EDP Sciences
Free access
Volume 418, Number 2, May I 2004
Page(s) 703 - 715
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20035717

A&A 418, 703-715 (2004)
DOI: 10.1051/0004-6361:20035717

Nitrogen abundances in planet-harbouring stars

A. Ecuvillon1, G. Israelian1, N. C. Santos2, 3, M. Mayor3, R. J. García López1, 4 and S. Randich5

1  Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
2  Centro de Astronomia e Astrofisica de Universidade de Lisboa, Observatorio Astronomico de Lisboa, Tapada de Ajuda, 1349-018 Lisboa, Portugal
3  Observatoire de Genève, 51 ch. des Maillettes, 1290 Sauverny, Switzerland
4  Departamento de Astrofísica, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez s/n, 38206 La Laguna, Tenerife, Spain
5  INAF/Osservatorio Astrofisico di Arcetri, Largo Fermi 5, 50125 Firenze, Italy

(Received 20 November 2003 / Accepted 4 February 2004 )

We present a detailed spectroscopic analysis of nitrogen abundances in 91 solar-type stars, 66 with and 25 without known planetary mass companions. All comparison sample stars and 28 planet hosts were analysed by spectral synthesis of the near-UV NH band at 3360 Å observed at high resolution with the VLT/UVES, while the near-IR N I 7468 Å was measured in 31 objects. These two abundance indicators are in good agreement. We found that nitrogen abundance scales with that of iron in the metallicity range -0.6 < [Fe/H]  <+0.4 with the slope $1.08 \pm 0.05$. Our results show that the bulk of nitrogen production at high metallicities was coupled with iron. We found that the nitrogen abundance distribution in stars with exoplanets is the high [Fe/H] extension of the curve traced by the comparison sample of stars with no known planets. A comparison of our nitrogen abundances with those available in the literature shows a good agreement.

Key words: stars: abundances -- stars: chemically peculiar -- stars: evolution -- stars: planetary systems -- Galaxy: solar neighbourhood

Offprint request: A. Ecuvillon, aecuvill@ll.iac.es

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