Results 21 to 30 of about 13,144 (210)

Asymptotic Giant Branch Stars and presolar grains [PDF]

EPJ Web of Conferences, 2020
Starting from the recognition that radioactive isotopes were present alive in the Early Solar System, inducing composition anomalies from their decay, and through the discovery that other important anomalies affected also stable species, we shall discuss
Busso Maurizio, Palmerini Sara, Vescovi Diego   +2 more
doaj   +1 more source

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
openaire   +1 more source

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., Bally, John, Esposito, Larry W., McCaughrean, Mark J.   +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

Kinetics of the tautomerization of thioimidic acids R−C(SH)NH → R−C(S)NH2: For R = H, F, HO, CN, NC, H2N, HC(O), HC(S), HC≡ C, CH3, CF3, H2C=CH, HOCH2, H2NCH2,CH3C(O), C2H5, (CH3)2CH, C6H5

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

Diagnostics of circumstellar grains in geometric models I: structure and composition [PDF]

Monthly Notices of the Royal Astronomical Society, 2017
Jonathan H P Dawes, J S Greaves
exaly   +3 more sources

Substituent effects in the tautomerization of imidic acids R−C(OH)=NH → R−C(O)NH2: Kinetic implications for the formation of peptide bonds in the interstellar medium

International Journal of Chemical Kinetics, Volume 55, Issue 7, Page 381-391, July 2023., 2023
Abstract A number of amides, RC(O)NH2, have been detected spectroscopically in the space between the stars. Naturally the study of how these are formed is an important question on the path of chemical evolution from the elements C, H, N, O, P, … to life because the so‐called peptide‐bond −C(O)−NH− is a key linkage in poly‐amino acids or proteins.
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, Joseph A. Nuth, Frank T. Ferguson   +2 more
doaj   +1 more source

Experimental Phase Function and Degree of Linear Polarization of Light Scattered by Hydrogenated Amorphous Carbon Circumstellar Dust Analogs

The Astrophysical Journal Supplement Series, 2023
Astronomical observations of the polarized intensity of scattered visible light have revealed the presence of dust envelopes around different types of evolved stars.
Juan Carlos Gómez Martín, Olga Muñoz, Julia Martikainen, Daniel Guirado, Isabel Tanarro, Ramón J. Peláez, Belén Maté, Miguel Jiménez-Redondo, Víctor J. Herrero, Marco Peiteado, Teresa Jardiel   +10 more
doaj   +1 more source

Grain Alignment in the Circumstellar Shell of IRC+10° 216

The Astrophysical Journal, 2022
Abstract Dust-induced polarization in the interstellar medium (ISM) is due to asymmetric grains aligned with an external reference direction, usually the magnetic field. For both the leading alignment theories, the alignment of the grain’s angular momentum with one of its principal axes and the coupling with the magnetic field requires ...
Andersson, B-G, Lopez-Rodriguez, Enrique, Medan, Ilija, Soam, Archana, Hoang, Thiem, Vaillancourt, John E., Lazarian, Alex, Sandin, Christer, Mattsson, Lars, Tahani, Mehrnoosh   +9 more
openaire   +1 more source