The Long Tails of the Pegasus-Pisces Arch Intermediate Velocity Cloud
arXiv:2203.00720 · doi:10.3847/1538-4357/ac39a4
Abstract
We present hydrodynamic simulations of the Pegasus-Pisces (PP Arch), an intermediate velocity cloud in our Galaxy. The PP Arch, also known as IVC 86-36, is unique among intermediate and high velocity clouds, because its twin tails are unusually long and narrow. Its -50 km/s line-of-sight velocity qualifies it as an intermediate velocity cloud, but the tails' orientations indicate that the cloud's total three-dimensional speed is at least ~100 km/s. This speed is supersonic in the Reynold's Layer and thick disk. We simulated the cloud as it travels supersonically through the Galactic thick and thin disks at an oblique angle relative to the midplane. Our simulated clouds grow long double tails and reasonably reproduce the H I 21~cm intensity and velocity of the head of the PP Arch. A bow shock protects each simulated cloud from excessive shear and lowers its Reynolds number. These factors may similarly protect the PP Arch and enable the survival of its unusually long tails. The simulations predict the future hydrodynamic behavior of the cloud when it collides with denser gas nearer to the Galactic midplane. It appears that the PP Arch's fate is to deform, dissipate, and merge with the Galactic disk.
17 pages in this format although it is only 15 in the ApJ; 6 multi-panel figures; recently published in the Astrophysical Journal
References in corpus (13)
- The Origin of the Magellanic Stream and Its Leading Arm
- Do cloud-cloud collisions trigger high-mass star formation? I. Small cloud collisions
- The COS/UVES Absorption Survey of the Magellanic Stream. III: Ionization, Total Mass, and Inflow Rate onto the Milky Way
- The Generation and Dissipation of Interstellar Turbulence - Results from Large Scale High Resolution Simulations
- Triggered O star formation in M20 via cloud-cloud collision: Comparisons between high-resolution CO observations and simulations
- A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey
- Optically thick HI dominant in the local interstellar medium; an alternative interpretation to "dark gas"
- All-sky census of Galactic high-latitude molecular intermediate-velocity clouds
- The Magellanic Stream and Debris Clouds
- Mixing between High Velocity Clouds and the Galactic Halo
- Physical effects on compact high-velocity clouds in the circumgalactic medium
- The Smith Cloud: surviving a high speed transit of the Galactic disc
- The collisions of high-velocity clouds with the galactic halo