June 28, 2013
NGC 2060, a star cluster and supernova remnant in the LMC
Image Credit: ESO
NGC 2060 is an open star cluster, located about 170,000 light-years away close to the center of the Tarantula Nebula, a vast star-forming cloud of gas and dust in our neighboring galaxy, the Large Magellanic Cloud, in the southern constellation of Dorado. This loose collection of stars is no longer gravitationally bound to each other. The stellar grouping will disperse in a few million years.
The cluster contains a supernova remnant of about 156 light-years across that has been given the same designation (NGC 2060, although it is also known as N157B, 30 Doradus B or ESO 57-EN1), that is formed by a supernova explosion some 5,000 – 10,000 years ago, blowing heated matter out into the surrounding space at great speed. The dark region below the cluster is a dense cloud of dust lying in front of the supernova remnant.
A supernova occurs when a star explodes in the final phase of its life. The exploding star can become billions of times as bright as the Sun before gradually fading from view. Supernova explosions are enriching the intergalactic gas with heavy chemical elements like oxygen, iron and silicon, necessary to build new generations of stars and planets, and to create life.
After some supernova explosions, when a massive star – more than 8 and below about 25 solar masses – collapses and becomes so dense that protons and electrons squish together to form neutrons, there remains a small, ultra-dense neutron star. Rapidly rotating, highly magnetized neutron stars are called pulsars. (Above this mass, the star collapses to form a black hole.) The explosion throws an expanding cloud of dust and hot gas into space surrounding the neutron star. When this slams into the existing interstellar medium, it heats up so much it glows in X-rays.
In 1998, an ultrafast pulsar (named PSR J0537-6910) was discovered – in X-rays – in NGC 2060 with the rotation period of 18 millisecond. This means that it is one of the fastest spinning pulsars in a supernova remnant.