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ISOCAM images at 6.75mu M and 15mu m: the circumnuclear region of NGC4321 (M100)
Martinet, L.; Wozniak, H.; Friedli, D. +1 more
We present ISOCAM images (1.5\arcsec px(-1) ) in the LW2 (6.75mu m) and LW3 (15mu m) broad band filters of the circumnuclear starburst of NGC4321 (M100). A detailed comparison with the emission at other wavelengths (U, B, Hα , and CO) is also presented. The nature and intensity of the mid-infrared emission is shown to be remarkably different from …
Pulsation of the lambda Bootis stars HD 111786 and HD 142994
Paunzen, E.; Matthews, J. M.; Kuschnig, R. +3 more
The detection of possible nonradial pulsation modes among some lambda Bootis stars offers the prospect of using asteroseismology to determine their masses and ages, thereby testing competing theories for the origin of their chemical peculiarities. As a step toward this goal, we conducted multi-site photometric campaigns spanning two weeks each for…
Simultaneous intensive photometry and high resolution spectroscopy of delta Scuti stars. III. Mode identifications and physical calibrations in HD 2724
Mantegazza, L.; Bossi, M.; Nunez, N. S.
On the basis of our new simultaneous photometry and spectroscopy (885 \( uvby \) differential measurements in 11 nights and 154 spectrograms of the FeII\( \lambda \)4508 region in 5 nights), we can detect 12 probable periodicities in the variability pattern of this star, determining the frequencies of 7 without any ambiguity. Through a direct fit …
Ultraviolet Observations of the Hot R Coronae Borealis-Type Star V348 Sagittarii during a Deep Minimum
Clayton, Geoffrey C.; Jeffery, C. S.; Drilling, John S. +1 more
We obtained three high-quality ultraviolet spectra of the hot R Coronae Borealis type star V348 Sgr using the Faint Object Spectrograph of the Hubble Space Telescope (HST). The first of these spectra was obtained when the star was in a shallow minimum (ΔV less than 1 mag), whereas the other two were obtained during a deep minimum (ΔV ~ 6 mag). Whi…
VCC 144: a star-bursting dwarf galaxy in the Virgo cluster
Brosch, N.; Almoznino, E.; Hoffman, G. Lyle
We describe results of a multi-spectral study of a blue compact dwarf galaxy in the Virgo Cluster. The object was observed with broad-band and Hα imaging, ultraviolet observations, and radio synthesis. Our data were combined with previously published optical observations, with HI single-beam observation and with far-infrared data, and were compare…
Bayesian image reconstruction with space-variant noise suppression
Nunez, J.; Llacer, J.
In this paper we present a Bayesian image reconstruction algorithm with entropy prior (FMAPE) that uses a space-variant hyperparameter. The spatial variation of the hyperparameter allows different degrees of resolution in areas of different statistical characteristics, thus avoiding the large residuals resulting from algorithms that use a constant…
The solar transition region: a time-varying interface between the chromosphere and corona?
Doyle, J. G.; Keenan, F. P.; O'Shea, E.
Using joint observations taken with the CDS and SUMER instruments onboard SOHO, we re-examine the solar transition region in an attempt to determine whether it is de-coupled from the over-lying coronal region. Line ratios calculated from temporal series observations of O iv and Fe xiii spectral lines were converted to electron density, and hence e…
Serendipitous Discovery of a Broad Absorption Line QSO at Z = 2.169
Roth, Katherine C.; Stockton, Alan; Canalizo, Gabriela
We report the serendipitous discovery of a broad absorption line (BAL) QSO at z = 2.169, located 41" southwest of 3C 48. We present Keck Low Resolution Imaging Spectrometer spectroscopy covering rest-frame wavelengths 1500-2300 Å. The C iv BAL has three components, and it extends to outflow velocities of at least 12,000 km s^-1. The BAL QSO has an…
A New Technique for Performing Two-Dimensional Spectroscopy of Objects of Large Dynamic Range: The Binary System HD 167605 A+B
Arribas, S.; Mediavilla, E.; Fuensalida, J. J.
We present a new technique for performing two-dimensional (integral-field) spectroscopy of objects with a large range in intensity. It is based on the capability of optical fibers to discretize the intensity distribution at the telescope focal plane. This allows not only reformatting but also the equalization of fiber output intensities, matching …
The Complex IUE Spectrum of the ``O VI Sequence'' Planetary Nebula NGC 2867
Feibelman, Walter A.
The IUE spectrum of the planetary nebula NGC 2867 and its central star displays a rich variety of emission lines that has not been reported before. Fluxes for more than 80 UV features were determined from low- and high-dispersion spectra. Electron densities of log Ne = 3.4 +/- 0.1 cm-3 from C III], log Ne = 3.9 +/-…