Astronomy

The effect of deformation history on the evolution of olivine CPO
Olivine crystallographic preferred orientation (CPO) is the primary cause of seismic anisotropy in the upper mantle. In tectonic environments with complex flow patterns, for example corner flow near mid-ocean ridges or subducting slabs, the interpretation of seismic anisotropy may be complicated by evolving thermochemical deformation conditions and the integrated deformation history. To underst...


Cracking the lid: Sill-fed dikes are the likely feeders of flood basalt eruptions
Although subparallel swarms of dikes are thought to be the primary feeders to voluminous volcanic eruptions, increasing recognition of volumetrically significant sill complexes suggests that they too play an important role in magma ascent through the shallow crust. However, the extent to which sills and interconnected, sill-fed dikes actually transport magma to the earth's surface in many large...
Neodymium isotopes and concentrations in Caribbean seawater: Tracing water mass mixing and continental input in a semi-enclosed ocean basin
We present the first full water column Nd isotope ( ε Nd ) and concentration data for Caribbean seawater, as well as for stations close to the Orinoco River mouth and in the Florida Straits. The surface inflow into the southeastern Caribbean via the Guyana Current is characterized by an ε Nd signature of −10.9, which is a consequence of the mixing of relatively unradiogenic ...


Pressure-induced elastic and structural changes in hydrous basalt glasses: The effect of H2O on the gravitational stability of basalt melts at the base of the upper mantle
To understand the effect of hydration on the elastic properties of silicate melts, we conducted in situ high-pressure Brillouin scattering measurements on two hydrous basalt glasses with different water contents in diamond anvil cells. Second-order phase transitions were observed in the hydrous basalt glasses and are due to the topological rearrangement of the silicate network to a high [Si, ...
The SLUGGS survey: Globular cluster stellar population trends from weak absorption lines in stacked spectra
As part of the SLUGGS survey, we stack 1137 Keck DEIMOS spectra of globularclusters from 10 galaxies to study their stellar populations in detail. Thestacked spectra have median signal to noise ratios of $sim 90$ AA$^{-1}$. Besides the calcium triplet, we study weaker sodium, magnesium, titanium andiron lines as well as the H$alpha$ and higher order Paschen hydrogen lines. Ingeneral, the stacke...


Light Echoes From Supernova 2014J in M82
Type Ia SN 2014J exploded in the nearby starburst galaxy M82 = NGC 3032, andwas discovered at Earth about seven days on 2014 January 21, reaching maximumlight around 2014 February 5. SN 2014J is the closest SN Ia in at least fourdecades and probably many more. Recent $HST$/WFC3 imaging (2014 September 5) ofM82 in the vicinity of SN 2014J reveals what is most probably a light echo atradii of abo...
Blind foreground subtraction for intensity mapping experiments
We make use of a large set of fast simulations of an intensity mappingexperiment with characteristics similar to those expected of the SquareKilometre Array (SKA) in order to study the viability and limits of blindforeground subtraction techniques. In particular, we consider differentapproaches: polynomial fitting, principal component analysis (PCA) andindependent component analysis (ICA). We r...

Hubble Frontier Fields : A High-Precision Strong-Lensing Mass Model of the Massive Galaxy Cluster Abell 2744 using ~150 Multiple Images
We present a high-precision mass model of galaxy cluster Abell 2744, based ona strong-gravitational-lensing analysis of the Hubble Space Telescope FrontierFields (HFF) imaging data, which now include both Advanced Camera for Surveysand Wide-Field Camera 3 observations to the final depth. Taking advantage ofthe unprecedented depth of the visible and near-infrared data, we identify 33new multiply...
The Universe as a Cellular System
Cellular systems are observed everywhere in nature, from crystal domains inmetals, soap froth and cucumber cells to the network of cosmological voids. Surprisingly, despite their disparate scale and origin all cellular systemsfollow certain scaling laws relating their geometry, topology and dynamics. Using a cosmological N-body simulation we found that the Cosmic Web, thelargest known cellular ...

Where are the Mini Kreutz-family Comets?
The Kreutz family of sungrazing comets contains over 2~000 known members,many of which are believed to be under $sim 100$~m sizes(textit{mini~comets}) and have only been studied at small heliocentricdistances ($r_mathrm{H}$) with space-based SOHO/STEREO spacecraft. Tounderstand the brightening process of mini Kreutz comets, we conducted a surveyusing CFHT/MegaCam at moderate $r_mathrm{H}$ guide...
The Secret Lives of Cepheids: Evolutionary Changes and Pulsation-Induced Shock Heating in the Prototype Classical Cepheid {delta} Cep
Over the past decade, the Secret Lives of Cepheids (SLiC) program has beencarried out at Villanova University to study aspects and behaviors of classicalCepheids that are still not well-understood. In this, the first of severalplanned papers on program Cepheids, we report the current results for deltaCep, the Cepheid prototype. Ongoing photometry has been obtained to search forchanges in the pu...

The masses and density profiles of halos in a LCDM galaxy formation simulation
We investigate the internal structure and density profiles of halos of mass$10^{10}-10^{14}~M_odot$ in the Evolution and Assembly of Galaxies and theirEnvironment (EAGLE) simulations. These follow the formation of galaxies in a$Lambda$CDM Universe and include a treatment of the baryon physics thought tobe relevant. The EAGLE simulations reproduce the observed present-day galaxystellar mass func...
Primordial black holes with mass $10^{16}-10^{17}$ g and reionization of the Universe
Primordial black holes (PBHs) with mass $10^{16}-10^{17}$ g almost escapeconstraints from observations so could essentially contribute to dark matterdensity. Hawking evaporation of such PBHs produces with a steady rate $gamma$-and $e^{pm}$-radiations in MeV energy range, which can be absorbed by ordinarymatter. Simplified estimates show that a small fraction of evaporated energyhad to be absorb...
Spectroscopic observations of the bright RV Tauri variable R Scuti
A series of spectra of the RV Tauri star R Scuti taken as it rose from a deepminimum to a bright maximum during 2013 October and November reveals majorchanges taking place in the photosphere and outer atmosphere of the star. Thismay be the first such series of spectra and demonstrates the capability ofamateur spectroscopy for studying these complex stars.
Towards a comprehensive model of Earth's disk-integrated Stokes vector
A significant body of work on simulating the remote appearance of Earth-likeexoplanets has been done over the last decade. The research is driven by theprospect of characterizing habitable planets beyond the Solar System in thenear future. In this work, I present a method to produce the disk-integratedsignature of planets that are described in their three-dimensional complexity,i.e. with both h...