Authors

Anjum S. Mukadam, University of Texas at Austin; McDonald Observatory, Fort Davis, TX
S. O. Kepler, Universidade Federal do Rio Grande do Sul - Brasil; Laboratório Nacional de Astrofisica - Brazil; Cerro Tololo Inter-American Obsrvatory, operated by AURA for the NSF
D. E. Nather, University of Texas at Austin; McDonald Observatory, Fort Davis, TX
M. Kilic, University of Texas at Austin; McDonald Observatory, Fort Davis, TX
F. Mullally, University of Texas at Austin; McDonald Observatory, Fort Davis, TX
T. von Hippel, Embry-Riddle Aeronautical UniversityFollow
S. J. Kleinman, Apache Point Observatory, NM
A. Nitta, Apache Point Observatory, NM
J. A. Guzik, Los Alamos National Laboratory, NM
P. A. Bradley, Los Alamos National Laboratory, NM
J. Matthews, University of British Columbia
K. Sekiguchi, National Astronomical Observatory of Japan, HI
D. J. Sullivan, Victoria University of Wellington
T. Sullivan, Victoria University of Wellington
R. R. Shobbrook, Australian National University
P. Birch, Perth Observatory, Australia
X. J. Jiang, National Astronomical Observatories of China, Beijing
D. W. Xu, National Astronomical Observatories of China, Beijing
S. Joshi, Uttar Pradesh State Observatory, India
B. N. Ashoka, Indian Space Research Organization, Technical Physics Division, ISRO Satellite Center, India
P. Ibbetson, Tel Aviv University, Israel
E. Leibowitz, Tel Aviv University, Israel
E. O. Ofek, Tel Aviv University, Israel
E. G. Meištas, Institute of Theoretical Physics and Astronomy, Lithuania; Vilnius University Observatory, Lithuania
R. Janulis, Institute of Theoretical Physics and Astronomy, Lithuania; Vilnius University Observatory, Lithuania
R. D. Ališauskas, Vilnius University Observatory, Lithuania
R. Kalytis, Vilnius University Observatory, Lithuania
G. Handler, South African Astronomical Observatory
D. Kilkenny, South African Astronomical Observatory
D. O'Donoghue, South African Astronomical Observatory
D. W. Kurtz, University of Central Lancashire, UK; Observatoire Midi-Pyrenees, France
M. Müller, University of Cape Town, South Africa
P. Moskalik, Polish Academy of Sciences
W. Ogloza, Polish Academy of Sciences; Cracow Pedagogical University, Poland
S. Zola, Cracow Pedagogical University, Poland; Jagiellonian University, Poland
J. Krzesiński, Cracow Pedagogical University, Poland
F. Johnannessen, Universitetet i Tromsø, Norway
J. M. Gonzalez-Perez, Universitetet i Tromsø, Norway
J. E. Solheim, Universitetet i Tromsø, Norway
R. Silvotti, Instituto Nazionale di AstroFisica-Osservatorio Astronomico di Capodimonte, Italy
S. Bernabei, Instituto Nazionale di AstroFisica-Osservatorio Astronomico di Bologna, Italy
G. Vauclair, Observatoire Midi-Pyrenees, France
N. Dolez, Observatoire Midi-Pyrenees, France
J. N. Fu, Observatoire Midi-Pyrenees, France
M. Chevreton, Observatoire de ParisMeudon, France
M. Manteiga, Universidade da Corunã, Spain
O. Suárez, Universidade da Corunã, Spain; Universidade de Vigo, Spain
A. Ulla, Universidade de Vigo, Spain
M. S. Cunha, Centro de Astrofisica da Universidade do Porto, Portugal; Instituto Superior da Maia
T. S. Metcalfe, University of Texas at Austin; Harvard-Smithsonian Center for Astrophysics, Cambridge, MA
A. Kanaan, Universidade Federal de Santa Catarina, SC Brazil
L. Fraga, Universidade Federal de Santa Catarina, SC Brazil
A. F. M. Costa, Universidade Federal do Rio Grande do Sul - Brasil; Laboratório Nacional de Astrofisica - Brazil;
O. Giovannini, Laboratório Nacional de Astrofisica - Brazil, Universidade de Caxias do Sul, RS Brazil
G. Fontaine, Université de Montréal
P. Bergeron, Université de Montréal
M. S. O'Brien, Space Telescope Science Institute, Baltimore, MD
D. Sanwal, Pennsylvania State University - University Park
M. A. Wood, Florida Institute of Technology - Melbourne
T. J. Ahrens, Middle Tennessee State University- Murfreesboro
N. Silvestri, Florida Institute of Technology - Melbourne
E. W. Klumpe, Middle Tennessee State University- Murfreesboro
S. D. Kawaler, Iowa State University - Ames
R. Riddle, Iowa State University - Ames
M. D. Reed, Southwest Missouri State University
T. K. Watson, Southwestern University - Georgetown, TX

Submitting Campus

Daytona Beach

Department

Department of Physical Sciences

Document Type

Article

Publication/Presentation Date

9-10-2003

Abstract/Description

We report our analysis of the stability of pulsation periods in the DAV star (pulsating hydrogen atmosphere white dwarf) ZZ Ceti, also called R548. On the basis of observations that span 31 years, we conclude that the period 213.13 s observed in ZZ Ceti drifts at a rate dP/dt (5:5 ± 1:9) x 10-15 s s-1, after correcting for proper motion. Our results are consistent with previous values for this mode and an improvement over them because of the larger time base. The characteristic stability timescale implied for the pulsation period is ⎸P / ⎸=⎹≥ 1:2 Gyr, comparable to the theoretical cooling timescale for the star. Our current stability limit for the period 213.13 s is only slightly less than the present measurement for another DAV, G117-B15A, for the period 215.2 s, establishing this mode in ZZ Ceti as the second most stable optical clock known, comparable to atomic clocks and more stable than most pulsars. Constraining the cooling rate of ZZ Ceti aids theoretical evolutionary models and white dwarf cosmochronology. The drift rate of this clock is small enough that we can set interesting limits on reflex motion due to planetary companions.

Publication Title

The Astrophysical Journal

Publisher

Institute of Physics Publishing, Inc.

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