Wednesday , August 4 2021

New study reveals unprecedented star formation in Milky Way



Using two of the world’s most powerful radio telescopes, astronomers have conducted a detailed and sensitive survey of much of our home galaxy, the Milky Way, detecting traces of unprecedented massive star formation, a process that dominates galactic ecosystems. Scientists combined the capabilities of the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and the 100-meter Effelsberg Telescope in Germany to produce high-quality data that will serve researchers for years to come.

Stars with more than about ten times the mass of our Sun are important components of the Galaxy and strongly influence their surroundings. However, understanding how these massive stars form has been challenging for astronomers. In recent years, this problem has been resolved by studying the Milky Way at various wavelengths, including radio and infrared. This new research, called GLOSTAR (Spherical view of Star formation in the Milky Way), is designed to take advantage of the greatly enhanced capabilities that an upgrade project completed in 2012 gave the VLA to generate data that was previously unachievable.

GLOSTAR has excited astronomers with new data on the birth and death processes of massive stars, as well as the thin material between stars. The GLOSTAR research team has published a series of articles in the journal. Astronomy and Astrophysics to report the first results of their work, including detailed studies of several individual objects. Observations are ongoing and more results will be published later.

The research detected revealing tracers of early stages of massive star formation, including compact regions of hydrogen gas ionized by strong radiation from young stars and radio emission from methanol (wood alcohol) molecules that can still deeply locate very young stars. They are obscured by the gas and dust clouds from which they form.

The survey also found many new remnants of supernova explosions—the dramatic deaths of massive stars. Previous studies had found less than a third of the expected supernova remnants in the Milky Way. In the region it studied, GLOSTAR has more than doubled the number found using VLA data alone, and more are expected to appear in the Effelsberg data.

“This is an important step towards solving the longstanding mystery of lost supernova remnants,” said Rohit Dokara, a doctoral student at the Max Planck Institute for Radioastronomy (MPIfR) and lead author of a paper on the remnants.

The GLOSTAR team combined data from the VLA and the Effelsberg telescope to get a complete view of the region they studied. The multi-antenna VLA – an interferometer – combines signals from widely separated antennas to create very high resolution images that show tiny details. However, such a system often cannot detect large-scale structures either. The 100-metre-wide Effelsberg telescope completed the image by providing data on structures larger than the VLA could detect.

“This clearly shows that even after 50 years of work, the Effelberg telescope is still very important,” said Andreas Brunthaler, project leader from MPIfR and first author of the survey’s overview report.

Visible light is strongly absorbed by dust, which radio waves can easily penetrate. Radio telescopes are essential to reveal dust-covered regions where young stars form.

The results from GLOSTAR, along with other radio and infrared studies, “offer astronomers an almost complete enumeration of massive star-forming clusters at various stages of formation, and this will be of lasting value for future studies,” said team member William Cotton. the National Radio Astronomy Observatory (NRAO), which specializes in combining interferometer and single telescope data.

“GLOSTAR is the first map of the Galactic Plane at radio wavelengths that detects most of the key star formation tracers in high spatial resolution. Detection of atomic and molecular spectral lines is critical to pinpointing the location of star formation and better understanding the structure of the Galaxy,” said NRAO again. from Dana Falser.

GLOSTAR’s initiator, Karl Menten of MPIFR, said: “It’s great to see the beautiful science that comes from joining forces with our two favorite radio telescopes.”

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