An artist's illustration of the Universe's first stars, called Population 3 stars. Pop 3 stars would have been much more massive than most stars today, and would have burned hot and blue. Their lifetimes would've been much shorter than stars like our Sun. Credit: Wikimedia Commons
Until recently, astronomers could not observe the first stars and galaxies that formed in the Universe. This occurred during what is known as the “Cosmic Dark Ages,” a period that took place between 380,000 and 1 billion years after the Big Bang. Thanks to next-generation instruments like the James Webb Space Telescope (JWST), improved methods and software, and updates to existing observatories, astronomers are finally piercing the veil of this era and getting a look at how the Universe as we know it began.
This includes new observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which obtained images of a stellar nursery inside a galaxy roughly 13.2 billion light-years away in the constellation Eridanus. This galaxy has a redshift value of more than 8.3, corresponding to when the Universe was less than 1 billion years old. The images discerned the sites of star formation and possible star death inside a nebula (MACS0416_Y1) located within this galaxy. This represents a major milestone for astronomy as this is the farthest distance such structures have been observed in our Universe.
The first released VST image shows the spectacular star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula. Credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute.
The Omega Nebula (Messier 17), also known as the Swan Nebula because of its distinct appearance, is one of the most well-known nebulas in our galaxy. Located about 5,500 light-years from Earth in the constellation Sagittarius, this nebula is also one of the brightest and most massive star-forming regions in the Milky Way. Unfortunately, nebulas are very difficult to study because of the way their clouds of dust and gas obscure their interiors.
For this reason, astronomers are forced to examine nebulas in the non-visible wavelength to get a better idea of their makeup. Using the Stratospheric Observatory for Infrared Astronomy (SOFIA), a team of NASA scientists recently observed the Swan Nebula in the infrared wavelength. What they found has revealed a great deal about how this nebula and stellar nursery evolved over time.
The Orion Nebula, one of the most studied objects in the sky. It's likely that many of its protostars and their planetary disks contain water in some form. Image: NASA
The Orion Nebula is one of the most observed and photographed objects in the night sky. At a distance of 1350 light years away, it’s the closest active star-forming region to Earth.
This diffuse nebula is also known as M42, and has been studied intensely by astronomers for many years. From it, astronomers have learned a lot about star formation, planetary system formation, and other bedrock topics in astronomy and astrophysics. Now a new discovery has been made which goes against the grain of established theory: stellar winds from newly-formed massive stars may prevent other stars from forming in their vicinity. They also play a much larger role in star formation, and in galaxy evolution, than previously thought.
The Solar System is 4.5 billion years old, but the Universe is much older. What was here before our Solar System formed?
The Solar System is old. Like, dial-up-fax-machine-old. 4.6 billion years to be specific. The Solar System has nothing on the Universe. It’s been around for 13.8 billion years, give or take a few hundred million. That means the Universe is three times older than the Solar System.
Astronomers think the Milky Way, is about 13.2 billion years old; almost as old as the Universe itself. It formed when smaller dwarf galaxies merged together to create the grand spiral we know today. It turns out the Milky Way has about 8.6 billion years of unaccounted time. Billions and billions of years to get up to all kinds of mischief before the Solar System showed up to keep an eye on things.
Our Galaxy takes 220 million years to rotate, so it’s done this about 60 times in total. As it turns, it swirls and mixes material together like a giant space blender. Clouds of gas and dust come together into vast star forming regions, massive stars have gone supernova, and then the clusters themselves have been torn up again, churning the stars into the Milky Way. This happens in the galaxy’s spiral arms, where the areas of higher density lead to regions of star formation.
So let’s go back, more than 4.6 billion years, before there was an Earth, a Sun, or even a Solar System. Our entire region was gas and dust, probably within one of the spiral arms. Want to know what it looked like? Some of your favorite pictures from the Hubble Space Telescope should help.
Here’s the Orion, Eagle, and the Tarantula Nebulae. These are star forming regions. They’re clouds of hydrogen left over from Big Bang, with dust expended by aging stars, and seeded with heavier elements formed by supernovae.
The Orion Nebula. Image Credit: Vasco Soeiro
After a few million years, regions of higher density began forming into stars, both large and small. Let’s take a look at a star-forming nebula again. See the dark knots? Those are newly forming stars surrounded by gas and dust in the stellar nursery.
You’re seeing many many stars, some are enormous monsters, others are more like our Sun, and some smaller red dwarfs. Most will eventually have planets surrounding them – and maybe, eventually life? If this was the environment, where are all those other stars?
Why do I feel so alone? Where are all our brothers and sisters? Where’s all the other stuff that’s in that picture? Where’s all my stuff?
TRAPPIST First Light Image of the Tarantula Nebula. Credit: ESO
Apparently nature hates a messy room and a cozy stellar nest. The nebula that made the Sun was either absorbed into the stars, or blown away by the powerful stellar winds from the largest stars. Eventually they cleared out the nebula, like a fans blowing out a smoky room.
At the earliest point, our solar nebula looked like the Eagle Nebula, after millions of years, it was more like the Pleiades Star Cluster, with bright stars surrounded by hazy nebulosity. It was the gravitational forces of the Milky Way which tore the members of our solar nursery into a structure like the Hyades Cluster. Finally, gravitational interactions tore our cluster apart, so our sibling stars were lost forever in the churning arms of the Milky Way.
We’ll never know exactly what was here before the Solar System; that evidence has long been blown away into space. But we can see other places in the Milky Way that give us a rough idea of what it might have looked like at various stages in its evolution.
What should we call our original star forming nebula? Give our own nebula a name in the comments below.
