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The newly discovered star system (shown in blue) orbits within our Milky Way Galaxy, in an orbit not unlike that of our sun (shown in green). Image via Kevin Schlaufman / Johns Hopkins.
The first stars to form after the Big Bang would have been made entirely of elements made in the Big Bang itself: the lightest and simplest elements like hydrogen, helium and lithium. The heavier and more complex elements – which astronomers call metals – were made in subsequent stars' thermonuclear furnaces. The first stars seeded the universe with the heavier elements when they exploded as supernovae. So when astronomers find a star with mostly light elements – and few heavier elements – This 13.5 billion-year-old star – a very tiny star in our own Milky Way galaxy – appears to be one of the oldest stars known and it's also the new record-holder for stars
The Johns Hopkins astronomers said this star is made almost entirely – but still not exclusively – from materials spewed from the Big Bang. They said in a statement:
The discovery of this [star] The world's first stars. The star is unusual because it is part of the Milky Way's 'thin disk' – the part of the galaxy in which the sun resides. And because this is so old, researchers say it's possible that our galactic neighborhood is at least 3 billion years older than previously thought.
And that is very interesting news! These findings have been accepted for publication in the peer-reviewed Astrophysical Journal.
The star carries the unwieldy label 2MASS J18082002-5104378 B. The paper's lead author is astronomer Kevin Schlaufman of Johns Hopkins. He said:
This star is maybe one in 10 million. It tells us something very important about the first generations of stars.
One interesting feature of the star is its orbit, which is one of the most metal-poor stars. Like our sun, the star never gets too far from the plane of the galaxy. In contrast, the most ultra-metal-poor stars have orbits that take them across the galaxy and far from its plane.
This research is based on the Magellan Clay Telescope at Las Campanas Observatory in Chile and the Gemini Observatories in Chile and Hawaii. The astronomers said:
This star is extremely low metallicity indicates that it has a cosmic family tree, it could be a little bit of a generation removed from the Big Bang. Indeed, it is the new record holder for the star with the smallest complement of heavy elements. In contrast, we have a lot of things in our minds.
Astronomers have found around 30 ancient, 'ultra-metal-poor' stars with the mass of the sun. The star Schlaufman and his team is only 14 percent of the mass of the sun.
The star is part of a two-star system orbiting around a common point. The team found the tiny, almost invisibly faint 'secondary' star after another group of astronomers discovered the much greater 'primary' star and measured its composition by studying the high-resolution optical spectrum of its light. The presence or absence of dark lines in a star's spectrum can identify the elements it contains, such as carbon, oxygen, hydrogen, iron, and more. In this case, the star had extremely low metallicity. Those astronomers also have an unusual presence in the star system that implied the presence of a neutron star or black hole. Schlaufman and his team found that to be incorrect, but in doing so they discovered the visible star's much smaller companion.
The existence of the smaller companion star in the big discovery. Schlaufman's team was able to make it to the masses by studying the primary star 's slight' wobble 'as the little star' s gravity tugged at it.
It's only been in the past couple of stars, in our universe. Prior to the late 1990s, they believed that they could only be observed because they burned their fuel and explode quickly as supernovae.
As astronomical simulations became more sophisticated – that is, as we learned more about how nature works in the vast realm of the cosmos – it began to seem that in certain situations, even more than 13 billion years since the Big Bang. The astronomers' statement explained:
Unlike huge stars, low-mass ones can live for exceedingly long times. Red dwarf stars, for instance, with a fraction of the mass of the sun, are thought to live to trillions of years.
The discovery of this new ultra-metal-poor star – 2MASS J18082002-5104378 B – opens up the possibility of observing even older stars. Schlaufman said:
If our inference is correct, then low-mass stars have a composition of the outcome of the Big Bang can exist. Even though we have not yet found an object like that in our galaxy, it can exist.
The newly discovered star is only 14 percent of the size of our sun. It's the new record holder for the star with the heavy elements, revealing the fact that it was early in the history of our cosmos, before the universe had a chance to be exploded. Image via Kevin Schlaufman / Johns Hopkins.
Bottom line: A newly discovered star – labeled 2MASS J18082002-5104378 B – turns out to have the least amount of heavy elements or "metals" known in a star so far. That means it's in the early morning, not long after the Big Bang.
Source: An Ultra Metal-poor Star Near the Hydrogen-burning Limit
Via Johns Hopkins
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