Search Publications
The Mass Distribution of the Central Stars of Planetary Nebulae in the Large Magellanic Cloud
Villaver, Eva; Shaw, Richard A.; Stanghellini, Letizia
We present the properties of the central stars from a sample of 54 planetary nebulae (PNe) observed in the Large Magellanic Cloud (LMC) with the Hubble Space Telescope Imaging Spectrograph (STIS). The Hubble Space Telescope's spatial resolution allows us to resolve the central star from its nebula (and line-of-sight stars) at the distance of the L…
A Low-Mass H2 Component to the AU Microscopii Circumstellar Disk
Redfield, Seth; Roberge, Aki; France, Kevin +2 more
We present a determination of the molecular gas mass in the AU Microscopii circumstellar disk. Direct detection of a gas component to the AU Mic disk has proven elusive, with upper limits derived from ultraviolet absorption line and submillimeter CO emission studies. Fluorescent emission lines of H2, pumped by the O VI λ1032 resonance l…
Integral-Field Spectroscopy of the Post-Red Supergiant IRC +10420: Evidence for an Axisymmetric Wind
Sahu, Kailash C.; Davies, Ben; Oudmaijer, René D.
We present NAOMI/OASIS adaptive-optics-assisted integral-field spectroscopy of the transitional massive hypergiant IRC +10420, an extreme mass-losing star apparently in the process of evolving from a red supergiant toward the Wolf-Rayet phase. To investigate the present-day mass-loss geometry of the star, we study the appearance of the line emissi…
A Synthetic Spectrum and Light-Curve Analysis of the Cataclysmic Variable IX Velorum
Szkody, Paula; Sion, Edward M.; Godon, Patrick +2 more
Spectrum synthesis analysis of FUSE and STIS spectra for the cataclysmic variable IX Vel shows that it is possible to achieve a close synthetic spectrum fit with a mass transfer rate of M˙=5×10-9 Msolar yr-1 and a modified standard model temperature profile. The innermost four annuli of the accretion disk model, ex…
The Linear Sensitivity of Helioseismic Ring Diagrams to Local Flows
Birch, A. C.; Gizon, L.; Hindman, B. W. +1 more
Ring-diagram analysis is a technique of local helioseismology used to infer plasma flows in the solar convection zone which generates intermediate data products known as ring-fitting parameters. Knowing the sensitivity of ring-fitting parameters to actual flows in the Sun is important for interpreting these measurements. Working in plane-parallel …
X-Ray and Optical Variability of the Ultraluminous X-Ray Source NGC 1313 X-2
Falomo, R.; Treves, A.; Turolla, R. +2 more
We present an analysis of recent XMM-Newton and HST archive data of the ultraluminous X-ray source NGC 1313 X-2. Quasi-simultaneous observations taken with XMM-Newton, HST, and VLT allow us to study both the X-ray light curve and its correlation with the optical emission of the two proposed counterparts of the ultraluminous X-ray source (ULX). At …
Helioseismic Holography of Simulated Solar Convection and Prospects for the Detection of Small-Scale Subsurface Flows
Birch, A. C.; Braun, D. C.; Nordlund, Å. +2 more
We perform helioseismic holography on realistic solar convection simulations and compare the observed travel-time perturbations with the expected travel times from the horizontal flows in the simulations computed from forward models under the assumption of the Born approximation. We demonstrate reasonable agreement between the observed and model t…
Chandra Observations of Candidate ``True'' Seyfert 2 Nuclei
Shields, Joseph C.; Pogge, Richard W.; Mathur, Smita +2 more
The unification model for AGNs posits that Seyfert 2 galaxies are intrinsically like Seyfert 1 galaxies, but that their broad-line regions (BLRs) are hidden from our view. A Seyfert 2 nucleus that truly lacked a BLR, instead of simply having it hidden, would be a so-called true Seyfert 2. No object has as yet been conclusively proven to be one. We…
Far-Infrared Characterization of an Ultraluminous Starburst Associated with a Massively Accreting Black Hole at z=1.15
Elbaz, D.; Le Floc'h, E.; Maiolino, R. +24 more
As part of the All-Wavelength Extended Groth Strip International Survey (AEGIS), we describe the panchromatic characterization of an X-ray-luminous active galactic nucleus (AGN) in a merging galaxy at z=1.15. This object is detected at infrared (8, 24, 70, and 160 µm), submillimeter (850 µm), and radio wavelengths, from which we derive…
Sizes of Confirmed Globular Clusters in NGC 5128: A Wide-Field High-Resolution Study
Woodley, Kristin A.; Gómez, Matías
Using Magellan/IMACS images covering a 1.2 × 1.2 deg2 field of view with seeing of 0.4"-0.6", we have applied convolution techniques to analyze the light distribution of 364 confirmed globular clusters in the field of NGC 5128 and to obtain their structural parameters. Combining these parameters with existing Washington photometry from …