Search Publications
The long-term behaviour of the pulsation periods and amplitudes of the β Cephei star 16 (EN) Lacertae
Pigulski, A.; Jerzykiewicz, M.
The blue-light observations of this pulsating and eclipsing variable (BCEP+EA) cover an interval from 1950 to 1992. The out-of-eclipse (that is, pulsational) variation contains three sinusoidal terms with variable amplitudes. In our 1996 paper (JP96), based on the 1950-1983 data, we showed that for the first two terms, having frequencies equal to …
Sinusoidal variables from the Tycho Epoch Photometry Annex
Koen, Chris; Schumann, Robert
The Tycho Epoch Photometry Annex A, a data base of photometry of more than 34 000 bright stars, has been searched for periodic variable stars with approximately sinusoidal light curves. Advantage was taken of special properties of the observing programme (photometry in two wavebands, availability of repeated measurements) to use simple but efficie…
The Hubble Deep Field North reveals a supernova at z~0.95
Mannucci, F.; Ferrara, A.
We report the discovery of a variable object in the Hubble Deep Field North (HDF-N) which brightened, during the 8.5d sampled by the data, by more than 0.9mag in I_814 and about 0.7mag in V_606, remaining stable in B_450. Subsequent observations of the HDF-N show that two years later this object has dimmed to about its original brightness in I_814…
Is LkHα 264 like a young, extremely active Sun?
Gameiro, J. F.; Costa, V. M.; Lago, M. T. V. T.
We combine calibrated International Ultraviolet Explorer (IUE) archive data and new low-resolution optical data for the T Tauri star LkHα 264 covering the region from 1200 to 7000Å. The UV continuum is well fitted by the combination of a blackbody at 4300K plus hydrogenic free-free and free-bound emission from a dense plasma at 3.5x10^4K plus the …
Candidate high-redshift and primeval galaxies in Hubble Deep Field South
Clements, D. L.; Eales, S. A.; Baker, A. C.
We present the results of colour selection of candidate high-redshift galaxies in Hubble Deep Field South (HDF-S) using the Lyman dropout scheme. The HDF-S data we discuss were taken in a number of different filters extending from the near-UV (F300W) to the infrared (F222M) in two different fields. This allows us to select candidates with redshift…
The optical/near-infrared broad-line emission and hard X-ray continuum of active galactic nuclei and ultraluminous infrared galaxies
Imanishi, Masatoshi; Ueno, Shiro
We compare the luminosities of the hard X-ray and optical/near-infrared broad-line emission from active galactic nuclei (AGNs) and ultraluminous infrared galaxies (ULIRGs). Both types of emission are thought to be good indicators of activity driven by supermassive black holes. We selected objects for which both X-ray and broad-line data are availa…
Understanding the atmospheric structure of T Tauri stars - I. Improved atomic physics applied to IUE data of BP Tauri
Lanzafame, A. C.; Brooks, D. H.; Costa, V. M. +1 more
Recent advances in modelling the radiating character of dynamic laboratory and astrophysical plasmas are applied here in a new examination of the properties of the atmosphere of the classical T Tauri star BP Tau. We analyse archived International Ultraviolet Explorer (IUE) UV spectra of BP Tau. We adopt a collisional-radiative model and utilize em…
[Alii] in the ultraviolet spectrum of the symbiotic star RR Telescopii
Feibelman, W. A.; Mathioudakis, M.; Keenan, F. P. +4 more
An inspection of a GHRS/HST spectrum of the symbiotic star RR Telescopii reveals the presence of the [Alii] 3s^2 ^1S - 3s3p ^3P_2 line at a vacuum wavelength of 2661.06+/-0.08Å, 8.89+/-0.08Å away from the Alii] 3s^2 ^1S - 3s3p ^3P_1 intercombination transition at 2669.95Å, in good agreement with the theoretical prediction of Δλ=8.80Å. We also find…
An ISO survey of possible water and hydroxyl IRASER transitions towards the star-forming regions W49, W3(OH) and Sgr B2M
Gray, M. D.; Yates, J. A.
We report ISO LWS observations towards the star-forming regions W49N, W3(OH) and Sgr B2M in LWS04 mode (high-resolution Fabry-Perot scans). Possible far-infrared laser emission was detected in a water line at 133.55µm towards W49N, but the spectral resolution was inadequate to establish firmly the nature of the emission. An additional water …
Calibration of the Faber--Jackson relation for M31 globular clusters using HIPPARCOS data
Paturel, G.; Lanoix, P.; Di Nella-Courtois, H.
In this paper we present data analysis regarding globular clusters as possible extragalactic distance indicators. For this purpose, we collected all velocity dispersion measurements published for Galactic and M31 globular clusters. The slope and zero-point of the Faber--Jackson relation were calibrated using Hipparcos distance measurements, and th…