Tag: Webb Space Telescope

Webb takes infrared image of Hubble’s Pillars of Creation

10:28 am

The Pillars of Creation, as seen by Hubble and Webb
Click for original image.

Not unexpectedly, astronomers have quickly begun aiming the Webb Space Telescope’s infrared eye at some of the most famous targets previously imaged in optical wavelengths by the Hubble Space Telescope.

The newest example is shown to the right and reduced and labeled to post here. It shows what NASA officials dubbed “The Pillars of Creation” when Hubble first photographed this nebula in 1995, with a later 2014 Hubble optical image at the top and the new 2022 Webb infrared image on the bottom. From this image’s caption:

A new, near-infrared-light view from NASA’s James Webb Space Telescope, at [bottom], helps us peer through more of the dust in this star-forming region. The thick, dusty brown pillars are no longer as opaque and many more red stars that are still forming come into view.

While the pillars of gas and dust seem darker and less penetrable in Hubble’s view [top], they appear more diaphanous in Webb’s. The background of this Hubble image is like a sunrise, beginning in yellows at the bottom, before transitioning to light green and deeper blues at the top. These colors highlight the thickness of the dust all around the pillars, which obscures many more stars in the overall region.

In contrast, the background light in Webb’s image appears in blue hues, which highlights the hydrogen atoms, and reveals an abundance of stars spread across the scene. By penetrating the dusty pillars, Webb also allows us to identify stars that have recently – or are about to – burst free. Near-infrared light can penetrate thick dust clouds, allowing us to learn so much more about this incredible scene.

While the Hubble colors attempt to mimic the colors seen by the human eye, the colors in the Webb image are all false colors, chosen by the scientists to distinguish the different infrared wavelengths produced by different features in the picture.

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Shells of dust surrounding massive binary star

10:07 am

Webb infrared image of dust shells surrounding binary star system
Click for full image.

Cool image time! Using the Webb telescope, astronomers have detected a series of concentric shells surrounding the massive binary star dubbed Wolf-Rayet 140.

The infrared image to the right shows these shells quite clearly. As noted by astronomer Ryan Lau:

“On the night that my team’s Early Release Science observations of the dust-forming massive binary star Wolf-Rayet (WR) 140 were taken, I was puzzled by what I saw in the preview images from the Mid-Infrared Instrument (MIRI). There seemed to be a strange-looking diffraction pattern, and I worried that it was a visual effect created by the stars’ extreme brightness. However, as soon as I downloaded the final data I realized that I was not looking at a diffraction pattern, but instead rings of dust surrounding WR 140 – at least 17 of them.

“I was amazed. Although they resemble rings in the image, the true 3D geometry of those semi-circular features is better described as a shell. The shells of dust are formed each time the stars reach a point in their orbit where they are closest to each other and their stellar winds interact. The even spacing between the shells indicates that dust formation events are occurring like clockwork, once in each eight-year orbit. In this case, the 17 shells can be counted like tree rings, showing more than 130 years of dust formation. Our confidence in this interpretation of the image was strengthened by comparing our findings to the geometric dust models by Yinuo Han, a doctoral student at the University of Cambridge, which showed a near-perfect match to our observations.

Furthermore, the spectroscopy from Webb says these dust shells are carbon-enriched, showing that the dust released by these aged massive stars is a significant source of the carbon in the universe, the fundamental atom needed for life.

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Chandra takes an X-ray look at early Webb infrared observations

9:54 am

Chandra's X-ray vision of the Cartwheel Galaxy
Chandra’s X-ray view of the Cartwheel Galaxy

Webb's view of the Cartwheel Galaxy
Webb’s infrared view of the Cartwheel Galaxy
Click for full image.

Hubble's optical view of the Cartwheel Galaxy
Hubble’s optical view of the Cartwheel Galaxy. Click for original image.

Astronomers have now taken X-ray images using the orbital Chandra X-ray Observatory of four of the first Webb Space Telescope observations. The four targets were the Cartwheel Galaxy, Stephan’s Quintet, galaxy cluster SMACS 0723.3–7327, and the Carina Nebula.

The three images to the right illustrate the importance of studying astronomy across the entire electromagnetic spectrum. Each shows the Cartwheel Galaxy as seen by three of the world’s most important space-based telescopes, each looking at the galaxy in a different wavelength.

The top picture is Chandra’s new X-ray observations. As the press release notes,

Chandra data generally show higher-energy phenomena (like superheated gas and the remnants of exploded stars) than Webb’s infrared view. … X-rays seen by Chandra (blue and purple) come from superheated gas, individual exploded stars, and neutron stars and black holes pulling material from companion stars.

The middle picture was produced by Webb, shortly after the start of its science operations. It looks at the galaxy in the infrared.

In this near- and mid-infrared composite image, MIRI data are colored red while NIRCam data are colored blue, orange, and yellow. Amidst the red swirls of dust, there are many individual blue dots, which represent individual stars or pockets of star formation. NIRCam also defines the difference between the older star populations and dense dust in the core and the younger star populations outside of it.

The bottom picture was taken by the Hubble Space Telescope in 1995. I have rotated the image to match the others. It looks at the galaxy in optical wavelengths, the wavelengths that our eyes perceive.

Note how bright the central galactic region is in the infrared and optical, but is invisible in X-rays. Chandra is telling us that all the most active regions in the Cartwheel are located in that outer ring, not in its center.

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Initial Webb results revised because telescope wasn’t yet fully calibrated

10:02 am

The uncertainty of science: Though it appears that no results will have to be abandoned, the scientists who published some of the very first results from the Webb Space Telescope have been scrambling to adjust and revise their papers because the telescope is only now getting fully calibrated.

“This caused a little bit of panic,” says Nathan Adams, an astronomer at the University of Manchester, UK, who, along with his colleagues, pointed out the problem in a 9 August update to a preprint they had posted in late July3. “For those including myself who had written a paper within the first two weeks, it was a bit of — ‘Oh no, is everything that we’ve done wrong, does it all need to go in the bin?’”

To try to standardize all the measurements, the STScI is working through a detailed plan to point Webb at several types of well-understood star, and observe them with every detector in every mode for every instrument on the telescope4. “It just takes a while,” says Karl Gordon, an astronomer at the STScI who helps lead the effort.

In the meantime, astronomers have been reworking manuscripts that describe distant galaxies on the basis of Webb data. “Everyone’s gone back over and had a second look, and it’s not as bad as we thought,” Adams says. Many of the most exciting distant-galaxy candidates still seem to be at or near the distance originally estimated. But other preliminary studies, such as those that draw conclusions about the early Universe by comparing large numbers of faint galaxies, might not stand the test of time. Other fields of research, such as planetary studies, are not affected as much because they depend less on these preliminary brightness measurements.

Overall, it does not appear the more precise calibrations will change much of signficance, since most of the earliest observations were simply that, observations, not theoretical. Because the distance estimates remain largely unchanged however the theorists are left with the same conundrum: The age and apparent nature of the most distant objects does not seem to fit with what the theories had predicted Webb would see.

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Hubble & Webb make first coordinated observations, tracking DART impact of Dimorphus

9:50 am

Webb and Hubble together look at DART impact of Dimorphus
Click for full image.

For the first time scientists have used both the Hubble Space Telescope and the James Webb Space Telescope to observe the same astronomical event, in this case the impact of the DART spacecraft on the asteroid Dimorphus on September 26, 2022.

The two images to the right show the asteroid several hours after impact. Both telescopes also captured images before the impact as well. From the press release:

Observations from Webb and Hubble together will allow scientists to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, and how fast it was ejected. Additionally, Webb and Hubble captured the impact in different wavelengths of light – Webb in infrared and Hubble in visible. Observing the impact across a wide array of wavelengths will reveal the distribution of particle sizes in the expanding dust cloud, helping to determine whether it threw off lots of big chunks or mostly fine dust. Combining this information, along with ground-based telescope observations, will help scientists to understand how effectively a kinetic impact can modify an asteroid’s orbit.

When Webb was first conceived in the late 1990s, it was exactly for this reason, to combine Hubble’s optical vision with Webb’s infrared view. Though more than a decade late, it has finally happened.

It will be months before scientists begin to decipher the data produced by all the telescopes and spacecraft used to observe the DART impact. What we are seeing now are merely hints at what has been learned.

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