Search Publications
Missions
Journals
Publication Years
Possible Precession Motion in the Bipolar Proto-Planetary Nebula IRAS 17441-2411
Volk, Kevin; Kwok, Sun; Hrivnak, Bruce J.
Mid-infrared imaging of two bipolar proto-planetary nebulae, IRAS 17150-3224 and IRAS 17441-2411, was obtained with the Gemini telescope. Dust emissions are detected in both the bipolar lobes and in the equatorial region of IRAS 17441-2411. In particular, the orientation of the axis of the infrared torus is found to be offset by 23° from the bipol…
A precessing accretion disc in the intermediate polar XY Arietis?
Mukai, K.; Norton, A. J.
Context: XY Ari is the only intermediate polar to show deep X-ray eclipses of its white dwarf. Previously published observations with Ginga and Chandra have also revealed a broad X-ray orbital modulation, roughly antiphased with the eclipse, and presumed to be due to absorption in an extended structure near the edge of an accretion disc. The X-ray…
An ultraluminous supersoft source with a 4 hour modulation in NGC 4631
Ehle, M.; Wilms, J.; King, A. R. +2 more
Context: Supersoft X-ray sources (SSSs) are characterised by very low temperatures (<100 eV). Classical SSSs have bolometric luminosities in the range of 1036-1038 erg s-1 and are modelled with steady nuclear burning of hydrogen on the surfaces of white dwarfs. However, several SSSs have been discovered with muc…
The Host Galaxies and Environment of Chandra-Selected Active Galactic Nuclei in the Deep ACS GTO Cluster Fields
Infante, Leopoldo; Tozzi, Paolo; Ford, Holland C. +2 more
We present catalogs and images of optical counterparts to the Chandra-selected X-ray sources found in the fields of the five clusters RX J0152-1357, RX J0849+4452, RDCS J0910+5422, MS 1054-0321, and RDCS J1252-2927, which were imaged with the Advanced Camera for Surveys as part of the ACS Guaranteed Time Observer programs. A total of 98 X-ray sour…
X-Ray and Ultraviolet Spectroscopy of Intermediate-Mass, First Crossing Giants
Ayres, Thomas R.; Brown, Alexander; Hodges-Kluck, Edmund
Chandra, FUSE, and HST STIS jointly have obtained spectra of four intermediate-mass giants (<~3 Msolar) crossing the Hertzsprung gap for the first time, passing through a ``rapid braking phase'' analogous to, but much briefer than, the more gradual prolonged decay of magnetic activity experienced by single low-mass stars like the Sun…
Emission heights of coronal bright points on Fe XII radiance map
Tu, C. -Y.; Marsch, E.; Tian, H. +1 more
The study of coronal bright points (BPs) is important for understanding coronal heating and the origin of the solar wind. Previous studies indicated that coronal BPs have a highly significant tendency to coincide with magnetic neutral lines in the photosphere. Here we further studied the emission heights of the BPs above the photosphere in the bip…
Analytical Models for Cross-Correlation Signal in Time-Distance Helioseismology
Kosovichev, A. G.; Scherrer, P. H.; Nigam, R.
In time-distance helioseismology, the time signals (Doppler shifts) at two points on the solar surface separated by a fixed angular distance are cross-correlated, and this leads to a wave packet signal. Accurately measuring the travel times of these wave packets is crucial for inferring the subsurface properties in the Sun. The observed signal is …
Two-Dimensional Spectroscopy of Photospheric Shear Flows in a Small δ Spot
Yurchyshyn, V.; Tritschler, A.; Denker, C. +1 more
In recent high-resolution observations of complex active regions, long-lasting and well-defined regions of strong flows were identified in major flares and associated with bright kernels of visible, near-infrared, and X-ray radiation. These flows, which occurred in the proximity of the magnetic neutral line, significantly contributed to the genera…
Submillimeter lightcurves of Vesta
Sykes, Mark V.; Lovell, Amy J.; Chamberlain, Matthew A.
Thermal lightcurves of Asteroid Vesta with significant amplitude have been observed at 870 µm (345 GHz) using the MPIfR 19-channel bolometer of the Heinrich-Hertz Submillimeter Telescope. Shape and albedo are not sufficient to explain the magnitude of this variation, which we relate to global variations in thermal inertia and/or other thermo…
Dynamics of two satellites in the 2/1 Mean–Motion resonance: application to the case of Enceladus and Dione
Yokoyama, T.; Callegari, N.
The dynamics of a pair of satellites similar to Enceladus–Dione is investigated with a two-degrees-of-freedom model written in the domain of the planar general three-body problem. Using surfaces of section and spectral analysis methods, we study the phase space of the system in terms of several parameters, including the most recent data. A detaile…