Search Publications
HUBBLE SPACE TELESCOPE Survey of Clusters in Nearby Galaxies. I. Detection and Photometry
Dolphin, Andrew E.; Kennicutt, Robert C., Jr.
We have developed photometric techniques that can be applied to images with highly variable backgrounds, as well as to slightly extended objects (object size comparable to or smaller than point-spread function [PSF] size). We have shown that ordinary stellar PSF-fitting photometry can be applied to slightly extended objects provided that one appli…
XMM-Newton observations of the nearby brown dwarf LP 944-20
Bouy, Hervé; Martín, Eduardo L.
The nearby ( d=5.0 pc) brown dwarf LP 944-20 was observed with the XMM-Newton satellite on 07 January 2001. The target was detected with the Optical Monitor ( V=16.736±0.081), but it was not detected during the ≈48 ks observation with the X-ray telescopes. We determine a 3 σ upper limit for the X-ray emission from this object of LX<3…
An Upper Limit on the Temporal Variations of the Solar Interior Stratification
Eff-Darwich, A.; Korzennik, S. G.; Jiménez-Reyes, S. J. +1 more
We have analyzed changes in the acoustic oscillation eigenfrequencies measured over the past 7 years by the GONG, MDI, and LOWL instruments. The observations span the period from 1994 to 2001 that corresponds to half a solar cycle, from minimum to maximum solar activity. These data were inverted to look for a signature of the activity cycle on the…
The Ultraviolet Spectrum of the Ultracompact X-Ray Binary 4U 1626-67
Anderson, Scott F.; Wachter, Stefanie; Margon, Bruce +1 more
We have obtained Hubble Space Telescope/Space Telescope Imaging Spectrograph low-resolution ultraviolet spectra of the X-ray pulsar 4U 1626-67 (=KZ TrA); 4U 1626-67 is unusual even among X-ray pulsars because of its ultrashort binary period (P=41.4 minutes) and remarkably low mass function (<=1.3×10-6 Msolar). The far-UV s…
H2O in stellar atmospheres. II. ISO spectra of cool red giants and hydrostatic models
Kerschbaum, F.; Aringer, B.; Jörgensen, U. G.
We present 26 ISO-SWS spectra taken from a sample of 13 M-type Semiregular, Lb and Mira variables and covering the wavelength range between 2.36 and 5 mu m at a medium resolution. All of the studied objects show intense water bands producing a deep absorption dip around 2.5 mu m. Features of CO, OH, SiO and CO2 are also visible. Using t…
ISO LWS Spectra of T Tauri and Herbig AeBe stars
van Dishoeck, E. F.; Blake, G. A.; Chiang, E. I. +2 more
We present an analysis of ISO-LWS spectra of eight T Tauri and Herbig AeBe young stellar objects. Some of the objects are in the embedded phase of star-formation, whereas others have cleared their environs but are still surrounded by a circumstellar disk. Fine-structure lines of [OI] and [CII] are most likely excited by far-ultraviolet photons in …
Solar mean magnetic field variability: A wavelet approach to Wilcox Solar Observatory and SOHO/Michelson Doppler Imager observations
Liu, Wei; Hoeksema, J. Todd; Scherrer, Philip H. +2 more
Solar mean magnetic field (SMMF) measurements from the Wilcox Solar Observatory and with the SOHO/MDI instrument are described and analyzed. Even though two completely different methods of observation are used, the two data sets obtained show a strong similarity. Using continuous wavelet transforms, SMMF variability is found at a number of tempora…
Multi-wavelength spectrophotometry of EX Hydrae
Gänsicke, B. T.; Beuermann, K.; Reinsch, K. +1 more
We present phase-resolved infrared and optical spectrophotometry of the intermediate polar EX Hya supplemented by archival ultraviolet data. The spin-modulated emission from the accretion funnel and the emission from the accretion disk or ring contain substantial optically thin components. The white dwarf dominates the unmodulated flux in the ultr…
Strongly absorbed quiescent X-ray emission from the X-ray transient XTE J0421+56 (CI Cam) observed with XMM-Newton
Orlandini, M.; Parmar, A. N.; Boirin, L. +3 more
We have observed the X-ray transient XTE J0421+56 in quiescence with XMM-Newton. The observed spectrum is highly unusual being dominated by an emission feature at ~ 6.5 keV. The spectrum can be fit using a partially covered power-law and Gaussian line model, in which the emission is almost completely covered (covering fraction of 0.98 -0.06
The FERRUM Project: Experimental oscillator strengths of the UV 8 multiplet and other UV transitions from the y6P levels of Fe II
Nilsson, H.; Johansson, S.; Hibbert, A. +2 more
We report on experimental branching fractions (BFs) for 19 transitions from the three 3d5(6S)4s4p(3P) y6P levels in Fe II, measured in Fourier transform spectra of a Penning discharge lamp and a hollow cathode lamp. The transition wavelengths span the interval between 1600 and 2850 Å. Absolute oscillator…