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Title: White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes

Abstract

While the spectrum of pure hydrogen plasmas at low densities seems well understood, at higher densities this is not the case. In this domain the line broadening can be extreme and the lines overlap, making the determination of the continuum problematic. The surfaces of white dwarf stars (WDs) fall into this high-density category. Observationally, we find a systematic offset between the masses of WDs derived using the gravitational-redshift method and those using the spectral line-shape fitting method (Falcon et al. 2010, ApJ, 712,585). Given the straightforward nature of the gravitational-redshift method, this discrepancy points toward incompleteness in the modeling of the broadening of hydrogen lines. The resulting uncertainty in mass hinders the many uses of WDs in astronomy and physics: for example, as Galactic chronometers (Winget et al. 1987, ApJL, 315, 77), tracers of stellar evolution, and probes of dense Coulomb plasmas (Winget et al. 2009, ApJL, 693, 6). This has motivated recent attempts to improve the theoretical line profiles used in white dwarf atmosphere models by independent groups, including us. Laboratory benchmarks are essential for assessing the viability of these new theories (Falcon et al. 2013, HEDP, 9, 82). Therefore, our goal is to make laboratory benchmark measurements ofmore » atomic line shapes in H – eventually He and C and O as well--for comparison with the lines observed in the photospheres of white dwarf stars.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Univ. of Texas at Austin, Austin, TX (United States). Dept. of Astronomy
Publication Date:
Research Org.:
The Univ. of Texas at Austin, Austin, TX (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
Contributing Org.:
Sandia National Laboratories, Albuquerque, NM
OSTI Identifier:
1421934
Report Number(s):
DOE-UTEX-10623
DOE Contract Number:  
SC0010623
Resource Type:
Technical Report
Resource Relation:
Related Information: N/A
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Laboratory Astrophysics; Plasma Physics; Experimental Physics; Astrophysics

Citation Formats

Winget, Donald E., Montgomery, Michael H., Gomez, Thomas A., Falcon, Ross E., and Schaeuble, Marc -Andre. White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes. United States: N. p., 2018. Web. doi:10.2172/1421934.
Winget, Donald E., Montgomery, Michael H., Gomez, Thomas A., Falcon, Ross E., & Schaeuble, Marc -Andre. White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes. United States. doi:10.2172/1421934.
Winget, Donald E., Montgomery, Michael H., Gomez, Thomas A., Falcon, Ross E., and Schaeuble, Marc -Andre. Wed . "White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes". United States. doi:10.2172/1421934. https://www.osti.gov/servlets/purl/1421934.
@article{osti_1421934,
title = {White Dwarf Photospheres in the Laboratory: A Testbed for Fundamental Atomic Processes},
author = {Winget, Donald E. and Montgomery, Michael H. and Gomez, Thomas A. and Falcon, Ross E. and Schaeuble, Marc -Andre},
abstractNote = {While the spectrum of pure hydrogen plasmas at low densities seems well understood, at higher densities this is not the case. In this domain the line broadening can be extreme and the lines overlap, making the determination of the continuum problematic. The surfaces of white dwarf stars (WDs) fall into this high-density category. Observationally, we find a systematic offset between the masses of WDs derived using the gravitational-redshift method and those using the spectral line-shape fitting method (Falcon et al. 2010, ApJ, 712,585). Given the straightforward nature of the gravitational-redshift method, this discrepancy points toward incompleteness in the modeling of the broadening of hydrogen lines. The resulting uncertainty in mass hinders the many uses of WDs in astronomy and physics: for example, as Galactic chronometers (Winget et al. 1987, ApJL, 315, 77), tracers of stellar evolution, and probes of dense Coulomb plasmas (Winget et al. 2009, ApJL, 693, 6). This has motivated recent attempts to improve the theoretical line profiles used in white dwarf atmosphere models by independent groups, including us. Laboratory benchmarks are essential for assessing the viability of these new theories (Falcon et al. 2013, HEDP, 9, 82). Therefore, our goal is to make laboratory benchmark measurements of atomic line shapes in H – eventually He and C and O as well--for comparison with the lines observed in the photospheres of white dwarf stars.},
doi = {10.2172/1421934},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {2}
}