Did you know there are some totally different set of vampires lurking around in our far neighbourhood? Lucky for us, they don’t feed on our blood but they do suck something and stay young – the two features which qualify them as vampires. Well, sort of. They are stars – Vampire Stars!
Any star, if it is heavy, then it is young and if it has low mass then, it is old. Got it? We are going to go a step further. The heavier a star is, the quicker it uses its energy and with low mass the star becomes stringent while using its hydrogen. Still with us? Good. Now the colour of a star is determined by its temperature and its mass. So, a heavy, hot and young star shines blue and a low-mass, somewhat-cool, and old star shines red. This introduction is important to understand the topic.
A densely-packed mass of stars is called as globular clusters. Now there are few stars which are present in these globular clusters which appear younger than their counterpart stars. How can we say that they appear younger? Remember we said that young stars are blue and old stars are red. These apparent young stars are not formed after the clusters are formed but they remain young for quite a lot of time. These stars show a mix of Rapunzel’s (Tangled movie) mother – Mother Gothel and Twilight’s savvy vampires to remain younger. They are old but look young and they suck other star’s hydrogen to stay young!
How do they do that? These stars, also called as blue stragglers, are present only in densely-packed globular clusters. The distance between any two random stars is around a light year or sometimes little less or more. With this small distance the chances of stars colliding with each other are very high. The blue stragglers either collide with other prey stars or they simply suck the hydrogen out of the stars which are near to them. Some scientists call this as a rejuvenating process.
The proof for such stragglers or say vampire stars in the universe was seen in a globular cluster named 47 Tucanae with the help of Hubble Space Telescope. It was observed that one blue straggler (BSS 19) had double the mass of other stars in that cluster and rotated 75 times faster than our Sun. it is thought that because of astral merger incident, this blue straggler got its size and rotation speed.
Image Credit: http://By ESA/Hubble, CC BY 4.0,