Laboratory observation of C and O emission lines of White Dwarf H1504+65-like atmosphere modelONLINE ONLY

H1504+65, a bare stellar nucleus, is an unusual white dwarf with a Carbon- and Oxygen-dominated atmosphere. The composition cannot be explained by current stellar evolution models. The analysis of the elemental abundance and the improvement of stellar atmospheric models depends heavily on spectral measurements and accurate spectral data. We used soft x-ray emission from a laser heated hohlraum to irradiate a foam target and obtained a Carbon-Oxygen plasma emission spectrum with temperature T=195 000K±10 000K and mass fraction ratio C/O=0.85, similar to that of H1504+65. We performed a detailed comparison of our spectra with the H1504+65 Chandra spectrum, and do observe the same O VI emission lines. Furthermore, most of the O V lines identified in our work correspond to unidentified absorption lines in the Chandra spectrum, where we are now able to provide a wealth of experimental data for the identification of the weaker absorption lines. Moreover, the Carbon-Oxygen plasma spectra of our work fill the gap between 15nm and 80nm caused by the high interstellar neutral hydrogen column density, where we find O V lines at 17.2 nm and 63.2 nm whose intensity ratio is temperature dependent, as well as abundant O IV-VI emission lines and distinct C IV lines.

Zoom-Meeting
https://gsi-fair.zoom.us/j/96629963798

Meeting-ID: 966 2996 3798
Kenncode: 130302