It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
IMAGE: A FLAT LINE IN A TRANSMISSION SPECTRUM, LIKE THIS ONE, CAN BE EXCITING – IT CAN TELL US A LOT ABOUT THE PLANET. RESEARCHERS USED NASA’S JAMES WEBB SPACE TELESCOPE’S NEAR-INFRARED SPECTROGRAPH (NIRSPEC) TO OBSERVE EXOPLANET LHS 475 B ON AUGUST 31, 2022. AS THIS SPECTRUM SHOWS, WEBB DID NOT OBSERVE A DETECTABLE QUANTITY OF ANY ELEMENT OR MOLECULE. THE DATA (WHITE DOTS) ARE CONSISTENT WITH A FEATURELESS SPECTRUM REPRESENTATIVE OF A PLANET THAT HAS NO ATMOSPHERE (YELLOW LINE). THE PURPLE LINE REPRESENTS A PURE CARBON DIOXIDE ATMOSPHERE AND IS INDISTINGUISHABLE FROM A FLAT LINE AT THE CURRENT LEVEL OF PRECISION. THE GREEN LINE REPRESENTS A PURE METHANE ATMOSPHERE, WHICH IS NOT FAVORED SINCE IF METHANE WERE PRESENT, IT WOULD BE EXPECTED TO BLOCK MORE STARLIGHT AT 3.3 MICRONS.view more
CREDIT: CREDITS: ILLUSTRATION: NASA, ESA, CSA, L. HUSTAK (STSCI); SCIENCE: K. STEVENSON, J. LUSTIG-YAEGER, E. MAY (JOHNS HOPKINS UNIVERSITY APPLIED PHYSICS LABORATORY), G. FU (JOHNS HOPKINS UNIVERSITY), AND S. MORAN (UNIVERSITY OF ARIZONA)
Researchers confirmed an exoplanet, a planet that orbits another star, using NASA’s James Webb Space Telescope for the first time. Formally classified as LHS 475 b, the planet is almost exactly the same size as our own, clocking in at 99% of Earth’s diameter. The research team is led by Kevin Stevenson and Jacob Lustig-Yaeger, both of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
The team chose to observe this target with Webb after carefully reviewing targets of interest from NASA’s Transiting Exoplanet Survey Satellite (TESS), which hinted at the planet’s existence. Webb’s Near-Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with only two transit observations. “There is no question that the planet is there. Webb’s pristine data validate it,” said Lustig-Yaeger. “The fact that it is also a small, rocky planet is impressive for the observatory,” Stevenson added.
“These first observational results from an Earth-size, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb,” agreed Mark Clampin, Astrophysics Division director at NASA Headquarters in Washington. “Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside our solar system, and the mission is only just getting started.”
Among all operating telescopes, only Webb is capable of characterizing the atmospheres of Earth-sized exoplanets. The team attempted to assess what is in the planet’s atmosphere by analyzing its transmission spectrum. Although the data shows that this is an Earth-sized terrestrial planet, they do not yet know if it has an atmosphere. “The observatory’s data are beautiful,” said Erin May, also of the Johns Hopkins University Applied Physics Laboratory. “The telescope is so sensitive that it can easily detect a range of molecules, but we can’t yet make any definitive conclusions about the planet’s atmosphere.”
Although the team can’t conclude what is present, they can definitely say what is not present. “There are some terrestrial-type atmospheres that we can rule out,” explained Lustig-Yaeger. “It can’t have a thick methane-dominated atmosphere, similar to that of Saturn’s moon Titan.”
The team also notes that while it’s possible the planet has no atmosphere, there are some atmospheric compositions that have not been ruled out, such as a pure carbon dioxide atmosphere. “Counterintuitively, a 100% carbon dioxide atmosphere is so much more compact that it becomes very challenging to detect,” said Lustig-Yaeger. Even more precise measurements are required for the team to distinguish a pure carbon dioxide atmosphere from no atmosphere at all. The researchers are scheduled to obtain additional spectra with upcoming observations this summer.
CAPTION
How do researchers spot a distant planet? By observing the changes in light as it orbits its star. A light curve from NASA’s James Webb Space Telescope’s Near-Infrared Spectrograph (NIRSpec) shows the change in brightness from the LHS 475 star system over time as the planet transited the star on August 31, 2022. LHS 475 b is a rocky, Earth-sized exoplanet that orbits a red dwarf star roughly 41 light-years away, in the constellation Octans. The planet is extremely close to its star, completing one orbit in two Earth-days. The planet’s confirmation was made possible by Webb’s data.
CREDIT
Credits: Illustration: NASA, ESA, CSA, L. Hustak (STScI); Science: K. Stevenson, J. Lustig-Yaeger, E. May (Johns Hopkins University Applied Physics Laboratory), G. Fu (Johns Hopkins University), and S. Moran (University of Arizona)
Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if clouds are detected, it may lead the researchers to conclude that the planet is more like Venus, which has a carbon dioxide atmosphere and is perpetually shrouded in thick clouds. “We’re at the forefront of studying small, rocky exoplanets,” Lustig-Yaeger said. “We have barely begun scratching the surface of what their atmospheres might be like.”
The researchers also confirmed that the planet completes an orbit in just two days, information that was almost instantaneously revealed by Webb’s precise light curve. Although LHS 475 b is closer to its star than any planet in our solar system, its red dwarf star is less than half the temperature of the Sun, so the researchers project it still could have an atmosphere.
The researchers’ findings have opened the possibilities of pinpointing Earth-sized planets orbiting smaller red dwarf stars. “This rocky planet confirmation highlights the precision of the mission’s instruments,” Stevenson said. “And it is only the first of many discoveries that it will make.” Lustig-Yaeger agreed. “With this telescope, rocky exoplanets are the new frontier.”
LHS 475 b is relatively close, at only 41 light-years away, in the constellation Octans.
The team’s results were presented at a press conference of the American Astronomical Society (AAS) on Wednesday, Jan. 11, 2023.
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).
New Webb image reveals dusty disk like never seen before
IMAGE: THESE TWO IMAGES ARE OF THE DUSTY DEBRIS DISK AROUND AU MIC, A RED DWARF STAR LOCATED 32 LIGHT-YEARS AWAY IN THE SOUTHERN CONSTELLATION MICROSCOPIUM. SCIENTISTS USED WEBB’S NEAR-INFRARED CAMERA (NIRCAM) TO STUDY AU MIC. NIRCAM’S CORONAGRAPH, WHICH BLOCKED THE INTENSE LIGHT OF THE CENTRAL STAR, ALLOWED THE TEAM TO STUDY THE REGION VERY CLOSE TO THE STAR. THE LOCATION OF THE STAR, WHICH IS MASKED OUT, IS MARKED BY A WHITE, GRAPHICAL REPRESENTATION AT THE CENTER OF EACH IMAGE. THE REGION BLOCKED BY THE CORONAGRAPH IS SHOWN BY A DASHED CIRCLE.view more
CREDIT: CREDITS: NASA, ESA, CSA, AND K. LAWSON (GODDARD SPACE FLIGHT CENTER). IMAGE PROCESSING: A. PAGAN (STSCI)
NASA’s James Webb Space Telescope has imaged the inner workings of a dusty disk surrounding a nearby red dwarf star. These observations represent the first time the previously known disk has been imaged at these infrared wavelengths of light. They also provide clues to the composition of the disk.
The star system in question, AU Microscopii or AU Mic, is located 32 light-years away in the southern constellation Microscopium. It’s approximately 23 million years old, meaning that planet formation has ended since that process typically takes less than 10 million years. The star has two known planets, discovered by other telescopes. The dusty debris disk that remains is the result of collisions between leftover planetesimals – a more massive equivalent of the dust in our solar system that creates a phenomenon known as zodiacal light.
“A debris disk is continuously replenished by collisions of planetesimals. By studying it, we get a unique window into the recent dynamical history of this system,” said Kellen Lawson of NASA’s Goddard Space Flight Center, lead author on the study and a member of the research team that studied AU Mic.
“This system is one of the very few examples of a young star, with known exoplanets, and a debris disk that is near enough and bright enough to study holistically using Webb’s uniquely powerful instruments,” said Josh Schlieder of NASA’s Goddard Space Flight Center, principal investigator for the observing program and a study co-author.
The team used Webb’s Near-Infrared Camera (NIRCam) to study AU Mic. With the help of NIRCam's coronagraph, which blocks the intense light of the central star, they were able to study the region very close to the star. The NIRCam images allowed the researchers to trace the disk as close to the star as 5 astronomical units (460 million miles) – the equivalent of Jupiter’s orbit in our solar system.
“Our first look at the data far exceeded expectations. It was more detailed than we expected. It was brighter than we expected. We detected the disk closer in than we expected. We're hoping that as we dig deeper, there's going to be some more surprises that we hadn't predicted,” stated Schlieder.
The observing program obtained images at wavelengths of 3.56 and 4.44 microns. The team found that the disk was brighter at the shorter wavelength, or “bluer,” likely meaning that it contains a lot of fine dust that is more efficient at scattering shorter wavelengths of light. This finding is consistent with the results of prior studies, which found that the radiation pressure from AU Mic — unlike that of more massive stars — would not be strong enough to eject fine dust from the disk.
While detecting the disk is significant, the team’s ultimate goal is to search for giant planets in wide orbits, similar to Jupiter, Saturn, or the ice giants of our solar system. Such worlds are very difficult to detect around distant stars using either the transit or radial velocity methods.
“This is the first time that we really have sensitivity to directly observe planets with wide orbits that are significantly lower in mass than Jupiter and Saturn. This really is new, uncharted territory in terms of direct imaging around low-mass stars,” explained Lawson.
These results are being presented today in a press conference at the 241st meeting of the American Astronomical Society. The observations were obtained as part of Webb’s Guaranteed Time program 1184.
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).
NASA's Webb uncovers star formation in cluster’s dusty ribbons
IMAGE: NGC 346, SHOWN HERE IN THIS IMAGE FROM NASA’S JAMES WEBB SPACE TELESCOPE NEAR-INFRARED CAMERA (NIRCAM), IS A DYNAMIC STAR CLUSTER THAT LIES WITHIN A NEBULA 200,000 LIGHT YEARS AWAY. WEBB REVEALS THE PRESENCE OF MANY MORE BUILDING BLOCKS THAN PREVIOUSLY EXPECTED, NOT ONLY FOR STARS, BUT ALSO PLANETS, IN THE FORM OF CLOUDS PACKED WITH DUST AND HYDROGEN. THE PLUMES AND ARCS OF GAS IN THIS IMAGE CONTAINS TWO TYPES OF HYDROGEN. THE PINK GAS REPRESENTS ENERGIZED HYDROGEN, WHICH IS TYPICALLY AS HOT AS AROUND 10,000 °C (APPROXIMATELY 18,000 °F) OR MORE, WHILE THE MORE ORANGE GAS REPRESENTS DENSE, MOLECULAR HYDROGEN, WHICH IS MUCH COLDER AT AROUND -200 °C OR LESS (APPROXIMATELY -300 °F), AND ASSOCIATED DUST. THE COLDER GAS PROVIDES AN EXCELLENT ENVIRONMENT FOR STARS TO FORM, AND, AS THEY DO, THEY CHANGE THE ENVIRONMENT AROUND THEM. THE EFFECT OF THIS IS SEEN IN THE VARIOUS RIDGES THROUGHOUT, WHICH ARE CREATED AS THE LIGHT OF THESE YOUNG STARS BREAKS DOWN THE DENSE CLOUDS. THE MANY PILLARS OF GLOWING GAS SHOW THE EFFECTS OF THIS STELLAR EROSION THROUGHOUT THE REGION. IN THIS IMAGE BLUE WAS ASSIGNED TO THE WAVELENGTH OF 2.0 MICRONS (F200W), GREEN WAS ASSIGNED TO 2.77 MICRONS (F277W), ORANGE WAS ASSIGNED TO 3.35 MICRONS (F335M), AND RED WAS ASSIGNED TO 4.44 MICRONS (F444W).view more
CREDIT: CREDITS: NASA, ESA, CSA, O. JONES (UK ATC), G. DE MARCHI (ESTEC), AND M. MEIXNER (USRA). IMAGE PROCESSING: A. PAGAN (STSCI), N. HABEL (USRA), L. LENKIC (USRA) AND L. CHU (NASA/AMES)
NGC 346, one of the most dynamic star-forming regions in nearby galaxies, is full of mystery. Now, it is less mysterious with new findings from NASA’s James Webb Space Telescope.
NCG 346 is located in the Small Magellanic Cloud (SMC), a dwarf galaxy close to our Milky Way. The SMC contains lower concentrations of elements heavier than hydrogen or helium, which astronomers call metals, compared to the Milky Way. Since dust grains in space are composed mostly of metals, scientists expected there would be low amounts of dust, and that it would be hard to detect. New data from Webb reveals the opposite.
Astronomers probed this region because the conditions and amount of metals within the SMC resemble those seen in galaxies billions of years ago, during an era in the universe known as “cosmic noon,” when star formation was at its peak. Some 2 to 3 billion years after the big bang, galaxies were forming stars at a furious rate. The fireworks of star formation happening then still shape the galaxies we see around us today.
“A galaxy during cosmic noon wouldn’t have one NGC 346 like the Small Magellanic Cloud does; it would have thousands” of star-forming regions like this one, said Margaret Meixner, an astronomer at the Universities Space Research Association and principal investigator of the research team. “But even if NGC 346 is now the one and only massive cluster furiously forming stars in its galaxy, it offers us a great opportunity to probe conditions that were in place at cosmic noon.”
By observing protostars still in the process of forming, researchers can learn if the star formation process in the SMC is different from what we observe in our own Milky Way. Previous infrared studies of NGC 346 have focused on protostars heavier than about 5 to 8 times the mass of our Sun. “With Webb, we can probe down to lighter-weight protostars, as small as one tenth of our Sun, to see if their formation process is affected by the lower metal content,” said Olivia Jones of the United Kingdom Astronomy Technology Centre, Royal Observatory Edinburgh, a co-investigator on the program.
As stars form, they gather gas and dust, which can look like ribbons in Webb imagery, from the surrounding molecular cloud. The material collects into an accretion disk that feeds the central protostar. Astronomers have detected gas around protostars within NGC 346, but Webb’s near-infrared observations mark the first time they have also detected dust in these disks.
“We’re seeing the building blocks, not only of stars, but also potentially of planets,” said Guido De Marchi of the European Space Agency, a co-investigator on the research team. “And since the Small Magellanic Cloud has a similar environment to galaxies during cosmic noon, it’s possible that rocky planets could have formed earlier in the universe than we might have thought.”
The team also has spectroscopic observations from Webb’s NIRSpec instrument that they are continuing to analyze. These data are expected to provide new insights into the material accreting onto individual protostars, as well as the environment immediately surrounding the protostar.
These results are being presented Jan. 11 in a press conference at the 241st meeting of the American Astronomical Society. The observations were obtained as part of program 1227.
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 the Canadian Space Agency.
For more information about the Webb mission, visit:
IMAGE: A TRIO OF FAINT OBJECTS (CIRCLED) CAPTURED IN THE JAMES WEBB SPACE TELESCOPE’S DEEP IMAGE OF THE GALAXY CLUSTER SMACS 0723 EXHIBIT PROPERTIES REMARKABLY SIMILAR TO RARE, SMALL GALAXIES CALLED “GREEN PEAS” FOUND MUCH CLOSER TO HOME. THE CLUSTER’S MASS MAKES IT A GRAVITATIONAL LENS, WHICH BOTH MAGNIFIES AND DISTORTS THE APPEARANCE OF BACKGROUND GALAXIES. WE VIEW THESE EARLY PEAS AS THEY EXISTED WHEN THE UNIVERSE WAS ABOUT 5% ITS CURRENT AGE OF 13.8 BILLION YEARS. THE FARTHEST PEA, AT LEFT, CONTAINS JUST 2% THE OXYGEN ABUNDANCE OF A GALAXY LIKE OUR OWN AND MIGHT BE THE MOST CHEMICALLY PRIMITIVE GALAXY YET IDENTIFIED.view more
CREDIT: CREDIT: NASA, ESA, CSA, AND STSCI
A new analysis of distant galaxies imaged by NASA’s James Webb Space Telescope shows that they are extremely young and share some remarkable similarities to “green peas,” a rare class of small galaxies in our cosmic backyard.
“With detailed chemical fingerprints of these early galaxies, we see that they include what might be the most primitive galaxy identified so far. At the same time, we can connect these galaxies from the dawn of the universe to similar ones nearby, which we can study in much greater detail,” said James Rhoads, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who presented the findings at the 241st meeting of the American Astronomical Society in Seattle.
A paper describing the results, led by Rhoads, was published Jan. 3 in The Astrophysical Journal Letters.
Green pea galaxies were discovered and named in 2009 by volunteers taking part in Galaxy Zoo, a project where citizen scientists help classify galaxies in images, starting with those from the Sloan Digital Sky Survey. Peas stood out as small, round, unresolved dots with a distinctly green shade, a consequence of both the colors assigned to different filters in the survey’s composite images and a property of the galaxies themselves.
Green pea galaxy colors are unusual because a sizable fraction of their light comes from brightly glowing gas clouds. The gases emit light at specific wavelengths – unlike stars, which produce a rainbow-like spectrum of continuous color. Peas are also quite compact, typically only about 5,000 light-years across or about 5% the size of our Milky Way galaxy.
“Peas may be small, but their star-formation activity is unusually intense for their size, so they produce bright ultraviolet light,” said Keunho Kim, a postdoctoral researcher at the University of Cincinnati and a member of the analysis team. “Thanks to ultraviolet images of green peas from Hubble and ground-based research on early star-forming galaxies, it’s clear that they both share this property.”
In July 2022, NASA and its partners in the Webb mission released the deepest and sharpest infrared image of the distant universe yet seen, capturing thousands of galaxies in and behind a cluster known as SMACS 0723. The cluster’s mass makes it a gravitational lens, which both magnifies and distorts the appearance of background galaxies. Among the faintest galaxies behind the cluster were a trio of compact infrared objects that looked like they could be distant relatives of green peas. The most distant of these three galaxies was magnified by about 10 times, providing a significant assist from nature on top of the telescope’s unprecedented capabilities.
Webb did more than image the cluster – its Near-Infrared Spectrograph (NIRSpec) instrument also captured the spectra of selected galaxies in the scene. When Rhoads and his colleagues examined these measurements and corrected them for the wavelength stretch resulting from the expansion of space, they saw characteristic features emitted by oxygen, hydrogen, and neon line up in a stunning resemblance to those seen from nearby green peas.
Additionally, the Webb spectra made it possible to measure the amount of oxygen in these cosmic dawn galaxies for the first time.
As stars produce energy, they transmute lighter elements like hydrogen and helium into heavier ones. When stars explode or lose their outer layers at the ends of their lives, these heavier elements become incorporated into the gas that forms the next stellar generations, and the process continues. Over cosmic history, stars have steadily enriched the universe.
Two of the Webb galaxies contain oxygen at about 20% of the level in our Milky Way. They resemble typical green peas, which nevertheless make up less than 0.1% of the nearby galaxies observed by the Sloan survey. The third galaxy studied is even more unusual.
“We’re seeing these objects as they existed up to 13.1 billion years ago, when the universe was about 5% its current age,” said Goddard researcher Sangeeta Malhotra. “And we see that they are young galaxies in every sense – full of young stars and glowing gas that contains few chemical products recycled from earlier stars. Indeed, one of them contains just 2% the oxygen of a galaxy like our own and might be the most chemically primitive galaxy yet identified.”
NIRSpec was built for ESA (European Space Agency) by Airbus Industries. Its array of nearly half a million microshutters – tiny doors that can be opened or closed to admit or block light – allow it to capture spectra of up to 100 individual objects at a time. The microshutter array and detector subsystems were fabricated by NASA.
The James Webb Space Telescope, an international mission led by NASA with its partners ESA and CSA (Canadian Space Agency), is the world's premier space science observatory. NASA Headquarters oversees the mission for the agency’s Science Mission Directorate. NASA’s Goddard Space Flight Center manages Webb for the agency and oversees work on the mission performed by the Space Telescope Science Institute, Northrop Grumman, and other mission partners. In addition to Goddard, several NASA centers contributed to the project, including the agency’s Johnson Space Center in Houston, Jet Propulsion Laboratory in Southern California, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in California’s Silicon Valley, and others.
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