We have developed a timing analysis method to determine the distances of variable galactic X-ray sources based on the method advanced by Trümper and Schönfelder in 1973. The light-curve of the halo produced by the scattering of X-rays off the interstellar dust is delayed and smeared by the dust grains. This method utilizes the differences between the power density spectra of the point source an...

We present a new instability driven by combination of coagulation and radial drift dust particles. refer to this as ``coagulation instability" regard it promising mechanism concentrate particles assist planetesimal formation in the very early stages disk evolution. Because dust-density dependence collisional efficiency, efficiently (inefficiently) grow region positive (negative) density perturb...

We present results from a spectroscopic search for massive companions to dust-making Galactic WC9 stars as a step to testing the paradigm that dust formation in these systems requires colliding winds to produce over densities. We find evidence for OB companions to the WC9 stars WR59 and WR65, but not WR121 or WR117. We identify lines of N iii-v and possibly N ii in the spectrum of WR88, one of ...

Isotopic characterization of aerosol mineral particles (atmospheric dust) of varying sizes is essential in classifying source areas, and for determining the source of dust deposited over oceans and icesheets. However, the effect of atmospheric transport on radiogenic isotopic compositions is not well constrained, making provenance interpretation difficult. In order to investigate the isotopic v...

We use the COMPLETE Survey’s observations of the Perseus star-forming region to assess and intercompare three methods for measuring column density in molecular clouds: near-infrared extinction mapping; thermal emission mapping in the far-IR; and mapping the intensity of CO isotopologues. Overall, the structures shown by all three tracers are morphologically similar, but important differences ex...

Accepted for publication in the Astrophysical Journal We estimate the intrinsic neutral gas density in Damped Lyman α systems (Ω (DLA) HI) in the redshift range 2.2 z 5 from the DLA SDSS DR 3 sample of optically selected quasars. We take into account self-consistently the obscuration on background quasars due to the dust present in Damped Lyman α systems. We model the column density and redshif...

I review the characteristics of high redshift galaxies, with particular attention to the effects of dust obscuration on the observed light. Galaxies at redshift z∼1 and at z>2 are discussed separately, as the accessible information for each redshift range are different. In the z≤1–2 redshift region, data on the Hα and mid/far-IR luminosity of the galaxies are becoming increasingly available, ef...

Null dust is a model for the incoherent superposition of waves with random polarizations and phases, moving in a single direction with the speed of light. It also describes the high frequency (geometrical optics) approximation for any type (including gravitational) radiation. Null dust is characterized by the energy-momentum tensor T ab = ρll. Neither the energy density ρ nor the null vector l ...

We investigate in this paper the effect of gas drag on the dynamics of the dust particles in the edge-on β Pictoris disc in order to derive an upper limit on the mass of gas in this system. Our study is motivated by the large uncertainties on the amount of gas in the β Pictoris disc currently found in the literature. The dust particles are assumed to originate from a colliding annulus of planet...

[1] Mineral dust interacts with radiation and impacts both the regional and global climate. The relative contribution of natural and anthropogenic dust sources, however, remains largely uncertain. Although human activities disturb soils and therefore enhance wind erosion, their contribution to global dust emission has never been directly evaluated because of a lack of data. The retrieval of aer...