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Browsing University of Hertfordshire by Author "Hussain, G A J"
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Comparisons of images derived from independent Zeeman Doppler imaging codes
Hussain, G A J; Donati, J F; Collier Cameron, A; Barnes, J R (2000-11-11)We compare surface brightness and magnetic field surface maps for the K0 dwarf AB Doradus, obtained using two independently developed Zeeman Doppler imaging codes. We find that even the fine structure in the two sets of ... -
The decrease in differential rotation with decreasing stellar mass in a sample of young rapidly rotating main sequence stars
Barnes, J R; Cameron, A C; Donati, J F; James, D J; Marsden, S C; Mengel, M; Petit, P (European Space Agency (ESA), 2005)In the Sun, global fluid circulation generates the large-scale magnetic field through cyclic dynamo action. Shear at the solar core/convection zone interface ensures that the convection zone does not rotate as a solid body. ... -
Dense spot coverage and polar caps on SV Cam
Jeffers, S V; Cameron, A C; Barnes, J R; Aufdenberg, J P; Hussain, G A J (European Space Agency (ESA), 2005)We have used spectrophotometric data from 9 HST orbits to eclipse-map the primary component of the RS CVn binary SV Cam. From these observations and SV Cam's HIPPARCOS parallax we find that the surface flux in the eclipsed ... -
Latitude distributions and lifetimes of star-spots on G dwarfs in the alpha Persei cluster
Barnes, J R; Collier Cameron, A; Unruh, Y C; Donati, J F; Hussain, G A J (1998-09-21)We present a set of maximum-entropy reconstructions of the star-spot distributions on two rapidly rotating G dwarfs in the alpha Persei cluster, from spectra taken at the William Herschel Telescope on three nights in 1996 ...