Astronomers using the Hubble Space Telescope have found the new record-breaking most distant star - the light from Earendel traveled to Earth for 12.9 billion years.
Gravitational lensing in scientific observations
The effect of gravitational lensing occurs due to the fact that an astronomical object, with its gravitational field, distorts and amplifies the light of the background object during its passage between it and the observer.
The more massive the object, the stronger it can influence the direction of propagation of electromagnetic radiation. In the case of galaxies or clusters of galaxies acting as a lens, it becomes possible to see objects located behind them, such as galaxies, supernovae, or stars.
In this case, the magnification of such lenses can reach tens or hundreds of times for galaxies, whose appearances are stretched into arcs, or thousands of times for individual stars.
Hubble found the new most distant star – Earendel
A team of astronomers announced the discovery of the most distant star to date, found during an analysis of data from the RELICS (Reionization Lensing Cluster Survey), conducted by the Hubble Space Telescope, which led to observations of 41 massive clusters of galaxies.
One of the objectives of the observations was the arc of the lensed galaxy cluster WHL0137-zD1, which received the designation “Sunrise Arc” and is characterized by a redshift value of z=6.2.
The arc is visible due to the gravitational lens, which is the galaxy cluster WHL0137-08, characterized by a redshift value of z=0.566. In the arc, scientists have discovered a highly magnified star at the top of the critical lensing curve – it has been designated WHL0137-LS, or Earendel (morning star).
The absolute magnitude of a star, determined in the ultraviolet range, is estimated at -10, which corresponds to a single and very massive star.
It can either be a massive O-type main-sequence star with an effective temperature of about 60,000 Kelvin and a mass of more than one hundred solar masses, or an evolved O-, B-, or A-type star with a mass of more than 40 solar masses and a temperature of 8 to 60 thousand kelvins.
The star existed at a time when the age of the universe is 900 million years. Confirmation of the discovery and spectral classification of the star will come from future planned observations with the James Webb Space Telescope.
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Sources:
• Choi, C. Q. (2022, March 30). Hubble Space Telescope spots most distant single star ever seen. Space.com.
• Drake, N. (2022, March 30). Most distant star ever seen found in Hubble Space Telescope Image. Science.
• ESO. (n.d.). A record broken: Hubble finds the most distant star ever seen.
• Letzter, R. (2022, March 30). Meet Earendel, the most distant star ever detected. The Verge. R
• Weisberger, M. (2022, March 30). Hubble spots most distant star ever seen, 28 billion light-years away. LiveScience.
• Welch, B., Coe, D., & Diego, J. M. (2022, March 30). A highly magnified star at redshift 6.2. Nature News.
