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Groundbreaking 3D Map of Cosmic Superbubble’s Magnetic Field Unveiled

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Astronomers have charted the magnetic field of the Local Bubble using data obtained by Planck and Gaia. Here, the short pink and purple vector lines on the surface of the bubble represent the orientation of the magnetic field discovered. The bubble sits within the Milky Way galaxy. Credit: Theo O’Neill / World Wide Telescope

 

Cosmic Superbubble’s Magnetic Field Charted in 3D for the First Time

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 has been unveiled by astronomers at the Center for Astrophysics | Harvard & Smithsonian (<span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

CfA
The Harvard-Smithsonian Center for Astrophysics (CfA) is a joint venture between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. Founded in 1973, the Harvard-Smithsonian Center for Astrophysics is comprised of six research divisions: Atomic and Molecular Physics; Optical and Infrared Astronomy; High Energy Astrophysics; Radio and Geoastronomy; Stellar, Solar, and Planetary Sciences; and Theoretical Astrophysics.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>CfA).

The map reveals the likely magnetic field structure of the Local Bubble — a giant, 1,000-<span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

light-year
A light year is the distance that a particle of light (photon) will travel in a year—about 10 trillion kilometers (6 trillion miles). It is a useful unit for measuring distances between stars.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>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.

 

Scientists’ overall understanding of superbubbles, however, remains incomplete. With the new 3D magnetic field map, researchers now have novel information that could better explain the evolution of superbubbles, their effects on star formation and on galaxies writ large.


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

“Putting together this 3D map of the Local Bubble will help us examine superbubbles in new ways,” says Theo O’Neill, who led the mapmaking effort during a 10-week, NSF-sponsored summer research experience at the CfA while still an undergraduate at the University of Virginia (UVA).

 

“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.”

Along with colleagues, O’Neill presented the findings at the American Astronomical Society’s 241st annual meeting on Wednesday, Jan. 11, in Seattle, Washington. 3D interactive figures and a pre-print of the research are currently available on Authorea. The research was conducted at CfA under the mentorship of Harvard professor and CfA astronomer Alyssa Goodman, in collaboration with Catherine Zucker, a Harvard PhD astronomy alumna, Jesse Han, a Harvard PhD student and Juan Soler, a magnetic field expert in Rome.

“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 PhD 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 <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

Big Bang
The Big Bang is the leading cosmological model explaining how the universe as we know it began approximately 13.8 billion years ago.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>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 <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

Milky Way
The Milky Way is the galaxy that contains our Solar System, and is named for its appearance from Earth. It is a barred spiral galaxy that contains an estimated 100-400 billion stars and has a diameter between 150,000 and 200,000 light-years.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>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 <span class=”glossaryLink” aria-describedby=”tt” data-cmtooltip=”

accuracy
How close the measured value conforms to the correct value.

” data-gt-translate-attributes=”[“attribute”:”data-cmtooltip”, “format”:”html”]”>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 minuscule 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.”

Support for this work was provided by the National Science Foundation, NASA, and the Gordon and Betty Moore Foundation.

About the 3D Milky Way Project

 

This research is part of an ongoing collaboration amongst several open-source software projects working together to create a 3D map of the Milky Way galaxy. The software packages, including glue, OpenSpace, and AAS WorldWide Telescope, are interconnected via API-like interfaces, and they access a wide variety of open data sets, including those from Planck and Gaia. Learn more about the 3D Milky Way project, which includes a collaboration with staff at the Hayden Planetarium at the American Museum of Natural History, where some results will be showcased, at MilkyWay3D.org. The 3D interactive figures in the Authorea preprint sharing this work are made possible via additional free software, including plot.ly and PyVista.

About the Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask—and ultimately answer—humanity’s greatest unresolved questions about the nature of the universe. The Center for Astrophysics is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world.

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Las Vegas Aces Rookie Kate Martin Suffers Ankle Injury in Game Against Chicago Sky

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Las Vegas Aces rookie Kate Martin had to be helped off the floor and taken to the locker room after suffering an apparent ankle injury in the first quarter of Tuesday night’s game against the Chicago Sky.

Late in the first quarter, Martin was pushing the ball up the court when she appeared to twist her ankle and lost her balance. The rookie was in serious pain, lying on the floor before eventually being helped off. Her entire team came out in support, and although she managed to put some pressure on the leg, she was taken to the locker room for further evaluation.

Martin returned to the team’s bench late in the second quarter but was ruled out for the remainder of the game.

“Kate Martin is awesome. Kate Martin picks up things so quickly, she’s an amazing sponge,” Aces guard Kelsey Plum said of the rookie during the preseason. “I think (coach) Becky (Hammon) nicknamed her Kate ‘Money’ Martin. I think that’s gonna stick. And when I say ‘money,’ it’s not just about scoring and stuff, she’s just in the right place at the right time. She just makes people better. And that’s what Becky values, that’s what our coaching staff values and that’s why she’s gonna be a great asset to our team.”

Las Vegas selected Martin in the second round of the 2024 WNBA Draft. She was coming off the best season of her collegiate career at Iowa, where she averaged 13.1 points, 6.8 rebounds, and 2.3 assists per game during the 2023-24 campaign. Martin’s integration into the Aces organization has been seamless, with her quickly earning the respect and admiration of her teammates and coaches.

The team and fans alike are hoping for a speedy recovery for Martin, whose contributions have been vital to the Aces’ performance this season.

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Asteroid Apophis will visit Earth in 2029, and this European satellite will be along for the ride

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The European Space Agency is fast-tracking a new mission called Ramses, which will fly to near-Earth asteroid 99942 Apophis and join the space rock in 2029 when it comes very close to our planet — closer even than the region where geosynchronous satellites sit.

Ramses is short for Rapid Apophis Mission for Space Safety and, as its name suggests, is the next phase in humanity’s efforts to learn more about near-Earth asteroids (NEOs) and how we might deflect them should one ever be discovered on a collision course with planet Earth.

In order to launch in time to rendezvous with Apophis in February 2029, scientists at the European Space Agency have been given permission to start planning Ramses even before the multinational space agency officially adopts the mission. The sanctioning and appropriation of funding for the Ramses mission will hopefully take place at ESA’s Ministerial Council meeting (involving representatives from each of ESA’s member states) in November of 2025. To arrive at Apophis in February 2029, launch would have to take place in April 2028, the agency says.

This is a big deal because large asteroids don’t come this close to Earth very often. It is thus scientifically precious that, on April 13, 2029, Apophis will pass within 19,794 miles (31,860 kilometers) of Earth. For comparison, geosynchronous orbit is 22,236 miles (35,786 km) above Earth’s surface. Such close fly-bys by asteroids hundreds of meters across (Apophis is about 1,230 feet, or 375 meters, across) only occur on average once every 5,000 to 10,000 years. Miss this one, and we’ve got a long time to wait for the next.

When Apophis was discovered in 2004, it was for a short time the most dangerous asteroid known, being classified as having the potential to impact with Earth possibly in 2029, 2036, or 2068. Should an asteroid of its size strike Earth, it could gouge out a crater several kilometers across and devastate a country with shock waves, flash heating and earth tremors. If it crashed down in the ocean, it could send a towering tsunami to devastate coastlines in multiple countries.

Over time, as our knowledge of Apophis’ orbit became more refined, however, the risk of impact  greatly went down. Radar observations of the asteroid in March of 2021 reduced the uncertainty in Apophis’ orbit from hundreds of kilometers to just a few kilometers, finally removing any lingering worries about an impact — at least for the next 100 years. (Beyond 100 years, asteroid orbits can become too unpredictable to plot with any accuracy, but there’s currently no suggestion that an impact will occur after 100 years.) So, Earth is expected to be perfectly safe in 2029 when Apophis comes through. Still, scientists want to see how Apophis responds by coming so close to Earth and entering our planet’s gravitational field.

“There is still so much we have yet to learn about asteroids but, until now, we have had to travel deep into the solar system to study them and perform experiments ourselves to interact with their surface,” said Patrick Michel, who is the Director of Research at CNRS at Observatoire de la Côte d’Azur in Nice, France, in a statement. “Nature is bringing one to us and conducting the experiment itself. All we need to do is watch as Apophis is stretched and squeezed by strong tidal forces that may trigger landslides and other disturbances and reveal new material from beneath the surface.”

The Goldstone radar’s imagery of asteroid 99942 Apophis as it made its closest approach to Earth, in March 2021. (Image credit: NASA/JPL–Caltech/NSF/AUI/GBO)

By arriving at Apophis before the asteroid’s close encounter with Earth, and sticking with it throughout the flyby and beyond, Ramses will be in prime position to conduct before-and-after surveys to see how Apophis reacts to Earth. By looking for disturbances Earth’s gravitational tidal forces trigger on the asteroid’s surface, Ramses will be able to learn about Apophis’ internal structure, density, porosity and composition, all of which are characteristics that we would need to first understand before considering how best to deflect a similar asteroid were one ever found to be on a collision course with our world.

Besides assisting in protecting Earth, learning about Apophis will give scientists further insights into how similar asteroids formed in the early solar system, and, in the process, how  planets (including Earth) formed out of the same material.

One way we already know Earth will affect Apophis is by changing its orbit. Currently, Apophis is categorized as an Aten-type asteroid, which is what we call the class of near-Earth objects that have a shorter orbit around the sun than Earth does. Apophis currently gets as far as 0.92 astronomical units (137.6 million km, or 85.5 million miles) from the sun. However, our planet will give Apophis a gravitational nudge that will enlarge its orbit to 1.1 astronomical units (164.6 million km, or 102 million miles), such that its orbital period becomes longer than Earth’s.

It will then be classed as an Apollo-type asteroid.

Ramses won’t be alone in tracking Apophis. NASA has repurposed their OSIRIS-REx mission, which returned a sample from another near-Earth asteroid, 101955 Bennu, in 2023. However, the spacecraft, renamed OSIRIS-APEX (Apophis Explorer), won’t arrive at the asteroid until April 23, 2029, ten days after the close encounter with Earth. OSIRIS-APEX will initially perform a flyby of Apophis at a distance of about 2,500 miles (4,000 km) from the object, then return in June that year to settle into orbit around Apophis for an 18-month mission.

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Furthermore, the European Space Agency still plans on launching its Hera spacecraft in October 2024 to follow-up on the DART mission to the double asteroid Didymos and Dimorphos. DART impacted the latter in a test of kinetic impactor capabilities for potentially changing a hazardous asteroid’s orbit around our planet. Hera will survey the binary asteroid system and observe the crater made by DART’s sacrifice to gain a better understanding of Dimorphos’ structure and composition post-impact, so that we can place the results in context.

The more near-Earth asteroids like Dimorphos and Apophis that we study, the greater that context becomes. Perhaps, one day, the understanding that we have gained from these missions will indeed save our planet.

 

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McMaster Astronomy grad student takes a star turn in Killarney Provincial Park

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Astronomy PhD candidate Veronika Dornan served as the astronomer in residence at Killarney Provincial Park. She’ll be back again in October when the nights are longer (and bug free). Dornan has delivered dozens of talks and shows at the W.J. McCallion Planetarium and in the community. (Photos by Veronika Dornan)

Veronika Dornan followed up the April 8 total solar eclipse with another awe-inspiring celestial moment.

This time, the astronomy PhD candidate wasn’t cheering alongside thousands of people at McMaster — she was alone with a telescope in the heart of Killarney Provincial Park just before midnight.

Dornan had the park’s telescope pointed at one of the hundreds of globular star clusters that make up the Milky Way. She was seeing light from thousands of stars that had travelled more than 10,000 years to reach the Earth.

This time there was no cheering: All she could say was a quiet “wow”.

Dornan drove five hours north to spend a week at Killarney Park as the astronomer in residence. part of an outreach program run by the park in collaboration with the Allan I. Carswell Observatory at York University.

Dornan applied because the program combines her two favourite things — astronomy and the great outdoors. While she’s a lifelong camper, hiker and canoeist, it was her first trip to Killarney.

Bruce Waters, who’s taught astronomy to the public since 1981 and co-founded Stars over Killarney, warned Dornan that once she went to the park, she wouldn’t want to go anywhere else.

The park lived up to the hype. Everywhere she looked was like a painting, something “a certain Group of Seven had already thought many times over.”

The dome telescopes at Killarney Provincial Park.

She spent her days hiking the Granite Ridge, Crack and Chikanishing trails and kayaking on George Lake.  At night, she went stargazing with campers — or at least tried to. The weather didn’t cooperate most evenings — instead of looking through the park’s two domed telescopes, Dornan improvised and gave talks in the amphitheatre beneath cloudy skies.

Dornan has delivered dozens of talks over the years in McMaster’s W.J. McCallion Planetarium and out in the community, but “it’s a bit more complicated when you’re talking about the stars while at the same time fighting for your life against swarms of bugs.”

When the campers called it a night and the clouds parted, Dornan spent hours observing the stars. “I seriously messed up my sleep schedule.”

She also gave astrophotography a try during her residency, capturing images of the Ring Nebula and the Great Hercules Cluster.

A star cluster image by Veronika Dornan

“People assume astronomers take their own photos. I needed quite a lot of guidance for how to take the images. It took a while to fiddle with the image properties, but I got my images.”

Dornan’s been invited back for another week-long residency in bug-free October, when longer nights offer more opportunities to explore and photograph the final frontier.

She’s aiming to defend her PhD thesis early next summer, then build a career that continues to combine research and outreach.

“Research leads to new discoveries which gives you exciting things to talk about. And if you’re not connecting with the public then what’s the point of doing research?”

 

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