A huge bubble of ‘Swiss cheese’ surrounding Earth has been painted in incredible new images
Our planet is surrounded by a huge “giant bubble” 1,000 light-years across. Now, astronomers have made the first 3D map of its magnetic field.
The giant structure, known as the Local Bubble, is a hollow bubble of hot, diffuse plasma surrounded by a shell of cold gas and dust from which surface stars are forming. It is just one of the many cavities found in Milky Way Making our galaxy look like an enormous slice of Swiss cheese.
Great bubbles are shock waves generated by the death agonies of many massive stars, which in their final acts explode in colossal supernovae that spew out the gas and dust needed to give birth to new stars. Over time, other stars, like our own, wander inside the cavities left by these explosions.
Related: Earth lies at the center of a 1,000 light-year-wide bubble of “Swiss cheese” carved by supernovae
Although there are some ideas about the formation of superbubbles, astronomers still aren’t sure how these giant bubbles evolve through interaction with our galaxy. magnetic fieldHow does this affect the formation of stars and galaxies? To find out more, a team of astronomers, working on a summer research program at the Harvard-Smithsonian Center for Astrophysics, mapped the magnetic field of the Local Bubble.
“Space is full of these super-bubbles that lead to the formation of new stars and planets and affect the general shapes of galaxies,” Theo O’Neillwho at the time was an undergraduate student in astronomy, physics, and statistics from the University of Virginia, he said in a statement. “By learning more about the exact mechanisms that drive the Local Bubble, which the Sun lives in today, we can learn more about the evolution and dynamics of superbubbles in general.”
The Milky Way, like many other galaxies, is filled with a magnetic field that gently guides stars, dust and gas into mind-boggling structures like Giant bone-like filaments. Astronomers aren’t sure what gives rise to the galaxy’s magnetic fields. The magnetic field of the Milky Way, although much weaker than EarthIt permeates throughout our galaxy and deep in its outer halo, subtly influencing the shaping of everything around it. However, because the strength of the magnetic field is weak compared to the force of gravity, and only acts on charged particles, astronomers long ago omitted magnetism from their calculations. This makes sense in the short term, but over wide cosmological timescales, it could mean that their models ignore intrinsic effects.
“From a fundamental physics point of view, we have long known that magnetic fields must play important roles in many astrophysical phenomena,” Alyssa GoodmanThe Harvard astronomer who was one of the mentors for the research program, said in the release. “But studying these magnetic fields has been very challenging. Computer simulations and surveys of the sky today may be good enough to begin to integrate magnetic fields into our broader picture of how the universe works, from the motions of tiny dust grains onward to the dynamics of galaxy clusters.”
To map the magnetic field, astronomers used previous information from the European Space Agency’s (ESA) Gaia space telescope, which inferred approximate boundaries of the Local Bubble from concentrations of distant cosmic dust. With this in mind, the researchers turned to data from another ESA space telescope, Planck, which showed faint microwave emissions of polarized light from the dust. Because the polarization, or direction of vibration, of light is a major giveaway to the magnetic field acting on the dust, astronomers have used it to stitch data points together into a vast three-dimensional texture of the superbubble’s surface.
To make their map, the researchers note, they made some big assumptions that they’ll need to test — in particular that polarized dust is located on the surface of the bubble — but, once fine-tuned, they believe it could become an invaluable tool for studying star formation across the galactic backyard.
“With this map, we can really begin to investigate the effects of magnetic fields on star formation in superbubbles,” Goodman said. “And in this regard, get a better understanding of how these fields influence many other cosmic phenomena.”