New 3D Map of Local Bubble Reveals Its Magnetic Field Structure That Will Help Examine Superbubbles in Novel Ways

For the first time, interstellar cartographers have mapped the magnetic field swept up by the Local Bubble in 3D. The Local Bubble or Local Cavity in the interstellar gas of the Orion Arm in the Milky Way galaxy is at least 1,000 light-years large in interstellar space, hence the term "superbubble."

It was born from a series of supernovae between 10 and 20 million years ago and is one of many such bubbles in the interstellar medium that riddle the Milky Way galaxy and others like Swiss cheese cavities.

Gathering the Data for the First 3D Map of the Local Bubble

The Center for Astrophysics | Harvard & Smithsonian (CfA) presented a first-of-its-kind map that might help address decades-old concerns about the formation of stars and the effects of magnetic fields in the universe, depicting the magnetic field structure of the Local Bubble.

The supernova deaths of huge stars blow up these bubbles, concentrating gas and dust that fuel the formation of new stars on the bubbles' outer surfaces. As a result, these thick surfaces provide fertile ground for later star and planet formation.

However, the general knowledge of superbubbles remains limited. According to a press release, the 3D map of the Local Bubble gives researchers fresh knowledge that might help them better comprehend the evolution of superbubbles, their influence on star formation, and their consequences on galaxies in general.

The Sun and Solar System presently residing in the Local Bubble has become a prominent issue in astrophysics. The Local Bubble's 3D shape was first worked out by academics in Greece and France in 2020. Then, in 2021, a team of international scientists demonstrated that the surface of the Local Bubble is the origin of all nearby, young stars.

Those investigations, as well as the new 3D magnetic field map, have relied on data from the European Space Agency's (ESA) space-based observatory Gaia. It was used to determine the location of cosmic dust while analyzing the positions and movements of stars, documenting their local concentrations, and displaying the approximate borders of the Local Bubble.

The team merged this data with data from Planck, another ESA-led satellite observatory, which conducted an all-sky survey from 2009 to 2013. The satellite collected microwave wavelength light measurements from all around the sky and its data were used as a subset of Planck measurements that detect emission from dust within the Milky Way to help map the magnetic field of the Local Bubble.

How the 3D Map of Local Bubble Was Created

The team initially created a 2D representation of the magnetic field as observed from Earth, Interesting Engineering reports. Then they established two assumptions in order to transform the map into three spatial dimensions.

Researchers noted that most of the interstellar dust that creates the polarization is observed on the surface of the Local Bubble. They added that previous models that predict its magnetic field will be "swept up" into the surface of the bubble as it expands are accurate.

They believed that most of the dust and magnetic activity will be concentrated on the surface and so they performed the complex geometrical analysis needed to generate the 3D magnetic map of the Local Bubble. The team made some big assumptions in creating the first 3D map of a magnetic field and it is by no means perfect but such as the first maps of Earth.

Nonetheless, the 3D view of the Local Bubble represents the magnetic field structure of the nearby superbubble if it was indeed swept up. Scientists can use this map to probe the influences of the magnetic field in the formation of stars and planets in the superbubbles.