Observations of the first-overtone silicon monoxide bands in late-type stars

Rinsland, C. P.; Wing, R. F.

doi:10.1086/160411

Cited by 29 publications

(20 citation statements)

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“…5 and 6. This agrees with the findings by Origlia et al (1993) for the CO first overtone and from Rinsland & Wing (1982) for the SiO first overtone lines. Contamination from the circumstellar shell could be a factor that would increase the scatter of the CO fundamental band strength.…”

Section: Discussionsupporting

confidence: 93%

“…6. Although this trend is present in both bands in K and M stars, the dependency of the SiO first overtone absorption is less pronounced for K stars, which is consistent with the observations of Rinsland & Wing (1982). Although there is a general increase of the SiO fundamental band strength from K to M stars, a clear trend is not well defined.…”

Section: Molecular Equivalent Widths and Mk Classsupporting

confidence: 85%

“…The dependence of the SiO first overtone absorption as a function of temperature was predicted by stellar model atmospheres (Rinsland & Wing 1982;Tsuji et al 1994;Aringer et al 1997;Decin 2000). With regard to the SiO fundamental, there are few observational studies in the literature due to the difficulties in observing this band from the ground.…”

Section: Discussionmentioning

confidence: 99%

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Infrared spectral classification of normal stars

Heras¹,

Shipman²,

Price³

et al. 2002

A&A

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Abstract. Moderate resolution (≈400) 2.38-45.2 µm infrared spectra of stars without dust features were obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). The observations are part of a larger program with the objective to extend and refine the current infrared classification schemes. In particular, our data provide the basis for a more detailed classification of the 1.N-1.NO sources (ordinary and oxygen rich naked stars) as defined by Kraemer et al. (2002) in a comprehensive classification of the ISO-SWS spectra. For our analysis, the continuum was determined by fitting Engelke's function (Engelke 1992) to the SWS data. The stellar angular diameters derived from these estimates of the continuum are in good agreement with values obtained by other methods. Analysis of the equivalent widths of the CO fundamental and first overtone molecular bands, the SiO fundamental and first overtone, as well as the H 2 O bending mode band as a function of MK class, reveals that there is sufficient information in the SWS spectra to distinguish between hot (B, A, F) and cool stars. Furthermore, it is possible to determine the spectral type for the G, K and M giants, and subtype ranges in a sequence of K and M giants. The equivalent widths of the CO and SiO bands are found to be well correlated in K and M stars, such that the equivalent widths of the CO fundamental, the SiO first overtone and the SiO fundamental can be reasonably well extrapolated from the depth of the CO first overtone. We have identified two stars, HR 365 and V Nor, whose mid-infrared spectrum does not correspond to their respective optical classification. HR 365 may have a late M companion, which dominates the observed infrared spectrum while V Nor is a late type giant that was included because its spectrum was classified as featureless under the IRAS LRS scheme. According to Kraemer et al. (2002), V Nor has a thin dust shell, which distorts the analysis of its mid-infrared absorption bands.

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Section: Discussionsupporting

confidence: 93%

Section: Molecular Equivalent Widths and Mk Classsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

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Infrared spectral classification of normal stars

Heras¹,

Shipman²,

Price³

et al. 2002

A&A

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“…Veiling by dust and/or chromospheric continuum emission, and/or band reversal due to pulsational shocks may have made the SiO bands appear weaker in their small sample (an example of filling-in of the absorption by diffuse emission is given by Sloan & Price (1998) for α Herculis). Indeed, these LMC stars resemble luminous, strongly pulsating stars in the Solar Neighbourhood (Rinsland & Wing 1982). Our larger compilation of LMC spectra do include some examples of SiO bands, e.g., HV 2532 (Fig.…”

Section: Oxygen Chemistrymentioning

confidence: 88%

Molecules and dust production in the Magellanic Clouds

Loon¹,

Cohen

Oliveira³

et al. 2008

A&A

146

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We present ESO/VLT spectra in the 2.9−4.1 μm range for a large sample of infrared stars in the Small Magellanic Cloud (SMC), mainly carbon stars, massive oxygen-rich Asymptotic Giant Branch (AGB) stars, and red supergiants. Strong emission from Polycyclic Aromatic Hyrdrocarbons (PAHs) is detected in the spectrum of the post-AGB object MSX SMC 29. Water ice is detected in at least one Young Stellar Object, IRAS 01042−7215, for the first time in the SMC. The strength and shapes of the molecular bands detected in the evolved stars are compared with similar data for stars in the Large Magellanic Cloud (LMC). Absorption from acetylene in carbon stars is found to be equally strong in the SMC as in the LMC, but the LMC stars show stronger dust emission in their infrared colours and veiling of the molecular bands. This suggests that a critical link exists in the formation of dust from the molecular atmosphere in carbon stars which scales with the initial metallicity. Nucleation seeds based on a secondary element such as titanium or silicon provide a plausible explanation. In oxygen-rich stars, both the nucleation seeds and molecular condensates depend on secondary elements (in particular titanium, silicon, and/or aluminium), which explains the observed lower molecular abundances and lower dust content in the SMC stars. Emission from silicon monoxide seen in some oxygen-rich AGB stars and red supergiants in the SMC suggests that these metal-poor stars are able to drive strong pulsation shocks through their molecular layers. Data for pulsating dusty AGB stars and supergiants in the LMC are used to show that pulsation is likely the critical factor in driving mass loss, as long as dust forms, rather than the stellar luminosity. Finally, we suggest that the reduced dust production and consequently slower winds of metal-poor AGB stars and red supergiants are more likely to result in chemical inhomogeneities and small-scale structure in the interstellar medium.

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“…This is the first use of these 4 µm lines at high resolution for monitoring the atmospheric changes in pulsating stars. However, the 4 µm spectrum of SiO has been monitored previously at medium and low resolution (Hinkle et al 1976;Rinsland & Wing 1982). Aringer et al (1997Aringer et al ( , 1999b have shown from medium resolution 4 µm spectra that hydrostatic models cannot reproduce the spectra properly.…”

Section: Introductionmentioning

confidence: 99%

4 $\mathsf{\mu}$m spectra of AGB stars I. Observations

Lebzelter

Hinkle

Aringer

2001

A&A

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Abstract. We present times series of high resolution spectra of AGB variables at 4 µm. Line profiles from the major contributors to the spectra of oxygen-rich stars at 4 µm, OH, H2O, HCl and SiO, are examined. The velocity as well as shape variations of these profiles with time are discussed. The line profiles investigated frequently have emission and multiple absorption components. The changes with time of the 4 µm region lines do not always follow the cyclic variability seen in NIR spectra and in the photometric light curve. We interpret and discuss the results qualitatively considering comparing the spectral variability with that of the well behaved 1.6 µm region and of dynamical model atmospheres. Miras and semiregular variables are compared. The origins of non-periodic behavior are discussed, including the role of spatial inhomogeneities in the stellar atmosphere.

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Observations of the first-overtone silicon monoxide bands in late-type stars

Cited by 29 publications

References 0 publications

Infrared spectral classification of normal stars

Infrared spectral classification of normal stars

Molecules and dust production in the Magellanic Clouds

4 $\mathsf{\mu}$m spectra of AGB stars I. Observations

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