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1. Introduction

Carbon stars have been, so far, mainly identified on objective prism survey plates (e.g., Stephenson 1989, hereinafter GCCCS). More recently, C-rich stars surrounded by a circumstellar dust shell (CDS) that blocks most of the optical radiation, have been recognized thanks to the emission feature of the SiC grains which are contained in their envelopes. A large number of these so-called Infrared Carbon Stars (hereinafter, IRCS) have been found by inspection of the Low Resolution Spectra that were obtained during the IRAS mission (LRS, IRAS Science Team 1986 and works by Volk & Cohen 1989 and Volk et al. 1992a). Most of them have been classified in the "4n" class of the LRS.

Epchtein et al. (1987) have shown that IRCS can also be reliably identified through the location of their representative points in a colour-colour diagram that combines a near-IR colour (e.g., K-L), and the IRAS colour [12-25]. In these diagrams C-rich and O-rich stars with circumstellar envelopes clearly break out, while they do not in a pure IRAS colour-colour diagram (e.g., van der Veen & Habing 1988, hereinafter VH).

The efficiency of this method has been demonstrated on a large sample of IRAS objects whose LRS exhibit the SiC feature (Epchtein et al. 1990), and has been successfully applied to various samples of IRAS Point Sources without LRS spectra, and has lead to the identification of more than 100 new IRCS, mainly in the southern sky (Guglielmo et al. 1993, Paper I).

In the present paper we present an extension of this search to a sample of 172 IRAS stars selected randomly in the area of the IRAS colour-colour diagram where the proportion of C-rich stars has been shown to be the largest (region VII of VH), or, which have a [12-25] colour index that corresponds to this region when the tex2html_wrap_inline933 IRAS flux measurement is either absent or of bad quality. A few additional stars (35) already known as carbon stars or with uncertain IRAS LRS spectra have been also observed.


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