Photo: Theo O’Neill and the Milkyway3d.org team
You may not realize it in your daily life, but we are all surrounded by a giant “superbubble” that exploded in space due to the explosive death of dozens of alien stars. Known as the Local Bubble, this structure extends for about 1,000 light-years around the solar system, and is one of countless similar bubbles in our galaxy that result from supernova fallout.
Cosmic superbubbles have remained somewhat of a mystery for decades, but recent astronomical developments are finally revealing key details about their evolution and structure. Just over the past few years, researchers have Geometry set of the local bubble in three dimensions f Show that its surface It is an active star birth site, as it picks up gas and dust as it expands through space.
Now, a team of scientists has added another layer to our evolving picture of the Local Bubble by mapping the structure’s magnetic field, which is thought to play a key role in star formation.
Astronomers led by Theo O’Neill, who conducted the new research during a summer research program at the Center for Astrophysics at Harvard and Smithsonian (CfA), Presented “The first-ever 3D map of a magnetic field above a superbubble” on Wednesday at the 241st Annual Meeting of the American Astronomical Society in Seattle, Washington. The team was also unveiled detailed visualizations of their new map, which leads to a clearer focus on the “Local Bubble”.
“We think the entire interstellar medium is really filled with all these bubbles that are driven by various forms of feedback from, especially, really massive stars, producing energy in one form or another in interstellar space,” said O’Neill, who just got his undergraduate degree in astronomy. and physics and statistics from the University of Virginia, on a joint call with his mentor Alyssa Goodman, a CfA astronomer who co-authored the new research.
Goodman added that magnetic fields outside the solar system are difficult to quantify in models, because they cannot be drawn as easily in 3D as those inside our solar system. As a result, she said, the new map should be seen as a preliminary sketch that will be refined by future observations and research methods.
“What Theo did was make a really good guess at a 3-D map of the magnetic field on the surface of a local bubble,” Goodman said. “That’s why it’s so exciting — because it’s the first time there’s been an extrasolar system estimate of what the field looks like in 3D.”
O’Neill and his colleagues combined the unprecedented map with the help of observations from two ESA space missions: Gaia, which is currently building the most detailed map of the Milky Way, and Planck, which has captured the world’s oldest light. Universe before retiring in 2013.
Both missions captured detailed observations of the distribution of dust across our galaxy, a dataset the team has used to explore the structure and elusive mechanics of the Local Bubble. Because dust particles drift in magnetic fields, the researchers looked for specific patterns in the light hitting the dust that might reveal the dimensions and direction of the bubble’s underlying magnetic forces.
In order to graft the 2D magnetic field observations into a 3D model, the researchers assumed that most of the observed dust, in addition to the magnetic activity, is located in the expanding surface of the bubble. While these assumptions are in line with the theories, Goodman noted that future observations will likely add more complexity to the team’s base map.
“It’s a first try, and it’s probably mostly correct,” Goodman said.
To that point, the team hopes their new map will provide a foundation on which other scientists can build to better understand the fantastic bubbles scattered across the Milky Way. In fact, the Sun only entered the Local Bubble a few million years ago, and will exit in a few more million years, floating in the galaxy where it will pass through countless other bubbles.
“Now that we have this map, there’s a lot of cool science all of us can do, but hopefully other people will do it too,” O’Neill said. “Because the stars are clustered together, it’s not like the Sun is very special, and it’s in the Local Bubble because we’re just lucky. We know that the interstellar medium is full of bubbles like this, and in fact there are a lot of them near our Local Bubble.”
“A great next step would be to look at where the local bubble is near other reaction bubbles,” they concluded. “What happens when these bubbles interact, and how does this lead to the initiation of formation in general, and the overall long-term evolution of galactic structures?”