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X-ray spectroscopy evidence for plasma shell formation in experiments modeling accretion columns in young stars
Recent achievements in laboratory astrophysics experiments with high-power lasers have allowed progress in our understanding of the early stages of star formation. In particular, we have recently demonstrated the possibility of simulating in the laboratory the process of the accretion of matter on y...
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Published in: | Matter and Radiation at Extremes 2019-11, Vol.4 (6), p.064402-064402-8 |
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Main Authors: | , , , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Recent achievements in laboratory astrophysics experiments with high-power lasers have
allowed progress in our understanding of the early stages of star formation. In
particular, we have recently demonstrated the possibility of simulating in the laboratory
the process of the accretion of matter on young stars [G. Revet et
al., Sci. Adv. 3, e1700982 (2017)]. The present paper focuses on
x-ray spectroscopy methods that allow us to investigate the complex plasma hydrodynamics
involved in such experiments. We demonstrate that we can infer the formation of a plasma
shell, surrounding the accretion column at the location of impact with the stellar
surface, and thus resolve the present discrepancies between mass accretion rates derived
from x-ray and optical-radiation astronomical observations originating from the same
object. In our experiments, the accretion column is modeled by having a collimated narrow
(1 mm diameter) plasma stream first propagate along the lines of a large-scale external
magnetic field and then impact onto an obstacle, mimicking the high-density region of the
stellar chromosphere. A combined approach using steady-state and quasi-stationary models
was successfully applied to measure the parameters of the plasma all along its
propagation, at the impact site, and in the structure surrounding the impact region. The
formation of a hot plasma shell, surrounding the denser and colder core, formed by the
incoming stream of matter is observed near the obstacle using x-ray spatially resolved
spectroscopy. |
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ISSN: | 2468-2047 2468-080X 2468-080X |
DOI: | 10.1063/1.5124350 |