Astronomers released new images this week of the Milky Way that offer an unprecedented look at an enormous slice of the galaxy, complete with star clusters, clouds of cosmic dust and the supermassive black hole Sagittarius A*.
The images published on Wednesday, a product of the National Science Foundation's dark energy camera — which captured two years' worth of data via a telescope at the agency's observatory in Chile — are the second of their kind to come from the NSF's Dark Energy Survey. The project is essentially designed to observe and track the expansion of the universe. The survey revealed slightly more than 3.3 billion celestial objects across the Milky Way's galactic plane, marking the largest catalog so far produced by a single camera.
"This is quite a technical feat. Imagine a group photo of over three billion people and every single individual is recognizable!" said Debra Fischer, the division director of astronomical sciences at NSF, in a statement to the Harvard and Smithsonian Center for Astrophysics. "Astronomers will be poring over this detailed portrait of more than three billion stars in the Milky Way for decades to come. This is a fantastic example of what partnerships across federal agencies can achieve."
NSF's dark energy camera, an instrument attached to the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Vicuña, surveys the plane of the Milky Way at optical and near-infrared wavelengths from the vantage point of the southern sky. It produced more than 10 terabytes of data from 21,400 individual exposures during the latest outer-space survey, according to the federal agency.
The instrument's first collection of data was released in 2017. When taken together, data collected during the first and second rounds of the dark energy survey now account for 6.5% of the night sky, spanning 130 degrees in length, the NSF said. This is a gargantuan feat, since most objects in the Milky Way exist within the galaxy's disk — seen in images as the bright band stretching horizontally across the center — and some of its properties prevent astronomers from being able to see objects clearly. The "sheer number of stars" also poses challenges to observation efforts, according to the NSF, since they can overlap in images.
Merging data collected during a 2014 cosmic survey called PS1, which was operated by the Pan-STARRS 1 Science Consortium, with images compiled using the dark energy camera can provide an even broader view of the galaxy, explained Edward Schlafly, a researcher at the AURA-managed Space Telescope Science Institute, in a statement to the NSF.
"When combined with images from Pan-STARRS 1, DECaPS2 [the dark energy camera] completes a 360-degree panoramic view of the Milky Way's disk and additionally reaches much fainter stars," said Schlafly, who also co-authored a paper describing DECaPS2 published in the Astrophysical Journal Supplement. "With this new survey, we can map the three-dimensional structure of the Milky Way's stars and dust in unprecedented detail."
Scientists, astronomers and members of the general public can explore the Dark Energy Survey's full dataset, including three-dimensional portraits of the galaxy, using an interactive online interface found here.
NASA has reportedly shed light on a new plan to build a successor to the James Webb Space Telescope,
The Habitable Worlds Observatory was announced Monday at the latest American Astronomical Society meeting, and its goal is to search for signs of life on habitable exoplanets.
Space.com said on Friday that the observatory will need a powerful coronograph, which is an instrument that allows scientists to study faint objects.
Mark Clampin, the director of NASA's astrophysics division, reportedly said that the agency would approach the project as if it faced a strict launch window, building on previous technology used for the Nancy Grace Roman Space Telescope as well as Webb.
The Habitable World Observatory would be sent to a point – known as L2, or the second Lagrange Point – a million miles away from the Earth and opposite the sun.
"We're also going to plan this mission from day one to be serviceable," Clampin said, noting that in 10 to 15 years companies could do "straightforward robotic servicing" there.
"It gives us flexibility, because it means we don't necessarily have to hit all of the science goals the first time," he told attendees. Being able to service the observatory can extend the life of its mission.
The agency will reportedly turn to the commercial sector for the launch vehicle.
Notably, with this observatory, NASA is following through on the U.S. National Academies’ latest decadal survey, which called for NASA to revive the "Great Observatories" program.
According to Science, the report said that a six-meter telescope sensitive to ultraviolet, optical and near-infrared wavelengths could mark the start of that effort.
Scientists have unveiled the first-of-its-kind map of a magnetic field in space. Specifically, the team has charted the magnetic field of our Local Bubble in 3D. The new strategy for tracing magnetized structures in 3D will help address key questions about the influence of magnetic fields in the cosmos. Credit: T. O'Neill, A. Goodman, J. Soler, J. Han and C. Zucker.
Astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA) have unveiled a first-of-its-kind map that could help answer decades-old questions about the origins of stars and the influences of magnetic fields in the cosmos.
The map reveals the likely magnetic field structure of the Local Bubble—a giant, 1,000-light-year-wide hollow in space surrounding our Sun. Like a hunk of Swiss cheese, our galaxy is full of these so-called superbubbles. The explosive supernova deaths of massive stars blow up these bubbles, and in the process, concentrate gas and dust—the fuel for making new stars—on the bubbles' outer surfaces. These thick surfaces accordingly serve as rich sites for subsequent star and planet formation.
"Space is full of these superbubbles that trigger the formation of new stars and planets and influence the overall shapes of galaxies," continues O'Neill, who graduated from UVA in December 2022 with a degree in astronomy-physics and statistics. "By learning more about the exact mechanics that drive the Local Bubble, in which the Sun lives today, we can learn more about the evolution and dynamics of superbubbles in general."
"From a basic physics standpoint, we've long known that magnetic fields must play important roles in many astrophysical phenomena," says Goodman, who wrote her Ph.D. thesis on the importance of cosmic magnetic fields thirty years ago. "But studying these magnetic fields has been notoriously difficult. The difficulty perpetually drives me away from magnetic field work, but then new observational tools, computational methods and enthusiastic colleagues tempt me back in. Today's computer simulations and all-sky surveys may just finally be good enough to start really incorporating magnetic fields into our broader picture of how the universe works, from the motions of tiny dust grains on up to the dynamics of galaxy clusters."
The Local Bubble has emerged as a hot topic in astrophysics by virtue of being the superbubble in which the Sun and our Solar System now find themselves. In 2020, the Local Bubble's 3D geometry was initially worked out by researchers based in Greece and France. Then in 2021, Zucker, now of Space Telescope Science Institute, Goodman, João Alves of the University of Vienna, and their team showed that the Local Bubble's surface is the source of all nearby, young stars.
Those studies, along with the new 3D magnetic field map, have relied on data in part from Gaia, a space-based observatory launched by the European Space Agency (ESA). While measuring the positions and motions of stars, Gaia was used to infer the location of cosmic dust as well, charting its local concentrations and showing the approximate boundaries of the Local Bubble.
These data were combined by O'Neill and colleagues with data from Planck, another ESA-led space telescope. Planck, which carried out an all-sky survey from 2009 to 2013, was primarily designed to observe the Big Bang's relic light. In the process, the spacecraft compiled measurements of microwave wavelength light from all over the sky. The researchers used a portion of Planck observations that trace emission from dust within the Milky Way relevant to helping map the Local Bubble's magnetic field.
Specifically, the observations of interest consisted of polarized light, meaning light that vibrates in a preferred direction. This polarization is produced by magnetically aligned dust particles in space. The alignment of the dust in turn speaks to the orientation of the magnetic field acting upon the dust particles.
Mapping the magnetic field lines in this way enabled researchers working on the Planck data to compile a 2D map of the magnetic field projected on to the sky as seen from Earth. In order to morph or "de-project" this map into three spatial dimensions, the researchers made two key assumptions: First, that most of the interstellar dust producing the polarization observed lies in the Local Bubble's surface, and second, that theories predicting that the magnetic field would be "swept up" into the bubble's surface as it expands are correct.
O'Neill subsequently carried out the complicated geometrical analysis needed to create the 3D magnetic field map during the summer CfA internship.
Goodman likens the research team to pioneering mapmakers who created some of the first maps of Earth.
"We've made some big assumptions to create this first 3D map of a magnetic field; it's by no means a perfect picture," she says. "As technology and our physical understanding improve, we will be able to improve the accuracy of our map and hopefully confirm what we are seeing."
The 3D view of magnetic whorls that emerged represent the magnetic field structure of our neighborhood superbubble, if the field was indeed swept-up into the bubble's surface, and if most of the polarization is produced there.
The research team further compared the resulting map to features along the Local Bubble's surface. Examples included the Per-Tau Shell, a giant spherical region of star formation, and the Orion molecular cloud complex, another prominent stellar nursery. Future studies will examine the associations between magnetic fields and these and other surface features.
"With this map, we can really start to probe the influences of magnetic fields on star formation in superbubbles," says Goodman. "And for that matter, get a better grasp on how these fields influence numerous other cosmic phenomena."
Because magnetic fields only affect the movement and orientation of charged particles in astrophysical environments, Goodman says there has been a tendency to set aside the fields' influence when building simulations and theories where gravity—which acts on all matter—is the primary force at play. Further discouraging its inclusion, magnetism can be a fiendishly complex force to model.
This omission of magnetic fields' influence, while understandable, often leaves out a key factor controlling motions of gas in the universe. These motions include gas flowing onto stars as they form, and flowing away from stars in powerful jets emanating from them as they gather matter into a planet-forming disk. Even if the effect of magnetic fields is miniscule from moment-to-moment in the low-density environments where stars form, given the millions-of-year timescales it takes to gather gas and turn it into stars, magnetic effects can plausibly add up to something substantial over time.
Goodman, O'Neill, and their colleagues look forward to finding out.
"I've had a great experience doing this research at CfA and assembling something new and exciting with this 3D magnetic map," says O'Neill. "I hope this map is a starting point for expanding our understanding of the superbubbles throughout our galaxy."
By peering into a well-known star cluster within the Small Magellanic Cloud, Webb’s NIRCam instrument has revealed many new pockets of star formation that have never been seen. Further, new structures appear in this image that provide a window into the stars feeding within.
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.
Galaxies shockingly similar to our own found near the beginning of the universe
The power of JWST to map galaxies at high resolution and at longer infrared wavelengths than Hubble allows it look through dust and unveil the underlying structure and mass of distant galaxies. This can be seen in these two images of the galaxy EGS23205, seen as it was about 11 billion years ago. In the HST image (left, taken in the near-infrared filter), the galaxy is little more than a disk-shaped smudge obscured by dust and impacted by the glare of young stars, but in the corresponding JWST mid-infrared image (taken this past summer), it’s a beautiful spiral galaxy with a clear stellar bar. Credit: NASA/CEERS/University of Texas at Austin
AUSTIN, Texas — New images from NASA’s James Webb Space Telescope (JWST) reveal for the first time galaxies with stellar bars — elongated features of stars stretching from the centers of galaxies into their outer disks — at a time when the universe was a mere 25% of its present age. The finding of so-called barred galaxies, similar to our Milky Way, this early in the universe will require scientists to refine their theories of galaxy evolution.
Prior to JWST, images from the Hubble Space Telescope had never detected bars at such young epochs. In a Hubble image, one galaxy, EGS-23205, is little more than a disk-shaped smudge, but in the corresponding JWST image taken this past summer, it’s a beautiful spiral galaxy with a clear stellar bar.
“I took one look at these data, and I said, ‘We are dropping everything else!’” said Shardha Jogee, professor of astronomy at The University of Texas at Austin. “The bars hardly visible in Hubble data just popped out in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” she said, describing data from the Cosmic Evolution Early Release Science Survey (CEERS), led by UT Austin professor, Steven Finkelstein.
The team identified another barred galaxy, EGS-24268, also from about 11 billion years ago, which makes two barred galaxies existing farther back in time than any previously discovered.
In an article accepted for publication in The Astrophysical Journal Letters, they highlight these two galaxies and show examples of four other barred galaxies from more than 8 billion years ago.
“For this study, we are looking at a new regime where no one had used this kind of data or done this kind of quantitative analysis before,” said Yuchen “Kay” Guo, a graduate student who led the analysis, “so everything is new. It’s like going into a forest that nobody has ever gone into.”
Bars play an important role in galaxy evolution by funneling gas into the central regions, boosting star formation.
“Bars solve the supply chain problem in galaxies,” Jogee said. “Just like we need to bring raw material from the harbor to inland factories that make new products, a bar powerfully transports gas into the central region where the gas is rapidly converted into new stars at a rate typically 10 to 100 times faster than in the rest of the galaxy.”
Bars also help to grow supermassive black holes in the centers of galaxies by channeling the gas part of the way.
The discovery of bars during such early epochs shakes up galaxy evolution scenarios in several ways.
“This discovery of early bars means galaxy evolution models now have a new pathway via bars to accelerate the production of new stars at early epochs,” Jogee said.
And the very existence of these early bars challenges theoretical models as they need to get the galaxy physics right in order to predict the correct abundance of bars. The team will be testing different models in their next papers.
JWST can unveil structures in distant galaxies better than Hubble for two reasons: First, its larger mirror gives it more light-gathering ability, allowing it to see farther and with higher resolution. Second, it can see through dust better as it observes at longer infrared wavelengths than Hubble.
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