Eärendil: Hubble discovers the Earliest and Farthest Star Known
Being a die hard Lord of the Rings fan, this news caught my eye immediately.
The discovery of the farthest and earliest star ever seen, a dot of light that shone 12.9 billion years ago, or just 900 million years after the Big Bang that gave birth to the universe, was announced by astronomers on Wednesday. The star’s light traveled 12.9 billion light-years to reach Earth.
The discovery was made as part of an effort to search for some of the universe’s farthest and earliest galaxies using the Hubble Space Telescope. By chance, the astronomers were able to identify a single star system within one of the galaxies.
“It was an unexpected surprise to find something so small,” said Brian Welch, a graduate student at Johns Hopkins University in Baltimore and co-author of a paper describing the discovery published Wednesday in the journal Nature. Objects that far away are usually too dim to be seen. However, Einstein’s general theory of relativity, which describes how gravity bends space, provides a convenient workaround. A massive galaxy cluster close to us can act as a lens, amplifying light from stars and galaxies much further away behind it.
According to Mr. Welch, the galaxy cluster typically magnifies the brightness of the object behind it by a factor of ten.
However, the light is not magnified evenly. Ripples in space-time can produce bright spots in the same way that ripples on the surface of a swimming pool produce patterns of bright spots at the pool’s bottom. When the astronomers examined one of the magnified distant galaxies, they discovered that a point of light lined up with one of the ripples, and its shine was magnified a thousandfold or more. Mr. Welch described the galaxy as “sort of stretched out into this long crescent-shaped arc.” “And then there’s the star, which is just one component of that.”
More distant objects are moving away faster as the universe expands. This causes the frequency of light to shift toward longer wavelengths. Mr. Welch and his colleagues discovered a star with a red shift of 6.2, which is far greater than the previous record-holder for most distant single star. That star, discovered in 2018, had a red shift of 1.5, corresponding to a time when the universe was approximately four billion years old.
The discoverers named the star Earendel, which comes from the Old English word for “Morning Star” or “Rising Light.” Eärendil is also the name of a half-elf character in J.R.R. Tolkien’s book The Silmarillion who travels through the sky with a radiant jewel as bright as a star; NASA astronomer Michelle Thaller confirmed that the reference to Tolkien was intentional.
Tolkien wrote a poem titled The Voyage of Eärendil the Evening Star in 1914. (published in The Book of Lost Tales Part Two, pages 267–269). Tolkien was also aware of the name’s Germanic cognates (Old Norse Aurvandill, Lombardic Auriwandalo), and the Notion Club papers allude to the question of why the Anglo-Saxon form rather than the Lombardic or Proto-Germanic form should be taken up in the mythology. The Old Norse and Anglo-Saxon evidence point to an astronomical myth, with the name referring to a star or group of stars, and the Anglo-Saxon evidence, in particular, points to the Morning Star as the herald of the rising Sun, as alluded to by Cynewulf in Crist.
Earendel will be one of the targets of the newly launched James Webb Space Telescope, which has a larger mirror than Hubble and gathers light at longer infrared wavelengths. The Webb observations will be able to measure brightness over a wide range of wavelengths. This will aid astronomers in determining the temperature of the star. “We really need that spectrum to say with absolute certainty that this is a star as opposed to some other type of object,” Mr. Welch explained.
The Webb telescope should be able to detect other distant magnified stars like Eärendil, though how many are coincidentally aligned with a gravitational lens remains to be seen. It may even be able to detect some stars with a red shift of 10 to 20, corresponding to a time period between 100 million and 500 million years after the Big Bang.
“Which is exactly in that window when we believe the first stars are forming,” Dr. Finkelstein explained.
I would personally love for Webb to break this record that Hubble has just set. Webb is set to start observations soon. I will be posting an article about it within the next few days.
