The findings suggest the earliest stars may not have died in regular supernovas but in hypernovas that are 10 times as powerful. “They’re very, very different kinds of stars”.
Advertisement
The unique chemical composition of these first stars, meant they were all giants, with masses over 40 times that of the Sunday.
It had been thought that the very first stars formed in the centre of the galaxy, where the effects of gravity are strongest.
The Big Bang gave rise to a universe filled only with hydrogen, helium, and trace levels of lithium. All of the other elements, like the oxygen we breathe or the sodium in our toothpaste, have been made inside stars or when they die as supernovae.
Cosmologists have developed a variety of strategies for understanding the what the universe looked like and how it behaved just after the Big Bang. Hypernova is also called a “superluminous supernova”.
The result is the formation of a black hole and the release of an enormous amount of energy, primarily in the form of gamma-rays – the most energetic form of light.
This has led astronomers to search for extremely metal-poor stars which are stars with lots of hydrogen, but very little of any other element.
The astronomers is believed to have observed over five million stars through the SkyMapper before selecting the purest and the oldest stars in the Milky Way. The study findings have been published in the journal Nature November 11 issue.
The team even demonstrated the stars had spent their whole lives in our galaxy near the center and weren’t just passing through it. This is another indication that they really are a part of the oldest stars known to man. Astronomers believe that this star is originally an average orange dwarf that possesses 0.8 solar masses that makes it slightly smaller and cooler than the Sunday.
Their best 23 candidates were all very metal-poor, leading the researchers to a larger telescope in the Atacama desert in Chile. The stars contain extremely low amounts of metal and could be termed as stars with the lowest metal content in our galaxy. They focused on the fingerprints of elements in the stars, which appear as distinct lines in the spectrum of their light.
There are nine of these ancient stars total and the astronomers studying them say that the pure stars have challenged theories about the environment in the early Universe where these stars formed. In addition, they should be in the center of the galaxy.
To do this, they measured distances and studied the stars’ movement in the sky to predict how they were moving, and where they had been in the past. These stars existed before the Milk Way was formed and the universe was just 300-million-years-old at the time, according to a study.
‘There are so many stars in the centre of our galaxy – finding these rare stars is really like looking for a needle in a haystack, ‘ said Dr Casey.
“Perhaps they ended their lives as hypernovae – poorly understood explosions of probably rapidly rotating stars producing 10 times as much energy as normal supernovae”.
Advertisement
“We didn’t think there would be so many”, says coauthor Andrew Casey, an astrophysicist at the University of Cambridge.
