Infant stars identified at the center of our galaxy

Date:
December 10, 2021
Source:
University of Cologne
Summary:
A cosmic object originally classified as a gas and dust cloud
actually consists of three stars and could resolve a controversy
among astronomers.



FULL STORY ==========================================================================
What was previously identified as a gas and dust cloud at the centre
of our galaxy actually consists of three very young stars. That is the
result of a new study led by scientists from the University of Cologne's Institute of Astrophysics. The European Southern Observatory's Very Large Telescope (VLT) - a telescope with mirror diameters of 8.20 metres on
the summit of Cerro Paranal in Chile - provided the data for the study,
which has appeared in The Astrophysical Journal. The stars began to
form less than 1 million years ago, which is very young in astrophysical
terms. By comparison, our sun is just under 5 billion years old.


==========================================================================
In 2011, an object was found by means of the infrared data measured by the
Very Large Telescope, promising to reveal an unprecedented process at the centre of our galaxy. Based on a multi-wavelength analysis, scientists determined that it must be a cloud of gas and dust, which was named
G2. The interaction with the black hole at the centre of our galaxy,
SgrA*, should have torn G2 apart and caused proverbial fireworks. The researchers assumed that when G2 collided with SgrA*, various processes
would cause the gas and dust to make the black hole flare up. But that
did not happen.

In addition, there were other factors that gave astronomers around the
world a headache and fuelled controversial discussions. Studies showed
that the temperature of G2 is almost twice as high as that of surrounding
dust sources.

One possible explanation for G2's temperature is the extreme number of
stars at the centre of our galaxy. So these stars could have heated up
G2. The only question is why all other known dust sources at the centre
of the galaxy show a much lower temperature. The black hole, SgrA*,
was also ruled out as a heat source. The temperature of G2 should have increased the closer the supposed dust cloud came to the black hole -
like we would feel if we approached a radiator. However, the temperature remained constant over a long period of time, although the distance to
the black hole varied. The more closely G2 was observed around the world,
the more it became apparent that the cosmic object had to be more than
just a cloud of gas and dust.

The new results show that G2 actually consists of three individual
stars. 'We had the opportunity to observe the centre of our galaxy
ourselves several times with the Very Large Telescope.

Together with the data from the Southern Observatory archive, we were
able to cover a period from 2005 to 2019,' said lead author Dr Florian
Peissker from the Institute of Astrophysics. The unusual structure of
the data was also helpful in locating G2. Each pixel of the captured
image has an associated spectrum that covers a very specific and
detailed waveband. For the scientists, this offers an enormous level
of detail. 'That G2 actually consists of three evolving young stars is sensational. Never before have stars younger than the ones found been
observed around SgrA*,' Peissker said.

The results open the door to many more fascinating research questions -
for example where these young stars come from. The radiation-intensive environment of a supermassive black hole is not necessarily the best place
to produce young stars. Peissker concludes, 'The new results provide
unique insights into how black holes work. We can use the environment
of SgrA* as a blueprint to learn more about the evolution and processes
of other galaxies in completely different corners of our Universe.' ========================================================================== Story Source: Materials provided by University_of_Cologne. Note: Content
may be edited for style and length.


========================================================================== Journal Reference:
1. Florian Peissker, Michal Zajaček, Andreas Eckart, Basel Ali,
Vladimi'r Karas, Nadeen B. Sabha, Rebekka Grellmann, Lucas Labadie,
Banafsheh Shahzamanian. The Apparent Tail of the Galactic Center
Object G2/DSO. The Astrophysical Journal, 2021; 923 (1): 69 DOI:
10.3847/1538- 4357/ac23df ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211210103108.htm

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