Pegasus Galaxy

NGC 7331 or Pegasus Galaxy

    New General Catalogue 7331 or Pegasus is otherwise called Caldwell 30. It is a unbarred spiral galaxy located at a distance of 40 million light-years away from our earth. It was first discovered by famous astronomer William Herschel in the year 1784. It is considered as one of the brightest member among the NGC 7331 group of galaxies. 

     The Pegasus is considered as twin sister of our Milkyway galaxy because of similar size and structure. It has a central bulge which is rotating in the opposite direction to the rest of the disk. There is a supernova called SN 1959D was the first supernova discovered and identified within this galaxy (Pegasus). The supernova was discovered by Milton Humason and H.S Gates at Palomar Observatory. Most recent discovered supernovae are SN 2013bu and SN 2014C. This galaxy was studied by visible and infrared images. The confirmation of similar size of Milkway and Pegasus was confirmed after 2000.  The approx size of the galaxy is about 120,000 light year.

This image was taken by Vicent Peris at Calar Obervatory in southern spain

Tags: Orion Nebula | Bow-Tie Nebula | Ornament Nebula | Tarantula Nebula | IC418 Nebula | Magellanic Nebula | NGC 7331

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Helix Nebula

Helix Nebula

About Nebula:

     The Helix nebula is also known as New General Catalogue 7293. It is a planetary nebula which can be located in the constellation of Aquarius in the night sky and it is the nearest nebula to our earth. It was first discovered by famous astronomer Karl Ludwig Harding in 1824 (approx). It's estimated distance from earth is about 700 light year and it looks like a Cat's eye. The physical characteristics of this nebula is similar to the Dumbbell Nebula. Due to the Cat eye appearance, sometimes it is referred to as the Eye of God. 

Location and Age:

The Helix nebula is located in the Aquarius constellation and it lies about 700 light years away from our earth which spans at a rate of 0.8 parsecs. Scientist estimated the current age of the nebula is about 10,600 +2300 or -1200 years with a expansion rate of 31 km per second.

Physical Structure:

NGC 7293

     The structure of the helix nebula is prolate spheroid and it was estimated that the expansion would have occurred in past 6,560 years and 12,100 years for the expansion of inner disk. Data from the spectroscopic studies reveal that the outer ring expansion rate is 40 km per second and the inner disk expansion rate is 32 km per second. It has many cometary knots and it was the first nebulae discovered to contain this. There are more than 20,000 cometary knots are estimated to be in the Helix. The temperature range increases from outer disk to the inner disk at the rate of 900 Kelvin to 1800 Kelvin.

Tags: Orion Nebula | Bow-Tie Nebula | Ornament Nebula | Tarantula Nebula | IC418 Nebula | Magellanic Nebula 

Image Credit : NASA's Hubble Space Telescope

Text Credit : Wiki and Team Fornax

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