Search Publications
The mass distribution of a moderate redshift galaxy group and brightest group galaxy from gravitational lensing and kinematics
Vegetti, S.; McKean, J. P.; Treu, T. +6 more
The gravitational lens system CLASS B2108+213 has two radio-loud lensed images separated by 4.56 arcsec. The relatively large image separation implies that the lensing is caused by a group of galaxies. In this paper, new optical imaging and spectroscopic data for the lensing galaxies of B2108+213 and the surrounding field galaxies are presented. T…
Temporal downflows in a penumbra
Katsukawa, Y.; Jurčák, J.
Aims: We analyze temporal downflow patches that are located in a penumbra and have the same polarity of the magnetic field as a sunspot umbra.
Methods: The repetitive 2'' wide raster scans of penumbral regions that are taken with one minute cadence by the Hinode spectropolarimeter are used to detect the line-of-sight velocities in the pe…
The ISO Long Wavelength Spectrometer line spectrum of VY Canis Majoris and other oxygen-rich evolved stars
Menten, K. M.; White, G. J.; van der Tak, F. F. S. +1 more
Context. The far-infrared spectra of circumstellar envelopes around various oxygen-rich stars were observed using the ISO Long Wavelength Spectrometer (LWS). These have been shown to be spectrally rich, particularly in water lines, indicating a high H2O abundance.
Aims: We have examined high signal-to-noise ISO LWS observations of …
Total solar irradiance since 1996: is there a long-term variation unrelated to solar surface magnetic phenomena?
Steinhilber, F.
Context. Total solar irradiance (TSI) has been measured with space-based instruments since 1978. The TSI during the recent solar minimum in 2009 has been lower than the two former minima around the years 1986 and 1996, which points to a long-term decrease.
Aims: In this study, we address the question of whether the observed decrease in the TS…
Hydrodynamical simulations of viscous overstability in Saturn’s rings
Ogilvie, Gordon I.; Latter, Henrik N.
We perform axisymmetric hydrodynamical simulations that describe the nonlinear outcome of the viscous overstability in dense planetary rings. These simulations are particularly relevant for Cassini observations of fine-scale structure in Saturn's A and B-ring, which take the form of periodic microstructure on the 0.1 km scale, and irregular larger…
Ultraviolet-bright Stellar Populations and Their Evolutionary Implications in the Collapsed-core Cluster M15
Anderson, Jay; Cool, Adrienne M.; Serenelli, Aldo M. +4 more
We performed deep photometry of the central region of the Galactic globular cluster M15 from archival Hubble Space Telescope data taken on the High Resolution Channel and Solar Blind Channel of the Advanced Camera for Surveys. Our data set consists of images in far-UV (FUV140; F140LP), near-UV (NUV220; F220W), and blue (B
High-Resolution UV Absorption Observations of the Local Interstellar Cavity
Welsh, Barry Y.; Lallement, Rosine
We present far-ultraviolet (1245-1680 Å), high-resolution (R ∼ 3 km s-1) spectroscopic observations of three early-type stars (HD 32630, HD 158427, and HD 175191) located within 75 pc of the Sun recorded with the recently refurbished HST-STIS instrument. These data have allowed an absorption study of the local interstellar gas to invest…
High resolution analysis of the ν26 and 2ν9-ν9 bands of propane: modelling of Titan's infrared spectrum at 13.4 µm
Nixon, C. A.; Flaud, J. -M.; Kwabia Tchana, F. +1 more
Using high-resolution Fourier transform spectra of propane recorded in the 13.4 µm (resolution 0.002 cm-1) and in the 27.4 µm (resolution 0.0011 cm-1) spectral regions, it was possible to perform a thorough assignment of both the ν26 band at 745 cm-1 and the 2ν9-ν9 band at about 370…
Early Observations by the GOES-13 Solar Extreme Ultraviolet Sensor (EUVS)
Plunkett, S. P.; Evans, J. S.; McMullin, D. R. +6 more
NOAA's GOES-13 satellite, launched in May 2006, includes a new solar sensor, called EUVS (Extreme UltraViolet Sensor), that measures energy fluxes in five broad-band spectral channels that span the region from 1 to 130 nm. Here, we report on measurements made during the mission's six-month post-launch test (PLT) period which provided nearly contin…
Characteristics of Langmuir electric field waveforms and power spectra exhibiting nonlinear behavior in Earth's foreshock
Gurnett, D. A.; Pickett, J. S.; Lucek, E. +6 more
Langmuir wave characteristics in the Earth's foreshock were examined to identify possible nonlinear wave behavior for two case studies with data from the Cluster Wideband Data Plasma Wave Receiver. The occurrence rates of four types of power spectra near the foreshock edge were determined: (1) spectra with power at the local plasma frequency f