Search Publications
Depth of excitation and reversal of asymmetry of low-l solar P modes: a complementary analysis of BiSON* and VIRGO/SPM† data
Chaplin, W. J.; Appourchaux, T.
We use the solutions to a simple, one-dimensional wave equation - which is intended to describe the essential elements of the solar resonant acoustic cavity - as formalistic models to which to fit low-l modes in observational helioseismic power spectra. We have analysed data collected in velocity, by the ground-based Birmingham Solar-Oscillations …
The kinematics of the planetary nebula BD+30 deg3639
Bryce, Myfanwy; Mellema, Garrelt
In this paper we describe the results of the first optical kinematic study of the planetary nebula BD+30 deg3639. This system has a central star of the Wolf-Rayet type and is believed to be fairly young. Emission-line spectra were obtained at high spectral and spatial resolution using the Utrecht echelle spectrometer at the William Herschel Telesc…
Magnetic braking of the present Sun
Li, Jianke
Magnetic braking is essential for angular momentum transport in late-type stars which have convective envelopes. The mechanism may be entirely responsible for the slow rotation of the present Sun, on which a braking model is normally calibrated. Recent or current satellite missions such as Helios and Ulysses have jointly revealed a more complete p…
H_2 emission from shocks in molecular outflows: the significance of departures from a stationary state
Pineau des Forêts, G.; Flower, D. R.
We have computed the time dependence of the H_2 rovibrational emission spectrum from molecular outflows. This emission arises in shock waves generated by the impact of jets, associated with low-mass star formation, on molecular gas. The shocks are unlikely to have attained a state of equilibrium, and so their structure will exhibit both C- and J-t…
Multisite observations of surface structures on AB Doradus in 1994 November
Catala, C.; Collier Cameron, A.; Janot-Pacheco, E. +15 more
We present time-resolved optical spectroscopy and broad-band photometry of the rapidly rotating southern K0 dwarf star AB Doradus, obtained during 1994 November. The data were obtained as part of a collaboration dedicated to MUlti-SIte COntinuous Spectroscopy (MUSICOS), and entailed coordinated observations on three continents to obtain the fulles…
NICMOS and VLBA observations of the gravitational lens system B1933+503
Jackson, N.; Browne, I. W. A.; Wilkinson, P. N. +1 more
NICMOS observations of the complex gravitational lens system B1933+503 reveal infrared counterparts to two of the inverted-spectrum radio images. The infrared images have arc-like structures. The corresponding radio images are also detected in a VLBA map made at 1.7 GHz with a resolution of 6 mas. We fail to detect two of the four inverted radio s…
Elemental abundances for Nova LMC 1990#1
Shore, Steven N.; Sonneborn, George; Starrfield, Sumner +1 more
We present our analysis of the UV spectra of the fast ONeMg Nova LMC 1990#1. Observations with the IUE began on 1990 January 18 and continued through to 1990 March 15. We have analysed these spectra, and determined line fluxes and physical parameters as a function of time. Using both Heii lines and the Balmer decrement, we find the reddening for t…
The outer atmosphere of Tau - II. Fluorescent lines
Carpenter, K. G.; McMurry, A. D.; Jordan, C.
The Goddard High Resolution Spectrograph (GHRS) on the Hubble Space Telescope has been used to observe α Tau (K5 III). The resulting spectra contain many sharp fluorescent lines. Most of these have been identified as lines of Fe ii, Ca ii and H2, radiatively excited by H Lyα. The chromospheric model developed in an accompanying paper ha…
The outer atmosphere of Tau - I. A new chromospheric model
McMurry, A. D.
A new model of the chromosphere of α Tau (K5 III) has been developed. The lower part of the model is based on an earlier one designed mainly to fit the Ca ii H and K lines. The new model extends through the upper chromosphere, to account for lines of C i, C ii, Si ii and Mg ii, and into the transition region up to 105 K to account for e…
Six intermediate-mass stars with far-infrared excess: a search for evolutionary connections
Wisniewski, John P.; Bjorkman, Karen S.; Miroshnichenko, Anatoly S. +3 more
We present the results of high-resolution spectroscopic, low-resolution spectrophotometric and spectropolarimetric and broad-band multicolour observations of four B-type stars (HD 4881, 5839, 224648 and 179218) and two A-type stars (HD 32509 and 184761) with strong far-infrared (IR) excesses. The excess in HD 184761, which is located at a distance…