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: http://star.arm.ac.uk/highlights/2011/578.html
Дата изменения: Mon Jun 20 13:36:22 2011 Дата индексирования: Tue Oct 2 03:16:08 2012 Кодировка: IBM-866 Поисковые слова: п п п п п п п п п п п п п п п п п п п п п п п п п п п п |
Gavin Ramsay, Ralf Napiwotzki, Thomas Barclay, Pasi Hakala, Stephen Potter, Mark Cropper
Figure 3.
The light curves of our blue candidate stellar pulsators identified in our survey and which had an amplitude less than 0.2 mag.
ABSTRACT
We report the discovery of 31 blue, short period, pulsators made using data taken as part of the Rapid Temporal Survey (RATS). We find they have periods between 51тАУ83 mins and full-amplitudes between 0.05тАУ0.65 mag. Using the period-luminosity relationship for short period pulsating stars we determine their distance. Assuming they are pulsating in either the fundamental or first over-tone radial mode the ma- jority are located at a distance greater than 3kpc, with several being more than 20 kpc distant. Most stars are at least 1 kpc from the Galactic plane, with three being more than 10 kpc. One is located in the direction of the Galactic anti-center and has Galactocentric distance of тИ®30 kpc and is тИ®20 kpc below the plane: they are therefore potential tracers of Galactic structure. We have obtained low-resolution spectra for a small number our targets and find they have temperatures between 7200тАУ7900K and a metal content less than Solar. The colours of the pulsators and the spectral fits to those stars for which we have spectra indicate that they are either SX Phe or δ Scuti stars. We estimate the number of SX Phe stars in our Galaxy and find significantly fewer per unit mass than reported in massive globular clusters or dwarf spheroidal galaxies.
Last Revised: 2011 June 20th |