Images of nearby galaxies resemble fireworks

New images of nearby galaxies resemble colourful cosmic fireworks.

The images show different components of the galaxies in distinct colours, allowing astronomers to pinpoint the locations of young stars and the gas they warm up around them.

Astronomers released the images, obtained with the European Southern Observatory’s Very Large Telescope (ESO’s VLT).

By combining these new observations with data from the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, the team is helping shed new light on what triggers gas to form stars.

What sets off star formation, and how galaxies as a whole play into it, has long been a mystery.

To understand this process, researchers looked at various nearby galaxies with powerful telescopes on the ground and in space, scanning the different galactic regions involved in stellar births.

Eric Emsellem is an astronomer at ESO in Germany and lead of the VLT-based observations conducted as part of the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) project.

He said: “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.

“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.”

The team have now released their latest set of galactic scans, taken with the Multi-Unit Spectroscopic Explorer (MUSE) instrument on ESO’s VLT in the Atacama Desert in Chile.

They used MUSE to trace newborn stars and the warm gas around them, which is illuminated and heated up by the stars and acts as a smoking gun of ongoing star formation, the researchers say.

By combining MUSE and ALMA images astronomers can examine galactic regions where stars are forming, compared to where it is expected to happen, so as to better understand what triggers, boosts or holds back the birth of new stars.

The resulting images offer a colourful insight into stellar nurseries in our neighbouring galaxies.

Kathryn Kreckel, from the University of Heidelberg in Germany and PHANGS team member, said: “There are many mysteries we want to unravel.

“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?”

The new data gathered by the research team will help astronomers answer these questions.

In addition to ALMA and MUSE, the PHANGS project also features observations from the Nasa/ESA Hubble Space Telescope.

The various observatories were selected to allow the team to scan nearby galaxies at different wavelengths (visible, near-infrared and radio), with each wavelength range unveiling distinct parts of the observed galaxies.

PHANGS team member Francesco Belfiore, from INAF-Arcetri in Italy, said: “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.”