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Title: A new detection of LYα absorption from the heliotail

We present new Hubble Space Telescope observations of H I Lyα absorption toward the F8 V star HD 35296. This line of sight is only a few degrees from the downwind direction of the local interstellar medium flow vector. As a consequence, Lyα absorption from the heliotail is detected in the spectrum, consistent with three previous downwind detections of heliotail absorption. The clustering of the heliotail absorption detections around the downwind direction demonstrates that the heliotail is pointed close to that direction, limiting the extent to which the interstellar magnetic field might be distorting and deflecting the heliotail. We explore this issue further using three-dimensional MHD models of the global heliosphere. The three computed models represent the first three-dimensional MHD models with both a kinetic treatment of neutrals and an extended grid in the tail direction, both of which are necessary to model Lyα absorption downwind. The models indicate only modest heliotail asymmetries and deflections, which are not large enough to be inconsistent with the clustering of heliotail absorption detections around the downwind direction. The models are reasonably successful at reproducing the observed absorption, but they do overpredict the Lyα opacity by a factor of 2-3. We discuss implications ofmore » these results in light of observations of the heliotail region from the Interstellar Boundary Explorer mission.« less
Authors:
 [1] ;  [2] ;  [3] ; ;  [4]
  1. Naval Research Laboratory, Space Science Division, Washington, DC 20375 (United States)
  2. Department of Air Mechanics and Gas Dynamics, Faculty of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow 119991 (Russian Federation)
  3. Space Research Institute of RAS, Moscow 117997 (Russian Federation)
  4. Astronomy Department, Van Vleck Observatory, Wesleyan University, 96 Foss Hill Drive, Middletown, CT 06459 (United States)
Publication Date:
OSTI Identifier:
22348282
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASYMMETRY; COMPUTERIZED SIMULATION; DETECTION; HELIOSPHERE; INTERSTELLAR MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; OPACITY; SOLAR WIND; SPACE; SPECTRA; SUN; TELESCOPES; ULTRAVIOLET RADIATION; VISIBLE RADIATION