Discovery of fourteen new ZZ Cetis with SOAR

We report the discovery of fourteen new ZZ Cetis with the 4.1 m Southern Astrophysical Research telescope, at Cerro Pachon, in Chile. The candidates were selected from the SDSS (Sloan Digital Sky Survey) DA white dwarf stars with Ten obtained from the optical spectra fit, inside the ZZ Ceti instability strip. Considering these stars are multi-periodic pulsators and the pulsations propagate to the nucleus of the star, they carry information on the structure of the star and evolution of the progenitors. The ZZ Cetis discovered till 2003 are mainly within 100 pc from the Sun, and probe only the solar vicinity. The recently discovered ones, and those reported here, may sample a distinct population as they were selected mainly perpendicular to the galactic disk and cover a distance up to 400 pc.

[1]  S. O. Kepler,et al.  Eleven New DA White Dwarf Variable Stars from the Sloan Digital Sky Survey , 2005 .

[2]  et al,et al.  Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs , 2004, astro-ph/0411199.

[3]  M. Montgomery White Dwarf Light Curves: Constraining Convection and Mode Identification Using Non-sinusoidal Light Curves , 2004, astro-ph/0411377.

[4]  H Germany,et al.  Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star HE 1429-1209 , 2004, astro-ph/0409243.

[5]  S. O. Kepler WHITE DWARFS AS LABORATORIES , 2004 .

[6]  P. Quirion,et al.  On the Driving Mechanism and the Coexistence of Variable and Nonvariable Stars in the Domain of the Pulsating PG 1159 Stars , 2004 .

[7]  S. O. Kepler,et al.  Thirty-Five New Pulsating DA White Dwarf Stars , 2004 .

[8]  D. Lamb,et al.  A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey , 2004, astro-ph/0402209.

[9]  M. H. Montgomery,et al.  Testing White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093 , 2004, astro-ph/0402046.

[10]  G. Fontaine,et al.  On the Purity of the ZZ Ceti Instability Strip: Discovery of More Pulsating DA White Dwarfs on the Basis of Optical Spectroscopy , 2003, astro-ph/0309483.

[11]  A. Mukadam,et al.  A CCD Time-Series Photometer , 2003, astro-ph/0306022.

[12]  S. Kawaler,et al.  A Strong Test of Electroweak Theory Using Pulsating DB White Dwarf Stars as Plasmon Neutrino Detectors , 2003, astro-ph/0312303.

[13]  B. N. Ashoka,et al.  Constraining the Evolution of ZZ Ceti , 2003 .

[14]  S. Kawaler,et al.  Probing the core and envelope structure of DBV white dwarfs , 2003, astro-ph/0306070.

[15]  T. Metcalfe,et al.  The core/envelope symmetry in pulsating stars , 2003, astro-ph/0305601.

[16]  S. O. Kepler,et al.  The everchanging pulsating white dwarf GD358 , 2003, astro-ph/0301477.

[17]  R. Paul Butler,et al.  Scientific Frontiers in Research on Extrasolar Planets , 2003 .

[18]  Drake Deming,et al.  Scientific Frontiers in Research on Extrasolar Planets , 2003 .

[19]  S. Dreizler,et al.  Wet Observations of PG 1159–035 , 2003 .

[20]  B. Gibson,et al.  The White Dwarf Cooling Sequence of the Globular Cluster Messier 4 , 2002, astro-ph/0205087.

[21]  S. Majewski,et al.  Absolute Proper Motions to B ~ 22.5. IV. Faint, Low-Velocity White Dwarfs and the White Dwarf Population Density Law , 2001, astro-ph/0112258.

[22]  A. Serenelli,et al.  New DA white dwarf evolutionary models and their pulsational properties , 2001, astro-ph/0110534.

[23]  D. Koester,et al.  Nonlinear effects in time-resolved spectra of DAVs , 2001, astro-ph/0105139.

[24]  Pierre Brassard,et al.  The Potential of White Dwarf Cosmochronology , 2001 .

[25]  Yanqin Wu Combination frequencies in the Fourier spectra of white dwarfs , 2000, astro-ph/0003101.

[26]  Souza Oliveira Kepler,et al.  Direct Measurement of a Secular Pulsation Period Change in the Pulsating Hot Pre-White Dwarf PG 1159–035 , 1999 .

[27]  M. Montgomery,et al.  The Effect of Crystallization on the Pulsations of White Dwarf Stars , 1999, astro-ph/9907040.

[28]  J. Liebert,et al.  Spectroscopic Studies of DB White Dwarfs: The Instability Strip of the Pulsating DB (V777 Herculis) Stars , 1999 .

[29]  A. Schwarzenberg-Czerny,et al.  Optimum Period Search: Quantitative Analysis , 1999 .

[30]  Jack J. Lissauer,et al.  The Effects of Post-Main-Sequence Solar Mass Loss on the Stability of Our Planetary System , 1998 .

[31]  David S. Finley,et al.  The Temperature Scale and Mass Distribution of Hot DA White Dwarfs , 1997 .

[32]  S. O. Kepler,et al.  An Empirical Test of the Theory of Crystallization in Stellar Interiors , 1997 .

[33]  G. Fontaine,et al.  Optical and Ultraviolet Analyses of ZZ Ceti Stars and Study of the Atmospheric Convective Efficiency in DA White Dwarfs , 1995 .

[34]  Brian Warner,et al.  Whole earth telescope observations of the DBV white dwarf GD 358 , 1994 .

[35]  Paul A. Bradley,et al.  An asteroseismological determination of the structure of the DBV white dwarf GD 358 , 1994 .

[36]  A. J. Brickhill The pulsations of ZZ Ceti stars. V - The light curves. VI - The amplitude spectra , 1992 .

[37]  A. Schwarzenberg-Czerny,et al.  Accuracy of period determination , 1991 .

[38]  Brian Warner,et al.  Asteroseismology of the DOV star PG 1159 - 035 with the Whole Earth Telescope , 1991 .

[39]  S. O. Kepler,et al.  An independent method for determining the age of the universe , 1987 .

[40]  I. Iben,et al.  Evolutionary period changes in variable helium-rich white dwarfs , 1986 .

[41]  E. L. Robinson,et al.  A measurement of secular evolution in the pre-white-dwarf star PG 1159-035 , 1985 .

[42]  S. O. Kepler Light and line profile variations due to r-mode pulsations, with an application to the ZZ ceti Star G117-B15A , 1984 .

[43]  E. L. Robinson,et al.  Multicolor variations of the ZZ Ceti stars , 1982 .

[44]  J. Christensen-Dalsgaard,et al.  Theory of Stellar Pulsation , 1982 .

[45]  John P. Cox,et al.  Theory of Stellar Pulsation No. 2 , 1980 .

[46]  J. McGraw Southern hemisphere ZZ Ceti stars: the new variable L19-2 and BPM 30551. , 1977 .

[47]  E. Nasi,et al.  Hard X-Ray Observations of AM Herculis. , 1977 .