Title: A measurement of the equation of state of carbon envelopes of white dwarfs

Abstract

White dwarfs represent the final state of evolution for most stars. Certain classes of white dwarfs pulsate, leading to observable brightness variations, and analysis of these variations with theoretical stellar models probes their internal structure. Modelling of these pulsating stars provides stringent tests of white dwarf models and a detailed picture of the outcome of the late stages of stellar evolution. However, the high-energy-density states that exist in white dwarfs are extremely difficult to reach and to measure in the laboratory, so theoretical predictions are largely untested at these conditions. In this paper we report measurements of the relationship between pressure and density along the principal shock Hugoniot (equations describing the state of the sample material before and after the passage of the shock derived from conservation laws) of hydrocarbon to within five per cent. The observed maximum compressibility is consistent with theoretical models that include detailed electronic structure. This is relevant for the equation of state of matter at pressures ranging from 100 million to 450 million atmospheres, where the understanding of white dwarf physics is sensitive to the equation of state and where models differ considerably. The measurements test these equation-of-state relations that are used in the modellingmore » of white dwarfs and inertial confinement fusion experiments, and we predict an increase in compressibility due to ionization of the inner-core orbitals of carbon. We also find that a detailed treatment of the electronic structure and the electron degeneracy pressure is required to capture the measured shape of the pressure–density evolution for hydrocarbon before peak compression. Our results illuminate the equation of state of the white dwarf envelope (the region surrounding the stellar core that contains partially ionized and partially degenerate non-ideal plasmas), which is a weak link in the constitutive physics informing the structure and evolution of white dwarf stars.« less

Authors:

Kritcher, Andrea L.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9694-1088"

Swift, Damian C. ^[1]; Döppner, Tilo  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5703-7125"

Bachmann, Benjamin  ^[1];

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Benedict, Lorin X. ^[1]; Collins, Gilbert W. ^[2]; DuBois, Jonathan L. ^[1]; Elsner, Fred ^[3]; Fontaine, Gilles ^[4]; Gaffney, Jim A. ^[1]; Hamel, Sebastien ^[1]; Lazicki, Amy ^[1]; Johnson, Walter R. ^[5]; Kostinski, Natalie  ^[1];

• Search DOE PAGES for author "Kostinski, Natalie"
• Search DOE PAGES for ORCID "0000-0002-9681-613X"

Kraus, Dominik  ^[6];

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• Search DOE PAGES for ORCID "0000-0002-6350-4180"

MacDonald, Michael J.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6295-6978"

Maddox, Brian ^[1]; Martin, Madison E. ^[1]; Neumayer, Paul ^[7]; Nikroo, Abbas ^[1] more »; Nilsen, Joseph ^[1]; Remington, Bruce A. ^[1]; Saumon, Didier ^[8]; Sterne, Phillip A. ^[1]; Sweet, Wendi ^[3]; Correa, Alfredo A. ^[1]; Whitley, Heather D. ^[1]; Falcone, Roger W. ^[9]; Glenzer, Siegfried H. ^[10] « less

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+ Show Author Affiliations

1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Rochester, NY (United States)
3. General Atomics, San Diego, CA (United States)
4. Univ. of Montreal, QC (Canada)
5. Univ. of Notre Dame, IN (United States)
6. Helmholtz-Zentrum Dresden-Rossendorf (Germany); Technische Univ. Dresden (Germany)
7. GSI Helmholtzzentrum fur Schwerionenforschung BmbH, Darmstadt (Germany)
8. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
9. Univ. of California, Berkeley, CA (United States)
10. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Publication Date:

Wed Aug 05 00:00:00 EDT 2020

Research Org.:

Univ. of Rochester, NY (United States); Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1658868

Alternate Identifier(s):

OSTI ID: 1688586; OSTI ID: 1899612

Report Number(s):

LLNL-JRNL-769585
Journal ID: ISSN 0028-0836; 89233218CNA000001;13-ERD-073;LFR-17-449059; FWP 100182; TRN: US2203372

Grant/Contract Number:  

SC0019269; AC52-07NA27344; NA0003842; SC0018298; 89233218CNA000001; 13-ERD-073; LFR-17-449059; FWP 100182

Resource Type:

Accepted Manuscript

Journal Name:

Nature (London)

Additional Journal Information:

Journal Name: Nature (London); Journal Volume: 584; Journal Issue: 7819; Journal ID: ISSN 0028-0836

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Astrophysical plasmas; Laser-produced plasmas; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS