41 research outputs found
Dust in Supernovae and Supernova Remnants I : Formation Scenarios
Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe
Dust in Supernovae and Supernova Remnants II: Processing and survival
Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations
Synthesis and Magnetic Properties of (C5H5)3Ce-Center-HMPA.
The 1:1 adduct (C5H5)3 de.O=P(NMe2)3 of cerium(III)-triscyclopentadienide with hexamethylphosphoric triamide (HMPA) was synthesized, isolated, purified and characterized by elemental analysis, IR- and 1H-NMR spectroscopy. The 1H-NMR spectrum obtained in solution in CDCl-3 at room temperature exhibits a single signal for the Cp-proton at 5.6 ppm and a signal for the CH3-proton of the base HMPA at 0.49 ppm. The paramagnetic shift due to the Ce(III) ion could be evaluated by comparison to the corresponding signals of the homologous diamagnetic compound Cp3La.HMPA. The temperature-dependent paramagnetic susceptibility of the compound was measured within the temperature range from 4.2 up to 300 K. From the 1/Chi-mol vs. T-plot the empirical constant C=(mu- eff) is consistent with a Ce(III) ion. The ground state of the Ce ion is only partially populated. The magnetic moment at room temperature is 2.25 mu-b=B, an indication of covalency, as it has been observed for several Ce(III)-organometallics.JRC.E-Institute for Transuranium Elements (Karlsruhe
Thermogravimetric Investigation Of 4-picoline-n-oxide (4-picno) Lanthanoid Trifluoromethanesulfonate Complexes
Complexes with composition Ln(CF3SO3)3 · n(4-picNO) (n = 8 for Ln = La-Gd, except Ce, and n = 7 for Ln = Tb-Lu, Y) have been recently reported [1]. In this note the thermogravimetric behaviour of such complexes are described. © 1987.115C389393C.A. Fantin, L.B. Zinner, G. Vicentini, C. Rodellas and L. Niinistö, Acta Chem. Scand., Ser. A, in pressRoberts, Bykowski, (1978) Thermochim. Acta, 25, p. 233Vicentini, Zinner, Silva, Dunstan, (1985) Lanthanide Actinide Res., 1, p. 143Zinner, Vicentini, Dunstan, (1985) J. Less-common Met., 112, p. 393P.O. Dunstan, L.B. Zinner and G. Vicentini, Thermochim. Acta, in pres
Thermogravimetric Studies Of Hexamethylphosphoramide (hmpa) Lanthanoid Perrhenate Complexes
[No abstract available]146C381383Vicentini, Zinner, Barreto, (1987) An. Acad. Bras. Ciênc., 59, p. 341Band, Capestan, (1967) Bull. Soc. Chim. Fr., 12, p. 4685Vicentini, Zinner, Dunstan, (1987) Thermochim. Acta, 118, p. 305Plyushchev, Varfolomeev, (1965) Khim. Teknol., 8, p. 361Plyushchev, Varfolomeev, (1965) Chem. Abstr., 63, p. 15789ePlyushchev, Varfolomeev, (1965) Russ. J. Inorg. Chem., 10, p. 55Plyuschev, Amosov, Varfolomeev, (1963) Dokl. Akad. Nauk SSSR, 150, p. 105Plyuschev, Amosov, Varfolomeev, (1963) Chem. Abstr., 59, p. 6013
Thermal Analysis Of Hydrated Rare-earth Trifluoromethanesulfonate Complexes With Trans-1,4-dithiane-1,4-dioxide (tdtd)
[No abstract available]107C387391Shearer, (1959) J. Chem. Soc., p. 477Karvinen, Niinistö, Zinner, Vicentini, Scoralick, (1985) J. Less-Common Met., 112, p. 363Roberts, Bykowski, (1978) Thermochim. Acta, 25, p. 233Vicentini, Zinner, Silva, Dunstan, (1985) Lanthanide Actinide Res., 1, p. 143Zinner, Vicentini, Dunstan, (1985) J. Less-Common Met., 112, p. 39
Cyclic sulphoxides as ligands—XVIII. Hydrated lanthanide iodide adducts of tetramethylene sulphoxide (TMSO)
Thermogravimetric And Differential Scanning Calorimetry Studies Of Hydrated Lanthanide Perrhenate Complexes With Trans-1,4-dithiane-1,4-dioxide
[No abstract available]118C305308Shearer, (1959) J. Chem. Soc., p. 477Oliveira, Miranda, Castellano, Scoralick, Zinner, Vicentini, (1985) Lanthanide Actinide Res., 1, p. 205J.M. Miranda, M.A. Oliveira, E.E. Castellano, E. Scoralick, L.B. Zinner and G. Vicentini, Inorg. Chim. Acta, in pressPlyushchev, Varfolomeev, (1965) Khim. Teknol., 8, p. 361. , Chem. Abstr. 63 1965 15789eVicentini, Umeda, Giolito, (1977) An. Acad. Bras. Ciênc., 49, p. 143Vicentini, Perrier, Prado, (1969) J. Inorg. Nucl. Chem., 31, p. 825Baud, Capestan, (1967) Bull. Soc. Chim. Fr., 12, p. 4685Plyushchev, Varfolomeev, (1965) Russ. J. Inorg. Chem., 10, p. 55Plyushchev, Amosov, Varfolomeev, (1963) Dokl. Akad. Nauk SSSR, 150, p. 105. , Chem. Abstr. 59 1963 6013
Thermal Study Of Rare-earth Trifluoroacetate Complexes With Thioxane-oxide
[No abstract available]781-3449454Zinner, (1982) Anais do VI Simpósio Anual da Academia de Ciências do Estado de São Paulo, 1, p. 185Lyle, Rahman, (1973) Talanta, 10, p. 1177Rillings, Roberts, A thermal study of the trifluoroacetates and pentafluoropropionates of praseodymium, samarium and erbium (1974) Thermochimica Acta, 10, p. 28