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Astron. Astrophys. Suppl. Ser. 141, 141-148

High resolution spectroscopy over 8500-8750 Å for GAIA[*],[*],[*]

II. A library of synthetic spectra for   7500 K

U. Munari1,2 - F. Castelli3

Send offprint request: U. Munari, e-mail:

1 - Osservatorio Astronomico di Padova, Sede di Asiago, I-36012 Asiago (VI), Italy
2 - Centro Interpardimentale Studi ed Attività Spaziali (CISAS "G. Colombo"), Università di Padova, Italy
3 - CNR-GNA-Osservatorio Astronomico di Trieste Via Tiepolo 11, I-34131 Trieste, Italy

Received September 9; accepted October 4, 1999


We present a library of synthetic spectra characterized by $-2.5 \leq
[Z/Z_\odot] \leq +0.5,\ 4.5 \leq \log~g\leq~1.0$, and $T\rm _{eff}$ $\leq
7500$ K computed at the same $\lambda/\bigtriangleup\lambda$ = 20000 resolving power of the observed spectra given in Paper I for 131 standard stars mapping the MKK spectral classification system. This range of parameters includes the majority of the galactic stars expected to dominate the GAIA target population, i.e. F-G-K-M type stars with metallicity ranging from that of the galactic globular clusters to Population I objects. Extension to $T\rm _{eff}$> 7500 K will be given later on in this series. The 254 synthetic spectra presented here are based on Kurucz's codes and line data and have been computed over a more extended wavelength interval (7650-8750 Å) than that currently baselined for implementation on GAIA, i.e. the 8500-8750 Å. This last range is dominated by the near-IR Ca II triplet and the head of the Paschen series. The more extended wavelength range allows us to investigate the behaviour of other strong near-IR spectral features (severely contaminated by telluric absorptions in ground-based observed spectra) as the K I doublet (7664, 7699 Å), the Na I doublet (8183, 8194 Å) and the lines of Fe I multiplet N.60 at 8327 and 8388 Å. The synthetic spectra support our previous conclusions about the superior performance of the Paschen/Ca II 8500-8750 Å region in meeting the GAIA requirements when compared to other near-IR intervals of similar $\bigtriangleup \lambda $ = 250 Å.

Key words: atlases -- surveys -- stars: fundamental parameters

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