Observed perturbations of the velocity distribution of interstellar hydrogen atoms in the solar system with Prognoz Lyman-alpha measurements

Rosine Lallement (1) , Jean-Loup Bertaux (1) , V. G. Kurt (2) , E. N. Mironova (2)

1 SA - Service d'aéronomie
2 IKI - Space Research Institute of the Russian Academy of Sciences

Observations of the interplanetary Lyman α emission made at five different places in the solar system with high apogee satellites Prognoz 5 and Prognoz 6 are reported. This Lyα emission is the result of resonance scattering of solar photons by H atoms of the local interstellar medium (LISM) flowing in the solar system at the velocity - Vw and the spectral profile is an image of the velocity distribution of the atoms. A hydrogen absorption cell was used to analyze the spectral profile, the variation of Doppler shift with looking direction providing its spectral scanning. A first estimate of the LISM temperature is derived, T ≅ 8000K, and also an approximate location of Vw in fair agreement with previous measurements. The observed variation of the heating effect is of 3000K, and is independent of the existence of a potential galactic background in the vicinity of the Lyα wavelength. An upper limit of this background is found to be 15 Rayleigh.

Keywords: Astronomical Spectroscopy; Hydrogen Atoms; Interplanetary Medium; Interstellar Gas; Lyman Alpha Radiation; Solar System; Galactic Radiation; Prognoz Satellites; Velocity Distribution; Astrophysics

Domains: Astrophysics [astro-ph]

Rosine Lallement, Jean-Loup Bertaux, V. G. Kurt, E. N. Mironova. Observed perturbations of the velocity distribution of interstellar hydrogen atoms in the solar system with Prognoz Lyman-alpha measurements. Astronomy and Astrophysics - A&A, 1984, 140 (2), pp.243-250. ⟨insu-03168761⟩