Record broken: Hubble spots farthest star ever seen

Date:
March 30, 2022
Source:
NASA/Goddard Space Flight Center
Summary:
NASA's Hubble Space Telescope has established an extraordinary new
benchmark: detecting the light of a star that existed within the
first billion years after the universe's birth in the big bang --
the farthest individual star ever seen to date.



FULL STORY ========================================================================== [Hubble Space Telescope | Credit: (c) dimazel / stock.adobe.com] Hubble
Space Telescope illustration (stock image; elements furnished by NASA).

Credit: (c) dimazel / stock.adobe.com [Hubble Space Telescope | Credit:
(c) dimazel / stock.adobe.com] Hubble Space Telescope illustration
(stock image; elements furnished by NASA).

Credit: (c) dimazel / stock.adobe.com Close NASA's Hubble Space Telescope
has established an extraordinary new benchmark: detecting the light of
a star that existed within the first billion years after the universe's
birth in the big bang -- the farthest individual star ever seen to date.


==========================================================================
The find is a huge leap further back in time from the previous single-star record holder; detected by Hubble in 2018. That star existed when the
universe was about 4 billion years old, or 30 percent of its current age,
at a time that astronomers refer to as "redshift 1.5." Scientists use
the word "redshift" because as the universe expands, light from distant
objects is stretched or "shifted" to longer, redder wavelengths as it
travels toward us.

The newly detected star is so far away that its light has taken 12.9
billion years to reach Earth, appearing to us as it did when the universe
was only 7 percent of its current age, at redshift 6.2. The smallest
objects previously seen at such a great distance are clusters of stars, embedded inside early galaxies.

"We almost didn't believe it at first, it was so much farther than the
previous most-distant, highest redshift star," said astronomer Brian
Welch of the Johns Hopkins University in Baltimore, lead author of the
paper describing the discovery, which is published in the March 30 journal Nature. The discovery was made from data collected during Hubble's RELICS (Reionization Lensing Cluster Survey) program, led by co-author Dan Coe
at the Space Telescope Science Institute (STScI), also in Baltimore.

"Normally at these distances, entire galaxies look like small smudges,
with the light from millions of stars blending together," said
Welch. "The galaxy hosting this star has been magnified and distorted by gravitational lensing into a long crescent that we named the Sunrise Arc." After studying the galaxy in detail, Welch determined that one feature
is an extremely magnified star that he called Earendel, which means
"morning star" in Old English. The discovery holds promise for opening
up an uncharted era of very early star formation.



========================================================================== "Earendel existed so long ago that it may not have had all the same raw materials as the stars around us today," Welch explained. "Studying
Earendel will be a window into an era of the universe that we are
unfamiliar with, but that led to everything we do know. It's like we've
been reading a really interesting book, but we started with the second
chapter, and now we will have a chance to see how it all got started,"
Welch said.

When Stars Align The research team estimates that Earendel is at least
50 times the mass of our Sun and millions of times as bright, rivaling
the most massive stars known. But even such a brilliant, very high-mass
star would be impossible to see at such a great distance without the
aid of natural magnification by a huge galaxy cluster, WHL0137-08,
sitting between us and Earendel. The mass of the galaxy cluster warps
the fabric of space, creating a powerful natural magnifying glass that
distorts and greatly amplifies the light from distant objects behind it.

Thanks to the rare alignment with the magnifying galaxy cluster, the
star Earendel appears directly on, or extremely close to, a ripple in the fabric of space. This ripple, which is defined in optics as a "caustic," provides maximum magnification and brightening. The effect is analogous
to the rippled surface of a swimming pool creating patterns of bright
light on the bottom of the pool on a sunny day. The ripples on the surface
act as lenses and focus sunlight to maximum brightness on the pool floor.

This caustic causes the star Earendel to pop out from the general glow of
its home galaxy. Its brightness is magnified a thousandfold or more. At
this point, astronomers are not able to determine if Earendel is a binary
star, though most massive stars have at least one smaller companion star.



========================================================================== Confirmation with Webb Astronomers expect that Earendel will remain highly magnified for years to come. It will be observed by NASA's James Webb
Space Telescope. Webb's high sensitivity to infrared light is needed to
learn more about Earendel, because its light is stretched (redshifted)
to longer infrared wavelengths due to the universe's expansion.

"With Webb we expect to confirm Earendel is indeed a star, as well as
measure its brightness and temperature," Coe said. These details will
narrow down its type and stage in the stellar lifecycle. "We also expect
to find the Sunrise Arc galaxy is lacking in heavy elements that form in subsequent generations of stars. This would suggest Earendel is a rare,
massive metal-poor star," Coe said.

Earendel's composition will be of great interest for astronomers, because
it formed before the universe was filled with the heavy elements produced
by successive generations of massive stars. If follow-up studies find
that Earendel is only made up of primordial hydrogen and helium, it would
be the first evidence for the legendary Population III stars, which are hypothesized to be the very first stars born after the big bang. While
the probability is small, Welch admits it is enticing all the same.

"With Webb, we may see stars even farther than Earendel, which would be incredibly exciting," Welch said. "We'll go as far back as we can. I would
love to see Webb break Earendel's distance record." The Hubble Space
Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute
(STScI) in Baltimore, Maryland, conducts Hubble science operations.

STScI is operated for NASA by the Association of Universities for Research
in Astronomy in Washington, D.C.


========================================================================== Story Source: Materials provided by NASA/Goddard Space Flight
Center. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* YouTube_video:_Record_Broken:_Hubble_Spots_Farthest_Star_Ever_Seen ========================================================================== Journal Reference:
1. Brian Welch, Dan Coe, Jose M. Diego, Adi Zitrin, Erik Zackrisson,
Paola
Dimauro, Yolanda Jime'nez-Teja, Patrick Kelly, Guillaume Mahler,
Masamune Oguri, F. X. Timmes, Rogier Windhorst, Michael Florian,
S. E. de Mink, Roberto J. Avila, Jay Anderson, Larry Bradley, Keren
Sharon, Anton Vikaeus, Stephan McCandliss, Marusa Bradač, Jane
Rigby, Brenda Frye, Sune Toft, Victoria Strait, Michele Trenti,
Soniya Sharma, Felipe Andrade-Santos, Tom Broadhurst. A highly
magnified star at redshift 6.2.

Nature, 2022; 603: 815-818 DOI: 10.1038/s41586-022-04449-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220330124628.htm

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