Astronomy department kicks off new academic year with ‘Nature’ Trifecta

0

AMHERST, Mass. – A twelve billion year old mystery of the early universe; the paradox of a recurrent supernova; the unknown process governing the growth of stars: these are among the topics recently explored in a remarkable series of articles published by the Department of Astronomy at UMass Amherst, all published in the “Nature” family of journals, among the journals most prestigious academic institutions in the world. world.

“The results published in these three papers address fundamental questions in astronomy, from understanding the evolution of stars and galaxies at the dawn of the Universe to discovering how stars, and possibly them planets, grow in our “cosmic” backyard, explains Daniela Calzetti, head of the astronomy department. “This trifecta of ‘Nature’ papers is both exciting and incredible.”

Why has the growth of some primitive galaxies stalled?

Shortly after the Big Bang, 14 billion years ago, some of the most massive galaxies in our universe mysteriously stopped producing new stars. “For some reason,” said Kate whitaker, professor of astronomy and lead author of a new article recently published in ‘Nature, ‘”they closed. They are no longer forming new stars. Astronomers knew those early massive galaxies had gone silent, but so far no one knew why.

Picture

The giant sleeping galaxy in the center of this image is 10 billion light years away. Credit: ESA / Hubble & NASA, A. Newman, M. Akhshik, K. Whitaker

Using a suite of instruments, including the The Hubble Space Telescope and ALMA, the Atacama Large Millimeter / submillimeter Array, the Whitaker team, which includes Alexandra Pope, professor of astronomy at UMass, and Christina C. williams, who obtained his doctorate. in astronomy at UMass, Whitaker’s team discovered that these early galaxies literally ran out of gas – cold gas, which fuels galaxy growth.

The galaxies studied by Whitaker’s team are 10 to 12 billion light years apart, meaning that the light the team observed was emitted 10 to 12 billion years ago. Indeed, Whitaker looks at the deep past of the universe.

The team’s findings mean that in the first billion years of the universe’s existence, these galaxies either burned their energy stores or ejected them and, moreover, something may be blocking physically the reconstitution of each galaxy in cold gas.

Together, this research is helping us rewrite the early history of the universe so that we can get a clearer idea of ​​how galaxies have evolved.

The paradox of the recurrent supernova

As if solving a 12 billion year old mystery wasn’t enough, Whitaker also recently co-wrote an article in “Nature astronomyRevealing a paradox: the recurring appearance of a supernova known as the Requiem.

Picture

NEWS • Three views of the same supernova appear in the 2016 image on the left, taken by the HubbleSpace telescope.  But they are gone in the 2019 image (right).  Credit: Steve A. Rodney, Gabriel Brammer, Joseph DePasquale
Three views of the same supernova appear in the 2016 image on the left, taken by the HubbleSpace Telescope. But they are gone in the 2019 image (right). Credit: Steve A. Rodney, Gabriel Brammer, Joseph DePasquale

When a star explodes it is called a supernova, so you would think there is only one chance to see the explosion. But, due to an effect called the “gravitational lens”, first predicted by Albert Einstein in his theory of general relativity, light can be bent, divided, amplified and distorted by immense gravitational forces.

The Requiem supernova is about 10 billion light years away, and as its light traveled to Earth, it passed a huge cluster of galaxies, the gravity of which pushed aside Requiem’s. The research, led by Steven Rodney of the University of South Carolina at Columbia, predicts that the next Supernova Requiem sighting will be in 2037. Although the light is too dim to be seen with the naked eye, it should be visible by advanced telescopes.

Reveal how stars are born

It starts with a cloud of dust and gas. Slowly, as gravity acts on the particles, the dust and gas begin to coalesce, eventually collapsing into a star and an accompanying disc. Then, in a process called magnetospheric accretion, particles at the inner edge of the disc fall at hundreds of kilometers per second toward the newborn star. When these particles hit the star’s surface, they produce shock waves and a tremendous amount of heat. A “hot spot” emerges on the star’s surface where the falling particles converge. These hot spots release radiation that many astronomical instruments can perceive.

Picture

NEWS • Computer simulation of a funnel-shaped accretion and flux disk (green) and magnetic field lines (multicolored) on an emerging star.  Credit: Marina Romanova.
Computer simulation of a funnel-shaped accretion and flux disk (green) and magnetic field lines (multicolored) on an emerging star. Credit: Marina Romanova.

Connor robinson, the Five College Astronomy Department Education and Research Fellow affiliated with the Department of Astronomy at UMass, was the second author of another recent “Nature” article, led by CC Espaillat of Boston University, who combined data from The Hubble Space Telescope, TRIAL (Satellite for the study of exoplanets in transit), Neil Gehrels Swift Observatory, Las Cumbres Observatory World Telescope, and SMARTS, which reveals, for the first time, the mechanics of the exact growth of stars.

“We now have a better understanding of how the accretion process works,” says Robinson, whose team focused on a star called GM Aur. “For the first time, we were able to deduce the azimuthal structure of accretion shocks using several telescopes sensitive to hot spots of different densities. As the star spins, these hot spots also spin in and out of view, allowing us to measure the density distribution of the hot spots on the star. We already knew that there were low and high density hot spots on the star’s surface, but this is the first time we have been able to map their structure.

It turns out that up to 20% of the star’s surface is covered with lower density hotspots, and the densest regions only make up about 0.1% of the surface. “This is the first empirical evidence we have of these azimuth hot spot gradients on growing stars. He tells us about the young star and the conditions in the internal regions of the protoplanetary disks that will one day become solar systems. “


Source link

Leave A Reply

Your email address will not be published.