منابع مشابه
Metallicities of Nearby K- Dwarfs
One of the main issues in the chemical evolution of galaxies is the so called " G-dwarf problem " (Pagel and Patchett, 1975) in which the observed stellar metal distribution differs from the predicted in the sense that there are too many metal deficient stars. The same problem was now been seen among K-dwarfs, indicating the problem is a general one (Flynn and Morell, 1997). We have used the Hi...
متن کاملMass Transfer between Double White Dwarfs
Three periodically variable stars have recently been discovered (V407 Vul, P = 9.5 min; ES Cet, P = 10.3 min; RX J0806.3+1527, P = 5.3 min) with properties that suggest that their photometric periods are also their orbital periods, making them the most compact binary stars known. If true, this might indicate that close, detached, double white dwarfs are able to survive the onset of mass transfe...
متن کاملMass-radius Relation for Magnetic White Dwarfs
Recently, several white dwarfs with very strong surface magnetic fields have been observed. In this paper we explore the possibility that such stars could have sufficiently strong internal fields to alter their structure. We obtain a revised white dwarf mass-radius relation in the presence of strong internal magnetic fields. We first derive the equation of state for a fully degenerate ideal ele...
متن کاملLow Mass Companions to White Dwarfs
This paper summarizes the results of over 17 years of work searching for low mass stellar and substellar companions to more than 370 nearby white dwarfs. Roughly 60 low mass, unevolved companions were found and studied all together, with over 20 discovered in the last few years, including the first unambiguous brown dwarf companion to a white dwarf, GD 1400B. The resulting spectral type distrib...
متن کاملA catalogue of bright ( K < 9 ) M dwarfs
Using the Position and Proper Motion Extended-L (PPMXL) catalogue, we have used optical and near-infrared colour cuts together with a reduced proper motion cut to find bright M dwarfs for future exoplanet transit studies. PPMXL’s low proper motion uncertainties allow us to probe down to smaller proper motions than previous similar studies. We have combined unique objects found with this method ...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1976
ISSN: 0074-1809
DOI: 10.1017/s0074180900008937