304 resultados para Dunes.
Resumo:
We present the first far-IR observations of the solar-type stars δ Pav, HR 8501, 51 Peg and ζ^2 Ret, taken within the context of the DUNES Herschel open time key programme (OTKP). This project uses the PACS and SPIRE instruments with the objective of studying infrared excesses due to exo-Kuiper belts around nearby solar-type stars. The observed 100 μm fluxes from δ Pav, HR 8501, and 51 Peg agree with the predicted photospheric fluxes, excluding debris disks brighter than L_dust/L_* ~ 5 x 10^-7 (1σ level) around those stars. A flattened, disk-like structure with a semi-major axis of ~100 AU in size is detected around ζ2 Ret. The resolved structure suggests the presence of an eccentric dust ring, which we interpret as an exo-Kuiper belt with L_dust/L_* ≈ 10^-5.
Resumo:
This report summarizes the impact of Hurricane Allen (August 1980) on dune configuration, sand accretion or erosion, and changes in the vegetation on north Padre Island. Four experimental foredunes, the result of grass plantings from 1969 to 1973, and an unplanted control section were monitored in 1975-1977 and also in 1981. The 1981 posthurricane data were compared where possilbe, with the previous studies. Foredune elevation surveys were completed in March 1981; accompanying vegetation transects were made in July 1981. Hurrican Allen causes erosion of the dune face of all the experimental dunes, but caused a breach in only one dune. The beach elevations had returned to approximately prehurricane heights by the time the area was resurveyed. The unplanted control dune provided little resistance to waves generated by the storm and a large quantity of sand was deposited inland.
Resumo:
Thesis (Ph.D.) - University of Chicago.
Resumo:
Mode of access: Internet.
Resumo:
Item 624-B
Resumo:
Mode of access: Internet.
Resumo:
Mode of access: Internet.
Resumo:
Mode of access: Internet.