The ZZ Ceti red edge
Departamento de Física, UFSC, CP 476, CEP 88040-900, Florianópolis SC, Brazil
2 Departamento de Astronomia, IF-UFRGS 91501-900, Porto Alegre RS, Brazil
3 University of Texas at Austin, Austin TX 78712, USA
Corresponding author: A. Kanaan, firstname.lastname@example.org
With a time-series CCD photometric survey, we have demonstrated clearly that the observed red edge for the ZZ Ceti stars instability strip at 11 000 K is real, with the pulsation amplitude decreasing at least by a factor of 50. Previous surveys for variability among hydrogen atmosphere white dwarfs around 11 000 K have been carried out using time-series photoelectric photometry, not differential photometry, insensitive for small amplitude periodicities of 15 min and longer. In our survey we constantly monitor the sky brightness as well as one or more comparison stars through the same color filter, reducing the adverse effects of differential extinction and sky fluctuations, obtaining true differential photometry.
Key words: stars: oscillations / stars: white dwarfs
© ESO, 2002