Results 21 to 30 of about 293,009 (201)
The Astrophysical Journal, 2023 The first step toward planet formation is grain growth from (sub)micrometer to millimeter/centimeter sizes. Grain growth has been reported not only in Class II protoplanetary disks but also in Class 0/I protostellar envelopes.
Ilseung Han +4 more
doaj +1 more source
Composite circumstellar dust grains [PDF]
Monthly Notices of the Royal Astronomical Society, 2016 We calculate the absorption efficiencies of composite silicate grains with inclusions of graphite and silicon carbide in the spectral range 5--25$\rm μm$. We study the variation in absorption profiles with volume fractions of inclusions. In particular we study the variation in the wavelength of peak absorption at 10 and 18$\rm μm$.
Gupta, Ranjan +2 more
openaire +2 more sources
Experimental Studies on Simulated Circumstellar Grains [PDF]
Symposium - International Astronomical Union, 1987 Over the last few years a better understanding of the chemistry inherent in the refractory nucleation process has emerged from experimental studies performed in several laboratories. These studies shed light not only upon the factors which might control the onset of grain formation, but also on the spectral characteristics of freshly condensed grains.
Joseph A. Nuth, Bertram Donn
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The temperature of nonspherical circumstellar dust grains [PDF]
Astronomy Letters, 2000 18 pages, 9 figures, to appear in Astronomy Letters, Vol.
Voshchinnikov, N. V., Semenov, D. A.
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Angewandte Chemie, Volume 135, Issue 12, March 13, 2023., 2023 Out of the cold: Ammonia (NH3) and acetaldehyde (CH3CHO) are exposed to galactic cosmic ray proxies while frozen at 5 K to simulate the environment of an interstellar molecular cloud. Reactants undergo dissociation and radical recombination to produce glycinal (NH2CH2CHO) and acetamide (CH3CONH2) prior to tautomerization to 2‐aminoethenol (HOCHCHNH2 ...
Joshua H. Marks +5 more
wiley +2 more sources
Condensation Chemistry of Circumstellar Grains [PDF]
Symposium - International Astronomical Union, 1999 Thermochemical equilibrium calculations are successful in predicting the mineralogy as well as the major and trace element chemistry of circumstellar grains found in meteorites. The calculations also explain observations of dust close to AGB stars (within 1–3 stellar radii).
Katharina Lodders, Bruce Fegley
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Evidence for Dust Grain Growth in Young Circumstellar Disks [PDF]
Science, 2001 Hundreds of circumstellar disks in the Orion nebula are being rapidly destroyed by the intense ultraviolet radiation produced by nearby bright stars. These young, million-year-old disks may not survive long enough to form planetary systems. Nevertheless, the first stage of planet formation—the growth of dust grains into larger particles—may have begun ...
Throop, Henry B. +3 more
openaire +3 more sources
Effects of Barnett Magnetic Dipole–Dipole Interaction on Grain Growth and Destruction
The Astrophysical Journal, 2023 Rapidly spinning magnetic grains can acquire large magnetic dipole moments due to the Barnett effect. Here we study the new effect of Barnett magnetic dipole–dipole interaction on grain–grain collisions and grain growth, assuming that grains are spun up ...
Thiem Hoang, Bao Truong
doaj +1 more source
International Journal of Chemical Kinetics, Volume 55, Issue 11, Page 731-742, November 2023., 2023 Abstract The kinetics of the tautomerization of thio‐imidic acids RC(SH)NH were determined at low (50–300 K) and high (500–1500 K) temperatures as R was varied to encompass mono‐ and diatomic species H, F, HO, NC, CN through H2N, HC(O), HC(S), HC≡ C, H3C, F3C, HOCH2, H2C=CH, CH3C(O), H2NCH2 and including ethyl, isopropyl and phenyl groups. The presence
Judith Würmel, John M. Simmie
wiley +1 more source
Dust Coagulation in Oxygen-rich Circumstellar Outflows
The Astrophysical Journal, 2023 We show that the inefficient growth of SiO molecules on (SiO) _x dust grains prolongs the period of maximum dust nucleation in circumstellar outflows resulting in a several orders-of-magnitude increase in the dust density near the star.
John A. Paquette +2 more
doaj +1 more source