The Milky Way's dust is of basic importance in astronomy. It is both crucial to the formation of stars and a pervasive observational nuisance. Despite the dust's importance, existing dust maps are largely limited to two dimensions, with the distance to the dust unknown. The advent of large surveys like Pan-STARRS1 has allowed us to map dust in three dimensions in unprecedented detail. In this talk, I will describe how we use observations of stars in the Milky Way to map dust, and I will discuss three major results: a catalog of distances to major molecular clouds, the discovery of a 100 pc ring of dust in Orion, and the 3D dust map itself. Upcoming surveys promise continued scientific returns: Gaia, DECam, and the LSST will provide more precise and deeper data than ever before, enabling unique maps of the Galaxy's spiral structure and the study of the dust's properties in 3D.

There are presently some 25 highly r-process-element-enhanced metal-poor (r-II) stars known in the Galactic halo, roughly twenty years after their first recognition. These stars exhibit enhancements of their r-process-element to iron ratios, relative to Solar ratios, by a factor of 10 to 100+ ([r-element/Fe] > +1.0). Despite their very low metallicities ([Fe/H < -2.0), these stars exhibit an apparently universal [r-element/Fe] pattern that is very well-matched to the Solar r-process pattern. As such, they have long been thought to provide fundamental information on the likely astrophysical site of the r-process. I report on a comparison of the observed properties of field r-II stars with the remarkable recent detection of a large sample of r-II stars identified in the Ultra Faint Dwarf (UFD) galaxy Reticulum-II, and suggest that the UFD environment is the natural birthplace of essentially all r-II stars – due to their relative rarity, the clear overlap in metallicity of the field r-II stars with that of UFDs, and the observed range in the absolute abundances of r-process elements in such stars. Other recent observational constraints, including the demonstration that the formation of r-II stars does not rely on the presence of a binary companion, will be described A new, much-expanded effort to dramatically increase the numbers of known r-II stars in the halo is now underway, and will also be discussed.

While some observational studies have placed limits on the quantity and nature of accreted dwarf galaxies’ contributions to the Milky Way (MW) stellar halo (e.g., Unavane et al. 1996; Schlaufman et al. 2012), none has given a detailed account of their total relative contributions. In this study we test the prospects of using chemical abundances found in stars of the stellar halo to determine its formation history. To do this we utilize a statistical procedure called the expectation-maximization (EM) algorithm on ≥ 103−4 mock observations of the stellar chemical abundance ratio distributions (CARDs) found in the eleven simulated “MW-like” halos of Bullock & Johnston (2005) to recover the relative stellar mass contributions from representative accreted dwarf galaxies (templates). Using these templates we find that in most cases investigated we can recover luminosity fractions that sum over 90% of the total relative stellar mass contributions (from each progenitor template) to within a factor of 2. We also find that this method is particularly sensitive to older accretion events involving low-luminous dwarfs e.g. ultra-faint dwarfs --- or precisely those events that are too ancient to be seen by phase-space studies of stars and too faint to be seen by high-z studies of the early Universe. Since our results only exploit two dimensions in chemical abundance space (while near-future surveys promise to provide ~6-9+ important dimensions) we conclude that new high-resolution spectroscopic surveys of the stellar halo will allow us to recover the luminosity function of accreted dwarf galaxies --- and a detailed accretion history of the halo --- across cosmic time.

We use HST spectra of AGN to study the gas inside and outside galaxy halos. These studies reveal that galaxies have extended (300 kpc) radius halos, which blend into the general intergalactic medium. I will show the first results of our study of the properties of the gas as function of location in the galaxy halos. I will also summarize a study of 24 AGN that provide the first 2-D view of a 30x6 Mpc filament at cz~3500 km/s. The baryonic mass inside filament galaxies is 1.4x10^13 Msun, while the mass of filament gas outside galaxy halos is found to be 5.2x10^13 Msun. We show that the gas is concentrated near the filament axis, but also that the simulations overpredict the detection rate between 2.1 and 5 Mpc from the axis.

Abstract: Some observed supernova remnants (SNR) are highly asymmetric. Multiple physical processes have been put forth to explain this phenomena, but the detailed physics of supernova explosions is still unknown. I am presenting the three dimensional SPH simulations of SNR development under the effects of velocity and density perturbations within the oxygen shell of progenitor stars (modeled after the progenitors of Cassiopeia A and G292 remnants). We hope to show that realistic introduced perturbations will produce asymmetry in the resulting remnant. Multiple perturbation modes were explored in this work, with unperturbed models for comparison. The simulations are linked to the observed asymmetries to gain greater understanding of the supernova explosion engine.

Nearby, young moving groups are ideal testbeds for studying stellar and planetary evolution. By definition, stars in a given moving group should not have significantly different ages or compositions, therefore one can see how the cluster evolves as a function of mass. Additionally, planetary systems around these young stars are still contracting, and thus are bright in the H and K photometric bands. For this reason, moving groups have become attractive targets for planet searches since the masses of photometrically discovered planets are well constrained from the ages of the host moving group (see Biller et al. 2013). Currently, moving groups are largely characterized based on youth indicators (e.g. lithium absorption, X-ray emission) and space velocities. In this talk, I will discuss recent results which more fully characterize moving groups based on (1) Chemical homogeneity, (2) Origin, and (3) Isochronal Age. These traits have been tested on the well established AB Doradus moving group and the newly discovered Octans-Near moving group. I will show that these methods provide a detailed picture of the AB Doradus group, however, Octans-Near remains difficult to characterize. I will also discuss the future of this technique on low mass members using high resolution H and K spectroscopy.

Supermassive black holes (SMBHs) are now known to be ubiquitous, with one present in the center of essentially every galaxy. The energy released by accretion onto an SMBH in the AGN phase is enough to not only outshine its host galaxy, but also to completely unbind the gas and rapidly quench star formation. But do SMBHs actually play an explosive role in galaxy evolution? In most cases, no! I will use a variety of observations - with careful consideration of selection effects - to demonstrate that AGN host galaxies are not particularly special. SMBH growth requires neither massive hosts nor violent angular momentum transport (i.e. mergers, disk instabilities, or large-scale bars). Instead AGNs are generally passengers on the road of galaxy evolution, fueled by the same gas reservoirs which drive star formation.

Abstract:
We now believe that every large galaxy hosts a supermassive black
hole at its core, with masses ranging from millions to billions of
times that of our Sun. At times, these black holes are actively
accreting, causing the nuclei of the galaxies to shine brightly
across the electromagnetic spectrum. However, in many, perhaps
most quasars, obscuring material along the line of sight shields
us from directly viewing the inner nucleus. This obscuring material
is heated, and emits strongly in the mid-infrared. The Wide-field
Infrared Survey Explorer, or WISE, has recently mapped the entire
sky in mid-infrared light with exquisite depth and clarity. WISE
has allowed us to find luminous quasars across the whole sky due
to this heated material, more than tripling the number of quasars
known. I will discuss several surprising new insights into quasars
that have come out of this work. In brief, the dominant paradigms
do not match our observations, with potentially important implications
for the role of quasars in the growth of galaxies. I will conclude
by discussing how these studies will be further enabled by the
Euclid and WFIRST satellites.

Lyman break galaxies (LBGs) are often used as prototypes to construct
strongly star-forming galaxies, since the Lyman break signature is
straightforward to identify at z>3 from the ground. However, at z~2,
the Lyman break is located in the UV wavelength range and can only be
observed from space. Until the launch of GALEX, large (wide-field)
ground-based proxy selection methods for LBGs had to be used, which
produce measurable differences from true LBG samples. We will use deep
GALEX and ground based U-images to select a true Lyman break sample of
z~2 LBGs, and investigate the nature of galaxies which produce the IR
background.

The GALEUS (GALaxy Evolution UV Survey) will use public wide-deep data
to study the physical properties of UV-selected star-forming galaxies
at z~2. We propose to investigate the contribution of UV and IR
luminous galaxies to the population of LBGs, using UV to FIR data (0.16
to 500~microns) observed by GALEX, Spitzer, and Herschel, with
supporting optical/IR data from HST+ACS and ground-based surveys. I
will show preliminary results based on spectral energy distributions.

   The disk of the Milky Way beyond the solar circle is not open to simple

interpretations. In short, it is a mess. From observations of interstellar

gas it is clear that the disk has both a warp and a flare.

The stellar component is riddled with stellar over-densities and/or streams,

the largest of which is the Monoceros stream. It is unclear whether gas

is in-falling and still building the outer disk, whether the distribution

of dark matter inflates the outer disk, if interactions with satellite

galaxies are perturbing the disk or if disrupted satellites are adding

to the disk. It is possible that all of these effects are contributing.

What is clear is that the outer disk of the Galaxy holds many clues as to

how galaxies form and evolve.



   Studying stellar populations in the outer disk is useful but currently has

limitations because spatial and kinematic distributions are not uniquely

described by the various Galactic models. I will discuss our current

attempts at helping to constrain properties of the outer disk using

spectroscopic analysis of A-star samples. Most of the talk will be dedicated

to our analysis of chemically peculiar A-stars in the SDSS DR8 sample and

whether the distribution of these stars indicate that the Monoceros stream

contains ancient blue stragglers or younger A-stars. The latter conclusion

might suggest that the stream is a component of disk of the Galaxy, while the

former might indicate dwarf disruption. I will conclude the talk by showing

our current work on the Canis Major Over-density and our future goal to explore

dust distribution in the disk using A-stars