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A Test of Three Optical Flow Techniques—LCT, DAVE, and NAVE
Chae, Jongchul; Sakurai, Takashi
A time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space may be utilized to determine the transverse flow field on the plane of the sky with the help of optical flow techniques. We have examined the performance of three different methods—a well-known technique called local correla…
Observational Test of Coronal Magnetic Field Models. I. Comparison with Potential Field Model
Liu, Yu; Lin, Haosheng
Recent advances have made it possible to obtain two-dimensional line-of-sight magnetic field maps of the solar corona from spectropolarimetric observations of the Fe XIII 1075 nm forbidden coronal emission line. Together with the linear polarization measurements that map the azimuthal direction of the coronal magnetic field projected in the plane …
X-Ray and Near-IR Variability of the Anomalous X-Ray Pulsar 1E 1048.1-5937: From Quiescence Back to Activity
Kaspi, Victoria M.; Bassa, Cees; Woods, Peter M. +3 more
We report on new and archival X-ray and near-IR observations of the anomalous X-ray pulsar 1E 1048.1-5937 performed between 2001 and 2007 with the Rossi X-Ray Telescope Explorer (RXTE), the Chandra X-Ray Observatory, the Swift Gamma-Ray Burst Explorer, the Hubble Space Telescope (HST), and the Very Large Telescope. Monitoring with RXTE revealed th…
Constraining Cosmic Evolution of Type Ia Supernovae
Becker, A. C.; Sollerman, J.; Spyromilio, J. +27 more
We present a large-scale effort of creating composite spectra of high-redshift SNe Ia and comparing them to low-redshift counterparts in an attempt to understand possible cosmic evolution of SNe Ia, which has major implications for studies of dark energy. Through the ESSENCE project, we have obtained 107 spectra of 88 high-redshift SNe Ia with exc…
3D Magnetic Field Configuration of the 2006 December 13 Flare Extrapolated with the Optimization Method
Ding, M. D.; Li, H.; Guo, Y. +1 more
The photospheric vector magnetic field of the active region NOAA 10930 was obtained with the Solar Optical Telescope (SOT) on board the Hinode satellite with a very high spatial resolution (about 0.3''). Observations of the two-ribbon flare on 2006 December 13 in this active region provide us a good sample to study the magnetic field configuration…
The Dearth of UV-Bright Stars in M32: Implications for Stellar Evolution Theory
Ferguson, Henry C.; Brown, Thomas M.; Kimble, Randy A. +3 more
Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we have obtained deep, far-ultraviolet images of the compact elliptical galaxy M32. When combined with earlier near-ultraviolet images of the same field, these data enable the construction of an ultraviolet color-magnitude diagram of the hot horizontal branch (HB) popula…
The Search for Muon Neutrinos from Northern Hemisphere Gamma-Ray Bursts with AMANDA
Kuehn, K.; Kowalski, M.; Ackermann, M. +223 more
We present the results of the analysis of neutrino observations by the Antarctic Muon and Neutrino Detector Array (AMANDA) correlated with photon observations of more than 400 gamma-ray bursts (GRBs) in the northern hemisphere from 1997 to 2003. During this time period, AMANDA's effective collection area for muon neutrinos was larger than that of …
Binarity in Cool Asymptotic Giant Branch Stars: A GALEX Search for Ultraviolet Excesses
Sahai, R.; Sánchez Contreras, C.; Gil de Paz, A. +1 more
The search for binarity in AGB stars is of critical importance for our understanding of how planetary nebulae acquire the dazzling variety of aspherical shapes which characterizes this class. However, detecting binary companions in such stars has been severely hampered due to their extreme luminosities and pulsations. We have carried out a small i…
Stellar Wind Variations during the X-Ray High and Low States of Cygnus X-1
Crenshaw, D. M.; Kaper, L.; Herrero, A. +10 more
We present results from Hubble Space Telescope ultraviolet spectroscopy of the massive X-ray and black hole binary system, HD 226868 = Cyg X-1. The spectra were obtained at both orbital conjunction phases in 2002 and 2003, when the system was in the X-ray high/soft state. The UV stellar wind lines suffer large reductions in absorption strength whe…
Complex Organic Materials in the Circumstellar Disk of HR 4796A
Weinberger, Alycia J.; Debes, John H.; Schneider, Glenn
We combine HST NICMOS imaging photometry of the HR 4796A disk at previously unobserved wavelengths between 1.71-2.22 µm with reprocessed archival observations to produce a measure of the dust's scattering efficiency as a function of wavelength. The spectrum of the dust, synthesized from the seven photometric measures, is characterized by a s…