Implementation of faster-than-light (FTL) interstellar travel via traversable wormholes, warp drives, or other spacetime modification schemes generally requires the engineering of spacetime into very specialized local geometries. The analysis of these via Einstein’s General Theory of Relativity plus the resultant equations of state demonstrates that such geometries require the use of “exotic” m...

We present simultaneous U BV polarimetric and photometric observations of the pre-main-sequence binary AK Sco, obtained over 12 nights, slightly less than the orbital period of 13.6 days. The polarization is a sum of interstellar and intrinsic polarization , with a significant intrinsic polarization of 1% at 5250Å, indicating the presence of circumstellar matter distributed in an asymmetric geo...

There is now ample evidence that the interstellar thick disks of spiral galaxies are dusty. Although the majority of extraplanar gas in the first few kiloparsecs above the plane of a spiral galaxy is matter that has been expelled from the thin disk, the feedback-driven expulsion does not destroy dust grains altogether (and there is not yet any good measure suggesting it changes the dust-to-gas ...

Although the space between stars in our galaxy appears to be completely empty of matter, there exists a very dilute gas even in “empty” space. This interstellar (meaning “between the stars”) medium varies in density (the amount of matter within a certain volume). Typical densities in the interstellar medium are one particle per cubic centimeter. Since hydrogen is the most single common element ...

We present models of the cosmological star formation and metal production history of (proto-)galaxies with varying axis ratios. More massive and/or roughly spherical systems reach the threshold-metallicity for a transition to a multi-phase interstellar medium earlier than less massive, more flattened systems. Therefore, more flattened, lower-mass systems start to form stars actively at smaller ...

The interstellar medium of low-metallicity systems undergoing star formation will show chemical abundance in-homogeneities due to supernova events enriching the medium on a local scale. If the star formation timescale is shorter than the timescale of mixing of the interstellar matter, the inhomogeneities are reflected in the surface abundances of low-mass stars and thereby detailed information ...

We have observed (with vby filters) a field north of the core of the most massive globular cluster in our galaxy, ω Centauri. We have found a correlation of age and metallicity in a region which avoids the dense core and the inhomogeneous foreground dust emission shown by the IRAS satellite. Our observations show that the comparatively metal-rich stars (as defined by the (b− y) and m1 colors) a...