Tag Archives: Ursa Major

Webb Telescope Brings a Star Into Focus as It Completes ‘Image Stacking’ Alignment Phase

The Webb telescope has completed the third stage in aligning its mirrors, a crucial process for getting state-of-the-art imagery out of this $10 billion space telescope. The feat comes right on time as the telescope heads into the second month of its three-month alignment period.

Since Webb arrived at its observation point in space, a place called L2, NASA team members have worked furiously to get the telescope ready to start doing science. That process has meant using one star, HD 84406, as a guidepost for aligning the 18 primary mirrors.

Engineers have brought 18 dots of starlight into a coherent pattern.
Image: NASA/STScI/J. DePasquale

The telescope fully deployed its mirrors in late January, saw its first light on February 4, and even snapped a sort-of selfie on February 11. The ultimate goal is to get the mirrors to match each other to about 50 nanometers, or 50 billionths of a meter. As Alise Fisher put it in a recent NASA blog, “if the Webb primary mirror were the size of the United States, each segment would be the size of Texas, and the team would need to line the height of those Texas-sized segments up with each other to an accuracy of about 1.5 inches.” Tweaks to the mirrors’ orientations are being made by humans here on Earth, a million miles from the telescope.

On February 18, the mirrors aligned enough to organize the 18 dots of light picked up by each of the 18 primary mirrors. The next step was to focus those 18 views of the same star into one point—literally by stacking the images on top of one another. That’s now done, as the image stacking alignment phase was completed February 25, three days ahead of schedule. HD 84406 as seen by Webb is now a single point of light, as it should be.

“We still have work to do, but we are increasingly pleased with the results we’re seeing,” said Lee Feinberg, optical telescope element manager for Webb at NASA’s Goddard Space Flight Center, in an agency release. “Years of planning and testing are paying dividends, and the team could not be more excited to see what the next few weeks and months bring.”

The mirrors are still functioning as single instruments, though, rather than one big telescope they need to be. Fine-tuning alignments are necessary. The fourth phase of mirror alignment, called coarse phasing, will now begin. That process involves pairing 20 different mirror segments to take in light together; the team can use those results to detect where differences in the segments’ heights are reducing the image sharpness.

Coarse phasing will take place in the next several weeks, after which will come fine phasing, telescope alignment across the rest of Webb’s instruments (right now the team is just tinkering with the primary mirror) and, at last, final corrections. More details of the alignment phases can be read about here.

Webb will expand our knowledge of the early universe, galaxies, and exoplanets, as well as some objects within our solar system. The telescope is not replacing the veteran Hubble Space Telescope; it will observe in the infrared and near-infrared wavelengths, while Hubble primarily works in ultraviolet and visible light.

But Hubble launched back in 1990. Webb will peer into the cosmos alongside its predecessor, but it will look further back in time than any device before it, with technology that wasn’t possible 30 years ago.

A fully aligned, scientifically operational Webb is still some ways away—the ballpark estimate is mid-summer 2022—but the fact that nothing has gone wrong yet is a testament to the hours and effort invested by the scientists and engineers eager to give the world a whole new look at the ancient universe.

More: Webb Space Telescope Captures Selfie as It Aligns Its Gold Mirrors

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Two New Ancient Galaxies Have Been Discovered

Artist’s impression of an ancient galaxy.
Image: University of Copenhagen/NASA

The presence of two previously undetected galaxies some 29 billion light years away suggests our understanding of the early universe is upsettingly deficient.

Introducing REBELS-12-2 and REBELS-29-2—two galaxies that, until very recently, we didn’t even know existed. The light from these galaxies took 13 billion years to get here, as these objects formed shortly after the Big Bang. The ongoing expansion of the universe places these ancient galaxies at roughly 29 billion light years from Earth.

New research published in Nature suggests REBELS-12-2 and REBELS-29-2 had escaped detection up until this point because our view of these galaxies is clouded by thick layers of cosmic dust. The Hubble Space Telescope, as mighty as it is, could not peer through the celestial haze. It took the ultra-sensitive ALMA radio telescope in Chile to spot the galaxies, in what turned out to be a fortuitous accident.

“We were looking at a sample of very distant galaxies, which we already knew existed from the Hubble Space Telescope. And then we noticed that two of them had a neighbor that we didn’t expect to be there at all,” Pascal Oesch, an astronomer from the Cosmic Dawn Center at the Niels Bohr Institute in Copenhagen, explained in a statement. “As both of these neighboring galaxies are surrounded by dust, some of their light is blocked, making them invisible to Hubble.”

Oesch is an expert at finding some of universe’s farthest galaxies. Back in 2016, he and his colleagues detected the 13.4 billion-year-old GN-z11 galaxy, setting a cosmic distance record. GN-z11 formed a mere 400 million years after the Big Bang.

The ALMA radio telescope made the discovery possible.
Image: University of Copenhagen/NASA

The new paper describes how ALMA and the new observing technique developed by Oesch and his colleagues might be able to spot similarly obscured ancient galaxies. And there’s apparently many more awaiting discovery. The astronomers compared the two newly detected galaxies to previously known galactic sources in the early universe, leading them to suspect that “up to one in five of the earliest galaxies may have been missing from our map of the heavens,” Oesch said.

To which he added: “Before we can start to understand when and how galaxies formed in the Universe, we first need a proper accounting.” Indeed, the new paper asserts that more ancient galaxies existed in the early universe than previously believed. This is significant because the earliest galaxies formed the building blocks of subsequent galaxies. So until we have a “proper accounting,” as Oesch put it, astronomers could be working with a deficient or otherwise inaccurate model of the early universe.

The task now will be to find these missing galaxies, and thankfully an upcoming instrument promises to make this job considerably easier: the Webb Space Telescope. This next-gen observatory, said Oesch, “will be much more sensitive than Hubble and able to investigate longer wavelengths, which ought to allow us to see these hidden galaxies with ease.”

The new paper is thus testable, as observations made by Webb are likely to confirm, negate, or further refine the predictions made by the researchers. The space telescope is scheduled to launch from French Guiana on Wednesday December 22 7:20 a.m. ET (4:30 a.m. PT).

More: Webb Telescope Not Damaged Following Mounting Incident, NASA Says.

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New Image Shows Messier 83 Galaxy in Exquisite Detail

An observatory in northern Chile has captured a stunning view of Messier 83, also known as the Spiral of the Southern Pinwheel.

Messier 83 is an almost perfect illustration of what a spiral galaxy is stereotypically supposed to look like. This is because we have the fortune of seeing it from a practically perfect overhead, or face-on, perspective.

The new image was acquired with the Dark Energy Camera (DECam) attached to the Víctor M. Blanco telescope at the Cerro Tololo Inter-American Observatory (CTIO) in northern Chile. DECam, having already fulfilled its primary duty as the Dark Energy Survey from 2013 to 2018, is now being used for other purposes, like gazing upon nearby celestial wonders.

Messier 83 is 15 million light-years away, which is actually quite close as far as neighboring galaxies are concerned. The spiral is about 50,000 light-years in diameter, making it about two-fifths as big as our Milky Way, another spiral galaxy. The Southern Pinwheel, as it’s also called, “probably gives a good approximation of how our Milky Way would look to a distant alien civilization,” according to the U.S. National Science Foundation’s NOIRLab, which manages the CTIO program.

Six light filters were used to make the image, all highlighting specific features within the galaxy. For example, the dark channels coursing through the spirals are large accumulations of dust, while the red spots are regions rich in hydrogen gas, within which new stars are being born. In total, the image is the product of 163 DECam exposures taken across 11.3 hours of observation time.

For those of you wanting to make this image your wallpaper, go here to download the version of your choosing.

Work done with DECam will inform future observations made by the new Vera C. Rubin Observatory, which should see first light later this year and become fully operational in 2023.

“The Messier 83 observations are part of an ongoing program to produce an atlas of time-varying phenomena in nearby southern galaxies in preparation for Rubin Observatory’s Legacy Survey of Space and Time,” Monika Soraisam, an astronomer at the University of Illinois and principal investigator for DECam’s observations of Messier 83, explained in the NOIRLab statement.

Incredibly, the Rubin Observatory will capture 1,000 images each night, which it will do continuously for an entire decade. So get ready for the next amazing chapter in astronomy, as scientists literally create a color motion picture of the cosmos.

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