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.
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.”
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.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
