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V644 Monocerotis, HD51480, HIP33436

V644 Monocerotis is a blue eruptive star that can be located in the constellation of Monoceros. The star can not be seen by the naked eye, you need a telescope to see it.

HIP33436 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD51480.

V644 Monocerotis has alternative name(s), V644 Mon.

Location of V644 Monocerotis


Proper Motion of V644 Monocerotis

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 -0.71 ± 0.46 miliarcseconds/year towards the north and -2.80 ± 0.65 miliarcseconds/year east if we saw them in the horizon. The Radial Velocity, that is the speed at which the star is moving away/towards us is 58.00000 km/s with an error of about 4.40 km/s .

Physical Properties (Colour, Temperature, Radius) of V644 Monocerotis

V644 Monocerotis has a spectral type of Ape. This means the star is a blue star. The star has a B-V Colour Index of 0.28 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 6,889 Kelvin. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

V644 Monocerotis Apparent and Absolute Magnitudes

V644 Monocerotis has an apparent magnitude of 6.90 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 -3.97. 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 V644 Monocerotis

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as -0.24 which gave the calculated distance to V644 Monocerotis as -13590.14 light years away from Earth or -4166.67 parsecs. It would take a spaceship travelling at the speed of light, -13590.14 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.

In 2007, Hipparcos data was revised with a new parallax of 0.67 which put V644 Monocerotis at a distance of 4868.11 light years or 1492.54 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.

Variable Type of V644 Monocerotis

The star is a eruptive Gamma Cassiopeiae 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. V644 Monocerotis brightness ranges from a magnitude of 7.032 to a magnitude of 6.911 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


V644 Monocerotis Facts

Alternative Names

Traditional/Proper NameV644 Monocerotis
Short NameV644 Mon
Hipparcos Library I.D.33436
Bonner DurchmusterungBD-10 1774
Henry Draper Designation51480

Visual Facts

Star Type star
Visual / Apparent Magnitude6.90
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)06h 57m 09.38
Declination (Dec.)-10d 49` 28.1
Galactic Latitude-3.66 degrees
Galactic Longitude223.22 degrees
1997 Distance from Earth-0.24 Parallax (milliarcseconds)
 -13590.14 Light Years
 -4166.67 Parsecs
2007 Revised Distance from Earth0.67 Parallax (milliarcseconds)
 4868.11 Light Years
 1492.54 Parsecs
Proper Motion Dec.-0.71 ± 0.46 milliarcseconds/year
Proper Motion RA.-2.80 ± 0.65 milliarcseconds/year
B-V Index0.28
Radial Velocity58.00 ± 4.40 km/s
Spectral TypeApe
Colour(A) blue

Variable Star Details

Variable Star ClassEruptive
Variable Star TypeGamma Cassiopeiae
Mean Variability Period in Days0.097
Variable Magnitude Range (Brighter - Dimmer)6.911 - 7.032

Estimated Facts

Calculated Effective Temperature6,889 Kelvin

Sources and Links

SIMBAD SourceLink

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