Megrez / Delta Ursae Majoris Star Facts (Type, Distance, Magnitude, Age, Colour, Location and more)

Megrez, also known as Delta Ursae Majoris (Bayer) is a main sequence star located in the constellation of Ursa Major, The Big Bear. Megrez is a major star and forms part of the constellation.

Based on the spectral type (A3Vvar), Megrez colour is blue - white, although not the hottest stars, they are considerably hotter than our own star which is white.

Megrez temperature is in the range of between 7,500 and 10,000 Kelvin. Megrez effective temperature is 6,907 Kelvin which is hotter than the Sun's effective temperature, which is 5,777 Kelvin. Based on a parallax of 40.51, Megrez distance from Earth can be calculated at being 80.51 light years away or 24.97 parsecs.

Megrez is a naked-eye star, so you don't need a telescope or binoculars when you look up on a clear night. The lower the magnitude, the easier it will be to see it.

Location

The location of the Megrez in the night sky is determined by the right ascension (R.A.) and declination (Dec.). These are equivalent to the Longitude and Latitude on Earth. The Right Ascension (Longitude) is expressed in time (hh:mm:ss) and is how far the star is along Earth's celestial equator. If the R.A. is positive, then it's eastwards and vice versa.

The Declination (Latitude) is how far north or south the object is compared to the celestial equator and is expressed in degrees. If the value is positive, it is north of the celestial equator. For Megrez, the location is 12h 15m 25.45 and +57° 01` 57.4 .

Based on the location of Ursa Major, Megrez can be located in the northern hemisphere of the celestial sky. The celestial hemisphere is equivalent to the hemispheres on Earth. Megrez is north of the Ecliptic. The Ecliptic is the path that the Earth takes as it orbits the Sun. As the Earth is titled, we therefore have Celestial and Ecliptic hemispheres and they can be different for a star.

Physical Properties

Spectral Type

Megrez spectral type of A3Vvar which means its colour and type is blue - white main sequence star. There is no relationship between colour and size. For example, a red star can be large or small. Small stars are more energy efficient than larger stars and live longer.

Megrez Luminosity

Luminosity is the amount of energy a star pumps out relative to the amount that our star, the Sun, gives out. Our star, the Sun's value is 1. Megrez Luminosity figure of 23.243 comes from the Vizier online catalogue. The star generates more energy than our star.

Megrez Size (Radius)

Megrez radius has been calculated as being 3.37 times bigger than the Sun. The Sun's radius is 695,800km, therefore, the Megrez radius is an estimated 2,344,846.km. If you need the star's diameter, you just need to multiply the radius by 2.

Magnitude (Apparent / Absolute / Visible)

A number represents a star’s magnitude, whether apparent/visual or absolute. The smaller the number, the brighter the star is. The Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Megrez apparent magnitude is 3.32, which is a measure of the star's brightness as seen from Earth. Apparent Magnitude is also known as Visual Magnitude.

If you use the 1997 parallax value, Megrez' absolute magnitude is 1.33. If you use the 2007 parallax value, Megrez' absolute magnitude is 1.36. Absolute Magnitude is the star's apparent magnitude from 10 parsecs or 32.6 light years. The magnitude assumes nothing is between the object and the viewer, such as dust clouds. To compare different stars' actual brightness, you would best use Absolute rather than Apparent Magnitude.

Megrez is visible from Earth without needing binoculars or a telescope. The lower the Apparent Magnitude of a star or other object is, the easier it is to see in the night sky. An object with a magnitude greater than 6.5 cannot be seen without a telescope or other device.

Nearby Objects of Interest

• Medusa Galaxy (Active Galactic Nuclei)