Webb telescope captures images, insight from one of Milky Way鈥檚 most extreme environments
An image of the Milky Way Galaxy captured by the MeerKAT radio telescope, with an inset showing a detailed image of Sagittarius C taken by the James Webb Space Telescope. Credit: NASA, ESA, CSA, STScI, SARAO, Samuel Crowe (UVA), John Bally (CU), Ruben Fedriani (IAA-CSIC), Ian Heywood (Oxford)
Sagittarius C is one of the most extreme environments in the Milky Way Galaxy. This cloudy region of space sits about 200 light-years from the supermassive black hole at the center of our galaxy. Here, a massive and dense cloud of interstellar gas and dust has collapsed on itself over millions of years to form thousands of new stars.
In a new study, a team of scientists used observations from NASA鈥檚 James Webb Space Telescope to study Sagittarius C in unprecedented detail. The research was led by 糖心Vlog破解版 astrophysicist John Bally, Samuel Crowe at the University of Virginia, Rub茅n Fedriani at the Instituto de Astrof铆sica de Andaluc铆a in Granada and their colleagues
The findings could help solve a long-running mystery about the innermost stretches of the galaxy, or what scientists call the Central Molecular Zone (CMZ): The region hosts high densities of interstellar gas. So why are fewer new stars born here than scientists once predicted? 听
The researchers discovered that powerful magnetic field lines seem to be threading through Sagittarius C, forming long and bright filaments of hot hydrogen gas that look a little like spaghetti noodles鈥攁 phenomenon that could slow down the pace of star formation in the surrounding gas.
鈥淚t鈥檚 in a part of the galaxy with the highest density of stars and massive, dense clouds of hydrogen, helium and organic molecules鈥 said Bally, professor in the Department of Astrophysical and Planetary Sciences at CU 糖心Vlog破解版. 鈥淚t鈥檚 one of the closest regions we know of that has extreme conditions similar to those in the young universe.鈥
He and his colleagues in The Astrophysical Journal. The research is part of an proposed and , a fourth-year undergraduate student at the University of Virginia who was recently named a Rhodes Scholar.
And, Crowe noted, the Webb telescope鈥檚 startling images show Sagittarius C as it鈥檚 never been seen before.
鈥淏ecause of these magnetic fields, Sagittarius C has a fundamentally different shape, a different look than any other star forming region in the galaxy away from the galactic center,鈥 Crowe said.
This image of Sagittarius C from the Webb telescope reveals several bands of plasma, which seem to have been formed by strong magnetic fields. Credit: NASA, ESA, CSA, STScI, SARAO, Samuel Crowe (UVA), John Bally (CU), Ruben Fedriani (IAA-CSIC), Ian Heywood (Oxford)
Stellar nurseries
The research sheds light on the violent births and deaths of stars in the Milky Way Galaxy.
Stars tend to form within what scientists call 鈥渕olecular clouds,鈥 or regions of space containing dense clouds of gas and dust. The closest such stellar nursery to Earth lies in the Orion Nebula, just below Orion鈥檚 belt. There, molecular clouds have collapsed over millions of years, forming a cluster of new stars.
Such active sites of star formation also spell their own demise. As new stars grow, they begin to emit vast amounts of radiation into space. That radiation, in turn, blows away the surrounding cloud, stripping the region of the matter it needs to build more new stars.
鈥淓ven the sun, we think, formed in a massive cluster like this,鈥 Bally said. 鈥淥ver billions of years, all of our sibling stars have drifted away.鈥
In a in the same journal, Crowe and his colleagues, including Bally, dove into the growing 鈥減rotostars鈥 forming in Sagittarius. Their data reveal a detailed picture of how these young stars are ejecting radiation and blowing away the gas and dust around them.
Magnetic fields
In the study led by Bally, the researchers explored Sagittarius C鈥檚 unusual appearance. Bally explained that while the Orion Nebula looks mostly smooth, Sagittarius C is anything but. Weaving in and out of this region are dozens of bright filaments, some several light-years long. These filaments are made up of plasma, a hot gas of charged particles.
鈥淲e were definitely not expecting those filaments,鈥 said Rub茅n Fedriani, a co-author of the study and postdoctoral researcher at the Instituto de Astrof铆sica de Andaluc铆a in Spain. 鈥淚t was a completely serendipitous discovery.鈥
Bally noted that the secret to Sagittarius C鈥檚 filaments, and the nature of its star formation, likely comes down to magnetic fields.
A supermassive black hole with a mass about four million times greater than our sun sits at the center of the galaxy. The motion of gas swirling around this behemoth can stretch and amplify the surrounding magnetic fields. Those fields, in turn, shape the plasma in Sagittarius C.
Bally suspects that the Orion Nebula looks much smoother because it resides within a much weaker magnetic environment.
Scientists, he added, have long known that the galaxy鈥檚 innermost regions are an important birthplace for new stars. But some calculations have suggested that the region should be producing a lot more young stars than observed. In the CMZ, magnetic forces may be strong enough to resist the gravitational collapse of molecular clouds, limiting the rate of new star formation.
Regardless, Sagittarius C鈥檚 own time may be drawing to a close. The region鈥檚 stars have blown away much of its molecular cloud already, and that nursery could disappear entirely in a few hundred thousand years.
鈥淚t鈥檚 almost the end of the story,鈥 Bally said.
听听Beyond the story
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