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, Howard A. Smith, Giles Novak, Sarah Sadavoy, Thushara Pillai, Zhi-Yun Li, Leslie W. Looney, Koji Sugitani, Simon Coudé, Andres Guzman, Alyssa GoodmanTakayoshi Kusune, Fabio P. Santos, Leah Zuckerman, Frankie Encalada

Research output: Contribution to journalArticlepeer-review


Star formation primarily occurs in laments where magnetic fields are expected to be dynamically
important. The largest and densest laments trace spiral structure within galaxies. Over a dozen of
these dense (∼10 4 cm-3) and long (>10 pc) laments have been found within the Milky Way, and they are often referred to as 'bones." Until now, none of these bones have had their magnetic field resolved and mapped in their entirety. We introduce the SOFIA legacy project FIELDMAPS which has begun mapping ∼10 of these Milky Way bones using the HAWC+ instrument at 214 μm and 18:002 resolution. Here we present a first result from this survey on the ∼60 pc long bone G47. Contrary to some studies of dense laments in the Galactic plane, we find that the magnetic field is often not perpendicular to the spine (i.e., the center-line of the bone). Fields tend to be perpendicular in the densest areas of active star formation and more parallel or random in other areas. The average field is neither parallel or perpendicular to the Galactic plane nor the bone. The magnetic field strengths along the spine typically vary from ∼20 to ∼100 μG. Magnetic fields tend to be strong enough to suppress collapse along much of the bone, but for areas that are most active in star formation, the fields are notably less able to resist gravitational collapse.
Original languageEnglish
JournalThe Astrophysical Journal Letters
Publication statusAccepted/In press - 20 Jan 2022


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