Images from Very Large Telescope offer insights into star formation

Portraits of nearby galaxies captured by VLT and ALMA have allowed scientists to identify concentrations of warm gas and young stars. Photo by ESO/PHANGS
Portraits of nearby galaxies captured by VLT and ALMA have allowed scientists to identify concentrations of warm gas and young stars. Photo by ESO/PHANGS

July 16 (UPI) -- A new survey by European Southern Observatory's Very Large Telescope has revealed the Milky Way's galactic neighbors in all their colorful brilliance.

The diversity of galactic portraits -- shared Friday by ESO -- recalls a shimmering fireworks display, but the project isn't simply an exercise in aesthetics and entertainment.


Using the new VLT images, as well as data captured by the Atacama Large Millimeter/submillimeter Array, ALMA, scientists are working to pinpoint populations of young stars and surrounding concentrations of warm gas.

Astronomers hope their observations -- part of the Physics at High Angular resolution in Nearby GalaxieS, PHANGS, project -- will offer new insights into what triggers star formation inside dense clouds of dust and gas.

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By surveying a diversity of relatively young, star-rich galaxies, scientists hope to identify links between large-scale galactic dynamics and localized star formation.

"For the first time we are resolving individual units of star formation over a wide range of locations and environments in a sample that well-represents the different types of galaxies," Eric Emsellem, an astronomer at ESO, said in a press release. "We can directly observe the gas that gives birth to stars, we see the young stars themselves, and we witness their evolution through various phases."


Emsellem is leading VLT's contribution to the PHANGS project, using the powerful Chilean telescope's Multi-Unit Spectroscopic Explorer, MUSE, instrument to locate concentrations of warm gas and intense star formation in nearby galaxies.

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MUSE is capable of fielding a wide range of spectra from every location within its field of view. For the PHANGS project, MUSE captured 15 million spectra from 30,000 gas nebulae.

By combining the observations of VLT with those of ALMA, which is better suited to image regions of cold gas, scientists hope to identify large-scale galactic characteristics that influence star formation.

"There are many mysteries we want to unravel," said PHANGS scientist Kathryn Kreckel, an astronomer at the University of Heidelberg in Germany. "Are stars more often born in specific regions of their host galaxies -- and, if so, why? And after stars are born, how does their evolution influence the formation of new generations of stars?"

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Researchers also supplemented their VLT and ALMA data with observations from the Hubble Space Telescope, revealing Milky Way's galactic neighbors in visible, near-infrared and radio wavelengths.

"Their combination allows us to probe the various stages of stellar birth -- from the formation of the stellar nurseries to the onset of star formation itself and the final destruction of the nurseries by the newly born stars -- in more detail than is possible with individual observations," said PHANGS scientist Francesco Belfiore, astronomer at INAF-Arcetri in Italy. "PHANGS is the first time we have been able to assemble such a complete view, taking images sharp enough to see the individual clouds, stars, and nebulae that signify forming stars."


Dozens of galactic images from the PHANGS project are available online. In the future, astronomers hope to use the James Webb Telescopes to study star formation regions in the nearby galaxies. James Webb is expected to launch this fall, but won't begin scientific operations until 2022.

Using the current images from VLT and ALMA, scientists are only able to distinguish between individual star-forming clouds. The powerful capabilities of the James Web Telescopes will allow astronomers to peer inside star-forming clouds.

"New observational efforts by our team and others are pushing the boundary in this direction, so we have decades of exciting discoveries ahead of us," said Eva Schinnerer, astronomer at the Max Planck Institute for Astronomy in Germany and principal investigator on the PHANGS project.

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