LJMU: New Stars Discovery Shed New Light on Galaxy's Formation

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LJMU: New Stars Discovery Shed New Light on Galaxy's Formation

Post by bystander » Tue Nov 22, 2016 5:15 pm

New Stars Discovery Shed New Light on Galaxy's Formation
Liverpool John Moores University | 2016 Nov 22

New family of stars discovered in Milky Way shed new light on Galaxy’s formation
[img3="The image above shows a visible picture of the inner 20 degrees of the Milky Way as seen from Earth (for comparison, the Moon is roughly 1/2 a degree on the sky). This part of the sky is extremely crowded due to the high density of the central regions of the Galaxy as well as the presence of many stars between Earth and the Galactic centre. Dark patches are due to absorption of visible light by dense dust clouds. Overall, the absorption by dust is largest in the centre than anywhere else in the Galaxy. The cyan circle shows the location of the Galactic centre, and the red stars indicate the positions of the stars newly discovered by APOGEE. Many of them coincide with regions of high dust absorption, which explains why APOGEE, observing in the infrared, was the first to detect the existence of this new stellar family.
Image Credit: Alex Mellinger
"]https://www.ljmu.ac.uk/about-us/news/~/ ... c3790.ashx[/img3][hr][/hr]
An astronomer from LJMU’s Astrophysics Research Institute has discovered a new family of stars in the core of the Milky Way Galaxy which provides new insights into the early stages of the Galaxy’s formation.

The discovery has shed new light on the origins of globular clusters – which are concentrations of typically a million stars, formed at the beginning of the Milky Way’s history.

LJMU is a member of Sloan Digital Sky Survey - an international collaboration of scientists at numerous institutions. One of the projects of this collaboration is APOGEE (the Apache Point Observatory Galactic Evolution Experiment) which collects infrared data for hundreds of thousands of stars in the Milky Way.

It was through observing stars in the infrared towards the Galactic centre that led to the discovery of a new population of stars, the likes of which had only been seen before inside globular clusters.

This intriguing new family of stars could have possibly belonged to globular clusters that were destroyed during the violent initial formation of the Galactic centre, in which case there would have been about 10 times more globular clusters in the Milky Way in early life than today. This means that a substantial fraction of the old stars inhabiting the inner parts of the Galaxy today may have been initially formed in globular clusters that were later destroyed. ...

Chemical Tagging with APOGEE: Discovery of a Large Population of N-rich Stars in the Inner Galaxy - Ricardo P. Schiavon et al
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Re: LJMU: New Stars Discovery Shed New Light on Galaxy's Formation

Post by Ann » Wed Nov 23, 2016 4:36 am

How fascinating!

I don't have the energy to search for it now, but there was an ArXiv paper a few years ago that argued that globular clusters were born from giant molecular clouds inside young galaxies, but most of the newborn globulars were gradually destroyed through repeated collisions with other giant molecular clouds. The constituent stars of the globulars would have slowly scattered across the galaxy.

According to the same paper, some globulars were sent into the halo of their galaxy due to tidal slingshot effects from near-collisions with other galaxies. In the halo, these globulars were safe from collisions with giant molecular clouds, and many of them have survived to this day.

But the most of the stars of the globulars that were broken up billions of years ago must still survive. it is certainly no wonder if we find some of these stars near the center of the Milky Way.

Ann
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