Lucky Imaging of M subdwarfs
نویسندگان
چکیده
منابع مشابه
M Subdwarfs: the Population Ii Luminosity Function
We present results of a study of very low mass halo stars. Using a sample of proper motion stars identified from plate material taken as part of the first and second Palomar Sky Surveys, we measure the space density, metallicity distribution, and kinematics of the Population II M subdwarfs. Our overall luminosity function is in good agreement with previous analyses of the space density of nearb...
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AstraLux is the Lucky Imaging camera for the Calar Alto 2.2-m telescope, based on an electron-multiplying high speed CCD. By selecting only the best 1-10% of several thousand short exposure frames, AstraLux provides nearly diffraction limited imaging capabilities in the SDSS i’ and z’ filters over a field of view of 24×24 arcseconds. By choosing commercially available components wherever possib...
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We present spectroscopic observations of two halo M subdwarfs which have Hα emission lines. We show that in both cases close companions are the likely cause of the chromospheric activity in these old, metal-poor stars. We argue that Gl 781 A’s unseen companion is most likely a cool helium white dwarf. Gl 455 is a near-equal-mass M subdwarf (sdM) system. Gl 781 A is rapidly rotating with v sin i...
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We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region λλ6200−7400Å. Our sample of cool stars covers the range from solar metallicity stars to the most extreme subdwarfs known. Using synthetic spectra computed by Allard and Hauschildt (1995), we derive metallicities for the stars. Stars are classified as...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2009
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/200911708