Search Publications
Assessing Formation Scenarios for the Double Nucleus of M31 Using Two-Dimensional Image Decomposition
Peng, Chien Y.
The double nucleus geometry of M31 is currently best explained by the eccentric disk hypothesis of Tremaine, but whether the eccentric disk resulted from the tidal disruption of an inbounding star cluster, from a nuclear black hole, or from an m=1 perturbation of a native nuclear disk remains debatable. I perform detailed two-dimensional decomposi…
Observation of the terrestrial bow shock in quasi-electrostatic subshock regime
Balogh, A.; Eriksson, A.; Walker, S. N. +8 more
Electric field measurements made on board the four Cluster II satellites are used to estimate the spatial scale of the electrostatic potential in the front of the terrestrial bow shock in the quasi-perpendicular regime. High-amplitude electric fields (up to 70 mV m-1) were measured at the shock fronts encountered on 31 March 2001. The m…
Tomographic Separation of Composite Spectra. IX. The Massive Close Binary HD 115071
Gies, Douglas R.; Stickland, D. J.; Lloyd, C. +2 more
We present the first orbital elements for the massive close binary HD 115071, a double-lined spectroscopic binary in a circular orbit with a period of 2.73135+/-0.00003 days. The orbital semiamplitudes indicate a mass ratio of M2/M1=0.58+/-0.02, and yet the stars have similar luminosities. We used a Doppler tomography algorit…
The radio galaxy 3C 356 and clues to the trigger mechanisms for powerful radio sources
Simpson, Chris; Rawlings, Steve
We present deep near-infrared images, taken with the Subaru Telescope, of the region around the z=1.08 radio source 3C 356 which show it to be associated with a poor cluster of galaxies. We discuss evidence that this cluster comprises two subclusters traced by the two galaxies previously proposed as identifications for 3C 356, which both seem to h…
Constraints on the Size Evolution of Brightest Cluster Galaxies
Gonzalez, Anthony H.; Zaritsky, Dennis; Dalcanton, Julianne J. +2 more
We measure the luminosity profiles of 16 brightest cluster galaxies (BCGs) at 0.4<z<0.8 using high-resolution F160W NICMOS and F814W WFPC2 Hubble Space Telescope imaging. The heterogeneous sample is drawn from a variety of surveys: seven from clusters in the Einstein Medium Sensitivity Survey, five from the Las Campanas Distant Cluster Surve…
FUSE Observations of the Cygnus Loop: O VI Emission from a Nonradiative Shock
Blair, William P.; Sankrit, Ravi
We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of a Balmer filament in the northeast region of the Cygnus Loop supernova remnant. The data consist of one spectrum obtained through the 30''×30'' (LWRS) aperture and three spectra at adjacent positions obtained through the 4''×20'' (M…
Temporal variability in the Doppler-shift of solar transition region lines
Doyle, J. G.; Madjarska, M. S.; Teriaca, L. +2 more
High cadence datasets taken in C III 977 Å, O VI 1032 Å and Ne VIII 720 Å were analysed in an effort to establish the extent of the variability in the Doppler-shift of typical mid-transition region lines. The shortest time-scale variability seems to occur in the network boundary regions where the line-shift can vary by 7-8 km s-1 in les…
Structure and Dynamics of Candidate O Star Bubbles in N44
Oey, M. S.; Nazé, Yaël; Guerrero, Martín A. +3 more
Dynamical studies of superbubbles and Wolf-Rayet ring nebulae show discrepancies from the standard adiabatic model for windblown bubbles. We therefore study the physical properties and kinematics of three candidate bubbles blown by single O stars to evaluate whether these discrepancies are also found in these simpler objects. Our sample candidates…
Small scale structure in circumstellar envelopes and the origin of globules in planetary nebulae
Mauron, N.; Huggins, P. J.
We analyze the small scale structure in the circumstellar envelopes of NGC 7027 and IRC+10216, using high resolution optical images in dust scattered light. We use the observations to test the proposal that globules in planetary nebulae, typified by globules in the Helix nebula, originate in high density contrast proto-globules in the atmosphere o…
Hubble Space Telescope Imaging of Bipolar Nuclear Shells in the Disturbed Virgo Cluster Galaxy NGC 4438
Kenney, Jeffrey D. P.; Yale, Elizabeth E.
We present broadband and narrowband Hubble Space Telescope (HST) images of the central region of the heavily disturbed Virgo cluster galaxy NGC 4438 (Arp 120), whose nucleus has been described as a type 1 LINER or dwarf Seyfert galaxy. Narrowband Hα and [N II] HST images reveal striking bipolar shell features, 1 kpc in projected length from end to…