[ad_1]
Astronomers from the Gaia Data Processing and Analysis Consortium today published the most detailed catalog ever made of the stars of the Milky Way. The new dataset, called Gaia Early Data Release 3 (EDR3), contains detailed information – stellar positions, movement, brightness and colors – on more than 1.8 billion sources, detected by ESA’s Gaia satellite. This represents an increase of over 100 million sources over the previous data release, which was made public in April 2018.
Data from over 1.8 billion stars was used to create this map of the entire sky. Shows the total brightness and color of stars observed by ESA’s Gaia satellite and released as part of the initial Gaia 3 data release. The brighter regions represent denser concentrations of bright stars, while the darker regions correspond to patches of sky where fewer and fainter stars are observed. . The color of the image is obtained by combining the total amount of light with the amount of blue and red light recorded by Gaia in each patch of sky. The bright horizontal structure that dominates the image is the plane of our Milky Way. It is actually a flattened disk seen from the front that contains most of the stars in the Galaxy. In the center of the image, the galactic center appears bright and crowded with stars. The darker regions of the galactic plane correspond to foreground clouds of interstellar gas and dust, which absorb light from more distant stars. Many of these clouds hide stellar nurseries where new generations of stars are currently being born. Dotted across the image are also many globular and open clusters, as well as entire galaxies beyond our own. The two bright objects in the lower right of the image are the Large and Small Magellanic Cloud, two dwarf galaxies orbiting the Milky Way. Image credit: ESA / Gaia / DPAC / CC BY-SA 3.0 IGO / A. Moitinho.
Launched on December 19, 2013, Gaia operates in an orbit around the so-called Lagrange 2 point (L2), located 1.5 million km behind the Earth in a direction away from the Sun.
At L2 the gravitational forces between the Earth and the Sun are balanced, so the spacecraft remains in a stable position, allowing for an essentially unobstructed long-term view of the sky.
Gaia’s main goal is to measure stellar distances using the parallax method.
In this case, astronomers use the observatory to continually scan the sky, measuring the apparent change in the position of the stars over time, resulting from the movement of the Earth around the Sun. Knowing that tiny shift in the positions of the stars allows them to calculate the their distances.
Gaia also tracks the brightness and changing positions of stars over time along the line of sight (their so-called proper motion) and, by breaking down their light into spectra, measures the speed at which they are moving towards o Chemical composition.
Equipped with 106 CCDs which are the equivalent of a camera with a resolution of one billion pixels, Gaia detects 50 million stars per day, taking ten measurements each time, representing a total of 500 million data points per day.
“Gaia is measuring the distances of hundreds of millions of objects that are many thousands of light years away, with an accuracy equivalent to measuring the thickness of hair at a distance of more than 2,000 km,” said Dr. Floor, lead of the UK Gaia DPAC project. van Leeuwen, astronomer at the Cambridge University Institute of Astronomy.
“These data are one of the cornerstones of astrophysics, enabling us to forensically analyze our stellar neighborhood and address crucial questions about the origin and future of our galaxy.”
Two previous versions – Gaia DR1 and Gaia DR2 – included the positions of 1.6 billion stars.
The Gaia EDR3 version brings the total to just under 2 billion stars, whose positions are significantly more accurate than previous data. This is the first of a two-part version; the full release of Gaia DR3 is scheduled for 2022.
“The new Gaia data promises to be a treasure trove for astronomers,” said Dr. Jos de Bruijne, an ESA astronomer, deputy scientist on the Gaia project.
The new data includes exceptionally accurate measurements of 331,312 objects – about 92 percent of stars within 100 parsecs (326 light years) of the Sun.
The previous solar quarter census, called the Gliese Catalog of Nearby Stars, was carried out in 1957. It initially possessed only 915 objects, but was updated in 1991 to 3,803 celestial objects.
It was also limited to a distance of 82 light years: Gaia’s census goes four times farther and contains 100 times more stars. It also provides position, motion, and brightness measurements that are orders of magnitude more accurate than old data.
The researchers also confirm that the Solar System is accelerating in its orbit around the Galaxy.
Using the observed motions of extremely distant galaxies, it was measured that the speed of our Solar System changes by 0.23 nm / s every second.
Due to this small acceleration, the trajectory of the Solar System is deviated by the diameter of an atom every second, and in a year it reaches about 115 km.
The acceleration measured by Gaia shows good agreement with theoretical expectations and provides the first measure of the curvature of the Solar System’s orbit around the Galaxy in the history of optical astronomy.
The team also sees evidence of the Milky Way’s past by looking at the stars in the direction of the Galaxy’s “anticenter”. This is exactly in the opposite direction in the sky from the center of the galaxy.
Computer models have predicted that the Milky Way’s disk will get larger over time as new stars are born.
The new data allows scientists to see the relics of the ancient 10-billion-year-old disk and then determine its smaller extent than the current size of the Milky Way disk.
Data from these outer regions also reinforces evidence of another major event in the Galaxy’s more recent past.
The data shows that in the outer regions of the disk there is a component of slowly moving stars above the plane of our Galaxy that are heading downward towards the plane and a component of fast-moving stars below the plane that are moving. upward.
This extraordinary model was not anticipated before. It could be the result of the near collision between the Milky Way and the dwarf galaxy of Sagittarius that took place in our Galaxy’s more recent past.
“The motion patterns in the stars on the disc are different from what we used to believe,” said Dr Teresa Antoja, an astronomer at the University of Barcelona.
“Although the role of the dwarf galaxy Sagittarius is still debated in some circles, it could be a good candidate for all of these disorders, as some simulations by other authors show.”
The new data from Gaia also deconstructs the Milky Way’s two largest companion galaxies, the Small and Large Magellanic Clouds, allowing astronomers to see their different stellar populations.
Having measured the motion of the stars in the Large Magellanic Cloud with greater accuracy than before, the team clearly shows that the galaxy has a spiral structure.
The data also resolves a stream of stars that is extracted from the Small Magellanic Cloud and alludes to previously invisible structures on the periphery of both galaxies.
“Gaia EDR3 is the result of a huge effort by all involved in the Gaia mission,” said Dr. Timo Prusti, an ESA astronomer, scientist on the Gaia project.
“It is an extraordinarily rich dataset and I look forward to the many discoveries that astronomers around the world will make with this resource.”
“And we’re not done yet; other big data will follow as Gaia continues to make measurements from orbit. “
These fascinating results come from a number of documents demonstrating the quality of the EDR3 version.
Source link
