Globular clusters are systems of extremely old stars attached gravitationally into a single structure of around 100-200 light years across.
They contain millions of stars, or maybe hundreds of thousands. The substantial mass of a cluster in the rich stellar center of a cluster pulls the stars inward to create a ball of stars.
The Latin term for globulus, from which these clusters arise, is small sphere.
Globular clusters are among the earliest known objects in the Universe, and are relics of the earliest epochs of the galaxy formation.
It’s thought that there’re a population of globular clusters in every galaxies. Our Milky Way Galaxy houses at least 150 such things, along with a handful more are likely to exist hidden behind the thick disk of our Galaxy.
The globular cluster NGC 6440 resides 8,470 parsecs (27,625 light years) from Earth in the constellation of Sagittarius.
Otherwise referred to as C 1746-203 or GCl 77, the cluster was found by the German-born British astronomer William Herschel on May 28, 1786.
The NGC 6440 has an apparent magnitude of about 10 and a diameter of aproximatelly six arcminutes.
“Globular clusters such as NGC 6440 are generally spherical, tightly packed collections of stars that live on the outskirts of galaxies,” said Hubble astronomers in a statement.
“They store hundreds of thousands to millions of stars which are approximately 1 light year apart, but they can be as close together because the dimensions of our Solar system,” he said.
“The Hubble data used to produce this picture originated from five different Hubble observing programs, four of which focused on the characteristics of pulsars,” the report stated.
“Pulsars are very magnetized, rotating neutron stars giving out a beam of electromagnetic radiation from its magnetic poles,” the report said.
“that beam shows up to us while a brief burst or pulse as the star rotates,’ he said.
“Pulsars spin very fast,” the scientists wrote.
“the astronomers have clocked the fastest pulsar at 716 rotations a second, but a pulsar could theoretically rotate as fast as 1,500 rotations per second before they gradually lose energy or break apart,” he said.
