~ Stars through the galaxy? ~ ~ Hypervelocity stars, Gaia mission & L2 ~

1 - Credits: NASA/JPL-Caltech/R. Hurt (SSC/Caltech) ©

Our galaxy, the Milky Way is dominated by a supermassive black hole. Its mass is estimated at four million solar masses. What gives it such a huge gravitational force that it is very difficult to imagine. Able to destroy solar systems in a blink can also eject stars at high speed from the center of the galaxy to the ends of it. So thanks to those tremendous forces that govern the center of the galaxy are born the Hypervelocity stars…

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Hypervelocity stars (HVSs)

2 - Artist’s impression of two stars speeding from the centre of our Galaxy / ESA, CC BY-SA 3.0 IGO ©

In 2005 Smithsonian astronomers discovered the first "hypervelocity star” and twelve years later we have only been able to identify about 20. That gives us an idea of ​​how difficult it is to locate this type of stars.

And the last six moving away at great speed from the center of our Galaxy has been detected by the ESA with Gaia satellite. With the help of a revolutionary software. A software that mimics the human brain.

“In the end, we chose to use an artificial neural network, which is software designed to mimic how our brain works,”
“After proper ‘training’, it can learn how to recognise certain objects or patterns in a huge dataset. In our case, we taught it to spot hypervelocity stars in a stellar catalogue like the one compiled with Gaia.”
Tommaso Marchetti, PhD student at Leiden University and lead author of the paper describing the results published in Monthly Notices of the Royal Astronomical Society.

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ESA’s Gaia satellite & L2

3 - ESA/ATG medialab; background: ESO/S. Brunier ©

Its main objective is to create the most accurate map of the Milky Way to date. It was launched in December 2013. At the time of launch it had the focal plane matrix that at that time was the largest digital camera manufactured. With a million megapixels.In addition to that Gaia camera is equipped with a Radial Speed ​​Spectrometer that will characterize the movement of the stars.It also "carries as standard a" Basic Angle Monitor, a control tool that will monitor the angle formed by the two telescopes to guarantee the accuracy of distance measurements to the stars. And the best place to host these types of observation satellites are the Lagrange points. In particular L2.

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L2.

4 - ESA Spacecraft in 'sync' with Earth orbit on L2 ©

Located at 1.5 million kilometres directly behind the Earth as viewed from the Sun. At point L2 despite having a more distant orbit which would produce a body or a satellite placed there are more distant from the Sun and therefore should orbit it more slowly than Earth. But at point L2 of the Sun-Earth system the additional force of Earth's gravity decreases the orbital period of the object. So within that point of Lagrange thanks to its unique properties we can send long-term space missions thanks to saving fuel to stay in orbit. Also the position of this point located behind the Earth allows the shielding to be simpler than the satellites of L1. And besides not to orbit the Earth can maintain a stable temperature (without Earth shadow) a very important fact even for terrestrial telescopes.

References

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https://doi.org/10.1093/mnras/stx1304

http://adsabs.harvard.edu/abs/2005ApJ...622L..33B

1
https://www.nasa.gov/jpl/charting-the-milky-way-from-the-inside-out

2, 3
http://m.esa.int/Our_Activities/Space_Science/Gaia/Artificial_brain_helps_Gaia_catch_speeding_stars

4
http://m.esa.int/spaceinimages/Images/2004/11/Spacecraft_on_L2

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~ L1 & SOHO ~

https://steemit.com/space/@teks/the-mysterious-regions-of-space-that-have-their-own-rules

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Let's take care of the pale blue dot

Enjoy your day. Enjoy your life.

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Gift-thanks to @stellabelle