The Most Distant Single Star Was Just Detected, as Ancient as The Cosmic Dawn

The light of a single star has been detected from billions of light-years across the vast gulf of space-time.

Earendel is the most distant object of its kind ever detected, dating to just 900 million years after the Big bang.

Earendel's light has traveled so far to reach us that follow-up observations have already been approved for the James Webb Space Telescope.

The Cosmic Dawn is the first billion years of the Universe's history, and it is difficult to see. It is murky and dark very early when the first stars and galaxies form. The ability of our technology and analysis techniques to find quasars is stretched.

There is a quirk of gravity that can show us things that are beyond our reach. It is related to the fact that space-time around large objects has a tendency to curve around them.

Light from a distant object will travel along the space-time curve if it is at the right place. The light from the distant object can be distorted and smeared, but it is also magnified and duplicated.

There is a diagram illustrating gravitational lensing.

Astronomers can use the light to figure out what the magnified object was. At the farthest away from the Cosmic Dawn, these are usually galaxies.

The home galaxy of Earendel was first seen by the Hubble Space Telescope as a small smudge, magnified by a massive galaxy cluster. There, a team of scientists led by Brian Welch found a bright object sitting on top of a critical curve.

When we see bright single objects in other galaxies, they tend to be brighter than a typical star, but anything brighter than a typical star also tends to be fleeting, like a nova, or a tidal disruption event around a black hole.

Earendel's brightness did not change over 3.5 years of observations. It was suggested that it was a bright star in the right place at the right time.

The light is stretched so far away that we know how far away it is. Light waves are attenuate by the expansion of the Universe. The redshift of the light is used to estimate the distance of early Universe objects.

Earendel found that the object is 50 times the mass of the Sun. It's hard to tease out more detail from the data. We don't know the classification of the star, which would be useful.

We have seen some very ancient stars that have survived billions of years, but more massive stars tend to die younger.

We don't know if it is a single star or a pair of stars with a combined mass of 50 solar mass. The team expects Earendel to be a massive star that emits most of the system's light.

The earliest star could tell us a lot about the early Universe. We haven't been able to observe the processes that led to light being able to stream freely throughout the Universe. Astronomers don't have direct observations of how it unfolded, but they believe stars and galaxies were behind it.

We have seen the stars in the Cosmic Dawn. It would be interesting to narrow our understanding down to the stars that were around at the time.

The time has been approved for Webb to take observations of Earendel, which they hope will reveal more information about the star, including its age, classification, a more detailed mass, and whether or not it is a binary system.

The research has been published.