Volume 484, Number 2, June III 2008
|Page(s)||503 - 509|
|Published online||16 April 2008|
Reversal-free Ca II H profiles: a challenge for solar chromosphere modeling in quiet inter-network
Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, 79104 Freiburg, Germany e-mail: [rrezaei;bruls;wolfgang;schliche]@kis.uni-freiburg.de
2 Instituto de Astrofísica de Canarias (IAC), Via Láctea, E 38 205, La Laguna, Spain e-mail: firstname.lastname@example.org
3 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA e-mail: email@example.com
Accepted: 11 March 2008
Aims. We study chromospheric emission to understand the temperature stratification in the solar chromosphere.
Methods. We observed the intensity profile of the H line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope. We analyze over 105 line profiles from inter-network regions. For comparison with the observed profiles, we synthesize spectra for a variety of model atmospheres with a non local thermodynamic equilibrium (NLTE) radiative transfer code.
Results. A fraction of about 25% of the observed H line profiles do not show a measurable emission peak in and wavelength bands (reversal-free). All of the chosen model atmospheres with a temperature rise fail to reproduce such profiles. On the other hand, the synthetic calcium profile of a model atmosphere that has a monotonic decline of the temperature with height shows a reversal-free profile that has much lower intensities than any observed line profile.
Conclusions. The observed reversal-free profiles indicate the existence of cool patches in the interior of chromospheric network cells, at least for short time intervals. Our finding is not only in conflict with a full-time hot chromosphere, but also with a very cool chromosphere as found in some dynamic simulations.
Key words: Sun: chromosphere / Sun: atmosphere
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.