A new code for automatic determination of equivalent widths: Automatic Routine for line Equivalent widths in stellar Spectra (ARES) ^*,**

¹ Centro de Astronomia e Astrofísica da Universidade de Lisboa, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal e-mail: sousasag@astro.up.pt
² Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
³ Departamento de Matemática Aplicada, Faculdade de Ciências da Universidade do Porto, Portugal
⁴ Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
⁵ Centro de Geofísica de Évora, Colégio Luis Antonio Verney, Évora, Portugal
⁶ Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain

Received: 13 February 2007
Accepted: 6 March 2007

Abstract

Aims.We present a new automatic code (ARES) for determining equivalent widths of the absorption lines present in stellar spectra. We also describe its use for determining fundamental spectroscopic stellar parameters.

Methods.The code is written in C++ based on the standard method of determining EWs and is available for the community. The code automates the manual procedure that the users normally carry out when using interactive routines such as the splot routine implemented in IRAF.

Results.We test the code using both simulated and real spectra with different levels of resolution and noise and comparing its measurements to the manual ones obtained in the standard way. The results shows a small systematic difference, always below 1.5 mÅ. This can be explained by errors in the manual measurements caused by subjective continuum determination. The code works better and faster than others tested before.