Monday, April 7, 2025
NASA Webb Explores Effect of Strong Magnetic Fields on Star Formation - UNIVERSE
Follow-up research on a 2023 image of the Sagittarius C stellar nursery in the heart of our Milky Way galaxy, captured by NASA’s James Webb Space Telescope, has revealed ejections from still-forming protostars and insights into the impact of strong magnetic fields on interstellar gas and the life cycle of stars.
“A big question in the Central
Molecular Zone of our galaxy has been, if there is so much dense gas and cosmic
dust here, and we know that stars form in such clouds, why are so few stars
born here?” said astrophysicist John Bally of the University of Colorado
Boulder, one of the principal investigators. “Now, for the first time, we are
seeing directly that strong magnetic fields may play an important role in
suppressing star formation, even at small scales.”
Detailed study of stars in this
crowded, dusty region has been limited, but Webb’s advanced near-infrared
instruments have allowed astronomers to see through the clouds to study young
stars like never before.
“The extreme environment of the
galactic center is a fascinating place to put star formation theories to the
test, and the infrared capabilities of NASA’s James Webb Space Telescope
provide the opportunity to build on past important observations from ground-based
telescopes like ALMA and MeerKAT,” said Samuel Crowe, another principal investigator on the research, a
senior undergraduate at the University of Virginia and a 2025 Rhodes Scholar.
Bally and Crowe each led a paper published in The Astrophysical
Journal.
Image A: Milky Way Center (MeerKAT
and Webb)
An image of the Milky Way captured by the MeerKAT
(formerly the Karoo Array Telescope) radio telescope array puts the James Webb
Space Telescope’s image of the Sagittarius C region in context. Like a
super-long exposure photograph, MeerKAT shows the bubble-like remnants of
supernovas that exploded over millennia, capturing the dynamic nature of the
Milky Way’s chaotic core. At the center of the MeerKAT image the region
surrounding the Milky Way’s supermassive black hole blazes bright. Huge
vertical filamentary structures echo those captured on a smaller scale by Webb
in Sagittarius C’s blue-green hydrogen cloud.
NASA, ESA, CSA, STScI, SARAO, Samuel Crowe (UVA), John
Bally (CU), Ruben Fedriani (IAA-CSIC), Ian Heywood (Oxford)
Image B: Milky Way Center (MeerKAT
and Webb), Labeled
The star-forming region Sagittarius C, captured by the
James Webb Space Telescope, is about 200 light-years from the Milky Way’s
central supermassive black hole, Sagittarius A*. The spectral index at the
lower left shows how color was assigned to the radio data to create the image.
On the negative end, there is non-thermal emission, stimulated by electrons
spiraling around magnetic field lines. On the positive side, thermal emission
is coming from hot, ionized plasma. For Webb, color is assigned by shifting the
infrared spectrum to visible light colors. The shortest infrared wavelengths
are bluer, and the longer wavelengths appear more red.
NASA, ESA, CSA, STScI, SARAO, Samuel Crowe (UVA), John
Bally (CU), Ruben Fedriani (IAA-CSIC), Ian Heywood (Oxford)
Using Infrared to Reveal Forming
Stars
In Sagittarius C’s brightest
cluster, the researchers confirmed the tentative finding from the Atacama Large
Millimeter Array (ALMA) that two massive stars are forming there. Along with
infrared data from NASA’s retired Spitzer Space Telescope and SOFIA (Stratospheric
Observatory for Infrared Astronomy) mission, as well as the Herschel Space
Observatory, they used Webb to determine that each of the massive protostars is
already more than 20 times the mass of the Sun. Webb also revealed the bright
outflows powered by each protostar.
Even more challenging is finding
low-mass protostars, still shrouded in cocoons of cosmic dust. Researchers
compared Webb’s data with ALMA’s past observations to identify five likely
low-mass protostar candidates.
The team also identified 88
features that appear to be shocked hydrogen gas, where material being blasted
out in jets from young stars impacts the surrounding gas cloud. Analysis of
these features led to the discovery of a new star-forming cloud, distinct from
the main Sagittarius C cloud, hosting at least two protostars powering their
own jets.
“Outflows from forming stars in
Sagittarius C have been hinted at in past observations, but this is the first
time we’ve been able to confirm them in infrared light. It’s very exciting to
see, because there is still a lot we don’t know about star formation,
especially in the Central Molecular Zone, and it’s so important to how the
universe works,” said Crowe.
Magnetic Fields and Star Formation
Webb’s 2023 image of Sagittarius C showed dozens of distinctive filaments in a region
of hot hydrogen plasma surrounding the main star-forming cloud. New analysis by
Bally and his team has led them to hypothesize that the filaments are shaped by
magnetic fields, which have also been observed in the past by the ground-based
observatories ALMA and MeerKAT (formerly the Karoo Array Telescope).
“The motion of gas swirling in the
extreme tidal forces of the Milky Way’s supermassive black hole, Sagittarius
A*, can stretch and amplify the surrounding magnetic fields. Those fields, in
turn, are shaping the plasma in Sagittarius C,” said Bally.
The researchers think that the
magnetic forces in the galactic center may be strong enough to keep the plasma
from spreading, instead confining it into the concentrated filaments seen in
the Webb image. These strong magnetic fields may also resist the gravity that
would typically cause dense clouds of gas and dust to collapse and forge stars,
explaining Sagittarius C’s lower-than-expected star formation rate.
“This is an exciting area for
future research, as the influence of strong magnetic fields, in the center of
our galaxy or other galaxies, on stellar ecology has not been fully
considered,” said Crowe.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing 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).
Source: NASA Webb Explores Effect of Strong Magnetic Fields on Star Formation - NASA Science
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
Saturday, April 5, 2025
Perseverance Rover Witnesses One Martian Dust Devil Eating Another - UNIVERSE
A Martian dust devil can be seen consuming its smaller
friend in this short video made of images taken at the rim of Jezero Crater by
NASA’s Perseverance Mars rover on Jan. 25, 2025.
NASA/JPL-Caltech/SSI
The six-wheeled explorer recently captured several Red Planet mini-twisters
spinning on the rim of Jezero Crater.
A Martian dust devil can be seen
consuming a smaller one in this short video made of images taken by a navigation camera aboard NASA’s Perseverance Mars rover. These swirling, sometimes
towering columns of air and dust are common on Mars. The smaller dust devil’s
demise was captured during an imaging experiment conducted by Perseverance’s
science team to better understand the forces at play in the Martian atmosphere.
When the rover snapped these images
from about 0.6 miles (1 kilometer) away, the larger dust devil was
approximately 210 feet (65 meters) wide, while the smaller, trailing dust devil
was roughly 16 feet (5 meters) wide. Two other dust devils can also be seen in
the background at left and center. Perseverance recorded the scene Jan. 25 as
it explored the western rim of Mars’ Jezero Crater at a location called “Witch
Hazel Hill.”
“Convective vortices — aka dust devils — can be rather fiendish,” said Mark Lemmon, a Perseverance scientist at the Space Science Institute in Boulder, Colorado. “These mini-twisters wander the surface of Mars, picking up dust as they go and lowering the visibility in their immediate area. If two dust devils happen upon each other, they can either obliterate one another or merge, with the stronger one consuming the weaker.”
While exploring the rim of Jezero Crater on Mars,
NASA’s Perseverance rover captured new images of multiple dust devils in
January 2025. These captivating phenomena have been documented for decades by
the agency’s Red Planet robotic explorers. NASA/JPL-Caltech/LANL/CNES/CNRS/INTA-CSIC/Space
Science Institute/ISAE-Supaero/University of Arizona
Science of
Whirlwinds
Dust devils are formed by rising
and rotating columns of warm air. Air near the planet’s surface becomes heated
by contact with the warmer ground and rises through the denser, cooler air
above. As other air moves along the surface to take the place of the rising
warmer air, it begins to rotate. When the incoming air rises into the column,
it picks up speed like a spinning ice skater bringing their arms closer to
their body. The air rushing in also picks up dust, and a dust devil is born.
“Dust devils play a significant role in Martian weather patterns,” said Katie Stack Morgan, project scientist for the Perseverance rover at NASA’s Jet Propulsion Laboratory in Southern California. “Dust devil study is important because these phenomena indicate atmospheric conditions, such as prevailing wind directions and speed, and are responsible for about half the dust in the Martian atmosphere.”
NASA’s Viking 1 orbiter captured this Martian dust
devil casting a shadow on Aug. 1, 1978. During the 15-second interval between
the two images, the dust devil moved toward the northeast (toward the upper
right) at a rate of about 59 feet (18 meters) per second.
NASA/JPL-Caltech/MSSS
Since landing in 2021, Perseverance has imaged whirlwinds on many
occasions, including one on Sept. 27, 2021, where a swarm of dust devils danced across the floor of Jezero Crater and the rover used its SuperCam microphone to record the first sounds of a Martian dust devil.
NASA’s Viking
orbiters, in the
1970s, were the first spacecraft to photograph Martian dust devils. Two decades
later, the agency’s Pathfinder mission was the first to image one from the surface and even detected a dust devil passing
over the lander. Twin rovers Spirit and Opportunity managed to capture their fair share of dusty
whirlwinds. Curiosity, which is exploring a location called Mount Sharp in
Gale Crater on the opposite side of the Red Planet as Perseverance, sees them
as well.
Capturing a dust devil image or
video with a spacecraft takes some luck. Scientists can’t predict when they’ll
appear, so Perseverance routinely monitors in all directions for them. When
scientists see them occur more frequently at a specific time of day or approach
from a certain direction, they use that information to focus their monitoring
to try to catch additional whirlwinds.
“If you feel bad for the little
devil in our latest video, it may give you some solace to know the larger
perpetrator most likely met its own end a few minutes later,” said Lemmon.
“Dust devils on Mars only last about 10 minutes.”
More About
Perseverance
A key objective of Perseverance’s
mission on Mars is astrobiology, including caching samples that may contain signs of
ancient microbial life. The rover is characterizing the planet’s geology and
past climate, to help pave the way for human exploration of the Red Planet and
as the first mission to collect and cache Martian rock and regolith.
NASA’s Mars Sample Return Program,
in cooperation with ESA (European Space Agency), is designed to send spacecraft
to Mars to collect these sealed samples from the surface and return them to
Earth for in-depth analysis.
The Mars 2020 Perseverance mission
is part of NASA’s Mars Exploration Program (MEP) portfolio and the agency’s
Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for
human exploration of the Red Planet.
NASA’s Jet Propulsion Laboratory,
which is managed for the agency by Caltech, built and manages operations of the
Perseverance rover.
For more about Perseverance:
https://science.nasa.gov/mission/mars-2020-perseverance
Source: Perseverance Rover Witnesses One Martian Dust Devil Eating Another - NASA
.jpg)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
.gif)
Subscribe to:
Posts (Atom)