Scientists using the James Webb Space Telescope (JWST) have imaged the most distant star ever observed thanks to a a ripple in spacetime that creates extreme magnification.
It’s currently 28 billion light-years away and its light has traveled 12.9 billion years into JWST’s optics. It existed just 900 million years after the big bang in a galaxy astronomers have nicknamed the Sunrise Arc.
The image of WHL0137-LS, above, was produced from over three hours of observations last weekend—but it’s not the star you think! Ignore the spiky star and instead go to the lower right-hand side (see below).
The ancient star is estimated to have a mass greater than 50 times the mass of the Sun.
Better known as “Earendel,” which means “morning star” or “rising light” in old English—was gravitationally lensed and magnified by a massive galaxy cluster called WHL0137–08 (a.k.a. “Sunrise Arc”) in the foreground.
In this zoomed-in image the Sunrise Arc is the curve of red light cutting through the center. Earendel is the second star in from the top of the arc. It’s between two slightly brighter stars.
This is gravitational lensing—nature’s magnifying glass. It occurs when the gravitational pull from a closer, but aligned galaxy distorts and bends the light from a distant star or galaxy, causing it to appear misshapen and be magnified.
It’s essentially a ripple in spacetime that gives it extreme magnification and it’s how JWST will study the most distant and intrinsically faint stars and galaxies close to the big bang 13.8 billion years ago.
Usually this technique finds ancient galaxies, not ancient stars.
The new image of Earendel was taken by Webb’s Near-Infrared Camera (NIRCam) in three hours. It takes the Hubble Space Telescope weeks to take deep field images like this, and in much lower resolution and sensitivity.
Scientists using the Hubble Space Telescope imaged Earendel in March. It was first discovered in 2017.
Astronomers know it’s very old because its light is very, very red. Very old light is red because it’s been stretched over time as it travels through space. Extremely distant stars and galaxies appear to move away from us at greater speeds than closer galaxies so their light is redder.
So the redder a star or galaxy, the earlier in the universe it exists. Earendel’s light has a redshift of 6.2 while most stars found using gravitational lensing have redshifts of about 1–1.5.
This new observation of Earendel is part of JWST program 2282. Next up for researchers is to use JWST’s NIRSpec instrument for six hours in October to measure the star’s brightness, temperature, mass and spectral properties.
Webb is the most ambitious and complex space science telescope ever constructed, with a massive 6.5-meter primary mirror that will be able to detect the faint light of far-away stars and galaxies. It’s designed solely to detect infrared light emitted by distant stars, planets and clouds of gas and dust.
It’s initial 10-year mission Webb will study the solar system, directly image exoplanets, photograph the first galaxies, and explore the mysteries of the origins of the Universe.
Wishing you clear skies and wide eyes.