Search Publications
Redshift survey of gravitational arclets in Abell 2390.
Soucail, G.; Bezecourt, J.
In this paper, we present new determinations of redshifts on a sample of gravitational arclets identified in the cluster of galaxies Abell 2390. The arclets candidates were selected from their elongated morphology as seen in recent deep HST images of the cluster. The spectra display various features, and the redshifts of the background objects ran…
HD 111786: a spectroscopic binary λ Boo star.
Gerbaldi, M.; Faraggiana, R.; Burnage, R.
HD 111786 = HR 4881 is one of the most interesting λ Boo stars; in fact it is one of the few stars of this class which shows narrow features that can be interpreted as remnants of the circumstellar matter from which star was formed. On the basis of optical observations and inspection of IUE spectra, we demonstrate that HD 111786 is, as a matter of…
An estimate of the solar background irradiance power spectrum.
Rabello-Soares, M. C.; Roca Cortes, T.; Jimenez, A. +2 more
Knowledge of the solar irradiance background is of great importance to solar and stellar physics. In particular, its contribution to the solar oscillations power spectrum is highly relevant as it represents the ultimate limit to the sensitivity of solar oscillations' observations. An analysis of the power spectra of the solar photometric data comi…
The Amount of CH Produced during CH+ Synthesis in Interstellar Clouds
Welty, D. E.; Federman, S. R.; Cardelli, Jason A.
A particularly useful constraint for models of CH+ formation in interstellar clouds is knowledge of the amount of CH associated with CH+ synthesis. For lines of sight with no detectable CN absorption, this column of CH can be inferred through a combined analysis of C I excitation and simplified chemical models. The approach i…
Doppler imaging of stellar surface structure. III. The X-ray source HD 116544 = IN Virginis.
Strassmeier, K. G.
We present the first Doppler image of the EXOSAT X-ray source EXO 1321.8-0203, recently identified to be a chromospherically active star exhibiting periodic light variations and consequently named INVirginis. Our high-resolution spectra show INVirginis to be a single-lined spectroscopic binary with an orbital period of 8.2 days, very strong CaII e…
Abell 2218: X-Ray Lensing, Merger, or Both?
Markevitch, Maxim
Comparison of the high-resolution X-ray image of A2218 obtained with the ROSAT HRI with the optical HST image shows several interesting correlations. The X-ray emission within a 1' radius core is resolved into several components; the central dominant galaxy does not coincide with either of them or with the emission centroid. The major X-ray peak i…
Pre-eclipse dips in the ultraviolet light curves of two eclipsing nova-like cataclysmic variables
Knigge, C.; Mason, K. O.; Drew, J. E.
Observations of the eclipsing nova-like variables UX UMa and RW Tri with the Hubble Space Telescope reveal substantial orbital modulations in their UV light. These modulations have a minimum about a quarter of an orbital cycle before eclipse. The modulation is deeper in RW Tri, which has the higher orbital inclination of the two binaries. The resi…
Bi-Dimensional Spectrography at HST-Like Spatial Resolution: [OIII] Kinematics and Ionization in the NLR of NGC 1068
Binette, L.; Wilson, A. S.; Ferruit, P. +1 more
We present a study at HST-like spatial resolution of the gas kinematics in the innermost part of NGC 1068. This work is based on observations with the integral field spectrograph TIGER mounted on the CFH Telescope. We first derived the final spatial PSF of our data and checked its photometric integrity by comparison with two independent [OIII] HST…
Globular Cluster Photometry with the Hubble Space Telescope.VI.WF/PC-I Observations of the Stellar Populations in the Core of M13 (NGC 6205)
Schneider, Donald P.; Yanny, Brian; Bahcall, John N. +2 more
We study the dense core of the globular cluster Messier 13 (NGC 6205) using pre-refurbishment Planetary Camera-I images obtained with the Hubble Space Telescope. Short exposures (60 s) through the F555W and F785LP filters (similar to Johnson V and I, respectively) have been used to obtain V and I photometry of 2877 stars brighter than V ~ 20 in a …
Signatures of Acoustic and Magnetic Waves in Solar and Stellar Coronae
Judge, Philip G.; Hansteen, Viggo H.; Wikstøl, Øivind
Time-dependent dynamical calculations of the radiating gas in solar coronal flux tubes are used to identify features of UV spectral-line profiles that can reveal the direction in which wave energy flows through the solar transition region. The profile features survive spatial and temporal averaging through nonlinear dependencies of line emission c…