Aliphatic hydrocarbons exhibit an absorption feature at 3.4 m, observed toward sources that sample diffuse regions of the interstellar medium (ISM). The absorbers responsible for this feature are assumed to reside in some component of interstellar dust, but the physical nature of the particles (size, shape, structure, etc.) is uncertain. Observations of interstellar polarization provide discrim...

We present optical observations and 2D hydrodynamic modeling of an isolated shocked ISM cloud. Hα images taken in 1992.6 and 2003.7 of a small optical emission cloud along the southwestern limb of the Cygnus Loop were used to measure positional displacements of ∼ 0. 1 yr for surrounding Balmer dominated emission filaments and 0. 025 − . 055 yr for internal cloud emission features. These measure...

The heliosphere serves as a probe of interstellar material (ISM) close to the Sun. Measurements of ISM inside and outside of the heliosphere show that we reside in typical warm partially ionized ISM that can be successfully modeled using equilibrium photoionization models. The heliosphere wake leaves a ∼ 200× 1000 AU trail in space of low density, n < 0.05 cm, cooling plasma comingled with ISM....

Arcsecond-resolution spectral observations toward the protobinary system IRAS 16293-2422 at 344 and 354 GHz were conducted using the Submillimeter Array. Complex organic molecules such as CH3OH and HCOOCH3 were detected. Together with the rich organic inventory revealed, it clearly indicates the existence of two, rather than one, compact hot molecular cores (. 400 AU in radius) associated with ...

Context. The 12C/13C isotope ratio in the interstellar medium (ISM), and its evolution with time, is an important tracer of stellar yields. Spatial variations of this ratio can be used to study mixing in the ISM. Aims. We want to determine this ratio and its spatial variations in the local ISM from CH absorption lines in the optical towards early-type stars. The aim is to determine the average ...