23,570 research outputs found
Sub-arcsecond Morphology of Planetary Nebulae
Planetary nebulae (PNe) can be roughly categorized into several broad
morphological classes. The high quality images of PNe acquired in recent years,
however, have revealed a wealth of fine structures that preclude simplistic
models for their formation. Here we present narrow-band, sub-arcsecond images
of a sample of relatively large PNe that illustrate the complexity and variety
of small-scale structures. This is especially true for bipolar PNe, for which
the images reveal multi-polar ejections and, in some cases, suggest turbulent
gas motions. Our images also reveal the presence or signs of jet-like outflows
in several objects in which this kind of component has not been previously
reported.Comment: 7 pages, 7 figures, Accepted for publication in PAS
Rare top quark decays in extended models
Flavor changing neutral currents (FCNC) decays t to H + c, t to Z + c, and H
to t + bar{c} are discussed in the context of Alternative Left-Right symmetric
Models (ALRM) with extra isosinglet heavy fermions where FCNC decays may take
place at tree-level and are only suppressed by the mixing between ordinary top
and charm quarks, which is poorly constraint by current experimental values.
The non-manifest case is also briefly discussed.Comment: Contributed talk given at the 10th Mexican Workhop on Particles and
Fields, Morelia, Michoacan, Mexico, 7-12 Nov 200
- …