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Astron. Astrophys. 323, 217-222 (1997)


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NGC 7027: discovery of a Raman line in a planetary nebula *

D. Péquignot 1, J.-P. Baluteau 2, C. Morisset 1 and C. Boisson 1

1 Laboratoire d'Astrophysique Extragalactique et de Cosmologie associé au CNRS (URA 173) et à l'Université Paris 7,
DAEC, Observatoire de Paris-Meudon F-92195 Meudon Cédex, France
2 Laboratoire d'Astronomie Spatiale, LP CNRS, BP 8, F-13376 Marseille Cédex 12, France (pequignot@obspm.fr, baluteau@astrsp-mrs.fr, morisset@obspm.fr, boisson@obspm.fr)

Received 28 November 1996 / Accepted 16 December 1996

Abstract

We report on the discovery of the He II Raman line [FORMULA] 485.1 nm in the spectrum of the planetary nebula NGC 7027.

This line is direct evidence for the presence of atomic hydrogen in the nebula.

It is shown that this Raman line can provide reliable pieces of information concerning both the velocity field of the He [FORMULA] region and the expansion velocity of the surrounding H0 shell.

Detection of self-Raman scattering of [FORMULA] is suspected.

Key words: atomic processes – line: identification – line: profiles – ISM: general – ISM: planetary nebulae: general – ISM: planetary nebulae: individual: NGC 7027

* Based on observations performed at Observatoire de Haute-Provence, France.

Send offprint requests to: D. Péquignot

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998

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