Title: Astronomers Gain Insight into the Farthest Known Star Using the JWST
Subtitle: Earendel’s Spectra and Home Galaxy Provide New Clues about the Early Universe
Date: March 2022
Byline: Universe Today
In a recent discovery, astronomers have unveiled new details about the farthest known star, Earendel, using the James Webb Space Telescope (JWST). Previously identified by the Hubble Space Telescope, this massive B-type star has now been observed with JWST’s Near-infrared Camera (NIRCam) and its NIRSpec spectrometer, shedding light on its characteristics and its home galaxy.
Earendel, named after the old English term for “morning star,” resides on the Main Sequence and is classified as a hydrogen-burning star. Comparing it to our Sun, Earendel is twice as hot and a million times more luminous. Astronomers speculate that Earendel may have a companion star, but their close proximity and the vast distance of approximately 13 billion light-years make it challenging to confirm this hypothesis.
However, careful analysis of Earendel’s spectra, which represents the colors of its light, shows hints of a companion star. Scientists believe that utilizing the gravitational lensing effect and conducting detailed observations using NIRCam on JWST will aid in distinguishing the presence of a companion star.
Due to the tremendous distance between Earth and Earendel, the light observed from the star was emitted around 900 million years after the Big Bang. Through gravitational lensing, which magnifies Earendel by a factor of 4,000, astronomers hope to determine if this star belongs to the first generations of stars ever to shine. If confirmed, its spectra would primarily consist of hydrogen and helium, suggesting it is a first-generation star. Conversely, if it turns out to be a second-generation star, additional elements would be present in its light.
Earendel’s host galaxy appears as a long crescent-shaped blur of light, observed due to gravitational lensing caused by the massive galaxy cluster WHL0137-08. JWST’s NIRCam captures detailed images of the distant galaxy, revealing regions of young star formation as well as older star clusters. The presence of a 10-million-year-old cluster opens doors to understanding the evolution of similar structures within our Milky Way galaxy.
Interestingly, the JWST image offers more insights into the gravitational lensing effect on the distant galaxy, demonstrating how Earendel is discernible from the smeared image of its host galaxy. Additionally, NirSpec’s infrared spectrometer provides astronomers with precise distance measurements to Earendel and its home galaxy, enhancing our understanding of their relationship.
By harnessing the power of JWST’s infrared-sensitive instruments, astronomers have also detected other distant stars. While Earendel holds the current record for the farthest known star, researchers are eager to continue their observations in their quest to discover the very first stars to ever shine. These primal objects could have emerged as early as 100 million years after the Big Bang, and studying them would provide valuable insights into the early universe, the distribution of matter (including dark matter), and the formation of galaxies during cosmic infancy.
As astronomers continue to explore the cosmos with JWST, the potential discovery of the first stars represents a significant milestone in understanding the origins and evolution of our universe.
(Note: This article was originally published by Universe Today. Read the original article.)