Hydrogen Atoms in the Heliosphere: The Interplanetary UV Glow
When
Where
Dr. Eric Quémerais
Director of Research
Laboratoire Atmosphéres, Milieux, Observations Spatiales (LATMOS)
Hydrogen atoms in the interplanetary medium have been studied by UV instruments since the discovery of the interplanetary UV glow by two instruments of the OGO-5 mission (Bertaux and Blamont, 1971 and Thomas and Krassa,1971). The interplanetary glow is caused by the backscatter of solar Lyman alpha photons by hydrogen atoms that originate from the interstellar medium. In the vicinity of the Sun, the hydrogen distribution is mainly influenced by the solar wind and the interplanetary glow reflects the spatial and temporal variations of the solar wind mass flux and of the solar Lyman alpha photon flux.
First we will summarize our current global model of the interplanetary glow including effects of the heliospheric interface on the hydrogen distribution. Then, we will present data obtained by various UV instruments including the UV Spectrometers on Voyager 1 and 2, the SWAN Lyman alpha photometer on SOHO or the MASCS spectrometer on MESSENGER. Many UV instruments have observed the interplanetary glow during their cruise to their target therefore the IP glow offers the possibility to cross-calibrate these different instrument, using our global model to fill gaps. Finally, we will give special attention to the Voyager UVS data obtained in the outer heliosphere.
Host: Dr. Walter Harris