EArendelle (“morning star” in Old English) was one of the first stars to exist in our universe, less than a billion years after the Big Bang. And Hubble Space Telescope just did amazing feat sensing light in it.
Most telescopes give us images of nearby galaxies with intricate detail, but images of distant galaxies are actually very dark. Astronomer Brian Welch and his team at Johns Hopkins University in Baltimore discovered the star to find hints about the early galaxies. This galaxy is very difficult to see, so the team decided to examine selected images from Hubble for clues.
Astronomers are not new to observing ancient light. Just this week, we released a stunning picture of a galaxy 500 million years ahead of Earendel. This goes beyond what we expected Hubble to be able to do, but it’s not quite as surprising a feat as resolving a single star, and it brings home how special Earendel is when looking at the shapeless specks of early galaxies.
In detective novels, a detective uses a magnifying glass to examine evidence left at a crime scene and moves a lens to magnify clues. You can’t launch a larger glass lens into space, but luckily, nature offers a much more powerful alternative.
Huge clusters of galaxies provide the gravitational force that causes light from the background star to bend around the cluster, as if light were bent through a magnifying glass. This effect (“gravity lensing effect”) is used in astronomy to see objects that are too faint or too far away to see anything else. But we can’t keep moving the galaxy to magnify where we like. We must follow where the universe leads us.
In one snapshot, Welch and his team saw a distant galaxy enlarged and distorted. Nothing new. But within the distorted galaxy was an unexpectedly bright speck. A star in the Milky Way is aligned so precisely with the lens that the image is enhanced thousands of times, making it appear large and bright. And the color of the light of Erendel indicates that we are seeing an ancient light.
Light has different properties depending on its energy. The electromagnetic spectrum extends from low-energy, long-wavelength radio waves through infrared and rainbow optical light to high-energy, short-wavelength X-rays. Starlight loses energy on its journey towards us and becomes redder as it slides down the spectrum. Earendel’s light is actually very red, suggesting that the light has traveled enormous distances over the better part of 13 billion years, putting it in the first star age. Observations of early galaxies are rare, and images of individual stars from this era have never existed.
Earendel isn’t the oldest star generation, but it’s tantalizingly close. Studying this era is like discovering the early evolution of mankind, but on a galactic scale. Our ancestors are similar to ours, but there are important differences that need to be explored. Compared to the universe then, the universe today is the same. We need to go back as far as possible to the Big Bang to fill the gap.
Earendel’s observations are record-breaking. It not only improved the previous record, but it could also be a record that was shattered and remains here. Airendel’s light is so faint that we wouldn’t be able to see it at all if it wasn’t perfectly aligned with the cosmic lens. There is no guarantee that we will stumble upon another cluster of stars with similar random alignments, and further stars are too faint to be seen. As with any major scientific advance, years of hard work, expertise, and guesswork have helped cross the finish line with the generous help of fortune.
As with all evidence to the test of our observational powers, there is the possibility of misidentification. Light from a distant blue star loses energy and appears redder, but we can see much closer, which is initially red. The chances of random red stars lining up with those old distorted galaxies are slim but not impossible, so the team will use infrared data from the new galaxies. James Webb Space Telescope to rule out suspects
The next lineup is a black hole, which can look like a star if you zoom in in certain ways with the surrounding matter swirling inward. This time, it’s an X-ray observation to help you decide for sure. Combining different wavelengths of light is not new to astronomy. It is not new in everyday life. Imagine a doctor diagnosing a broken arm yourself. They will examine your arm in a well-lit room, but how do you know if your arm is broken? How bad is a break? Will you play tennis again? I hope you at least send it in for an x-ray. To distinguish what we see from space, we must use different wavelengths of light in a similarly exhaustive way and interpret our observations professionally as a doctor would.
Earendel appears to be the most distant star we have ever detected, and probably will in the future. The accidental alignment of celestial bodies from incomprehensiblely vast distances has provided interesting evidence for the early stages of the universe. We may be holding onto the trail of the faintest stars in the universe, but we’ll need more than a magnifying glass to be sure. We have to think about a completely different wavelength.
A Star Reborn: How Hubble Astronomers See Early Light | universe
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