Search Publications
Galactic component mapping of galaxy UGC 2885 by machine learning classification
Holwerda, Benne W.; Barmby, Pauline; Kwik, Robin J. +1 more
Automating classification of galaxy components is important for understanding the formation and evolution of galaxies. Traditionally, only the larger galaxy structures such as the spiral arms, bulge, and disc are classified. Here we use machine learning (ML) pixel-by-pixel classification to automatically classify all galaxy components within digit…
Insights from multi-wavelength observations during high and low states of non-magnetic CVs
Szkody, Paula
Close binaries containing a white dwarf accreting from a disk that receives material from a late stellar companion show an interesting variety of behaviors that depend on their accretion rates and the changes in this rate. The highest accretion rates are evident during the bright states of novalikes, as well as the superoutbursts of the shortest p…
The X-ray emission of the γ Cassiopeiae stars
Smith, Myron A.; Motch, C.; Lopes de Oliveira, R.
Long considered as the ;odd man out; among X-ray emitting Be stars, γ Cas (B0.5e IV) is now recognized as the prototype of a class of stars that emit hard thermal X-rays. Our classification differs from the historical use of the term ; γ Cas stars; defined from optical properties alone. The luminosity output of this class contributes significantly…
The role of ultraviolet imaging in studies of resolved and unresolved young stellar populations. M31 and M33
Bianchi, Luciana; Hodge, Paul; Williams, Benjamin +2 more
We discuss the relevance of UV data in the detection and characterization of hot massive stars and young stellar populations in galaxies. We show results from recent extensive surveys in M31 and M33 with Hubble Space Telescope (HST) multi-wavelength data including UV filters, which imaged several regions at a linear resolution (projected) of less …
High resolution science with high redshift galaxies
Hathi, N. P.; Jansen, R. A.; Driver, S. P. +4 more
We summarize the high-resolution science that has been done on high redshift galaxies with Adaptive Optics (AO) on the world’s largest ground-based facilities and with the Hubble Space Telescope (HST). These facilities complement each other. Ground-based AO provides better light gathering power and in principle better resolution than HST, giving i…
Modeling Pulsar Wind Nebulae
Bucciantini, N.
In the last few years, new observations by CHANDRA and XMM have shown that Pulsar Wind Nebulae present complex but similar inner features, with the presence of axisymmetric rings and jets, which are generally referred to as a jet-torus structure. Due to the rapid growth in accuracy and robustness of numerical schemes for relativistic fluid-dynamic…
Observational appearances of isolated stellar-mass black hole accretion Theory and observations
Karpov, S.; Beskin, G.; Biryukov, A. +2 more
General properties of accretion onto isolated stellar-mass black holes in the Galaxy are discussed. An analysis of plasma internal energy growth during the infall is performed. Adiabatic heating of collisionless accretion flow due to magnetic adiabatic invariant conservation is 25% more efficient than in the standard non-magnetized gas case. It is…
QSO number counts to B < 24.5 from hubble space telescope WFPC2 images
Anderson, Scott F.; Beck-Winchatz, Bernhard
We have conducted a survey for faint quasars to B < 24.5, z < 2.1 based on archival high-latitude Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) images covering 0.04 deg2 of the sky in three filters spanning 2300 9600 Å. Taking advantage of the superb 0.1″ resolution of WFPC2, we have developed an approach to select …
Cassini observations of the Interplanetary Medium Upstream of Saturn and their relation to the Hubble Space Telescope aurora data
Dougherty, M. K.; Jackman, C. M.; Clarke, J. T. +3 more
We present Cassini magnetometer and plasma data for the January 2004 ‘solar wind campaign’ in which the particles and fields instruments monitored the solar wind and interplanetary magnetic field, while the Hubble Space Telescope (HST) simultaneously observed the UV aurora in Saturn’s southern ionosphere. Clear structuring is evident in the data w…
Ceres: High-resolution imaging with HST and the determination of physical properties
Russell, C. T.; Stern, S. A.; Young, E. F. +4 more
Nine HST orbits have been used to image Ceres using the High Resolution Camera of the Advanced Camera for Surveys. Two hundred and fifty-nine images in three filters (F555W, F330W and F220W) were obtained covering the entire surface. Two visible features are readily apparent, a dark patch and a bright point. The bright spot was suitable for contro…