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Projeto Observacional para 2016B - SO2016B-001
Autor: Ingrid Pelisoli
Título: Photometry of Extremely-Low Mass White Dwarf Candidates
Resumo: White dwarfs with log g lower than 7.0 are called Extremely Low Mass white dwarfs (ELMs). They were first found as companions to pulsars, followed by companions to other white dwarfs and main sequence stars (The ELM Survey: 2010 to 2016), and can only be formed in interacting binaries in the age of the Universe. ELMs can present photometric variations due to pulsations and/or eclipses. Out of the 88 known ELMs, six are known eclipsing and six are known pulsators (Gianninas et al. 2015). Besides the ~1000s g-modes common to other classes of white dwarf pulsators, some also show ~100s p-mode pulsations. In the SDSS DR12 catalog, we found a few thousand stars with log g > 5.5, what means they are potentially ELM white dwarfs. To confirm this hypothesis, we will search for pulsations and eclipses characteristic to this new class of object. Increasing the ELMs sample would help constrain the number of close binaries in the Galaxy. If they turn out to be A stars with an overestimated log g, the distance modulus would put these young stars in the halo, several with velocities above 500km/s.