Webb highlights exciting details in latest image of a very distant galaxy
The James Webb Space Telescope peeked into a galaxy cluster, revealing a known but very distant galaxy in the early universe. How did the gigantic telescope do it?
Webb was designed to detect faint infrared light from very distant galaxies. Supplemented by gravitational lensing by a cluster of galaxies in the foreground that act as cosmic telescopes, faint background galaxies can be magnified and appear multiple times in different parts, according to a press release.
The gravitational lensing of the massive galaxy cluster MACS0647 has lensed into three images — JD1, JD2, and JD3 — that are magnified by factors of eight, five, and two. In the image below from Webb’s Near Infrared Camera (NIRCam) instrument, blue was assigned to wavelengths of 1.15 and 1.5 microns (F115W, F150W), green to wavelengths of 2.0 and 2.77 microns (F200W, F277W) and red to wavelengths of 3.65 and 4.44 microns (F365W, F444W).
The study has not been peer-reviewed yet and is in the early stages of discussion.
Two galaxies or two clumps of stars in a galaxy?
Though the galaxy MACS0647-JD was discovered 10 years ago with the Hubble Space Telescope, the latter limited it to a small red dot. "Now we look with Webb, and we’re able to resolve TWO objects! We’re actively discussing whether these are two galaxies or two clumps of stars within a galaxy. We don’t know, but these are the questions that Webb is designed to help us answer," said Dan Coe of AURA/STScI for the European Space Agency and the Johns Hopkins University, in a conversation with NASA.
According to NASA, the galaxy is a window to a time when the universe was only three percent of its age of 13.7 billion years, back in 2012. At the time, it was observed 420 million years after the Big Bang.
"This object may be one of many building blocks of a galaxy," said Coe, the study's lead author, in a release from November 2012. "Over the next 13 billion years, it may have dozens, hundreds, or even thousands of merging events with other galaxies and galaxy fragments."
Astronomers haven't been able to study galaxies in the early universe in intricate detail. Studying them could largely help understand how they "evolved into the ones like the galaxy we lived today," according to Rebecca Larson, a National Science Foundation fellow and Ph.D. graduate student at the University of Texas at Austin.
Witness to a distant galaxy merger in the early universe
Tiger Hsiao of the Johns Hopkins University, one of the scientists observing the distant galaxy MACS0647-JD with Webb, said that it was likely we were witness to a galaxy merger in the very early universe. "If this is the most distant merger, I will be really ecstatic!," he said.
Hsaio also drew attention to the colors between the two objects. While one is bluer, the other is redder.
"The blue gas and the red gas have different characteristics. The blue one actually has very young star formation and almost no dust, but the small, red object has more dust inside, and is older. And their stellar masses are also probably different," he said.
Larson expressed her joy at the amount of information that we're getting, thanks to Webb.
"And this is not a deep field. This is not a long exposure. We haven’t even really tried to use this telescope to look at one spot for a long time. This is just the beginning!," she said.
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