2017/07/31 by Asger Grønnow, Thor Tepper-García, Joss Bland-Hawthorn +2 · 3 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Cloud computing #Field (mathematics) #Galactic halo #Halo #Magnetic field #Measure (data warehouse) #Molecular cloud #Rotation (mathematics) #Solar and Space Plasma Dynamics #Transverse plane #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aa7ed2
published as ApJ.845.69(2017) · 18 pages, 14 figures. Published in ApJ
openalex publication_date 2017/08/10 · openalex created_date 2017/08/17 · arxiv created 2017/08/23 · arxiv updated 2017/08/24 · openalex updated_date 2026/08/05
Abstract High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy’s halo. One component of this gas, H i high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain controversial in terms of their origins, largely due to the lack of reliable distance estimates. The recent discovery of enhanced magnetic fields toward HVCs has encouraged us to explore their connection to cloud evolution, kinematics, and survival as they fall through the magnetized Galactic halo. For a reasonable model of the halo magnetic field, most infalling clouds see transverse rather than radial field lines. We find that significant compression (and thereby amplification) of the ambient magnetic field occurs in front of the cloud and in the tail of material stripped from the cloud. The compressed transverse field attenuates hydrodynamical instabilities. This delays cloud destruction, though not indefinitely. The observed field compression is related to the cloud’s distance from the Galactic plane. As a result, the observed rotation measure provides useful distance information on a cloud’s location.