Search Publications
A multiwavelength study of the starburst galaxy NGC7771
Alonso-Herrero, Almudena; Davies, Richard I.; Ward, Martin J.
We present a multiwavelength study of the interacting starburst galaxy NGC7771, including new optical and ultraviolet spectra and a previously unpublished soft X-ray ROSAT image and spectrum. The far-infrared, radio and X-ray fluxes suggest that a massive burst of star formation is currently in progress, but the small equivalent width of the Balme…
Circumstellar PAHs and Carbon Stardust
Tielens, A. G. G. M.
The SWS on ISO has revealed the incredible richness of IR emission features in the spectra of post-AGB objects and planetary nebulae. Besides the well known features at 3.3, 6.2, 7.7, 8.6, and 11.3 µm, a wealth of weaker features is present as well. These studies also reveal detailed variations from source to source, which may be of key impo…
Refined analysis of interplanetary H-Lyα spectra obtained with the Hubble-Space Telescope GHRS spectrometer.
Clarke, J. T.; Scherer, H.; Fahr, H. J.
Here we present a new synoptic analysis of 5 HST-GHRS interplanetary H-Lyα spectra obtained at different lines of sight from different positions of the earth in its orbit. The spectral analysis aimed at the derivation of actual interstellar gas parameters is carried out on the basis of a newly developed Lyα radiation transport code taking into acc…
Multicolor CCD Photometry of the Poorly Studied Globular Cluster NGC 6541
Alcaino, G.; Liller, W.; Alvarado, F. +3 more
We have carried out the first accurate multicolor (UBVRI) CCD photometry for more than 3000 stars (12m.3<V<21m.0) in the field of the globular cluster NGC 6541. This cluster was neglected in photometric studies after two photographic investigations by Alcaino (1971, A&A;, 13, 399; 1979, A&AS, 35, 233). The color…
Spectral Components in the Optical Emission of the Seyfert Galaxy NGC 5548 and the Comparison of Intrinsic Nuclear Spectra with Accreting Corona Model
Czerny, B.; Kuraszkiewicz, J.; Loska, Z.
We study the extensively monitored Seyfert galaxy NGC 5548 and compare its nuclear emission with models of accretion disk with accreting corona. To obtain the intrinsic nuclear spectra from the observed spectra we had to estimate and subtract the contribution from circumnuclear components such as stars, the Balmer continuum and blended FeII lines,…
The Greatly Expanded IUE Spectrum of the Planetary Nebula NGC 2371-2 and Its Central Star
Feibelman, Walter A.
Early IUE low-dispersion SWP and LWR spectra have been reexamined by means of refined current data reduction routines. These spectra contain much more information than was reported in 1981. A high-dispersion SWP spectrum was obtained in 1994 from which more than 80 emission and absorption features were identified, and log Ne = 3.0 +/- 0…
Ultraviolet and Optical Observations of Hen 1213, Hen 1341, and Hen 1761
Feibelman, W. A.; Gutiérrez-Moreno, A.; Moreno, H. +1 more
We present UV observations of the symbiotic stars Hen 1213, Hen 1341, and Hen 1761, made almost simultaneously with optical observations during 1995; previous optical observations were made during 1987 and 1991. The UV spectrum of Hen 1213 was badly affected by background radiation, and only a rough description of the spectrum could be given here;…
The Extremely Active Single Giant 1E 1751+7046 = ET Draconis: Revised Properties and a Reevaluation of Its Evolutionary Status
Guinan, Edward F.; Hrivnak, Bruce J.; Fekel, Francis C. +1 more
New spectroscopic observations have resulted in significant revisions to several of the orginally published properties of the X-ray bright, chromospherically active star 1E 1751+7046: the spectral classification has been revised from K5 IV to K0 III, v sin i from 30-40 km s-1 to 23 km s-1, and the reported nondetection of the…
Convection, Thermal Bifurcation, and the Colors of A Stars
Simon, Theodore; Landsman, Wayne B.
Broadband ultraviolet photometry from the TD-1 satellite and low-dispersion spectra from the short wavelength camera of IUE have been used to investigate a long-standing proposal of Böhm-Vitense that the normal main-sequence A and early-F stars may divide into two different temperature sequences: (1) a high-temperature branch (and plateau) compris…
The FUOR characteristics of the PMS star BN Orionis inferred from new spectroscopic and photometric observations
de Winter, D.; van den Ancker, M. E.; Tjin A Djie, H. R. E. +3 more
BN Ori is a young emission-line star with a peculiar light curve. During the first half of this century the star showed strong irregular brightness- variations, similar to those of Herbig Ae stars. In the current half of the century the light curve resembles that of a FU Ori-object (FUOR, after Ambartsumian 1971). It can be characterised by an ini…