Using the Multi-Element Radio-Linked Interferometer Network (MERLIN), we have acquired a high spatial resolution spectral image of the OH megamaser (OHMM) in the nearby starburst 'galaxy' known as IIZw 096. We have also acquired optical B, V, R, I and H alpha images with the 1.5-m telescope in San Pedro Martir. By comparing the MERLIN observations with Hubble archive images, we are able to pinpoint the location of the OH maser emission in this object; the OHMM emission seems to be associated with a faint and reddish, compact-round structure (a few hundred parsecs) off-centre of a merging system of galaxies. From the colour and strong Ha emission, this object is consistent with the remains of the nucleus of a very perturbed galaxy in interaction. Assuming a Keplerian bounded system the mass necessary to produce a velocity range of approximate to 200 km s(-1) for the OHMM is of the order of 10(9) M-circle dot, which is consistent with a massive black hole. Consequently, although the OHMM was previously suspected to be of starburst origin, our analysis suggests that an active galactic nucleus (AGN) could also be present in this merging system making it a composite source. IIZw 096 is a nearby example which shows how high spatial resolution data of the OHMM emission region, and supporting optical data, can be extremely helpful in determining the nature (starburst, AGN or composite) of such phenomenon.

We present results of single-dish and very long baseline interferometry (VLBI) observations of a strong 1000-Jy OH maser flare in the star-forming region W75N. The flare was first seen in 2003, and persisted for at least four years. Three major spectral features were present during the whole period of observations, with N(1) being the strongest initially and N(2) becoming stronger later. The large velocity range of 43 km s-1 observed during the flare is not kinematic in origin, but is caused by the Zeeman splitting in the strong magnetic field generated by the central star. The maps and proper motion of the maser spots were monitored over eight epochs, between 1998 and 2006, using the European VLBI Network (EVN) supplemented by published Very Large Baseline Array (VLBA) data. Mapping of the maser spots has shown that all the new spectral features of the flare were located close to the ultracompact H ii region VLA2, while the quiescent maser features were found near VLA1. We suggest that the flare was initiated by a disturbance, probably an magnetohydrodynamic (MHD) shock launched from the massive young star, also responsible for the excitation of the ultracompact H ii region. The proper motion of the majority of the maser spots was not detected at 1665 and 1667 MHz with the upper limit of several km s-1. The only positive detection of the proper motion was made for the two brightest flare features N(1) and N(2). The spot N(2) is moving along the filamentary spot N(3), with a tangential velocity of 14 km s-1. This motion is caused by the MHD shock propagating along the filament. The measured low upper limit for the velocity of OH maser spots is consistent with models of a slowly rotating Keplerian disc rather than with outflows, jets or expanding shells.

We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemisphere globular clusters. Here we present representative observations of RR Lyrae stars located in these clusters, including light curves. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC. We find that for well-separated stars, DAOPHOT and ISIS provide comparable results. However, for stars within the cluster core, ISIS provides superior results. These improved techniques will allow us to better measure the properties of cluster variable stars.

We have obtained deep observations of the metal-rich open cluster NGC
6253 with GMOS on the Gemini-South telescope, with the goal of observing the cluster
white dwarfs for the first time. These observations are an important piece and further
test of the variously proposed scenarios to explain the formation of the strange white
dwarfs in the metal rich open cluster NGC 6791. We will use the new observations of
NGC 6253 to measure the cluster’s white dwarf age and search for any anomalies in the
white dwarf luminosity function. The high metallicity of this cluster will allow us to
explore and better understand the formation of white dwarfs in such a high metallicity
environment. These observations are an important piece in the continuing puzzle that
has important implications on mass loss, white dwarf cooling, and stellar evolution as
a whole.

We apply a self-consistent and robust Bayesian statistical approach along with modern model ingredients to determine the posterior age distributions for nine DC field white dwarfs. Our technique requires only quality optical and near-IR photometry to derive ages with uncertainties that range from as little as 4% to as much as 27%, depending on the star. We use these results to demonstrate the non-Gaussian nature of white dwarf age posteriors and to compare the effect on ages of two modern initial final mass relations. We additionally predict the capabilities of our Bayesian technique in the GAIA era, when we will possess distances accurate to 1-2% for thousands of white dwarfs.