25.10.2022
James Webb Space Telescope spies galaxies merging around 'monster' black hole
Astronomers have discovered a cluster of galaxies merging around a rare red quasar, a "monster" supermassive black hole that is greedily feeding on gas and other material.
An international team of scientists made the surprising discovery as they were using the James Webb Space Telescope (JWST) to stare billions of years back in time. The finding represents an opportunity to observe how early galaxiesmerged forming the universe as we see it today. The blindingly bright quasar and extremely red quasar, known as SDSS J165202.64+172852.3, is about 11.5 billion years old and one of the most powerful ever seen from a such tremendous distance away, according to the researchers, who describe it as a black hole in formation.
"We think something dramatic is about to happen in these systems," Andrey Vayner, research co-author and an astrophysicist at Johns Hopkins University in Maryland, said in a statement. "The galaxy is at this perfect moment in its lifetime, about to transform and look entirely different in a few billion years."
Earlier observations of this region of space using the Hubble Space Telescopeand the Gemini-North telescope in Hawaii had revealed the quasar and hinted at a galaxy in a transitional phase. But it was only further observation with JWST that revealed not one but at least three galaxies all swirling around the quasar.
"With previous images, we thought we saw hints that the galaxy was possibly interacting with other galaxies on the path to a merger because their shapes get distorted in the process and we thought we maybe saw that," Nadia L. Zakamska, co-principal investigator and Johns Hopkins astrophysicist, said in the same statement. "But after we got the JWST data, I was like, 'I have no idea what we're even looking at here, what is all this stuff!' We spent several weeks just staring and staring at these images."
The JWST images of the region also showed that the three galaxies are moving incredibly quickly, suggesting the presence of a tremendous mass, which leads the team to think this could be the densest area of galaxy formation ever seen in the early universe.
"Even a dense knot of dark matter isn't sufficient to explain it," Dominika Wylezalek, an astronomer at Heidelberg University in Germany who led the research, said in a Webb statement. "We think we could be seeing a region where two massive halos of dark matter are merging together."
Even Vayner, who had imagined observing this quasar with JWST as much as a decade ago, was shocked that the space telescope, which only started sending science images back to Earth in July, has produced observations of the region with such clarity.
"It really will transform our understanding of this object," he added.
The team will now attempt to follow up this observation of this unexpected galaxy cluster hoping to decipher the secrets of how such dense groupings of galaxies formed in the early universe and how this process is affected by the supermassive black holes that lurk at their hearts.
"What you see here is only a small subset of what's in the data set," Zakamska said.
"There's just too much going on here so we first highlighted what really is the biggest surprise," she said. "Every blob here is a baby galaxy merging into this mommy galaxy and the colors are different velocities and the whole thing is moving in an extremely complicated way. We can now start to untangle the motions."
The team's research is being published in the Astrophysical Journal Letters and a preprint is also available on the paper repository arXiv.
Quelle: SC
+++
Webb uncovers dense cosmic knot in the early Universe
Astronomers looking into the early Universe have made a surprising discovery using the NASA/ESA/CSA James Webb Space Telescope. Webb’s spectroscopic capabilities, combined with its infrared sensitivity, have uncovered a cluster of massive galaxies in the process of formation around an extremely red quasar. The result will expand our understanding of how galaxies in the early Universe coalesced into the cosmic web we see today.
The quasar in question, SDSS J165202.64+172852.3, is an “extremely red” quasar that exists in the very early Universe, 11.5 billion years ago. Quasars are a rare, incredibly luminous type of active galactic nucleus (AGN). This quasar is one of the most powerful known galactic nuclei that’s been seen at such an extreme distance. Astronomers had speculated that the quasar’s extreme emission could cause a “galactic wind”, pushing free gas out of its host galaxy and possibly greatly influencing future star formation there.
An AGN is a compact region at the centre of a galaxy, which is emitting enough electromagnetic radiation to outshine all the galaxy’s stars. AGNs, including quasars, are powered by gas falling into a supermassive black hole at the centre of their galaxy. They typically emit vast amounts of light across all wavelengths, but this galactic core is a member of an unusually red class. In addition to its intrinsic red colour, the galaxy’s light has been further redshifted by its vast distance. That made Webb, having unparalleled sensitivity in infrared wavelengths, perfectly suited to examine the galaxy in detail.
To investigate the movement of the gas, dust and stellar material in the galaxy, the team used the telescope’s Near Infrared Spectrograph (NIRSpec). This powerful instrument can simultaneously gather spectra across the telescope’s whole field of view, instead of just from one point at a time – a technique known as integral field unit (IFU) spectroscopy. This enabled them to simultaneously examine the quasar, its galaxy and the wider surroundings.
Spectroscopy was critical to understand the movement of the various outflows and winds surrounding the quasar. The motions of the gases affect the light that they emit and reflect, causing it to be red- or blueshifted in proportion to their speed and direction [1]. The team was able to see and characterise this movement by tracking ionised oxygen in the NIRSpec spectra. The IFU observations were especially useful, with the team taking full advantage of the ability to collect spectra from a wide area around the quasar itself.
Previous studies by, among others, the NASA/ESA Hubble Space Telescope and the Near-Infrared Integral Field Spectrometer instrument on the Gemini-North telescope called attention to the quasar’s powerful outflows, and astronomers had speculated that its host galaxy could be merging with some unseen partner. But the team was not expecting Webb’s NIRSpec data to clearly indicate that they were not just looking at one galaxy, but at least three more swirling around it. Thanks to the IFU spectra over a broad area, the motions of all this surrounding material could be mapped, resulting in the conclusion that SDSS J165202.64+172852.3 was in fact part of a dense knot of galaxy formation.
"There are few galaxy protoclusters known at this early time. It’s hard to find them, and very few have had time to form since the Big Bang,” said astronomer Dominika Wylezalek of Heidelberg University in Germany, who led the study into this quasar. “This may eventually help us understand how galaxies in dense environments evolve… It’s an exciting result.”
Using the IFU observations from NIRSpec, the team was able to confirm three galactic companions to this quasar and show how they are connected. Archive data from Hubble hints that there may be even more. Images from Hubble’s Wide Field Camera 3 had shown extended material surrounding the quasar and its galaxy, prompting its selection for this study into its outflow and the effects on its host galaxy. Now, the team suspects they could have been looking at the core of a whole cluster of galaxies – only now revealed by Webb’s crisp imaging.
"Our first look at the data quickly revealed clear signs of major interactions between the neighbouring galaxies,” shared team member Andrey Vayner of Johns Hopkins University in Baltimore, USA. “The sensitivity of the NIRSpec instrument was immediately apparent, and it was clear to me that we are in a new era of infrared spectroscopy."
The three confirmed galaxies are orbiting each other at incredibly high speeds, an indication that a great deal of mass is present. When combined with how closely they are packed into the region around this quasar, the team believes this marks one of the densest known areas of galaxy formation in the early Universe.“Even a dense knot of dark matter isn’t sufficient to explain it,” Wylezalek says. “We think we could be seeing a region where two massive halos of dark matter are merging together.”
The study conducted by Wylezalek’s team is part of Webb’s investigations into the early Universe. With its unprecedented ability to look back in time, the telescope is already being used to investigate how the first galaxies were formed and evolved, and how black holes formed and influenced the structure of the Universe. The team is planning follow-up observations into this unexpected galaxy proto-cluster, and hope to use it to understand how dense, chaotic galaxy clusters like this one form, and how it’s affected by the active, supermassive black hole at its heart.
They aim first to return to the question of galactic winds and quasar feedback. Quasars have long been suspected as the culprit of reduced star formation in their host galaxies by this feedback mechanism, but firm evidence to link the two has been difficult to come by. The present observations are just the first in a set which will study three quasars with Webb, each at different times in the past of the Universe.
“To disentangle the incredibly bright light of a distant quasar from the much dimmer host and its companions is almost impossible from the ground. Uncovering the details of the galactic winds that may produce feedback is even more challenging,” shared team member David Rupke of Rhodes College in Memphis, USA. “Now with Webb, we can already see that’s changing.”
This research was completed as part of Webb’s Early Release Science (ERS) Programs. These observations are taking place during the first 5 months of Webb science operations. The Webb observations that yielded this result were taken from the ERS program #1335.
Notes
[1] When light waves are emitted by a moving source, they can be squashed together or stretched apart from our perspective here on Earth, depending on the direction the source is moving. If a light source moves away from us, the stretching shifts its light into redder wavelengths, and if the source is moving towards us its light becomes bluer. This is known as the Doppler effect, analogous to how sound waves are shifted when emitted by a moving vehicle such as an ambulance. Light waves can also be redshifted because the space between it and us is expanding - so-called cosmological redshift.
Quelle: ESA
----
Update: 26.10.2022
.
Webb explores a pair of merging galaxies
Hubble
Webb
Here, the Webb Picture of the Month of merging galaxies IC 1623 A and B is juxtaposed with a new image from the NASA/ESA Hubble Space Telescope. This image on the right, combining data from Hubble’s ACS and WFC3 instruments, gives a familiar visible-light view of these colliding galaxies, where the centres of the individual galaxies are much more obscured by dark dust. Meanwhile, in Webb’s combined MIRI and NIRCam view of the galaxies on the left, the gas being used as fuel by the stellar nurseries is especially apparent. Webb’s ability to pierce the gaseous veil obscuring the bright galactic cores also causes prominent diffraction spikes to appear.
The image on the left from the NASA/ESA/CSA James Webb Space Telescope depicts IC 1623, an entwined pair of interacting galaxies which lies around 270 million light-years from Earth in the constellation Cetus. The two galaxies in IC 1623 are plunging headlong into one another in a process known as a galaxy merger. Their collision has ignited a frenzied spate of star formation known as a starburst, creating new stars at a rate more than twenty times that of the Milky Way galaxy.
This interacting galaxy system is particularly bright at infrared wavelengths, making it a perfect proving ground for Webb’s ability to study luminous galaxies. A team of astronomers captured IC 1623 across the infrared portions of the electromagnetic spectrum using a trio of Webb’s cutting-edge scientific instruments: MIRI, NIRSpec, and NIRCam. In so doing, they provided an abundance of data that will allow the astronomical community at large to fully explore how Webb’s unprecedented capabilities will help to unravel the complex interactions in galactic ecosystems. These observations are also accompanied by data from other observatories, including the NASA/ESA Hubble Space Telescope, and will help set the stage for future observations of galactic systems with Webb.
The merger of these two galaxies has long been of interest to astronomers, and has previously been imaged by Hubble and by other space telescopes. The ongoing, extreme starburst causes intense infrared emission, and the merging galaxies may well be in the process of forming a supermassive black hole. A thick band of dust has blocked these valuable insights from the view of telescopes like Hubble. However, Webb’s infrared sensitivity and its impressive resolution at those wavelengths allows it to see past the dust and has resulted in the spectacular image above, a combination of MIRI and NIRCam imagery.
The luminous core of the galaxy merger turns out to be both very bright and highly compact, so much so that Webb’s diffraction spikes appear atop the galaxy in this image. The 8-pronged, snowflake-like diffraction spikes are created by the interaction of starlight with the physical structure of the telescope. The spiky quality of Webb’s observations is particularly noticeable in images containing bright stars, such as Webb’s first deep field image.
MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona.
NIRSpec was built for the European Space Agency (ESA) by a consortium of European companies led by Airbus Defence and Space (ADS) with NASA’s Goddard Space Flight Center providing its detector and micro-shutter subsystems.
Quelle: ESA
----
Update: 28.10.2022
.
New James Webb Space Telescope photos show a massive galaxy cluster bending light
Is it two galaxies, or two star clusters? Astronomers aren't yet sure what the James Webb Space Telescope spotted in an image of the early universe.
The massive gravity of galaxy cluster MACS0647 is gravitationally lensing several other systems in this image. (Image credit: SCIENCE: NASA, ESA, CSA, STScI, and Tiger Hsiao (Johns Hopkins University) IMAGE PROCESSING: Alyssa Pagan (STScI))
In a dance of dark matter, NASA's deep-space observatory caught light being bent in the distant universe.
The massive James Webb Space Telescope mirror used a galaxy cluster's gravityto take a look at a known galaxy far behind, but there's a twist: the new research published Wednesday (Oct. 26) suggests Webb may be viewing two galaxies and not one. (The region has been imaged before by the Hubble Space Telescope, but this new view is sharper than ever.)
"We're actively discussing whether these are two galaxies, or two clumps of stars within a galaxy," Space Telescope Science Institute astronomer Dan Coe, an instrument scientist for Webb's near-infrared camera, said in a NASA statement(opens in new tab). "We don't know, but these are the questions that Webb is designed to help us answer."
Hubble saw the objects, found 10 years ago and called MACS0647-JD, as a "pale, red dot" formed just 400 million years after the Big Bang that kickstarted the universe, according to Coe. While Webb revealed that one object was actually two, the nature of what the new telescope is seeing remains a mystery.
Webb's team is committed to releasing science in progress and as such, this finding is not yet peer-reviewed and is still in early discussion. If Webb spotted two galaxies, there's an even more intriguing possibility: a galactic merger might be in progress in the early universe.
"If this is the most distant merger, I will be really ecstatic," said Tiger Yu-Yang Hsiao, a Ph.D. graduate student at john Hopkins University, in the same statement. But whether Webb is viewing two star clusters or two galaxies, there are clear differences between them: one object set is slightly bluer with lots of stars, and the other is slightly redder with lots of dust.
Webb's use of gravitational lensing is not new to astronomy, but exploiting the ability of massive objects to bend light will bring new insights with the telescope's sensitive instruments. Webb is optimized to look at the early universe, which is receding rapidly from us in infrared wavelengths.
Webb's expected 20 years of space observations will greatly expand our catalog of early galaxies from "only tens" of objects to many more, said Rebecca Larson, a National Science Foundation fellow and Ph.D. graduate student at the University of Texas at Austin.
"Studying them can help us understand how they evolved into the ones like the galaxy we live in today, and also, how the universe evolved throughout time," Larson said in the same statement(opens in new tab). She added she is looking forward to when Webb can create "deep fields" of a single spot in the sky, as Hubble did numerous times, as this will uncover even more objects in the early universe.
Quelle: SC
----
Update: 30.10.2022
.
James Webb telescope's ghostly 'Pillars of Creation'
It would take years to traverse the pillars even moving at the speed of light
Why satisfy yourself with one course when you can have a double helping?
The US space agency Nasa has issued a second image of the famous "Pillars of Creation" taken by the new super space telescope, James Webb.
This week we get a rendering of the active star-forming region as seen by Webb's Mid-Infrared Instrument (MIRI).
Last week, it was the observatory's Near-Infrared Camera (NIRCam) that was highlighting this remarkable location some 6,500 light-years from Earth.
The pillars lie at the heart of what astronomers refer to as Messier 16 (M16), or the Eagle Nebula.
They are the subject of intense study. Every great telescope is pointed in their direction to try to understand the physics and the chemistry in play as new stars are birthed in great clouds of gas and dust.
Webb, with its 6.5m-wide mirror and high-fidelity sensors, is the latest, biggest and best space observatory to take in the scene.
What's interesting about the new MIRI picture is the choice of wavelengths used to display the pillars.
Ordinarily, astronomers might filter the light to make the dusty columns go very largely translucent, so that their interior, nascent stars can be seen in greater detail. This is what the NIRCam image did: it emphasised the thousands of young blue stars that are present.
And MIRI is capable of taking this approach on another step. But on this occasion, the filtering has selected those wavelengths at which the dust itself actually glows.
"Defying expectations that mid-infrared observations let you see through dust, this stunning image shows that they're also great for studying dust and complex molecules made to glow by the intense light of nearby hot stars," explained Prof Mark McCaughrean, the senior advisor for science at the European Space Agency.
Some of the complex chemistry this helps accentuate involves polycyclic aromatic hydrocarbons, PAHs. These are very carbon-rich compounds. You find them on burnt toast and in the exhaust from motor vehicles. PAHs produced by stars are thought to enrich the carbon content throughout the Universe.
MIRI was developed in a collaborative effort between scientists and engineers from 10 European countries, led by the UK, and Nasa's Jet Propulsion Laboratory.
Its co-principal investigator is Prof Gillian Wright.
"It's simply thrilling to see how well MIRI is performing. It's producing radically new science information - stuff we've never had before," the director of the UK Astronomy Technology Centre told BBC News.
"What we see in this new image is akin to the 'skin' of the pillars, if you like. You can see filamentary structures which are where the stars are starting to burn through the dust. And you can see regions that are dark - they're so dense and cold that they're not even lighting up for MIRI."
James Webb is a collaborative project of the US, European and Canadian space agencies. It was launched in December last year and is regarded as the successor to the Hubble Space Telescope.
Quelle: BBC
----
Update: 4.11.2022
.
Should Webb telescope’s data be open to all?
NASA plans to end policy of giving most observers 1 year’s exclusive access to data
The $10 billion James Webb Space Telescope (JWST) has been observing for less than 4 months, but already a storm is brewing over access to its data. Webb images and spectra all end up in an archive at the Space Telescope Science Institute (STScI) in Baltimore, yet most of them aren’t freely available until 1 year after the data were collected. This gives the researchers who proposed the observations time to analyze them and publish results without being scooped.
But some astronomers question the practice, arguing that data from federally funded projects should be free for all to use. NASA, Webb’s primary backer, is facing an open data push from the White House and may soon end the restriction. Having so much Webb data locked away “doesn’t pass the smell test. It’s just not right,” says astronomer Garth Illingworth of the University of California, Santa Cruz, who from 2009 to 2017 chaired a committee advising STScI on Webb’s future science operations.
He and other proponents of an open data policy also make a practical argument. They say so-called proprietary time prevents other astronomers from using fresh data to shape their own observing plans, reducing the efficiency of a highly sought-after instrument that has consumed billions of dollars of public money.
But others say instant access to data may clash with pressing efforts to improve diversity, equity, and inclusion in astronomy. Scientists at smaller institutions, many of which serve underrepresented groups, may need more time for analysis compared with the well-resourced teams at established research universities. Eliminating proprietary time could “put people in a position where they can’t succeed,” says astronomer Mercedes Lopez-Morales of Harvard University, chair of the influential JWST Users Committee, which recently urged NASA to maintain a data embargo period but reduce it to 6 months.
To find a way forward, STScI will begin to poll more than 12,000 astronomers later this month about their attitudes to proprietary time. “There are mixed feelings in the community,” says Neill Reid, STScI’s associate director for science. “There’s definitely a feeling that open access is a good way to go, but without disadvantaging [some observers]. There’s not one size that fits all.”
Astronomers have long been pioneers in putting data into open archives for anyone to use. Typically, data from automated survey telescopes, which systematically scan the sky night after night, are deposited straightaway. But proprietary time remains a tradition at general purpose telescopes, which give astronomers whose observing proposals are chosen exclusive access to their data for as long as 18 months.
After often-heated debate, the Webb advisory committee that Illingworth chaired before the telescope’s launch urged that its proprietary period last just 6 months. Any longer, the committee concluded, and most of the data collected during the first year of observing, known as cycle 1, would be unavailable to astronomers trying to plan what to look for in cycle 2, or even some of cycle 3. For a mission then expected to only last 5 years, that was unsupportable in the view of some committee members.
In recent years, NASA has reduced the proprietary time for the Hubble Space Telescope and the Chandra X-ray Observatory to 6 months. But it did not do the same for Webb, in part because the academic teams that built its four instruments and the European and Canadian space agencies that partnered in the project had 12 months’ proprietary time written into their agreements.
Webb planners did, however, adopt the committee’s suggestion to provide immediate access to a key subset of data: 500 hours of observations made during the first 5 months of cycle 1, covering all Webb’s key science areas and employing all its instruments and observing modes. This Early Release Science (ERS) program amounts to about 5% of cycle 1’s total observing time (see table, above) and its data are put in the archive immediately, providing some material for scientists devising cycle 2 proposals.
Webb’s successful launch has also tempered the data-access debate somewhat because it required fewer course corrections than expected, leaving a fuel reserve that could extend the telescope’s lifetime and allow more time for observing.
But proprietary time still galls many astronomers. On 15 November, STScI will put out the call for cycle 2 proposals, for observations to start in July 2023. Although the ERS data are helping many plan future observations, most cycle 1 data are still locked up and some will remain so until the second half of 2024. NASA is also under pressure from the White House. On 25 August, the White House’s Office of Science and Technology Policy ordered departments and agencies to move toward making the results of all federally funded research freely and immediately available by 2026.
In response, NASA asked the JWST Users Committee, which was meeting that same day, to look again at the telescope’s proprietary time. It, too, recommended moving to 6 months. A year “won’t fly anymore,” Lopez-Morales says. But the committee recognized that its members, 12 senior astronomers, may have a biased view, so they asked STScI to consult with the wider community.
Mark McCaughrean, an astronomer with the European Space Agency, says the 12-month embargo should remain in place because it helps level the field. Astronomers at small universities often shoulder heavy teaching loads and other responsibilities. If their Webb observations were publicly released straight away, they could be scooped by teams at large, well-resourced research institutions before they had a chance to analyze the data over the summer, for example. The situation is trickier still for European astronomers who don’t get automatic funding for postdocs and other expenses linked to winning time on a space telescope as U.S. astronomers do. “We should be aiming to improve diversity by removing structural biases against smaller institutions, early-career researchers, and historically disadvantaged groups: Fixed proprietary periods can help with this,” McCaughrean says.
Illingworth says underrepresented groups could be helped by making proprietary time optional, with space in the proposal form for researchers to request it and explain their need. Marcia Rieke of the University of Arizona, principal investigator of Webb’s near-infrared camera, favors the opposite: giving everyone proprietary time with the expectation that those who don’t need it will give it up, or at least release their data when they publish. Proprietary time “encourages people to do a good job analyzing data,” she says.
“It’s complicated,” Lopez-Morales concedes. On the one hand, she says, reducing proprietary time could be “in conflict with [NASA’s] other efforts” to widen the pool of astronomers. Yet instant access to data means the many groups who are unsuccessful at applying for observing time—in cycle 1, the rejection rate was 75%—can still get a crack at using the data. “We need to see what the community wants,” Lopez-Morales says, “and we will advocate for that.”
Michael New, NASA’s deputy associate director for research, says even if the community comes down in favor of 6 months, that will be a stepping stone to fully removing proprietary time. A NASA policy, now being finalized, will mandate instant access to instrument data in line with White House policy. New says the Webb agreements with other space agencies contain clauses allowing proprietary time to be reduced once the telescope is operating and discussions to do so are already taking place. “It’s not if we do it, but when,” he says. “Will everyone be happy? No, but we will listen to all sides.”
NASA is already working to provide support for researchers who will be disadvantaged, New adds. If some are underresourced, “solve that problem, don’t preserve proprietary time.”
Quelle: AAAS
----
Update: 6.11.2022
.
NASA, Webb Telescope Partners Receive Aviation Week Grand Laureate Award
On Nov. 3, the James Webb Space Telescope team was named a Grand Laureate winner during the Aviation Week Network's 65th Annual Laureate Awards in Washington. NASA led the international Webb partnership with ESA (European Space Agency) and CSA (Canadian Space Agency).
The Aviation Week Network’s Laureate Awards recognize the extraordinary achievements of individuals and teams in aviation, aerospace, and defense. They seek to highlight accomplishments embodying the spirit of exploration, innovation, and vision that inspire others to strive for progress, change, and leadership in aviation and aerospace. This honor recognizes NASA’s James Webb Space Telescope team and Northrop Grumman for building and delivering the largest, most technologically advanced infrared observatory to orbit, and for the telescope’s considerable contribution to the scientific community.
After an early morning liftoff on Dec. 25, 2021, the James Webb Space Telescope team went on to complete the most challenging and complex on-orbit deployment sequence ever attempted. All the telescope’s 18 individual primary mirror segments were then brought into precise alignment, forming the largest, most sensitive mirror system ever launched to space. Webb’s four powerful scientific instruments completed commissioning activities over a six-month period and have begun delivering stunning insights and imagery of the outside universe, as well as planets within and beyond our own solar system.
“We are thrilled that our teamwork has led to such immediate, important, and beautiful scientific results,” said John Mather, Nobel Prize winner and senior project scientist for Webb at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.
Due to precision engineering, and an accurate insertion into orbit by an Ariane 5 rocket – one of the many contributions of the mission’s international partnerships – Webb is expected to have enough fuel to support science operations for over 20 years.
The James Webb Space Telescope is the world’s premier space science observatory. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
Quelle: NASA
----
Update: 10.11.2022
.
James Webb Space Telescope's supercold camera bounces back from glitch
MIRI will soon observe Saturn's polar regions.
The James Webb Space Telescope's supercold camera MIRI is back in full science mode after a technical problem on its grating wheel forced scientists to halt some observations.
The grating wheel on the Medium Resolution Spectrometer (MRS) of James Webb Space Telescope's Mid-Infrared Instrument (MIRI) allows astronomers to choose in which wavelengths of light to observe the surrounding universe. The wheel, which is used in only one of MIRI's four observing modes, started showing signs of friction in August, forcing the mission team to suspend observations in the affected mode.
After weeks of remote scrutinizing, engineers concluded that the problem was caused by "increased contact forces between the wheel central bearing assembly’s sub-components under certain conditions," the Space Telescope Science Institute (STScI) in Baltimore, which is responsible for Webb's operations, said in a statement(opens in new tab).
The engineers have now given a green light for the affected spectroscopy mode to resume operations and are developing a set of recommendations on how to safely use the affected wheel, STScI said in the statement.
"An engineering test demonstrating new operational parameters for the grating wheel mechanism was successfully executed on November 2, 2022," STScI said in the statement. "MIRI is resuming MRS science observations, including taking advantage of a unique opportunity to observe Saturn’s polar regions. The JWST team will schedule additional MRS science observations, initially at a highly orchestrated cadence with additional trending measurements to monitor the new operational regime of the mechanism to prepare MIRI’s MRS mode for a return to full science scheduling."
When operating in the MRS mode, MIRI doesn't take images but light spectra, essentially light absorption fingerprints that reveal chemical compositions of the observed objects.
MIRI's other three observing modes — imaging, coronagraphic imaging and low-resolution spectroscopy — have continued as normal during the MRS outage. The supercold camera has demonstrated its powers with a range of stunning images including a snap of the iconic Pillars of Creation, which revealed the intricate dusty formation in eerie detail.
MIRI, a specialist in detecting mid-infrared wavelengths, requires the coldest temperatures of all Webb's instruments to operate accurately. While the other three instruments — NIRCam, NIRSpec and FGS/NIRISS — rely on the telescope's location and its giant sunshield to maintain temperatures of minus 369.4 degrees Fahrenheit (minus 223 degrees Celsius), MIRI requires additional cryocoolers to get to an even colder temperature of minus 447 degrees F (minus 266 degrees C). That's only 12 degrees F (7 degrees C) above absolute zero, the temperature at which the motion of atoms stops. Since MIRI detects infrared light, which is essentially heat, any additional warmth would decrease the sensitivity of its measurements.
Quelle: SC
+++
James Webb Space Telescope could search for 'laughing gas' to find alien life