منابع مشابه
Mapping the Radio Coronae of Cool Stars and Brown Dwarfs
The pulsing radio emission detected from ultracool dwarfs can be used as a powerful diagnostic of magnetic field strengths and topologies at and below the substellar boundary. Studies thus far have confirmed magnetic field strengths of 3 kG for two late M dwarfs and 1.7 kG for an L3.5 dwarf, the latter being the first confirmation of kG magnetic fields for an L dwarf. Ongoing long term monitori...
متن کاملCoronae on solar-like stars
The results of a complete and sensitive X-ray survey of all known stars of spectral type A, F, and G in the immediate solar vicinity with distances less than 13 pc are presented. The X-ray data were obtained primarily from the ROSAT all-sky survey (RASS); those program stars not detected in the RASS data, were subsequently studied in the ROSAT pointed observation program. The detection rate amo...
متن کاملSpectropolarimetry of cool stars
In recent years, the development of spectropolarimetric techniques deeply modified our knowledge of stellar magnetism. In the case of solar-type stars, the challenge is to measure a geometrically complex field and determine its evolution over very different time frames. In this article, I summarize some important observational results obtained in this field over the last two decades and detail ...
متن کاملFluorine in R Coronae Borealis Stars
Neutral fluorine (F i) lines are identified in the optical spectra of several RCoronae Borealis stars (RCBs) at maximum light. These lines provide the first measurement of the fluorine abundance in these stars. Fluorine is enriched in some RCBs by factors of 800 to 8000 relative to its likely initial abundance. The overabundances of fluorine are evidence for the synthesis of fluorine. These res...
متن کاملMagnetic topologies of cool stars
Stellar magnetic fields can be investigated using several, very complementary approaches. While conventional spectroscopy is capable of estimating the average magnetic strength of potentially complex field configurations thanks to its low sensitivity to the vector properties of the field, spectropolarimetry can be used to map the mediumand large-scale structure of magnetic topologies. In partic...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 2004
ISSN: 0074-1809
DOI: 10.1017/s007418090018218x