23,384 research outputs found
Is there a propeller neutron star in Cas?
Cas is the prototype of a small population of B0-B1.5 III-V
classical Be (cBe) stars that emit anomalous and hard X-rays with a unique
array of properties. Cas is known to host, like other cBe stars, a
decretion disk and also a low mass companion. Recently Postnov et al. have
posited that this companion is a magnetized rapidly spinning neutron star that
deflects direct gravitational accretion from a stellar/disk wind via the
"propeller mechanism." These authors state that the key X-ray observations are
"remarkably well produced" in this scenario. We reexamine this mechanism in
detail and conclude that there are a number of fatal objections in its
application to the Cas case. Among other considerations these issues
include the prediction under the propeller scenario of a much smaller
population of Cas stars than is observed and the lack of allowance for
observed correlations of X-ray and UV and/or optical properties over a variety
of timescales.Comment: 9 page
BRS Apinajé: cultivar de arroz para a agricultura familiar nas condições de terra firme do Estado do Pará.
bitstream/item/27797/1/Com.tec.207.pdfDisponível também on-line
BRS Jaçanã: cultivar de arroz para áreas de várzea do Estado do Pará.
bitstream/item/27800/1/Com.tec.197.pd
Comportamento da cultivar de arroz BRS Aroma em terra firme no Estado do Pará.
bitstream/item/27840/1/Com.Tec.217.pdfVersão eletrônica. 1ª impressão: 2010
Ensaio comparativo avançado de arroz de sequeiro em Capitão Poço, Pará - ano agrícola 1998/1999.
bitstream/item/52949/1/PesquisaAnd0150001.pd
BRS Sertaneja: cultivar precoce de arroz para terra firme do Estado do Pará.
bitstream/item/27808/1/Com.tec.198.pd
Ensaio comparativo avançado de arroz de sequeiro em Altamira, Pará - ano agrícola 1998/1999.
bitstream/item/52948/1/PesquisaAnd0160001.pd
- …