Search Publications
Elemental abundances of Galactic bulge planetary nebulae from optical recombination lines
Wang, W.; Liu, X. -W.
Deep long-slit optical spectrophotometric observations are presented for 25 Galactic bulge planetary nebulae (GBPNe) and six Galactic disc planetary nebulae (GDPNe). The spectra, combined with archival ultraviolet (UV) spectra obtained with the International Ultraviolet Explorer and infrared spectra obtained with the Infrared Space Observatory, ha…
The escape of Lyman photons from a young starburst: the case of Haro11†
Hayes, Matthew; Östlin, Göran; Leitherer, Claus +5 more
Lyman α (Lyα) is one of the dominant tools used to probe the star-forming galaxy population at high redshift (z). However, astrophysical interpretations of data drawn from Lyα alone hinge on the Lyα escape fraction which, due to the complex radiative transport, may vary greatly. Here, we map the Lyα emission from the local luminous blue compact ga…
Towards an understanding of the Of?p star HD 191612: optical spectroscopy
Walborn, Nolan R.; Donati, J. -F.; Herrero, A. +17 more
We present extensive optical spectroscopy of the early-type magnetic star HD 191612 (O6.5f?pe-O8fp). The Balmer and He I lines show strongly variable emission which is highly reproducible on a well-determined 538-d period. He II absorptions and metal lines (including many selective emission lines but excluding He IIλ4686 Å emission) are essentiall…
Asteroseismic signatures of stellar magnetic activity cycles
Judge, P. G.; Dziembowski, W. A.; Metcalfe, T. S. +1 more
Observations of stellar activity cycles provide an opportunity to study magnetic dynamos under many different physical conditions. Space-based asteroseismology missions will soon yield useful constraints on the interior conditions that nurture such magnetic cycles, and will be sensitive enough to detect shifts in the oscillation frequencies due to…
Structure and clumping in the fast wind of NGC6543
Prinja, R. K.; Fullerton, A. W.; Massa, D. L. +2 more
Far-ultraviolet spectroscopy from the FUSE satellite is analysed to uniquely probe spatial structure and clumping in the fast wind of the central star of the H-rich planetary nebula NGC 6543 (HD 164963). Time-series data of the unsaturated PV λλ1118, 1128 resonance line P Cygni profiles provide a very sensitive diagnostic of variable wind conditio…
Multiwavelength investigation of a near-solar metallicity sub-DLA at zabs = 1.3647 towards PKS0237-233
Petitjean, Patrick; Srianand, Raghunathan; Gupta, Neeraj
We searched for 21-cm absorption associated with the zabs = 1.3647 absorption system towards the gigahertz peaked-spectrum source PKS0237-233 using the Giant Metrewave Radio Telescope (GMRT). A high quality Ultraviolet and Visible Echelle Spectrograph (UVES) spectrum shows that CI and CI* are detected at this redshift together with CII*…
OI line emission in cool stars: calculations using partial redistribution
Jordan, C.; Koncewicz, R.
Radiative transfer calculations have been performed for five cool stars: α Tau, β Gem, Procyon, ɛ Eri and the Sun, for the purpose of investigating the behaviour of the OI emission over a wide range of stellar types, and its dependence on coherent photon scattering. These stars span a range of spectral types from F5 IV-V to K5 III and surface grav…
A spectroscopic search for non-radial pulsations in the δ Scuti star γ Bootis
Christensen-Dalsgaard, J.; Catanzaro, G.; Ventura, R. +2 more
High-resolution spectroscopic observations of the rapidly rotating δScuti star γBootis have been carried out in 2005, over six consecutive nights, in order to search for line-profile variability. Time-series, consisting of flux measurements at each wavelength bin across the TiII 4571.917 Å line profile as a function of time, have been Fourier anal…