85,715 research outputs found
Spectro-astrometry of V1515 Cyg
Full text linkFU Orionis objects are a class of young stars with important bursts in
luminosity and which show evidence of accretion and ejection activity. It is
generally accepted that they are surrounded by a Keplerian circumstellar disk
and an infalling envelope. The outburst would occurs because of a sudden
increase in the accretion rate. We aim at studying the regions closer to the
central star in order to observe the signs of the accretion/ejection activity.
We present optical observations of the Halpha line using the Integral Field
Spectrograph OASIS, at the William Herschel Telescope, combined with Adaptive
Optics. Since this technique gives the spectral information for both spatial
directions, we carried out a two-dimensional spectro-astrometric study of the
signal. We measured a clear spectro-astrometric signal in the North-South
direction. The cross-correlation between the spectra showed a spatial
distribution in velocity suggestive of scattering by a disk surrounding the
star. This would be one of the few spatial inferences of a disk observed in a
FU Orionis object. However, in order to fully understand the observed
structure, higher angular and spectral resolution observations are required.
V1515 Cyg appears now as an important object to be observed with a new
generation of instruments to increase our knowledge about the disk and outflows
structure in FU Orionis objects
Vortex bending and tightly packed vortex lattices in Bose-Einstein condensates
Full text linkWe study in detail the counterintuitive result that in elongated rotating
Bose--Einstein condensates the ground state is composed of one or more vortex
lines which bend even in completely symmetric setups. This symmetry breaking
allows the condensate to smoothly adapt to rotation and to produce tightly
packed arrays of vortex lines.Comment: 4 pages, 4 eps picture
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