The solar hydrogen Lyman α to Lyman β line ratio
1 Institut d’Astrophysique Spatiale (IAS), CNRS – Université Paris-Sud, 91405 Orsay, France
2 Max-Planck-Institut für Sonnensystemforschung, Max-Planck -Str. 2, 37191 Katlenburg-Lindau, Germany
3 Laboratory for Atmospheric and Space Physics (LASP), University of Colorado, Boulder, Colorado, USA
Received: 13 February 2012
Accepted: 25 April 2012
Aims. We investigate the variation in the solar hydrogen Lyman α (Lyα) to Lyman β (Lyβ) line ratio as a function of the solar activity by taking into account new results obtained by SoHO/SUMER and TIMED/SEE.
Methods. We reanalyze data of quiet and active regions previously collected with the LPSP multichannel instrument on OSO8. We then re-examine data obtained on the solar disk with SUMER and compare them with previous data. In a second step, we use the full Sun H i Lyβ profiles to determine the Lyβ contribution to the SEE profiles obtained with a 0.4 nm full width at half-maximum. The variation in the Lyα to Lyβ line ratio is then measured for part of the solar cycle 23 (2002–2008).
Results. We determine the radiance line ratio of the solar H i Lyα to Lyβ line for a quiet Sun area and the relation between the ratio of the Lyα to Lyβ irradiance and the Lyα solar irradiance.
Key words: Sun: chromosphere / Sun: UV radiation / Sun: activity / Sun: heliosphere
© ESO, 2012