86 GHz SiO maser survey of late-type stars in the inner Galaxy

Abstract

Abstract. We have determined extinction corrections for a sample of 441 late-type stars in the inner Galaxy, which we previously searched for SiO maser emission, using the 2MASS near-infrared photometry of the surrounding stars. From this, the near-infrared extinction law is found to be approximated by a power law A λ ∝ λ −1.9±0.1 . Near-and mid-infrared colour-colour properties of known Mira stars are reviewed. From the distribution of the dereddened infrared colours of the SiO target stars we infer mass-loss rates between 10 −7 and 10 −5 M yr −1 .

Near- and mid-infrared colors of evolved stars in the Galactic plane. TheQ1 andQ2 parameters

“…(1) in Indebetouw et al (2005), and A J /A Ks from Messineo et al (2005). The assumed and resulting quantities are listed in Table 1.…”

“…In order to identify photometric criteria that might separate early-type stars from late-type stars and identify specific types Messineo et al (2005) of stars (e.g. WRs and RSGs), we analyzed the distribution of evolved stars in several color-color diagrams.…”

“…Figure 1 shows the H−K s versus J − H diagram of our samples of evolved stars. Two continuous lines are plotted, showing the loci of a "naked" M5 star (left/higher dashed line) and of an O9 star (right/lower line) (Koornneef 1983) with varying interstellar extinction, as well as the reddening vector (Messineo et al 2005). It is not possible to classify stars with this diagram alone, e.g.…”

“…The combined use of near-and mid-infrared measurements permits detection of evolved mass-losing stars, as demonstrated with ISOGAL and MSX data (e.g. Alard et al 2001;Messineo et al 2005). However, the classification of evolved stars using GLIMPSE data is still largely unexplored.…”

“…Successful selection of mass-losing latetype stars has been made with data from the MSX survey (e.g. Messineo et al , 2005Sevenster 2002;Sjouwerman et al 2009). A dust sequence of O-rich envelopes is seen also with MSX colors (Sjouwerman et al 2009;Sevenster 1999).…”