Article (Scientific journals)
The Impact of White Dwarf Luminosity Profiles on Oscillation Frequencies
Timmes, F. X.; Townsend, R. H. D.; Bauer, E. B. et al.
2018In Astrophysical Journal. Letters, 867 (2)
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Abstract :
[en] KIC 08626021 is a pulsating DB white dwarf (WD) of considerable recent interest, and the first of its class to be extensively monitored by Kepler for its pulsation properties. Fitting the observed oscillation frequencies of KIC 08626021 to a model can yield insights into its otherwise-hidden internal structure. Template-based WD models choose a luminosity profile where the luminosity is proportional to the enclosed mass , Lr ∝ Mr, independent of the effective temperature T eff. Evolutionary models of young WDs with T eff 25,000 K suggest that neutrino emission gives rise to luminosity profiles with L r M r. We explore this contrast by comparing the oscillation frequencies between two nearly identical WD models: one with an enforced luminosity profile, and the other with a luminosity profile determined by the star's previous evolution history. We find that the low-order g-mode frequencies differ by up to ≃70 μHz over the range of Kepler observations for KIC 08626021. This suggests that by neglecting the proper thermal structure of the star (e.g., accounting for the effect of plasmon neutrino losses), the model frequencies calculated by using an profile may have uncorrected, effectively random errors at the level of tens of μHz. A mean frequency difference of 30 μHz, based on linearly extrapolating published results, suggests a template model uncertainty in the fit precision of ≃12% in WD mass, ≃9% in the radius, and ≃3% in the central oxygen mass fraction. © 2018. The American Astronomical Society.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Timmes, F. X.;  School of Earth and Space Exploration, Arizona State University, Tempe, AZ, United States, Joint Institute for Nuclear Astrophysics, Center for the Evolution of the Elements, United States
Townsend, R. H. D.;  Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706, United States
Bauer, E. B.;  Department of Physics, University of California, Santa Barbara, CA 93106, United States
Thoul, Anne  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique et astérosismologie
Fields, C. E.;  Joint Institute for Nuclear Astrophysics, Center for the Evolution of the Elements, United States, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States, Center for Theoretical Astrophysics, Los Alamos National Lab, Los Alamos, NM 87545, United States
Wolf, W. M.;  School of Earth and Space Exploration, Arizona State University, Tempe, AZ, United States
Language :
English
Title :
The Impact of White Dwarf Luminosity Profiles on Oscillation Frequencies
Publication date :
2018
Journal title :
Astrophysical Journal. Letters
ISSN :
2041-8205
eISSN :
2041-8213
Publisher :
Institute of Physics Publishing
Volume :
867
Issue :
2
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
MSU Texas - Midwestern State University [US-TX] [US-TX]
AAG - American Association of Geographers [US-DC] [US-DC]
Ford Foundation [US-NY] [US-NY]
PFC - Physiotherapy Foundation of Canada [CA]
NSF - National Sleep Foundation [US-VA] [US-VA]
Funding text :
Midwestern State UniversityAmerican Association of Geographers: PHY-1430152, AST-1716436Ford Foundation: DGE1424871Physiotherapy Foundation of CanadaNational Sleep Foundation: ACI-1663684, ACI-1663696, ACI-1663688Applied Scientific Research Fund
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