Astron. Astrophys. 336, L57-L60 (1998)

Letter to the Editor

The prolate solar chromosphere

F. Auchère ¹, S. Boulade ², S. Koutchmy ², R.N. Smartt ³, J.P. Delaboudinière ¹, A. Georgakilas ⁴, J.B. Gurman ⁵ and G.E. Artzner <sup>1

1</sup> Institut d'Astrophysique Spatiale, Bâtiment 121, Université Paris XI, F-91405 Orsay Cedex, France
² Institut d'Astrophysique de Paris, 98 bis Boulevard Arago, F-75014 Paris, France
³ NSO/Sacramento Peak Observatory, Sunspot, NM 88349, USA
⁴ National Observatory, Athens, Greece
⁵ NASA/Goddard Space Flight Center, Greenbelt, MD, USA

Received 27 April 1998 / Accepted 18 June 1998

Abstract

We present a comparative analysis of the chromospheric solar limb prolateness, using strictly simultaneous ground-based observations and HeII space-based observations. The typical prolateness is found to be in HeII and in . The first measurements in the 30.4 nm HeII line over a period of two years, as well as coronal data, are discussed to explore further the origin of the prolateness and its possible consequences.

Key words: Sun: chromosphere corona

Send offprint requests to: F. Auchère

This article contains no SIMBAD objects.

Contents

• 1. Introduction
• 2. Results of the August 1997 observing campaign
  • 2.1. Limb features
  • 2.2. The overall limb
  • 2.3. The solar prolateness
• 3. Improved analysis with the EIT images alone
  • 3.1. Data processing
  • 3.2. Results and first comments
• 4. Discussions
• References

© European Southern Observatory (ESO) 1998

Online publication: July 27, 1998
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