A European space telescope capable of estimating the weight, age and temperature of a star just by looking at it has completed the largest map of the Milky Way.
The robotic spacecraft, called Subject, was launched by the European Space Agency in 2013. It was sent to the Lagrangian Sun-Earth point, a prime location of observation 1.5 million kilometers from Earth, and from there it has observed 1,800 millions of stars. Its mission is to draw a three-dimensional map of much of the Milky Way, which is home to the Solar System, and another 100 billion stars, many of them also with planetary systems.
This new batch of data, taken by Subject between 2014 and 2017 – has created the most complete map of the Milky Way, a giant disk-like structure measuring 170,000 light-years in diameter but only 1,000 light-years thick. The vast majority of stars are clustered in the center of the galaxy, which is characterized by two large spiral arms.
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“Before this mission, it was like we were in a forest and we only saw trees, but now we are in the sky and we can see everything from a bird’s eye view,” said Finnish astronomer Timo Prusti, scientific director of project. explains to this newspaper. Researchers leading the mission at the European Space Agency presented the new data on Monday, coinciding with the publication of a collection of scientific studies analyzing the findings in depth.
The distances on the new map are staggering. Each light year is nearly 10 trillion miles. The Earth and the rest of the Solar System travel around the center of the Milky Way, where there is a supermassive black hole called Sagittarius A *, at 720,000 kilometers per hour. But even at this rate, it will take 230 million years to make a complete revolution. Similarly, the Milky Way is a small island of stars that travels through an immense universe, where there are 100 billion more galaxies separated by mind-boggling distances.
The new map confirms that the Solar System is within the so-called “local bubble”, an area with few stars and a low concentration of gases and interstellar dust, which allows a fairly clear view of the rest of the galaxy. Prusti points out. out.
Before this mission, it was like we were in a forest and we only saw trees, but now we are in the sky and we can see everything from a bird’s eye view.
Finnish astronomer Timo Prusti
Subject He has also observed that stars are born inside a young galaxy called Gaia-Enceladus that was devoured by the Milky Way 10 billion years ago. “We have discovered other galaxies that have also been absorbed by ours. This helps us to understand that some galaxies, including the Milky Way, grow and evolve, assimilating others, “explains Prusti.
This is the third batch of data provided by Subject Since its launch in 2013, but for the first time, the mission has provided key information about the speed with which 33 million stars are moving away or toward us. Carme Jordi, an astronomer involved in the mission, explains another of the main discoveries. “Now we not only know how bright the stars are, but we can decompose them into a prism of different colors, which shows us which chemical elements are most abundant. From this, we can know if the stars are very cold or hot, if they have just been born or are very old, ”explains the researcher. This data is already available for 200 million stars, which allows us to identify the different generations of stars in the galaxy.
Besides, Subject it captures images so high definition that it can even capture small changes in the shape of some stars. These measurements revealed stars whose surface had deformed as if they had been affected by an earthquake, a phenomenon known as an earthquake. “Suddenly there is a sudden change inside the star, the effects of which move outwards and change the outer layers, just as a tsunami shakes the surface of the sea. [on Earth]”, Explains Jordi.
These phenomena can be very useful for understanding the interior of stars, which cannot be seen with conventional telescopes. This is where the star generates all its energy by nuclear fusion of hydrogen atoms to form helium. One of the biggest scientific projects today is to find a way to produce this nuclear fusion in the Earth’s reactors, a feat that could generate virtually inexhaustible and clean energy.
He Subject The mission will continue to collect data on stars and other objects within the Solar System and beyond the Milky Way until 2025, when it is expected to complete its scientific operations.