An artist's illustration of some of the Universe's first stars. Called Population 3 stars, they formed a few hundred million years after the Big Bang. Image Credit: By NASA/WMAP Science Team - https://www.nasa.gov/vision/universe/starsgalaxies/fuse_fossil_galaxies.html (image link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=1582286
When the first stars in the Universe formed, the only material available was primordial hydrogen and helium from the Big Bang. Astronomers call these original stars Population Three stars, and they were extremely massive, luminous, and hot stars. They’re gone now, and in fact, their existence is hypothetical.
But if they did exist, they should’ve left their fingerprints on nearby gas, and astrophysicists are looking for it.
Three-color image of HD1, the most distant galaxy candidate to date, created using data from the VISTA telescope. The red object in the center of the zoom-in image is HD1. Credit: Harikane et al.
Since the Renaissance astronomer Galileo Galilee first studied the heavens using a telescope he built himself, astronomers have been pushing the boundaries of what they can observe. After centuries of progress, they have been able to study and catalog objects in all but the earliest periods of the Universe. But thanks to next-generation instruments and technologies, astronomers will soon be able to observe the “Cosmic Dawn” era – ca. 50 million to billion years after the Big Bang.
In recent years, astronomers have made discoveries that preview what this will be like, the most recent of which is the galaxy candidate known as HD1. This galaxy is about 13.5 billion light-years from Earth (32.2 billion light-years in terms of “proper distance“), making it the farthest ever observed. This discovery implies that galaxies existed as early as 300 million years after the Big Bang, a finding which could have drastic implications for astronomy and cosmology!
Galaxy GN-z11 superimposed on an image from the GOODS-North survey. Credit: NASA/ESA/P. Oesch (Yale University)/G. Brammer (STScI)/P. van Dokkum (Yale University)/G. Illingworth (University of California, Santa Cruz)
Since time immemorial, philosophers and scholars have contemplated the beginning of time and even tried to determine when all things began. It’s only been in the age of modern astronomy that we’ve come close to answering that question with a fair degree of certainty. According to the most widely-accepted cosmological models, the Universe began with the Bang Bang roughly 13.8 billion years ago.
Even so, astronomers are still uncertain about what the early Universe looked like since this period coincided with the cosmic “Dark Ages.” Therefore, astronomers keep pushing the limits of their instruments to see when the earliest galaxies formed. Thanks to new research by an international team of astronomers, the oldest and most distant galaxy observed in our Universe to date (GN-z11) has been identified!
Galaxy GN-z11 superimposed on an image from the GOODS-North survey. Credit: NASA/ESA/P. Oesch (Yale University)/G. Brammer (STScI)/P. van Dokkum (Yale University)/G. Illingworth (University of California, Santa Cruz)
Since it was first launched in 1990, the Hubble Space Telescope has provided people all over the world with breathtaking views of the Universe. Using its high-tech suite of instruments, Hubble has helped resolve some long-standing problems in astronomy, and helped to raise new questions. And always, its operators have been pushing it to the limit, hoping to gaze farther and farther into the great beyond and see what’s lurking there.
And as NASA announced with a recent press release, using the HST, an international team of astronomers just shattered the cosmic distance record by measuring the farthest galaxy ever seen in the universe. In so doing, they have not only looked deeper into the cosmos than ever before, but deeper into it’s past. And what they have seen could tell us much about the early Universe and its formation.
Due to the effects of special relativity, astronomers know that when they are viewing objects in deep space, they are seeing them as they were millions or even billions of years ago. Ergo, an objects that is located 13.4 billions of light-years away will appear to us as it was 13.4 billion years ago, when its light first began to make the trip to our little corner of the Universe.
An international team of scientists has used the Hubble Space Telescope to spectroscopically confirm the farthest galaxy to date. Credits: NASA/ESA/B. Robertson (University of California, Santa Cruz)/A. Feild (STScI)
This is precisely what the team of astronomers witnessed when they gazed upon GN-z11, a distant galaxy located in the direction of the constellation of Ursa Major. With this one galaxy, the team of astronomers – which includes scientists from Yale University, the Space Telescope Science Institute (STScI), and the University of California – were able to see what a galaxy in our Universe looked like just 400 million years after the Big Bang.
Prior to this, the most distant galaxy ever viewed by astronomers was located 13.2 billion light years away. Using the same spectroscopic techniques, the Hubble team confirmed that GN-z11 was nearly 200 million light years more distant. This was a big surprise, as it took astronomers into a region of the Universe that was thought to be unreachable using the Hubble Space Telescope.
In fact, astronomers did not suspect that they would be able to probe this deep into space and time without using Spitzer, or until the deployment the James Webb Space Telescope – which is scheduled to launch in October 2018. As Pascal Oesch of Yale University, the principal investigator of the study, explained:
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. We see GN-z11 at a time when the universe was only three percent of its current age. Hubble and Spitzer are already reaching into Webb territory.”
The Hubble Space Telescope in 1997, after its first servicing mission. Credit: NASA
In addition, the findings also have some implications for previous distance estimates. In the past, astronomers had estimated the distance of GN-z11 by relying on Hubble and Spitzer’s color imaging techniques. This time, they relied on Hubble’s Wide Field Camera 3 to spectroscopically measure the galaxies redshift for the first time. In so doing, they determined that GN-z11 was farther way than they thought, which could mean that some particularly bright galaxies who’s distanced have been measured using Hubble could also be farther away.
The results also reveal surprising new clues about the nature of the very early universe. For starters, the Hubble images (combined with data from Spitzer) showed that GN-z11 is 25 times smaller than the Milky Way is today, and has just one percent of our galaxy’s mass in stars. At the same time, it is forming stars at a rate that is 20 times greater than that of our own galaxy.
As Garth Illingworth – one of the team’s investigator’s from the University of California, Santa Cruz – explained:
“It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon. This new record will likely stand until the launch of the James Webb Space Telescope.”
Last, but not least, they provide a tantalizing clue as to what future missions – like the James Webb Space Telescope – will be finding. Once deployed, astronomers will likely be looking ever farther into space, and farther into the past. With every step, we are closing in on seeing what the very first galaxies that formed in our Universe looked like.
