49 research outputs found
UV emission from young and middle-aged pulsars: Connecting X-rays with the optical
We present the UV spectroscopy and timing of three nearby pulsars (Vela,
B0656+14 and Geminga) recently observed with the Space Telescope Imaging
Spectrograph. We also review the optical and X-ray properties of these pulsars
and establish their connection with the UV properties. We show that the
multiwavelengths properties of neutron stars (NSs) vary significantly within
the sample of middle-aged pulsars. Even larger differences are found between
the thermal components of Ge-minga and B0656+14 as compared to those of
radio-quiet isolated NSs. These differences could be attributed to different
properties of the NS surface layers.Comment: To appear in Astrophysics and Space Science, Proceedings of "Isolated
Neutron Stars: from the Interior to the Surface", eds. D. Page, R. Turolla
and S. Zane; 10 pages, 4 figures, 3 table
Spatio-temporal variability of polynya dynamics and ice production in the Laptev Sea between the winters of 1979/80 and 2007/08
Polynyas in the Laptev Sea are examined with respect to recurrence and
interannual wintertime ice production.We use a polynya classification method
based on passive microwave satellite data to derive daily polynya area from
long-term sea-ice concentrations. This provides insight into the spatial and
temporal variability of open-water and thin-ice regions on the Laptev Sea
Shelf. Using thermal infrared satellite data to derive an empirical thin-ice
distribution within the thickness range from 0 to 20 cm, we calculate daily
average surface heat loss and the resulting wintertime ice formation within the
Laptev Sea polynyas between 1979 and 2008 using reanalysis data supplied by
the National Centers for Environmental Prediction, USA, as atmospheric
forcing. Results indicate that previous studies significantly overestimate the
contribution of polynyas to the ice production in the Laptev Sea. Average
wintertime ice production in polynyas amounts to approximately 55 km39
27% and is mostly determined by the polynya area, wind speed and associated
large-scale circulation patterns. No trend in ice production could be detected in
the period from 1979/80 to 2007/08