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arXiv · 1611.08203

Stability of the interstellar hydrogen inflow longitude from 20 years of SOHO/SWAN observations

Dimitra Koutroumpa·Eric Quémerais·Olga Katushkina·Rosine Lallement·Jean-Loup Bertaux·Walter Schmidt
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Abstract

Aims. A recent debate on the decade-long stability of the interstellar He flow vector, and in particular the flow longitude, has prompted us to check for any variability in the interstellar H flow vector as observed by the SWAN instrument on board SOHO. Methods. We used a simple model-independent method to determine the interstellar H flow longitude, based on the parallax effects induced on the Lyman-α intensity measured by SWAN following the satellite motion around the Sun. Results. Our results show that the interstellar H flow vector longitude does not vary significantly from an average value of 252.9$^{\circ}$ $\pm$ 1.4$^{\circ}$ throughout the 20-year span of the SWAN dataset, further strengthening the arguments for the stability of the interstellar gas flow.

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Dimitra Koutroumpa, Eric Quémerais, Olga Katushkina, Rosine Lallement, Jean-Loup Bertaux, Walter Schmidt. 2016-11-24. Stability of the interstellar hydrogen inflow longitude from 20 years of SOHO/SWAN observations. https://doi.org/10.1051/0004-6361%2F201629840

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