Helium at white dwarf photosphere conditions: experimental ... · Helium at white dwarf photosphere...
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Helium at white dwarf photosphere conditions: experimental line shapes and shifts (SAND2017-6564 C) Marc Schaeuble 1 , Ross Falcon 2 , Thomas Gomez 1,2 , Don Winget 1 , Michael Montgomery 1 , Jim Bailey 2 We present preliminary results of an experimental study exploring He line shapes and shifts at photospheric conditions of white dwarf stars. These data were collected as part of the White Dwarf Photosphere Experiment (WDPE) on Sandia National Laboratories’ Z-machine, the largest x-ray source on earth. Our helium results could have many applications ranging from validating current DB white dwarf atmospheric models to providing accurate He pressure shifts at varying temperatures and densities. In a much broader context, these helium data can be used to guide theoretical developments in new continuum-lowering models for two-electron atoms. Experimental Setup Experimental Results (cont.) Abstract Fig. 1 – Exploded and cross-sectioned view of the WDPE gas cell. Components are identified as follows: 1 – WDPE gas cell 2 – optical buffers 3 – optics assembly for emission 4 – optics assembly for absorption 5 – Mylar window through which x-rays enter gas cell 6 – gold back wall 7 – backlighter for absorption High-resolution He data References and Acknowledgements Beauchamp, A., Wesemael, F., Bergeron, P., 1997, ApJS, 108, 559 Bergeron, P., Wesemael, F., Dufour, P., Beauchamp, A., Hunter, C., Saffer, Rex A., Gianninas, A., Ruiz, M. T., Limoges, M.-M., Dufour, P., et al., 2011, ApJ, 737, 28 Falcon, R. E., Rochau, G. A., Bailey, J. E., Ellis, J. L., Carlson, A. L., Gomez, T. A., Montgomery, M. H., Winget, D. E., Chen, E. Y., et al., 2013, HEDP, 9, 82 Falcon, R. E., Rochau, G. A., Bailey, J. E., Gomez, T. A., Montgomery, M. H., Winget, D. E., Nagayama, T., 2015, ApJ, 806, 214 Gigosos, M. A., Djurović, S., Savić, I., González-Herrero, D., Mijatović, Z., and Kobliarov, R., 2014, A&A, 561, A135 Koester, D., Kepler, S. O., 2015, A&A, 583, 86 The above gas cell represents a major update from the previous WDPE cell presented in Falcon et al. (2013). Changes include: - Optical setup has been altered such that we can now accommodate a total of four lines of sight. Each of these are used to observe the plasma in low- and high-resolution, allowing us to capture both broad plasma spectra as well as detailed line shapes, widths, and shifts. – Data collection, reduction, and calibration methods have been altered to allow for precise determination of wavelengths, line widths, and shapes. This work was performed at Sandia National Laboratories and is supported by the Laboratory Directed Research and Development program. We thank the Z- facility teams and in particular, D. Scogiletti, D. Begay, D. Bliss, K. Shelton, A. York, and P. Lake for experimental support. Sandia National Laboratories is a multi- mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.. We also thank A. Wooton for for championing our fundamental science research efforts. M.S., M.H.M, and D.E.W. acknowledge support from the United States Department of Energy grant under DE-SC0010623. T.A.G. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant DGE-1110007. Fig. 3 – High-resolution CCD absorption image of experiment z3095, which contained a 2:1 molar mix of H 2 and He. We indicate locations of the timing comb (1), the timing impulse (2), the onset of x- rays (3), as well as the location of the 5875 Å He I absorption feature. These data were obtained using a Sydor streak camera with a 600 g/mm grating blazed at 5000Å. A preliminary analysis indicates that we have a time resolution of ~0.3 ns and a wavelength resolution of ~0.25 Å. This resolution allows is to measure precise line widths and shifts. Experimental Results Fig. 2 – Medium-resolution CCD emission image of experiment z3093, which contained a 2:1 molar mix of H 2 and He. We indicate locations of the timing comb (1), the timing impulse (2), the onset of x-rays (3), as well as the location of the 5875 Å He I emission feature. These data were obtained using a Sydor streak camera with a 300 g/mm grating blazed at 5000Å. A preliminary analysis indicates that we have a time resolution of ~0.3 ns, and a wavelength resolution of ~0.5 Å. Low-resolution He data Fig. 1 – Transmission spectra of experiment z3093, which contained a 2:1 molar mix of H 2 and He. We indicate locations of the major spectral lines. Using the Hβ line as our diagnostic (see Falcon et al. 2015), we estimate 1 x 10 17 cm -3 < n e < 6 x 10 17 cm -3 and 1.0 eV < T plasma < 1.5 eV for this particular experiment, which puts us at DB photospheric conditions. The transmission spectra in this plot have been offset for clarity. Summary / Future work The results presented on this poster represent first advances into elements beyond hydrogen as part of the WDPE. In our helium experiments, we have already reached plasma conditions comparable to those of DB photospheres. Using Hβ as our diagnostic, we are now able to compare our He profiles to those initially calculated by Beauchamp et al. (1997). Additionally, we may also be able to investigate the sharp upturn in DB mass observed by Koester & Kepler (2015) and Bergeron et al. (2011). 1 Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712, USA 2 Sandia National Laboratories, Albuquerque, NM 87185, USA
Transcript of Helium at white dwarf photosphere conditions: experimental ... · Helium at white dwarf photosphere...
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Helium at white dwarf photosphere conditions: experimental line shapes and shifts (SAND2017-6564 C)
Marc Schaeuble1, Ross Falcon2, Thomas Gomez1,2, Don Winget1, Michael Montgomery1, Jim Bailey2
We present preliminary results of an experimental study exploring He line shapes and shifts at photospheric conditions of white dwarf stars. These data were collected as part of the White Dwarf Photosphere Experiment (WDPE) on Sandia National Laboratories’ Z-machine, the largest x-ray source on earth. Our helium results could have many applications ranging from validating current DB white dwarf atmospheric models to providing accurate He pressure shifts at varying temperatures and densities. In a much broader context, these helium data can be used to guide theoretical developments in new continuum-lowering models for two-electron atoms.
Experimental Setup
Experimental Results (cont.)Abstract
Fig. 1 – Exploded and cross-sectioned view of the WDPE gas cell. Components are identified as follows:1 – WDPE gas cell2 – optical buffers3 – optics assembly for emission4 – optics assembly for absorption5 – Mylar window through which
x-rays enter gas cell6 – gold back wall7 – backlighter for absorption
High-resolution He data
References and Acknowledgements
Beauchamp, A., Wesemael, F., Bergeron, P., 1997, ApJS, 108, 559 Bergeron, P., Wesemael, F., Dufour, P., Beauchamp, A., Hunter, C., Saffer, Rex A., Gianninas, A., Ruiz, M. T., Limoges, M.-M., Dufour, P., et al., 2011, ApJ, 737, 28Falcon, R. E., Rochau, G. A., Bailey, J. E., Ellis, J. L., Carlson, A. L., Gomez, T. A., Montgomery, M. H., Winget, D. E., Chen, E. Y., et al., 2013, HEDP, 9, 82Falcon, R. E., Rochau, G. A., Bailey, J. E., Gomez, T. A., Montgomery, M. H., Winget, D. E., Nagayama, T., 2015, ApJ, 806, 214Gigosos, M. A., Djurović, S., Savić, I., González-Herrero, D., Mijatović, Z., and Kobliarov, R., 2014, A&A, 561, A135Koester, D., Kepler, S. O., 2015, A&A, 583, 86
The above gas cell represents a major update from the previous WDPE cell presented in Falcon et al. (2013). Changes include:- Optical setup has been altered such that we can now accommodate a total of four lines of sight. Each of these are used to observe the plasma in low- and high-resolution, allowing us to capture both broad plasma spectra as well as detailed line shapes, widths, and shifts.– Data collection, reduction, and calibration methods have been altered to allow for precise determination of wavelengths, line widths, and shapes.
This work was performed at Sandia National Laboratories and is supported by the Laboratory Directed Research and Development program. We thank the Z-facility teams and in particular, D. Scogiletti, D. Begay, D. Bliss, K. Shelton, A. York, and P. Lake for experimental support. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.. We also thank A. Wooton for for championing our fundamental science research efforts. M.S., M.H.M, and D.E.W. acknowledge support from the United States Department of Energy grantunder DE-SC0010623. T.A.G. acknowledges support from the National Science Foundation Graduate Research Fellowship under grant DGE-1110007.
Fig. 3 – High-resolution CCD absorption image of experiment z3095, which contained a 2:1 molar mix of H2 and He. We indicate locations of the timing comb (1), the timing impulse (2), the onset of x-rays (3), as well as the location of the 5875 Å He I absorption feature.
These data were obtained using a Sydorstreak camera with a 600 g/mm grating blazed at 5000Å. A preliminary analysis indicates that we have a time resolution of ~0.3 ns and a wavelength resolution of ~0.25 Å. This resolution allows is to measure precise line widths and shifts.Experimental Results
Fig. 2 – Medium-resolution CCD emission image of experiment z3093, which contained a 2:1 molar mix of H2 and He. We indicate locations of the timing comb (1), the timing impulse (2), the onset of x-rays (3), as well as the location of the 5875 Å He I emission feature.
These data were obtained using a Sydorstreak camera with a 300 g/mm grating blazed at 5000Å. A preliminary analysis indicates that we have a time resolution of ~0.3 ns, and a wavelength resolution of ~0.5 Å.
Low-resolution He data
Fig. 1 – Transmission spectra of experiment z3093, which contained a 2:1 molar mix of H2and He. We indicate locations of the major spectral lines.
Using the Hβ line as our diagnostic (see Falcon et al. 2015), we estimate 1 x 1017 cm-3 < ne < 6 x 1017 cm-3 and 1.0 eV < Tplasma < 1.5 eV for this particular experiment, which puts us at DB photospheric conditions.
The transmission spectra in this plot have been offset for clarity.
Summary / Future work
The results presented on this poster represent first advances into elements beyond hydrogen as part of the WDPE. In our helium experiments, we have already reached plasma conditions comparable to those of DB photospheres. Using Hβ as our diagnostic, we are now able to compare our He profiles to those initially calculated by Beauchamp et al. (1997). Additionally, we may also be able to investigate the sharp upturn in DB mass observed by Koester & Kepler (2015) and Bergeron et al. (2011).
1Department of Astronomy and McDonald Observatory, The University of Texas, Austin, TX 78712, USA2Sandia National Laboratories, Albuquerque, NM 87185, USA
