Dust grains exist, if not abundantly, in systems composed of a Type II supernova and a circumstellar

We have used the InfraRed Spectrograph on the Spitzer Space Telescope to study the fine dust orbiting around the 29 pc distant ? Pic analogue star HD172555. The dust mineralogy is is very peculiar, composed primarily of highly refractory, non-equilibrium materials, with 3/4 of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra ...

We have used the IRS Spectrograph onboard the Spitzer Space Telescope to study the warm dust orbiting around the 29 pc distant ? Pic analogue star HD172555. The dust mineralogy is very peculiar, composed primarily of highly refractory, non-equilibrium materials, with 3/4 of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra ...

The fine dust detected by IR emission around the nearby Beta Pic analogue star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, non-equilibrium materials, with approximately three-quarters of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (non-equilibrium glassy silicas ...

The fine dust detected by infrared (IR) emission around the nearby ? Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO2) species. Tektite and obsidian lab thermal emission spectra (nonequilibrium glassy silicas ...

The fine dust detected by infrared (IR) emission around the nearby {beta} Pic analog star HD172555 is very peculiar. The dust mineralogy is composed primarily of highly refractory, nonequilibrium materials, with approximately three quarters of the Si atoms in silica (SiO{sub 2}) species. Tektite and obsidian lab thermal emission spectra (nonequilibrium glassy ...

There is abundant inferential evidence for massive collisions in the early solar system [1]: Mercury's high density; Venus' retrograde spin; Earth's Moon; Mars' North/South hemispherical cratering anisotropy; Vesta's igneous origin [2]; brecciation in meteorites [3]; and Uranus' spin axis located near the plane of the ecliptic. Recent work [4] analyzing Spitzer mid-IR spectra ...

Rocks of these three plutons record a transition from silica-poor magmas (little to no minerals such as quartz or feldspar) to silica-rich magmas (abundant ...

Rocks of these three plutons record a transition from silica-poor magmas (little to no minerals such as quartz or feldspar) to silica-rich magmas (abundant ...

A current listing of IR observations of circumstellar molecules is presented. These observations were performed using Fabry-Perot, Fourier transform, and laser heterodyne spectroscopy. The most abundant species were CO, SiO, and HCN, while trace species included NH3, CH4, SiH4, and CS. Among the undetected species were H2, HCl, and CH2.

We report the detection of several metals in atomic form in the gas phase of the envelope of IRC+10216, the archetype of evolved carbon-rich AGB stars.By observing with VLT-UVES a background star located behind the envelope at 35 arcsec from center, optical absorption lines of Na, K, Ca, Fe and Cr are revealed. It is the first time that circumstellar Fe is detected in a ...

High-level ab initio calculations, using the CP-dG2thaw method and related approaches, are combined with VTST computations of radiative association rate coefficients to explore the reactivity of atomic metal ions and metal-containing molecular ions with abundant interstellar and circumstellar neutrals. Consequences of the calculated energetics and kinetics ...

We have analysed optical spectra of the carbon-rich post-AGB star IRAS 22272+5435. The circumstellar components of molecular lines of CN (Red System) and C2 (Phillips and Swan bands) were identified and measured. The mechanism of excitation of the rotational levels of the ground electronic states of CN and C2 was analysed with a non-LTE code. An empirical model accounting for ...

Twenty six individual circumstellar SiC grains extracted from the Murchison meteorite were analyzed for their strontium isotopic compositions by resonant ionization mass spectrometry. Large abundance deficits were found for the p-process isotope 84Sr. The measured grains had 87Sr/86Sr ratios indistinguishable from the primordial solar value, but several ...

The molecular spectrum of the bipolar nebula OH 231.8 + 4.2 was studied with an aim to shed light on its evolution, chemistry, and structure. The observational results on the emission lines of molecules observed in the circumstellar outflow of this nebula, including HCO(+), OCS, HNC, CS, and NH3, are presented. The implications of these data for the structure and composition ...

Two previously unknown technetium stars have been found: the MS irregular variable OP Her and the MS semiregular variable T Cet. An intercomparison of the spectra of these and 13 other red giants, five of which are technetium stars, indicates that the strength of Tc I is closely correlated with the strengths of other s-process element lines, but not necessarily with spectroscopic criteria of ...

The existence of anomalously high abundances of gaseous CH4 has been invoked to explain the unexpectedly high abundances of the carbon-bearing molecules HCN and H2CO in the outflows from O-rich red giants. We have modeled the chemistry that proceeds in th...

We propose to determine the compositions of two very important types of interstellar grains, oxygen-type silicates and carbon-type grains, by deriving the elemental depletions in the circumstellar envelopes where these grams form. After obtaining high-resolution IUE spectra of binary cool-supergiant plus hot-star systems, and after retrieving relevant archival spectra of ...

The blue supergiant Sher25 is surrounded by an asymmetric, hourglass-shaped circumstellar nebula. Its structure and dynamics have been studied previously through high-resolution imaging and spectroscopy, and it appears dynamically similar to the ring structure around SN1987A. Here, we present long-slit spectroscopy of the circumstellar nebula around ...

An intensive observational program of Asymptotic Giant Branch (AGB) and post-AGB stars has been conducted in order to investigate the role of metal-containing compounds in the circumstellar envelopes surrounding these objects. The role of metal bearing molecules in the chemical evolution of these envelopes was also examined. These studies have led to the detection of a new ...

We report the detection of two new circumstellar HC/sub 3/N sources (GL 618 and IRC+40540) and one new circumstellar CS source (CIT 6). We have also confirmed the tentative detection of HC/sub 3/N in GL 3068 reported by us earlier, and the detection of HC/sub 3/N in the bipolar nebula GL 2688 reported by others. Limited searches for ...

The circumstellar envelopes of carbon-rich AGB stars show a chemical complexity that is exemplified by the prototypical object IRC +10216, in which about 60 different molecules have been detected to date. Most of these species are carbon chains of the type C n H, C n H2, C n N, HC n N. We present the detection of new species (CH2CHCN, CH2CN, H2CS, CH3CCH and C3O) achieved ...

Infrared excitation is investigated for the rotational transitions of HC5N with special emphasis on the circumstellar envelope of IRC + 10216. Infrared radiation from the dust shell surrounding the carbon star elevates the molecule to the higher rotational levels through the excitation of transitions associated with the bending modes (Delta J = 2 selection rule) as well as the ...

Global hydrogen abundance and equivalent H2O; Ground ice to +/-60� in high ... formed later with opal/hydrated silica; Few hydrated mineral deposits since ...

Aug 24, 2006 ... The abundance of potassium and sodium determines the kinds of minerals that make up igneous rocks. If igneous rocks have enough silica, ...

Water column and seabed samples were obtained from 92 stations on the Amazon continental shelf during October of 1979. Uptake of silica near and southeast of the river mouth began at a salinity of 8%. and accounted for 17% of the riverine silica flux to this region. Uptake northwest of the river mouth began at a salinity of 20%. and resulted in 33% removal ...

Metallic iron is one of the most abundant condensing materials in systems of solar abundance. Because metallic iron is responsible for the continuum opacity of dust particles, it has a large contribution to the thermal structure of circumstellar environments and hence to dust evolution itself. In order to understand the formation ...

Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the ...