In a previous paper (Ginestet et al. 1994) we have shown the
interest of the near infrared region for the accurate
classification of the cooler components of composite spectra.
This is due to the fact that the magnitude difference favors
the late-type giant or supergiant companions. In that paper we
examined in detail the behavior of the MK standards and we
found that with the exception of a few (6%), the MK standards
can also be used as standards in the near infrared domain (8380-
8780 Å). We provided a number of classification criteria using
the equivalent widths (
) of a number of features (due for
instance to FeI, TiI, CaII, blend at 8468, etc ...) plotted
against the MK spectral type and luminosity class of the star.
We remarked however that it is not enough to apply simply the
criteria, but that the whole spectrum has to be examined
carefully. This is entirely in line with similar remarks by the
authors of the MK system. We thought therefore that it would be
worthwhile to reproduce the spectra themselves, which lead
quite naturally to the present Atlas.
Table 2: Stars with spectral peculiarities
The present Atlas (Part II) covers the later type stars and is
to be taken as a continuation of Part I, which presented the
early type stars (Andrillat et al. 1995). Both parts are based
on spectra obtained with the same instrument and the same
dispersion (33 Å/mm) covering the same spectral interval. It
should be added that a few peculiar stars, signaled in the
text, have been obtained with the AURELIE spectrometer.
We would like to recall that the near infrared has been studied
by a number of authors which we would like to mention briefly.
The infrared region has been studied:
- to emphasize the interest it presents for the obtention of
luminosity criteria (Merrill 1934; Keenan & Hynek 1945)
- for the classification of later type stars, essentially
those of type M (Sharpless 1956; Parsons 1964;
Solf 1978;
Barbieri et al. 1981; Kirkpatrick et al. 1991;
Huang et al. 1994).
Very often the infrared CaII triplet lines alone have been
analysed for a classification of the late type stellar
components of galaxies (Jones et al. 1984;
Carter et al. 1986;
Alloin & Bicca 1989;
Diaz et al. 1989;
Zhou 1991;
Mallik 1994).
Two atlases should also be signaled, based upon material
obtained on a much lower scale. The first one is by Danks &
Dennefeld (1994) and is based upon southern MK standards
observed over an extended region (5800-10200 Å) at a dispersion
of 171 Å/mm and the other one is by Torres-Dodgen & Weaver
(1993). The latter covers the region 5800-8900 Å at
approximately 15 Å resolution.
In what follows we shall describe first the material used and
the reduction procedure (for more details see Ginestet et al.
1994) and then the atlas itself and the classification
procedure.
