We simulated the behavior of interstellar gas clouds in a companion galaxy during a gas-dynamical interaction with the halo and disk of a spiral galaxy. By ram pressure, the gas clouds are stripped from the companion, and accreted toward the disk of the spiral galaxy. If the companion’s orbit is retrograde with respect to the rotation of the spiral galaxy, infalling clouds hit the nuclear regio...

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 conditions change with time. Data and theoretical models now support densities in the cloud surrounding the solar system of n(H)=0.22±0.06 cm, and n(e)∼0.1 cm, with...

In the search for carriers of the diffuse interstellar bands (DIBs), a nearly ubiquitous, as-of-yet unattributed interstellar absorption spectrum, new theories are being proffered to explain this astronomical phenomenon. One of these is that rarely occurring excited states of anions may be responsible for some of these features. Using state-of-the-art quantum chemical techniques we examine near...

Galaxies are attractive objects to study. The magnetism of their natural beauty adds to the fascinating diversity of physical processes that occur over an enormous range of scales from the global dimension of order 10 kpc down to the viscous turbulent scales of 1000 km and less. The visual image of a galaxy (see Fig. 1) is dominated by the optical light mostly produced by stars that contribute ...

The history of gamma-ray astronomy began in the 1950’s when Hayakawa [1] and Morrison [2] predicted that gamma-rays would be produced via neutral pion decays generated in collisions of cosmic-rays with interstellar matter. Cherenkov observation of air showers was pioneered by Jelly [3] and Chudakov applied this technique to search for gamma-ray signals from celestial sources [4]. Since this ear...

Carbon solids are ubiquitous material in the interstellar space. However, the formation pathway of carbonaceous matter in astrophysical environments as well as in terrestrial gas-phase condensation reactions is not yet understood. Laser ablation of graphite in different quenching gas atmospheres such as pure He, He/H2, and He/H2O at varying pressures is used to synthesize very small, fullerene-...

GRB afterglows close to their peak intensity are among the brightest sources in the sky. We discuss how GRB optical-to-X-ray afterglows can be used as probes of the metal enrichment of the interstellar matter in the GRB host galaxies and of the heating history of the intergalactic matter in filaments and outskirts of clusters of galaxies along the line of sight. The key points of the proposed o...

We study the distribution of cold dark matter (CDM) in cosmological simulations from the FIRE (Feedback In Realistic Environments) project, for M∗ ∼ 104–11 M galaxies in Mh ∼ 109–12 M haloes. FIRE incorporates explicit stellar feedback in the multiphase interstellar medium, with energetics from stellar population models. We find that stellar feedback, without ‘fine-tuned’ parameters, greatly al...