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We present two sets of grid-based hydrodynamical simulations of high-velocity clouds (HVCs) traveling through the diffuse, hot Galactic halo. These HI clouds have been suggested to provide fuel for ongoing star formation in the Galactic…

Astrophysics of Galaxies · Physics 2011-02-11 Fabian Heitsch , Mary E. Putman

Ultracompact and hypercompact HII regions appear when a star with a mass larger than about 15 solar masses starts to ionize its own environment. Recent observations of time variability in these objects are one of the pieces of evidence that…

Astrophysics of Galaxies · Physics 2015-05-28 Roberto Galván-Madrid , Thomas Peters , Eric Keto , Mordecai-Mark Mac Low , Robi Banerjee , Ralf S. Klessen

We present the results of a comparative study of HI narrow self-absorption (HINSA), OH, 13CO, and C18O in five dark clouds. The HINSA follows the distribution of the emission of the carbon monoxide isotopologues, and has a characteristic…

Astrophysics · Physics 2009-11-10 P. F. Goldsmith , D. Li

Formation of interstellar clouds as a consequence of thermal instability is studied using two-dimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the…

Astrophysics of Galaxies · Physics 2015-05-14 Tsuyoshi Inoue , Shu-ichiro Inutsuka

Condensation in cumulus clouds plays a key role in structuring the mean, non-precipitating trade-wind boundary layer. Here, we summarise how this role also explains the spontaneous growth of mesoscale ($>O(10)$ km) fluctuations in clouds…

It remains a major challenge to derive a theory of cloud-scale ($\lesssim100$ pc) star formation and feedback, describing how galaxies convert gas into stars as a function of the galactic environment. Progress has been hampered by a lack of…

Observations of clusters and groups imply that such halos are roughly in global thermal equilibrium, with heating balancing cooling when averaged over sufficiently long time- and length-scales; the ICM is, however, very likely to be locally…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Prateek Sharma , Michael McCourt , Eliot Quataert , Ian J. Parrish

The interstellar cloud surrounding the solar system regulates the galactic environment of the Sun, and determines the boundary conditions of the heliosphere. Both the Sun and interstellar clouds move through space, so these boundary…

Astrophysics · Physics 2009-10-30 Priscilla C. Frisch

Recent observations suggest galaxies may ubiquitously host a molecular component to their multiphase circumgalactic medium (CGM). However, the structure and kinematics of the molecular CGM remains understudied theoretically and largely…

Astrophysics of Galaxies · Physics 2023-08-16 Ryan Jeffrey Farber , Max Gronke

We present hydrodynamic simulations of high-velocity clouds (HVCs) traveling through the hot, tenuous medium in the Galactic halo. A suite of models was created using the FLASH hydrodynamics code, sampling various cloud sizes, densities,…

Astrophysics of Galaxies · Physics 2015-05-28 Kyujin Kwak , David B. Henley , Robin L. Shelton

We discuss the role of turbulence in cloud and star formation, as observed in numerical simulations of the interstellar medium. Turbulent compression at the interfaces of colliding gas streams is responsible for the formation of…

Astrophysics · Physics 2007-05-23 E. Vazquez-Semadeni , T. Passot , A. Pouquet

Because the opacity of clouds in substellar mass object (SMO) atmospheres depends on the composition and distribution of particle sizes within the cloud, a credible cloud model is essential for accurately modeling SMO spectra and colors. We…

Star clusters interact with the interstellar medium (ISM) in various ways, most importantly in the destruction of molecular star-forming clouds, resulting in inefficient star formation on galactic scales. On cloud scales, ionizing radiation…

Astrophysics of Galaxies · Physics 2017-07-25 Daniel Rahner , Eric W. Pellegrini , Simon C. O. Glover , Ralf S. Klessen

New 21cm observations with the Green Bank Telescope show that a significant fraction of the HI in the inner Galaxy's halo 1 kpc from the midplane exists in the form of discrete clouds. Some look very much like a Spitzer ``standard'' diffuse…

Astrophysics · Physics 2007-05-23 Felix J. Lockman

We review recent results from numerical simulations and related models of MHD turbulence in the interstellar medium (ISM) and in molecular clouds. We discuss the implications of turbulence for the processes of cloud formation and evolution,…

Astrophysics · Physics 2007-05-23 E. Vazquez-Semadeni , E. C. Ostriker , T. Passot , C. F. Gammie , J. M. Stone

Dealing numerically with the turbulent nature and non-linearity of the physical processes involved in the ISM requires the use of sophisticated numerical schemes coupled to HD and MHD mathematical models. SNe are the main drivers of the…

Astrophysics · Physics 2007-05-23 Miguel A. de Avillez , Dieter Breitschwerdt

We suggest that molecular clouds can be formed on short time scales by compressions from large scale streams in the interstellar medium (ISM). In particular, we argue that the Taurus-Auriga complex, with filaments of 10-20 pc $\times$ 2-5…

Astrophysics · Physics 2010-04-06 Javier Ballesteros-Paredes , Lee Hartmann , Enrique Vazquez-Semadeni

Ambipolar diffusion likely plays a pivotal role in the formation and evolution of dense cores in weakly-ionized molecular clouds. Linear analyses show that the evolutionary times and fragmentation scales are significantly greater than the…

Astrophysics of Galaxies · Physics 2021-05-17 Indrani Das , Shantanu Basu , Philippe Andre

We use new high-resolution HI data from the Australian Square Kilometre Array Pathfinder (ASKAP) to investigate the dynamics of the Small Magellanic Cloud (SMC). We model the HI gas component as a rotating disc of non-negligible angular…

We investigate the dissolution process of young embedded star clusters with different primordial mass segregation levels using fractal distributions by means of N-body simulations. We combine several star clusters in virial and subvirial…

Astrophysics of Galaxies · Physics 2021-09-29 R. Domínguez , J. P. Farias , M. Fellhauer , Ralf S. Klessen