The Morphology of the Asteroidal Dust around White Dwarf Stars: Optical and Near-infrared Pulsations in G29-38
von Hippel T. Farihi J. Provencal J.L. Kleinman S.J. Pringle J.E. Swan A. Fontaine G. Hermes J.J. Sargent J. Savery Z. Cooper W. Kim V. Kozyreva V. Krugov M. Kusakin A. Moss A. Ogloza W. Pakštienė E. Serebryanskiy A. Sonbas E. Walter B. Zejmo M. Zola S.
1 March 2024Institute of Physics
Astrophysical Journal
2024#963Issue 2
More than 36 yr have passed since the discovery of the infrared excess from circumstellar dust orbiting the white dwarf G29-38, which at 17.5 pc it is the nearest and brightest of its class. The precise morphology of the orbiting dust remains only marginally constrained by existing data, subject to model-dependent inferences, and thus fundamental questions of its dynamical origin and evolution persist. This study presents a means to constrain the geometric distribution of the emitting dust using stellar pulsations measured at optical wavelengths as a variable illumination source of the dust, which reradiates primarily in the infrared. By combining optical photometry from the Whole Earth Telescope with 0.7-2.5 μm spectroscopy obtained with SpeX at NASA’s Infrared Telescope Facility, we detect luminosity variations at all observed wavelengths, with variations at most wavelengths corresponding to the behavior of the pulsating stellar photosphere, but toward the longest wavelengths the light curves probe the corresponding time variability of the circumstellar dust. In addition to developing methodology, we find the pulsation amplitudes decrease with increasing wavelength for principal pulsation modes, yet increase beyond ≈2 μm for nonlinear combination frequencies. We interpret these results as combination modes derived from the principal modes of identical ℓ values and discuss the implications for the morphology of the warm dust. We also draw attention to some discrepancies between our findings and theoretical expectations for the results of the nonlinearity imposed by the surface convection zone on mode-mode interactions and on the behavior of the first harmonic of the highest-amplitude pulsation mode.
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Department of Physical Sciences, SARA, Embry-Riddle Aeronautical University, Daytona Beach, 32114, FL, United States
Department of Physics and Astronomy, University College London, London, WC1E 6BT, United Kingdom
Department of Physics and Astronomy, SARA, University of Delaware, Newark, 19716, DE, United States
Astromanager LLC, Hilo, HI, United States
Institute of Astronomy, Cambridge, CB3 0HA, United Kingdom
Department of Physics, University of Warwick, Coventry, CV4 7AL, United Kingdom
Département de Physique, Université de Montréal, Montréal, QC, Canada
Department of Astronomy, Boston University, 725 Commonwealth Ave., Boston, 02215, MA, United States
Department of Physics and Astronomy, The University of Georgia, Athens, 30602, GA, United States
Fesenkov Astrophysical Institute, Almaty, 50020, Kazakhstan
Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow, 119991, Russian Federation
Department of Physics and Astronomy, The University of Oklahoma, Norman, 73019, OK, United States
Mt. Suhora Observatory, Pedagogical University, Kraków, PL-30-084, Poland
Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio Av. 3, Vilnius, 10257, Lithuania
Astrophysics Application and Research Center, Department of Physics, Adiyaman University, Adiyaman, 02040, Turkey
Meyer Observatory and Central Texas Astronomical Society, Waco, 76705, TX, United States
Janusz Gil Institute of Astronomy, University of Zielona Gora, Zielona Gora, 65-516, Poland
Astronomical Observatory of the Jagiellonian University, ul. Orla 171, Kraków, 30-244, Poland
Department of Physical Sciences
Department of Physics and Astronomy
Department of Physics and Astronomy
Astromanager LLC
Institute of Astronomy
Department of Physics
Département de Physique
Department of Astronomy
Department of Physics and Astronomy
Fesenkov Astrophysical Institute
Sternberg Astronomical Institute
Department of Physics and Astronomy
Mt. Suhora Observatory
Institute of Theoretical Physics and Astronomy
Astrophysics Application and Research Center
Meyer Observatory and Central Texas Astronomical Society
Janusz Gil Institute of Astronomy
Astronomical Observatory of the Jagiellonian University
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