Search Publications
Tidal Stripping of Globular Clusters
Coenda, V.; Muriel, H.; Donzelli, C.
We have analyzed 9 galaxies taken from the ACS Virgo Cluster Survey to study the tidal stripping of globular clusters in early type galaxies. We estimate the specific frequency (S_N) of globular clusters in the cluster galaxies, our results indicate that the mean S_N increases with the galactocentric distance. However, if the blue and red globular…
Diffracto-Astrometry with Hubble Space Telescope and Adaptive Optics Images
Sánchez, L. J.; Ruelas-Mayorga, A.; Allen, C. +1 more
Following the lead established by Allen et al. (1974, 2004) in the study of internal movements in Trapezium-type systems, we decided to investigate the possibility of performing precision astrometry on Hubble Space Telescope (HST) images and on images obtained with Adaptive Optics (AO) systems. A region widely observed by the HST is that of the Or…
Classifying the stellar environment around V838 Monocerotis
Schaefer, G. H.; Rosero-Rueda, V. A.; Bond, H. E. +2 more
The V838 Mon's behavior and the nature of the progenitor object are not well understood. Type B stars recently have been found in the vicinity of V838 Mon and it is thought that they may be part of a young open cluster. Since the cluster is in a spiral arm of the Galaxy, the identification of additional member stars is complicated; therefore, phot…
The Circumstellar Environments of the Cool Hypergiants: Implications for the Mass Loss Mechanism
Humphreys, R. M.
The cool hypergiants are the most luminous known stars in the upper HR Diagram in the apparent temperature range represented by the spectral types A to M. Most of these stars in this regime are unstable as evidenced by their high mass loss rates, variability, and in some cases large IR excesses and circumstellar ejecta. In this brief paper, I desc…
The mid-infrared emission of local Luminous Infrared Galaxies
Alonso-Herrero, A.
In this paper we use the complementary imaging capabilities of Spitzer (sensitivity) and Gemini-South/T-ReCS (spatial resolution) to study the mid-IR properties of local (d < 75Mpc) LIRGs. The T-ReCS 8 - 10µm imaging observations of LIRGs have allowed us to spatially resolve the nuclear emission (star formation and/or AGN) and that of H I…
Observational studies of Cataclysmic Variable evolution: Of samples, biases and surprises
Gänsicke, B. T.
I present brief status reports on three large observational projects that are designed to test our current understanding of the evolution of cataclysmic variables (CVs): The spectroscopic selection of new CVs in the Hamburg Quasar Survey, the search for pre-CVs based on Sloan colours and UK Schmidt/6dF multiobject spectroscopy, and the identificat…
Accretion Processes in Mira AB
Raymond, J. C.; Marengo, M.; Karovska, M. +3 more
The Mira AB interacting binary provides an ideal laboratory for studying mass loss and accretion processes in systems containing an AGB star and a compact accretor, because its components have been resolved and can be studied individually. We present here results from our long term study of accretion processes in this system. These include recent …
A ULX in NGC 4559: a ``mini-cartwheel'' scenario?
Soria, R.; Cropper, M. S.; Pakull, M. W.
We have studied the peculiar environment around a ULX in NGC 4559 (with L[x] ≈ 2×1040 erg s-1 and M[BH] ≳ 50M⊙). The X-ray source is located near the rim of a young (age < 30 Myr), large (diameter ≈ 700 pc) ring-like star forming complex possibly triggered by the impact of a dwarf satellite galaxy through the gas-rich oute…
Far-Ultraviolet Surveys of Globular Clusters: Searching for the Products of Stellar Collisions and Near Misses
Knigge, C.; Charles, P. A.; Long, K. S. +3 more
Far-ultraviolet (FUV) observations with the Hubble Space Telescope are an excellent way to find and study the hot, blue stellar populations in the cores of globular clusters. These populations include dynamically-formed blue stragglers and interacting binaries (such as cataclysmic variables, i.e. the products of stellar collisions and near misses.…
Disentangling X-ray Reprocessing Sites in EXO 0748-676
Charles, P. A.; Horne, K.; O'Brien, K. +5 more
We present first results from a coordinated multiwavelength study of the neutron star low-mass X-ray binary EXO 0748-676. Fast UV, X-ray, and optical data were obtained including both spectral and timing information. We discuss how this study allows us to probe the temperature distribution within the binary and hence the geometry and efficiency of…