SOFIA is the Stratospheric Observatory for Infrared Astronomy, a joint project of NASA and the German Space Agency at DLR. Now, thanks to the SOFIA observations, astronomers have cleared up the mystery about whether or not the magnetic fields in the “skeleton” (or bone) of the galaxy are aligned . The new observations suggest that this is generally not the case: the magnetic fields do not follow the spiral shape of the galaxy’s arms, nor are they generally perpendicular to the ‘bone’.
Star formation in our galaxy occurs primarily in long, dense filaments of gas and dust along its spiral arms. Astronomers call these structures “bones” because they outline the densest skeletal spiral structures in the galaxy.
These bones are typically at least fifty times as long as they are wide and exhibit consistent internal movement along their length. The problem, until now, is that many details about its magnetic field properties were unknown.
“Before SOFIA, it was difficult to obtain high-resolution magnetic field images of the entire bone. We can now get so many independent measurements of the direction of the magnetic field through these bones, allowing us to really delve into the importance of the magnetic field in these massive filamentary clouds,” explains Ian Stephens, an astrophysicist at Worcester State University and co-author. of the work published in The Astrophysical Journal Letters .
Mapping the magnetic field of galactic bones
The Filaments Extremely Long and Dark: a MAgnetic Polarization Survey (FIELDMAPS) project is the first to attempt to map the magnetic field of any galactic bone in its entirety. Of the ten bones the group plans to initially map, the first has been G47, a giant filamentary bone within the Milky Way that is 200 light-years long and 5 light-years wide.
“Magnetic fields can potentially set the rate at which stars form in a cloud of gas. They can also guide the flow of gas, shape the bones, and affect the number and size of denser pockets of gas that will eventually collapse to form stars.” “By mapping the orientation of the fields, we can estimate the relative importance of the magnetic field with respect to gravity to quantify how much magnetic fields affect the star formation process.”
By doing just that, they were able to determine that magnetic fields are strong enough to prevent gas in many areas from succumbing to gravitational collapse to form stars.
In the case of the Milky Way’s bone G47, these magnetic fields are complex and frequently change direction ; this means that parallel fields from the less dense regions are feeding material to the denser regions, where magnetic fields play a key role in the rate of star formation by preventing the birth of new stars.
SOFIA is a joint project of NASA and the German Space Agency at the German Aerospace Center.
Referencia: The Magnetic Field in the Milky Way Filamentary Bone G47. Ian W. Stephens, Philip C. Myers, Catherine Zucker, James M. Jackson, B.-G. Andersson, Rowan Smith, Archana Soam, Cara Battersby, Patricio Sanhueza, Taylor Hogge
Published 2022 February 15 • © 2022. The Author(s). Published by the American Astronomical Society. The Astrophysical Journal Letters, Volume 926, Number 1 Citation Ian W. Stephens et al 2022 ApJL 926 L6
