Star formation was the subject of an ESA study using Hubble Telescope. Find out why what they didn’t find was more important than what they did.
I’ve owned astronomical telescopes of one kind or another for about 25 years. I’ve always loved stargazing. While I was working on a consulting project in Edmonton, I discovered the science centre run by the Edmonton Space and Science Foundation.
I was out there on my own, and I spent a lot of my downtime at the centre. Between the IMAX theatre and the state-of-the-art planetarium, they ha me hooked.
When I got home, I bought a simple astronomical telescope and started exploring on my own. The experience reminded me that for most of human history, we studied the stars with the naked eye.
For Most of Human History, We Studied the Stars with the Naked Eye
It was only about 400 years ago that Galileo bought a telescope and pointed it at the stars and planets. Seeing the moons of Jupiter, the rings of Saturn, and the phases of Venus directly is a profound encounter.
Galileo must have found it even more extraordinary because he was discovering these things for the first time. I can’t imagine seeing these features without any prior understanding and trying to understand what they were.
Galileo and I, and every stargazer, have the same problem. The quality of what we can see depends on the weather.
The Quality of What We Can See Depends on the Weather
If the atmosphere is clear and stable, we say that we have “good seeing.” More often than not, the atmosphere gives us one thing or another to complain about, and if it’s overcast, we’re out of luck that night.
That’s why NASA built and launched the Hubble Space Telescope in 1990. The idea was to get above the atmosphere, so we don’t have to worry about the weather.
NASA planned on Hubble lasting about fifteen years. NASA marked its 30th anniversary in April.
The Hubble has made countless discoveries during its tenure. Still, a team from the European Space Agency announced an especially important one last week. It has to do with when the earliest stars in the universe began to form.
Between 200 and 500 Million Years After Big Bang
Scientists have estimated that the earliest galaxies and stars began to form somewhere between 200 and 500 million years after the Big Bang. The universe broke up into separate clouds, which became the galaxies.
Stars formed within these molecular hydrogen clouds. Despite all we’ve discovered with our telescopes, gaining a clear understanding of precisely when and how this took place is still problematic to this day.
When we look through any telescope, including Hubble, out into space, we also look back into time. Because of Hubble’s location and sophisticated optics, it can look further back in time to about 500 million years after the Big Bang.
Hubble Can Look Back to 500 Million Years After Big Bang
The research team, led by Rachana Bhatawdekar, worked to learn more about early star formation. They used Hubble to study a galaxy cluster called MACSJ0416 and a field of space parallel to it.
Stars consist mainly of hydrogen and helium. There are three generations of stars called populations. Relatively young stars like our sun in the Milky Way galaxy contain smaller amounts of heavier elements as well. They’re called Population I stars. Population II stars are older and contain fewer heavier atoms.
The only elements in the universe when the first stars formed were hydrogen, helium and trace amounts of lithium, and that’s what would make up the original Population III stars. No other elements existed then because stars are what create and release the more massive elements when they explode at the end of their life cycle.
Population III — Hydrogen, Helium and Traces of Lithium
The researchers used the Hubble telescope to look for Population III stars in the MACSJ0416 galaxy cluster. The stars and galaxies in this cluster began between 500 million and one billion years after the Big Bang.
Their findings are a case where discovering nothing was more important than finding something. They didn’t find a single Population III star from that period.
Astronomers know that only hydrogen, helium and lithium could have made up the earliest stars. Yet, the team didn’t identify a single star made solely from those elements during the entire period of the study.
Finding Surprised the Researchers
Their absence must mean that the original Population III stars formed within galaxies less than 500 billion years after the Big Bang. That finding surprised the researchers.
Professor Bhatawdekar explained, “These results have profound astrophysical consequences as they show that galaxies must have formed much earlier than we thought.”
The formation of the galaxies and their stars is a fascinating topic that cosmologists don’t fully understand. It’s part of a mysterious, self-organizing property that the universe seems to have.
Mysterious, Self-Organizing Property of the Universe
The star formation process involves massive clouds of hydrogen molecules. The cloud cores became very dense and collapsed under their own gravity, forming black holes.
Smaller dense regions also collapsed but, because of their lower mass, they became star-forming regions, causing nuclear fusion to form stars.
Every culture tells a story about how our world. Science has robbed us of these fanciful stories and the meanings they gave us.
We Now Have the Discoveries to Craft a New Story
In return, it provides us with a new challenge. For the first time in history, we now have the discoveries to craft a new story that we know to be factually true.
Hubble has taken us back as far as it can. However, a new replacement space telescope is in the works that will be able to see further back in time.
NASA, the European Space Agency and the Canadian Space Agency are developing the James Webb Space Telescope. It will have five times the light-gathering power of Hubble as well as improved infrared instruments on top of its improved visible light capabilities.
“Further Research for James Webb Telescope”
The European Space Agency said, “This leaves an exciting area of further research for the upcoming NASA/ESA/CSA James Webb Space Telescope — to study the Universe’s earliest galaxies.”
We always have more to learn if we dare to know.
Hubble Makes Surprising Find in the Early Universe
James Webb Space Telescope
Hubble Space Telescope Discoveries
Newborn Stars Bringing Forth Solar Systems
Where Do Heavy Metals Come From? (Not Ozzy Osborne!)
Originally published at https://daretoknow.ca on June 15, 2020.