Spectroscopy of the Kleinmann-Low nebula - Scattering in a solid absorption band

Knacke, R. F.; McCorkle, S.

doi:10.1086/114530

Cited by 24 publications

(13 citation statements)

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“…Earlier detections in a number of sources (Hagen et al 1980, Knacke et al 1982 could not be confirmed by later observations (Knacke & McCorkle 1987;Smith et al 1989). A detection in HH 100-IRS by Graham & Chen (1991) could not be confirmed by Whittet et al (1996).…”

Section: Introductionmentioning

confidence: 82%

Detection of solid ammonia, methanol, and methane with ISOPHOT

Gürtler¹,

Klaas

Henning

et al. 2002

A&A

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Abstract. We report on a search for the NH 3 inversion band at 9.0 µm, the CH 4 band at 7.7 µm, and the CH 3 OH band at 9.7 µm in the spectra of 10 heavily obscured stellar objects taken with the spectrophotometer ISOPHOT-S aboard the Infrared Space Observatory (ISO). Four of them show indications of the NH 3 inversion band at 9.0 µm superimposed on the always strong silicate band. The results show that ammonia ice may be abundant in some cool and dense molecular circumstellar regions. The 9.7 µm band of solid CH 3 OH was detected in 5 of the sources, and also the 7.7 µm band of solid CH 4 was found in 5 sources. The PHT-S detections were cross-checked against ISO-SWS spectra from archive data. Considering the different beam sizes (24 × 24 versus 14 × 20 ), there is good agreement.

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Section: Introductionmentioning

confidence: 82%

Detection of solid ammonia, methanol, and methane with ISOPHOT

Gürtler¹,

Klaas

Henning

et al. 2002

A&A

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“…Studies by Greenberg (1973) and Merrill, Russell & Soifer (1976) indicate that the ice to silicate ratio by volume in dense clouds is between 0.04 and 1. Lee & Draine (1985) found the ratio may be as high as 5 towards the Becklin–Neugebauer object, while Knacke & McCorkle (1987) suggest a value of 0.37 in the vicinity of this same object. Thus, for the thickest mantles employed in the current study, considerably more water–ice is present on an individual grain than even the largest of the above estimates.…”

Section: The Opacity Datamentioning

confidence: 92%

Why is the librational water-ice band at 11.5 μm so difficult to detect?

Robinson

Maldoni

2010

Monthly Notices of the Royal Astronomical Society

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Radiative transfer models have been produced for stars surrounded by circumstellar dust shells in order to investigate the detectability of the 11.5-µm librational band due to water-ice (H 2 Oice). The dust grains were assumed to be composed of a core material of either amorphous silicate of olivine composition (MgFeSiO 4 ) or alumina (Al 2 O 3 ), both grain species being coated with a water-ice mantle. The models may be divided into three classes: those with small, intermediate and large optical depths. It is found that in all three cases, even with only olivine present, the water-ice librational band feature is masked by radiative transfer effects and is therefore difficult to detect.For the librational band to display its characteristic shape requires far larger amounts of water-ice than are present in any known circumstellar dust shell, as indicated by the depth of the much stronger 3.1-µm water-ice band. The best prospect for finding some evidence of the librational band is likely to be via using a small beam centred on the cooler outer regions of the dust shell; in this case the line of sight may encounter only water-ice coated grains, thereby reducing the contaminating effect of bare grains. If a grain species such as alumina is present, with a broad absorption band in the vicinity of 11.5 µm, the identification of the librational band may be possible, perhaps surprisingly, as result of the sharpening of the 11.5-µm feature. We have fitted the spectrum of IRAS 22036+5306 and find that, although water-ice is clearly present in this object, as evidenced by the presence of the strong 3.1-µm band, the librational band has no obvious effect on its 10-µm spectrum.

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“…van de Hulst 1949) and because is NH 3 readily photolyzed by FUV photons. However, observational reports of solid-state ammonia have been controversial over the years (Knacke et al 1982 ; Knacke & McCorkle 1987 ;Smith, Sellgren, & Tokunaga 1989 ;Smith, Sellgren, & Brooke 1993 ;Graham & Chen 1991 ;Whittet et al 1996a). Upper limits for the abundance of relative NH 3 to of 5% are given by Tielens & Whittet (1997).…”

Section: Introductionmentioning

confidence: 99%

R—O—C≡N Species Produced by Ion Irradiation of Ice Mixtures: Comparison with Astronomical Observations

Palumbo

Strazzulla

Pendleton

et al. 2000

ApJ

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We have investigated the effects induced by ion bombardment of mixtures containing nitrogen-bearing compounds at low temperatures. The results show the formation of a band at 2080 cm-1 in binary mixtures, NH3:CH4 and N2:CH4, which we attribute to HCN embedded in the organic residue formed by ion irradiation. In addition to this band, ternary mixtures containing an oxygen-bearing species (i.e., H2O) form a compound with a prominent absorption band at about 2165 cm-1 (4.62 microns). We ascribe this band to a nitrile compound containing O that is bonded to the organic residue. A detailed comparison of the laboratory results with astronomical data of the 4.62 microns absorption band in protostellar spectra shows good agreement in peak position and profile. Our experimental studies show that N2, which is a more likely interstellar ice component than NH3, can be the molecular progenitor of the carrier of the interstellar band. This is an alternative to the pathway by which UV photolysis of NH3-containing ices produces the 4.62 microns band and implies that ion bombardment may well play an important role in the evolution of interstellar ices. Here, we discuss the implications of our studies for the chemical route by which the carrier of the 4.62 microns band is formed in these laboratory experiments.

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Spectroscopy of the Kleinmann-Low nebula - Scattering in a solid absorption band

Cited by 24 publications

References 0 publications

Detection of solid ammonia, methanol, and methane with ISOPHOT

Detection of solid ammonia, methanol, and methane with ISOPHOT

Why is the librational water-ice band at 11.5 μm so difficult to detect?

R—O—C≡N Species Produced by Ion Irradiation of Ice Mixtures: Comparison with Astronomical Observations

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