منابع مشابه
JHK′-band IOTA interferometry of the circumstellar environment of R CrB
We report the first long-baseline interferometry of the circumstellar dust environment of R CrB. The observations were carried out with the Infrared Optical Telescope Array (IOTA), using our new JHK′ beam combiner which enables us to record fringes in the J, H, and K′ bands simultaneously. The circumstellar dust envelope of R CrB is resolved at a baseline of 21 m along a position angle of ∼170◦...
متن کاملAbundance similarities between the R CrB star V854 Cen and the born-again Sakurai’s object
The elemental abundances of the mildly hydrogendeficient R Coronae Borealis (RCrB) star V854Cen have been estimated. The RCrB stars have been divided into majority and minority classes judging by their abundance patterns. Class assignment has previously been unambiguous but V854Cen has traits of both the minority and majority class. Neither V854Cen nor the three obvious minority members show an...
متن کاملPulsational Instabilities in Accreting White Dwarfs
The Cataclysmic Variable (CV) population harbors a diverse range of donor stars and accreting white dwarfs (WDs). A range of WD masses is expected, from low mass Helium core WDs, to massive WDs which have previously accreted at rates high enough for Hydrogen to burn steadily. Furthermore, a wide range of Helium enrichment is expected in the accreted material depending on the degree to which the...
متن کاملWhen periodicities enforce aperiodicity
Non-periodic tilings and local rules are commonly used to model the long range aperiodic order of quasicrystals and the finite-range energetic interactions that stabilize them. This paper focuses on planar rhombus tilings, that are tilings of the Euclidean plane which can be seen as an approximation of a real plane embedded in a higher dimensional space. Our main result is a characterization of...
متن کاملCongruences, Automata and Periodicities
We show the deep connection between two apparently unrelated topics in automata theory and combinatorics on words: the equivalence problem of nite automata and the Fine and Wilf's periodicity theorem. In fact they both refer to the problem of checking whether two congruences agree on a nite set. This also allows us to introduce a notion of periodicity for labelled trees and to derive a periodic...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1989
ISSN: 0252-9211
DOI: 10.1017/s0252921100063120