Serenity in the Milky Way


Some of the most beautiful sights in the universe are ones that we could never see with our eyes. One such example is this lovely composite of the Carina Nebula made with visible and radio light.

The visible light image is a wide-angle view of an active star forming region of our galaxy. This large complex of gas clouds can be seen from the Southern Hemisphere, but it is not as famous as its cousin, the Orion Nebula.

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Over a year ago, astronomers using the Atacama Pathfinder EXperiment, or APEX, studied the parts of the nebula that are not visible to our eyes or to optical telescopes.

The orange “blobs” in this image represent the regions that glow as seen by a sub-millimeter telescope such as APEX. Most of this emission comes from dust which is warmed up by ultraviolet and visible light from the young stars that then radiates at longer wavelengths. Many of the young stars are extremely large, hot, and will not live for much longer in cosmic timescales.

However, not all of the gas in the nebula will actually form stars. Only about 10 percent of this gas is dense enough to start the star birth process, and this is pretty typical for our galaxy.

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A small fraction of interstellar gas in the Milky Way is creating new stars at any given time while the rest is just… there. That may be a little stellar-centric of me to say, but as a living being on a planet, I am prejudiced towards environments that make planets.

The stuff of life itself may be in these clouds. Astronomers estimate that the cloud is 200,000 times the mass of our sun, and most of the material is in a molecular state. That means that the atoms are combining in ways similar to the chemistry that governs life on Earth. It’s almost sad to think of all that raw material that orbits in our galaxy, perhaps never to be used to build a new star or planets.

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The nebula may increase its star formation efficiency in the future if disturbed by the shock waves of supernovae that result from an explosion of a massive stars. All those newborn, giant blue stars only have a few millions years or so to live, and their deaths may encourage new star formation in the parts of the nebula that are currently quiet.

The most famous star in this nebula, Eta Carinae, has had several bright outbursts, but the star has survived and not gone supernova. At least, not yet. Maybe then, some serene part of the cloud will turn into a new star or even become part of a new planet. In the stellar life cycle, violence begets creation.

Image Credit: ESO/APEX/T. Preibisch et al.; N. Smith, University of Minnesota/NOAO/AURA/NSF 

This research is published in Astronomy & Astrophysics, and a preprint is available on

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