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MR Delphini, HD195434, HIP101236

MR Delphini is a orange to red eclipsing binary system star that can be located in the constellation of Delphinus. MR Delphini is the brightest star in Delphinus based on the Hipparcos 2007 apparent magnitude. The star can not be seen by the naked eye, you need a telescope to see it.

HIP101236 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD195434.

MR Delphini has alternative name(s), MR Del.

Location of MR Delphini

The location of the star in the galaxy 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 star is compared to the celestial equator and is expressed in degrees. For MR Delphini, the location is 20h 31m 13.29 and +05d13`06.1 .

Proper Motion of MR Delphini

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 281.28 ± 1.49 miliarcseconds/year towards the north and 304.70 ± 2.47 miliarcseconds/year east if we saw them in the horizon.

Physical Properties (Colour, Temperature, Radius) of MR Delphini

MR Delphini has a spectral type of K0. This means the star is a orange to red star. The star is 7371.00000000 Parsecs from the Galactic Centre or terms of Light Years is 24041.5000862400000000s. The star has a B-V Colour Index of 0.69 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 5,671 Kelvin.

MR Delphini Radius has been calculated as being 0.76 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 527,247.15.km. However with the 2007 release of updated Hipparcos files, the radius is now calculated at being round 0.83. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures.

MR Delphini Apparent and Absolute Magnitudes

MR Delphini has an apparent magnitude of 8.77 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 5.53 If you used the 2007 Parallax value, you would get an absolute magnitude of 5.34. 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 MR Delphini

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 22.53 which gave the calculated distance to MR Delphini as 144.77 light years away from Earth or 44.39 parsecs. It would take a spaceship travelling at the speed of light, 144.77 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 20.60 which put MR Delphini at a distance of 158.33 light years or 48.54 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.

The star's Galacto-Centric Distance is 7,371.00 Parsecs or 24,041.50 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Variable Type of MR Delphini

The star is a eclipsing binary system Beta Persei (Algol) 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. MR Delphini brightness ranges from a magnitude of 9.160 to a magnitude of 8.850 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 0.5 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.

MR Delphini Facts

Alternative Names

Traditional/Proper NameMR Delphini
Short NameMR Del
Hipparcos Library I.D.101236
Bonner DurchmusterungBD+04 4470
Henry Draper Designation195434

Visual Facts

Star Type star
Absolute Magnitude5.53 / 5.34
Visual / Apparent Magnitude8.77
Naked Eye VisibleRequires a 7x50 Binoculars - Magnitudes
Right Ascension (R.A.)20h 31m 13.29
Declination (Dec.)+05d13`06.1
Galactic Latitude-19.41 degrees
Galactic Longitude49.72 degrees
1997 Distance from Earth22.53 Parallax (milliarcseconds)
 144.77 Light Years
 44.39 Parsecs
2007 Revised Distance from Earth20.60 Parallax (milliarcseconds)
 158.33 Light Years
 48.54 Parsecs
Galacto-Centric Distance24,041.50 Light Years / 7,371.00 Parsecs
Proper Motion Dec.281.28 ± 1.49 milliarcseconds/year
Proper Motion RA.304.70 ± 2.47 milliarcseconds/year
B-V Index0.69
Radial Velocity-51.10 ± 0.60 km/s
Spectral TypeK0
Colour(K) Orange to Red

Variable Star Details

Variable Star ClassEclipsing binary system
Variable Star TypeBeta Persei (Algol)
Mean Variability Period in Days0.522
Variable Magnitude Range (Brighter - Dimmer)8.850 - 9.160

Estimated Facts

Calculated Effective Temperature5,671 Kelvin

Sources and Links

SIMBAD SourceLink

Related Stars

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
195434+04 4470.0A9.80000333.00000302.00000K0Orange
B9.900001957

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