1. Mapping the solar wind HI outflow velocity in the inner heliosphere by coronagraphic ultraviolet and visible-light observations
- Author
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Gianalfredo Nicolini, Daniele Telloni, Roberto Susino, Ester Antonucci, Clementina Sasso, Rita Ventura, Vincenzo Andretta, S. Dolei, Silvano Fineschi, Lucia Abbo, Giampiero Naletto, F. Frassetto, Maurizio Pancrazzi, Daniele Spadaro, Piergiorgio Nicolosi, Marco Romoli, Mauro Focardi, V. Da Deppo, Federico Landini, Alessandro Bemporad, Silvio Giordano, and ITA
- Subjects
Brightness ,010504 meteorology & atmospheric sciences ,Solar wind ,Astrophysics ,01 natural sciences ,law.invention ,Orbiter ,law ,Sun: corona ,Sun: UV radiation ,Astronomy and Astrophysics ,Space and Planetary Science ,0103 physical sciences ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,0105 earth and related environmental sciences ,Line (formation) ,Physics ,Corona ,Physics::Space Physics ,Solar rotation ,Outflow ,Astrophysics::Earth and Planetary Astrophysics ,Heliosphere - Abstract
We investigated the capability of mapping the solar wind outflow velocity of neutral hydrogen atoms by using synergistic visible-light and ultraviolet observations. We used polarised brightness images acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα line observations of the UVCS/SOHO spectrometer to obtain daily maps of solar wind H I outflow velocity between 1.5 and 4.0 R⊙ on the SOHO plane of the sky during a complete solar rotation (from 1997 June 1 to 1997 June 28). The 28-days data sequence allows us to construct coronal off-limb Carrington maps of the resulting velocities at different heliocentric distances to investigate the space and time evolution of the outflowing solar plasma. In addition, we performed a parameter space exploration in order to study the dependence of the derived outflow velocities on the physical quantities characterising the Lyα emitting process in the corona. Our results are important in anticipation of the future science with the Metis instrument, selected to be part of the Solar Orbiter scientific payload. It was conceived to carry out near-sun coronagraphy, performing for the first time simultaneous imaging in polarised visible-light and ultraviolet H I Lyα line, so providing an unprecedented view of the solar wind acceleration region in the inner corona.
- Published
- 2018