Search Publications
The weak magnetic field of the O9.7 supergiant ζOrionisA
Bouret, J. -C.; Martins, F.; Donati, J. -F. +4 more
We report here the detection of a weak magnetic field of 50-100G on the O9.7 supergiant ζOrionisA (ζOriA), using spectropolarimetric observations obtained with NARVAL at the 2-m Télescope Bernard Lyot atop Pic du Midi (France). ζOriA is the third O star known to host a magnetic field (along with θ1OriC and HD191612), and the first detec…
Chandra spectroscopy of the hot star βCrucis and the discovery of a pre-main-sequence companion
Miller, Nathan A.; Cohen, David H.; Jensen, Eric L. N. +2 more
In order to test the O star wind-shock scenario for X-ray production in less luminous stars with weaker winds, we made a pointed 74-ks observation of the nearby early B giant, βCrucis (βCru B0.5III), with the Chandra High Energy Transmission Grating Spectrometer. We find that the X-ray spectrum is quite soft, with a dominant thermal component near…
The fundamental parameters of the roAp star α Circini
Tuthill, P. G.; Davis, J.; Kurtz, D. W. +12 more
We have used the Sydney University Stellar Interferometer to measure the angular diameter of α Cir. This is the first detailed interferometric study of a rapidly oscillating A (roAp) star, α Cir being the brightest member of its class. We used the new and more accurate Hipparcos parallax to determine the radius to be 1.967 ± 0.066 R⊙. W…
Effective temperatures of magnetic chemically peculiar stars from full spectral energy distributions
Lipski, Ł.; Stȩpień, K.
New determinations of effective temperatures of 23 magnetic, chemically peculiar (mCP) stars were obtained from a fit of metal-enhanced model atmospheres to the observed spectral energy distributions (SED) from ultraviolet (UV) to red. Temperatures of four more CP stars without magnetic measurements were also obtained, of which three show light va…
The angular separation of the components of the Cepheid AWPer
Massa, D.; Evans, N. R.
The 6.4d classical Cepheid AWPer is a spectroscopic binary with a period of 40yr. Analysing the centroids of Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) spectra obtained in 2001 November, we have determined the angular separation of the binary system. Although we currently have spatially resolved data for a single epoch …
Dissecting the star formation history of starburst galaxies: the case of NGC 7673
Pasquali, A.; Castangia, P.
We have collected archival data on NGC 7673 to constrain the star formation history that produced the young star clusters and the field stellar population in this galaxy during the last 2 Gyr. We have considered the sample of 50 star clusters detected by Hubble Space Telescope/WFPC2 in the UV,V and I bands and estimated their age, intrinsic redden…
A three-dimensional automated classification scheme for the TAUVEX data pipeline
Singh, Harinder P.; Murthy, Jayant; Gupta, Ranjan +3 more
In order to develop a pipeline for automated classification of stars to be observed by the Tel-Aviv University Ultra-Violet Experiment (TAUVEX) ultraviolet space telescope, we employ an artificial neural network (ANN) technique for classifying stars by using synthetic spectra in the ultraviolet (UV) region from 1250 to 3220 Å as the training set a…