Multi-fluid model of a sun-grazing comet in the rapidly ionizing, magnetized low corona

Journal Article · Thu Nov 20 00:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/796/1/42· OSTI ID:22369968

Jia, Y. -D.; Russell, C. T. ^[1]; Liu, W. ^[2]

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1. IGPP and EPSS, University of California, Los Angeles, CA 90095 (United States)
2. Stanford-Lockheed Institute for Space Research, Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

Two Sun-grazing comets were recently imaged in the low solar corona by space telescopes in unprecedented detail, revealing a wide range of new phenomena. This sparked growing interest in the interaction of comets with the coronal plasma and magnetic field and their diagnostic potential as solar probes. However, interpretation of such rich observational data requires profound understanding of relevant physical processes in an unexplored regime. Here advanced numerical modeling can provide critical clues. To this end, we present a prototype, multi-fluid, magnetohydrodynamic model of a steady-state comet in the low solar corona. These simulation results are compared with previously modeled comets in the solar wind environment. By inspecting their projection and column densities, we find a dominance of O{sup 6+} ions in the cometary tail, which can explain the observed extreme ultraviolet emission. The tail is found to be comparable to recent EUV images of these comets. In addition, the comet tail appears wider when the observer's line of sight is perpendicular rather than parallel to the local magnetic field. This is opposite to the trend in the interplanetary space permeated in the solar wind, because the ratio between dynamic pressure and magnetic pressure is an order of magnitude smaller than at 1 AU. On the other hand, we find that iron ions in the comet head build up to a density comparable to that of oxygen ions, but are unlikely to form a visible tail because of the shorter mean free paths of the neutrals.

• OSTI ID: 22369968
• Journal Information: Astrophysical Journal, Vol. 796, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COMETS
COMPARATIVE EVALUATIONS
DENSITY
EMISSION
EXTREME ULTRAVIOLET RADIATION
INTERPLANETARY SPACE
IRON IONS
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MEAN FREE PATH
OXYGEN IONS
PLANETS
PLASMA
SATELLITES
SIMULATION
SOLAR CORONA
SOLAR WIND
STEADY-STATE CONDITIONS
SUN
TELESCOPES