Cepheus spur: Spanish astrophysicists discover new region of the US Milky Way

A team of researchers from the Spanish Astrobiology Center (CAB) presented the most accurate map of the Milky Way to date and described the existence of the “Cepheus spur”, a formation of blue stars warmer than the sun that remained hidden until now.

The team compiled the map of the Earth’s “solar power neighborhood” using the Gaia Telescope of the European Space Agency, which sets out the spiral arms of the stars that make up our galaxy. These include Orion, where the solar system is located; Perseus, on the outside of the galaxy, and Sagittarius, to the center of the Milky Way.

When we discovered the urge, there was no explosive revelation, but something inside me changed

Michelangelo Pantaleoni González, Scientist of the Spanish Astrobiology Center

Scientists led by Michelangelo Pantaleoni González and Jesús Maíz Apellániz also discovered a hidden structure they called the Cepheus incentive, a bridge of massive blue stars between the Orion arm and the Perseus constellation. A blue star has at least three times the mass of the sun and has its name, because the heat means that it looks blue to our eyes.

The Cepheus incentive remained unnoticed due to the previous lack of detail in the ‘star catalog’ that the researchers had just updated. The new map they drew has ‘20,000 classified celestial objects’, says Pantaleoni González. “A density of stars can be observed in a space that was apparently previously empty.” Their work is in the Monthly notices from Britain’s Royal Astronomical Society in March.

For scientists, one important aspect of the newly discovered stimulus is the constant motion, which shows that it is not a random alignment of stars, but a structure that sits above the ‘galactic disk’, the thin, circular distribution of stars. , dust and gas that often display beautiful spiral patterns. This position can be caused by contractions of the kind observed in other neighboring galaxies, but not seen in the Milky Way. ‘Maybe it’s oscillations of the galactic disk due to the convulsive evolution of the galaxy. Maybe it’s the echo of collisions with other galaxies billions of years ago, or maybe it’s something else, ”says Pantaleoni González.

The massive blue stars that make up the Cepheus incentive, also known as OB stars among astrophysicists, are the largest, rarest, and hottest stars in the galaxy. Of the estimated 400 billion stars in the Milky Way, less than one in every million is an OB star, so rare that Pantaleoni González describes them as a ‘rare disease’.

While the temperature on the surface of a star such as the Sun is about 5 500 ° C, OB stars can exceed 30 000 ° C and their mass can be ten times greater. Pantaleoni González explains that the relationship between the temperature of an object and the color it glows is called Planck’s law. ‘If we heat a piece of charcoal to more than 1000 ° C, we will see that it shines a dark red color. If we heat the bulb more and more, it will reach the temperature of the sun and it will glow yellowish white, and if we continue, the color of that glow will be blue, ”explains Pantaleoni González. “There are jokes about astrophysicists burning their hands in public toilets because they do not understand the color code of the taps.”

For Pantaleoni González, blue stars are the most interesting objects in the universe because the nuclear reactions within them are particularly violent, meaning that they produce elements that helped build the earth. “The elements that make up our planet, such as silicon or the phosphorus atoms in our DNA, mostly come from inside stars of this species that died billions of years ago,” says the young scientist who has not yet graduated.

Massive blue stars also create new stars when they die, releasing enormous amounts of energy in the form of a supernova, which compresses gas at very high temperatures and then erupts into a new formation. “One OB star can bring to life hundreds of stars like the sun,” says Pantaleoni González.

While blue stars blaze brightly in life, they fade rapidly. “Some of them live barely a few million years, five thousand times less than the sun’s expected life,” the researcher explains. ‘This means that they can not change their position in the galaxy much. We find them almost always near star-forming regions, where the galaxy is active, where it lives. ”His discovery therefore helps to understand where new stars are born, by identifying a group of blue stars that give birth to much more. “The new incentive shows how the production of new elements is maintained and how matter is recycled in the universe. Ultimately, it is directly related to the formation of planets in other stars and to the chemical bases of life, ”he says.

The massive blue stars that make up the Cepheus incentive are the galaxy’s largest, rarest and hottest stars.

Rodolfo Barbá, co-author of the paper and professor of astrophysics at La Serena University in Chile, compares the task of creating galactic maps to Earth maps compiled during the Enlightenment. “We can not send space probes even to our nearest stars, but we are examining the sides of the Milky Way using the light we reach from distant beacons – the OB stars,” he says. We are in the era of the discovery of galaxies, Barbá adds, and are experiencing in the 16th and 17th centuries the same debates and problems of great explorers on earth. In the early cart expeditions, the Baja California Peninsula seemed separate from the American continent until enough data was obtained to show that it was not an island. Now we discuss whether the galactic arm to which the sun belongs connects at some point with the other arms or whether it is just on an island. ”

Pantaleoni González recounts the moment the team found the Cepheus incentive. ‘When we discovered the incentive, there was no explosive revelation, but something inside me changed. This is what attracts you and gives you so much effort, ”he says. ‘We were in front [astrophysicist] Jesus [Apellániz]’s computer when he started inspecting this density of dots on the map. I ran to make a special diagram to see if it was in line with the idea that there was a structure, and it appeared. ‘

The young scientist alternates his university classes with work in the Spanish Astrobiology Center. He explains that Apellániz, his mentor, has an unusual research method: ‘Instead of drawing general conclusions by examining thousands of data, he investigates case by case. This ‘artisanal’ approach is ineffective when looking for obvious things, but it’s extremely productive if you want to discover subtle clues about what nature shows us. ”