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Astron. Astrophys. 340, L15-L17 (1998)

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Letter to the Editor

The O V 1213.9 Å forbidden line in the quiet Sun

D.J. Pinfield 1, M. Mathioudakis 1, F.P. Keenan 1, K.J.H. Phillips 2 and W. Curdt 3

1 Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast, BT7 1NN, Northern Ireland
2 Space Science Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, UK
3 Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany

Received 25 August 1998 / Accepted 13 October 1998


We present the first unambiguous detection of the O V 1213.9 Å (2s2 1S0 [FORMULA] 2s2p 3P2) forbidden line in the solar spectrum, using observations obtained with the SUMER instrument on board SOHO. The wavelength separation of the forbidden to the (2s2 1S0 [FORMULA] 2s2p 3P1) intercombination line at 1218.35 Å is 4.5[FORMULA]0.1 Å in excellent agreement with theoretical predictions. The observed line ratio, combined with the latest calculations, allows us to derive an electron density of [FORMULA] for the quiet Sun. However, the O V 1213.9 Å line was not detected in the HST spectra of Procyon and we can only place a lower limit of [FORMULA] to the electron density in this object.

Key words: atomic data – line identification – Sun: chromosphere – Sun: corona – stars: individual: procyon

Send offprint requests to: dpi@star.pst.qub.ac.uk

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© European Southern Observatory (ESO) 1998

Online publication: November 3, 1998