Search Publications
Fast, Gusty Winds Blowing from the Core of the Pre-planetary Nebula M 2-56
Sánchez Contreras, C.; Bujarrabal, V.; Miranda, L. F. +2 more
We report optical long-slit spectra and direct imaging (ground-based and with the Hubble Space Telescope (HST)) of the pre-planetary nebula M 2-56 obtained at different epochs. The optical nebula is composed of shock-excited material distributed in two pairs of nested lobes with different sizes and surface brightness. The compact, bright inner lob…
Multiwavelength Observations of the Hot DB Star PG 0112+104
Kruk, J. W.; Chayer, P.; Fontaine, G. +8 more
We present a comprehensive multiwavelength analysis of the hot DB white dwarf PG 0112+104. Our analysis relies on newly acquired FUSE observations, on medium-resolution FOS and GHRS data, on archival high-resolution GHRS observations, on optical spectrophotometry both in the blue and around Hα, as well as on time-resolved photometry. From the opti…
Photospheric Radius Expansion During Magnetar Bursts
Watts, Anna L.; Kouveliotou, Chryssa; Göǧüş, Ersin +6 more
On 2008 August 24 the new magnetar SGR 0501+4516 (discovered by Swift) emitted a bright burst with a pronounced double-peaked structure in hard X-rays, reminiscent of the double-peaked temporal structure seen in some bright thermonuclear bursts on accreting neutron stars. In the latter case this is due to Photospheric Radius Expansion (PRE): when …
Fold Lens Flux Anomalies: A Geometric Approach
Goldberg, David M.; Richards, Gordon T.; Chessey, Mary K. +1 more
We develop a new approach for studying flux anomalies in quadruply imaged fold lens systems. We show that in the absence of substructure, microlensing, or differential absorption, the expected flux ratios of a fold pair can be tightly constrained using only geometric arguments. We apply this technique to 11 known quadruple lens systems in the radi…
The Energetics of Molecular Gas in NGC 891 from H2 and Far-infrared Spectroscopy
Boulanger, F.; Charmandaris, V.; Combes, F. +5 more
We have studied the molecular hydrogen energetics of the edge-on spiral galaxy NGC 891, using a 34 position map in the lowest three pure rotational H2 lines observed with the Spitzer Infrared Spectrograph. The S(0), S(1), and S(2) lines are bright with an extinction-corrected total luminosity of ~2.8 × 107 L sun, o…
Analyzing the Low State of EF Eridani with Hubble Space Telescope Ultraviolet Spectra
Holtzman, Jon; Walter, Frederick M.; Harrison, Thomas E. +10 more
Time-resolved spectra throughout the orbit of EF Eri during its low accretion state were obtained with the solar blind channel on the Advanced Camera for Surveys on board the Hubble Space Telescope. The overall spectral distribution exhibits peaks at 1500 and 1700 Å, while the UV light curves display a quasi-sinusoidal modulation over the binary o…
Significant X-ray Line Emission in the 5-6 keV Band of NGC 4051
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +4 more
A Suzaku X-ray observation of NGC 4051 taken during 2005 November reveals line emission at 5.44 keV in the rest frame of the galaxy which does not have an obvious origin in known rest-frame atomic transitions. The improvement to the fit statistic when this line is accounted for establishes its reality at >99.9% confidence: we have also verified…
Ultraluminous X-ray Sources in Arp 147
Rappaport, S.; Levine, A.; Pooley, D. +1 more
The Chandra X-Ray Observatory was used to image the collisional ring galaxy Arp 147 for 42 ks. We detect nine X-ray sources with luminosities in the range of (1.4-7) × 1039 erg s-1 (assuming that the sources emit isotropically) in or near the blue knots of star formation associated with the ring. A source with an X-ray lumino…
X-Ray and Optical Study of Low Core Density Globular Clusters NGC6144 and E3
Anderson, Scott F.; Kong, Albert K. H.; Verbunt, Frank +4 more
We report on the Chandra X-ray Observatory and Hubble Space Telescope (HST) observations of two low core-density globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found six X-ray sources within the half-mass radius of NGC6144, of which four are expected to be background sou…
Chromospheric Signatures of Small-scale Flux Emergence as Observed with New Solar Telescope and Hinode Instruments
Chae, J.; Goode, P. R.; Abramenko, V. I. +4 more
With the ever-increasing influx of high-resolution images of the solar surface obtained at a multitude of wavelengths, various processes occurring at small spatial scales have become a greater focus of our attention. Complex small-scale magnetic fields have been reported that appear to have enough stored energy to heat the chromosphere. While sign…