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Observations of circumstellar disks around stars as a function of stellar properties such as mass, metallicity, multiplicity, and age, provide constraints on theories concerning the formation and evolution of planetary systems. Utilizing…
The Sun is depleted in refractory elements compared to nearby solar twins, which may be linked to the formation of giant or terrestrial planets. Here we present high-resolution, high signal-to-noise spectroscopic data for 17 solar-like…
We conducted sub-millimeter observations with the Atacama Large Millimeter/sub-millimeter Array (ALMA) of star-forming galaxies at $z\sim3.3$, whose gas-phase metallicities have been previously measured. We investigate the dust and gas…
We present preliminary results of a detailed chemical abundance analysis for a sample of solar-type stars known to exhibit excess infrared emission associated with dusty debris disks. Our sample of 28 stars was selected based on results…
The luminosity functions at z < 4 - 5 suggest that most galaxies have a relatively low stellar mass (logM_star = 10) and a low dust attenuation (A_FUV = 1.0). The physical properties of these objects are quite homogeneous. We used an…
One of the key questions in understanding the formation and evolution of galaxies is how starbursts affect the assembly of stellar populations in galaxies over time. We define a burst indicator ($\eta$), which compares a galaxy's star…
If the photospheres of solar-type stars represent the composition of circumstellar disks from which any planets formed, spectroscopic determinations of stellar elemental abundances offer information on the composition of those planets,…
With the aim of investigating whether stellar sources can account for the >10^8 Msun dust masses inferred from mm/sub-mm observations of samples of 5<z<6.4 quasars,we develop a chemical evolution model which follows the evolution of metals…
Although the basic physics of star formation is classical, numerical simulations have yielded essential insights into how stars form. They show that star formation is a highly nonuniform runaway process characterized by the emergence of…
The effects of wind-driven star formation feedback on the spatio-temporal organization of stars and gas in galaxies is studied using two-dimensional intermediate-representational quasi-hydrodynamical simulations. The model retains only a…
The nature of dust in distant galaxies is not well understood, and until recently few direct dust measurements have been possible. We investigate dust in distant star-forming galaxies using near-infrared grism spectra of the 3D-HST survey…
We test emission models of circum-nuclear dust torii around quasars, at low and high redshifts, by using a large collection of photometric data for an unbiased sample of 120 optically-selected objects with millimetric and sub-millimetric…
The internal dust extinction in spiral galaxies can affect our understanding of their structure and morphology, as well as our perception of the distant universe in the background. The intrinsic properties of the stellar and dust components…
We study the recent star formation histories of local galaxies by analyzing the scatter in their colours and spectral properties. We present evidence that the distribution of star formation histories changes qualitatively above a…
A broad array of interstellar absorption features that appear in the ultraviolet spectra of bright sources allows us to measure the abundances and ionization states of many important heavy elements that exist as free atoms in the…
We combine high-resolution ALMA and HST/CANDELS observations of 20 submillimeter galaxies (SMGs) predominantly from the AS2UDS survey at z~2 with bright rest-frame optical counterparts (Ks < 22.9) to investigate the resolved structural…
We present a compilation of measurements of the stellar mass density as a function of redshift. Using this stellar mass history we obtain a star formation history and compare it to the instantaneous star formation history. For z<0.7 there…
Several models have predicted that stars could form inside galactic outflows and that this would be a new major mode of galaxy evolution. Observations of galactic outflows have revealed that they host large amounts of dense and clumpy…
We conducted a survey for infrared excess emission from 16 nearby main sequence shell stars using the Multiband Imaging Photometer for Spitzer (MIPS) on the Spitzer Space Telescope. Shell stars are early-type stars with narrow absorption…
Systematic abundance differences that depend on the condensation temperatures of elements have been observed, in particular for stars similar to the Sun; solar twins and solar analogs. Similar differences have also recently been shown to…