis

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 -29.62 ± 1.53 milliarcseconds/year towards the north and 11.38 ± 2.64 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 37.90000 km/s with an error of about 3.30 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 ER Orionis

ER Orionis Temperature and Colour

Based on the star's spectral type of F8V , ER Orionis's colour and type is yellow to white main sequence star. The star has a B-V Colour Index of 0.48 which means the star's temperature is about 6,369 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

ER Orionis Radius

ER Orionis Apparent and Absolute Magnitudes

ER Orionis has an apparent magnitude of 9.40 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 1.34. 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 ER Orionis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -6.68000 which gave the calculated distance to ER Orionis as -488.27 light years away from Earth or -149.70 parsecs. If you want that in miles, it is about -2,870,356,410,964,361.25, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 2.44000 which put ER Orionis at a distance of 1336.74 light years or 409.84 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 84,534,979.14 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 ER Orionis

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 A3807361,217,989,229.14
Speed of Sound (Mach 1)767.2691,168,351,741.89
Concorde (Mach 2)1,534.54584,175,109.58
New Horizons Probe33,00027,164,850.69
Speed of Light670,616,629.001,336.74

Variable Type of ER Orionis

The star is a eclipsing W Ursae Majoris/Cont 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. ER Orionis brightness ranges from a magnitude of 10.000 to a magnitude of 9.411 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.4 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 ER Orionis Facts and Figures

Visual Facts

Primary / Proper / Traditional NameER Orionis
Alternative NamesER Ori, HIP 24156, BD-08 1050, ER Ori
Spectral TypeF8V
Constellation's Main StarNo
Multiple Star SystemNo / Unknown
Star Type Main Sequence Dwarf Star
ColourYellow - White
GalaxyMilky Way
Absolute Magnitude / 1.34
Visual / Apparent Magnitude9.40
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)05h 11m 14.50
Declination (Dec.)-08° 33` 24.4
Galactic Latitude-26.13369093 degrees
Galactic Longitude209.19636778 degrees
1997 Distance from Earth-6.68000 Parallax (milliarcseconds)
 -488.27 Light Years
 -149.70 Parsecs
2007 Distance from Earth2.44000 Parallax (milliarcseconds)
 1336.74 Light Years
 409.84 Parsecs
 84,534,979.14 Astronomical Units
Proper Motion Dec.-29.62000 ± 1.53000 milliarcseconds/year
Proper Motion RA.11.38000 ± 2.64000 milliarcseconds/year
B-V Index0.48
Radial Velocity37.90000 ± 3.30 km/s

Companions (Multi-Star and Exoplanets) Facts

Exoplanet CountNone/Unaware

Variable Star Details

Variable Star ClassEclipsing
Variable Star TypeW Ursae Majoris/Cont
Mean Variability Period in Days0.423
Variable Magnitude Range (Brighter - Dimmer)9.411 - 10.000

Estimated Calculated Facts

Effective Temperature6,369 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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