Zaurak (Gamma Eridani) Star Facts

Zaurak, also known as Gamma Eridani (Bayer) is a giant star located in the constellation of Eridanus, River Eridanus. It is not part of the Eridanus constellation outline but is within the borders of the constellation.

Based on the spectral type (M1IIIb Ca-1), Zaurak colour is red, which means that the star is one of the colder stars in the Universe, colder than our star.

Zaurak temperature is in the range of between 2,400 to 3,700 Kelvin. Zaurak effective temperature is 4,732 Kelvin which is cooler than the Sun's effective temperature which is 5,777 Kelvin. A star's size doesn't determine a star's temperature, the majority of the largest and smallest stars in the Universe are red stars. Red stars are also amongst the coolest with only brown dwarf stars cooler. Based on a parallax of 16.04, Zaurak distance from Earth can be calculated at being 203.34 light years away or 67.80 parsecs.

Zaurak 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.

Zaurak is a long period variable star. Variable stars are stars whose size and/or brightness changes over time. Zaurak brightness ranges from 3.101 (dimmest) to 3.049 over a period of 0.038 days.

Location

The location of the Zaurak 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 Zaurak, the location is 03h 58m 01.73 and -13° 30` 29.7 .

Based on the location of Eridanus, Zaurak can be located in the equatorial region of the celestial sky. The celestial hemisphere is equivalent to the hemispheres on Earth. Being in the equatorial region, Zaurak can be seen in both terrestrial hemispheres but there is a caveat of depending how far south and north you are. Zaurak is south 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

Zaurak 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. Zaurak Luminosity figure of 807.29 comes from the Vizier online catalogue. The star generates more energy than our star.

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.

Zaurak apparent magnitude is 2.97, 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, Zaurak' absolute magnitude is -1.19. If you use the 2007 parallax value, Zaurak' absolute magnitude is -1.00. 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.

Zaurak 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.