Results 21 to 30 of about 3,519 (205)

Pulsed accretion in a variable protostar [PDF]

Nature, 2013
Periodic increases in luminosity arising from variable accretion rates have been predicted for some close pre-main sequence binary stars as they grow from circumbinary disks. The phenomenon is known as "pulsed accretion" and can affect the orbital evolution and mass distribution of young binaries, as well as the potential for planet formation in the ...
Muzerolle, James, Furlan, Elise, Flaherty, Kevin, Balog, Zoltan, Gutermuth, Robert   +4 more
openaire   +3 more sources

Protostar Formation in the Early Universe [PDF]

Science, 2008
The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability.
Yoshida, N., Omukai, K., Hernquist, L.
openaire   +6 more sources

The birth and early evolution of a low-mass protostar

, 2023
Context. Understanding the collapse of dense molecular cloud cores to stellar densities and the subsequent evolution of the protostar is of importance to model the feedback effects such an object has on its surrounding environment, as well as describing ...
González, M., Hennebelle, P., P. Hennebelle, B. Commerçon, M. González, Ahmad, A., Commerçon, Benoît, A. Ahmad, Ahmad, Adnan Ali, González, Matthias, Hennebelle, Patrick   +10 more
core   +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

Atomistic Modeling of Methyl Formate and Glycolaldehyde Formation on Interstellar Dirty Ice Mantles via a "Radical + Ice" Mechanism. [PDF]

Chempluschem
The presence of interstellar complex organic molecules (COMs) has been baffling astrochemists for a long time. Methyl formate and glycolaldehyde are widely detected but their abundances mismatch kinetic astrochemical model predictions. Here, the formation of these two COMs is characterized onto a mixed ice surface, highlighting the importance of ...
Perrero J, Pantaleone S, Ugliengo P, Rimola A.   +3 more
europepmc   +2 more sources

Bulk mineralogy, water abundance, and hydrogen isotope composition of unequilibrated ordinary chondrites

Meteoritics &Planetary Science, Volume 58, Issue 9, Page 1365-1381, September 2023., 2023
Abstract The origin and transport of water in the early Solar System is an important topic in both astrophysics and planetary science, with applications to protosolar disk evolution, planetary formation, and astrobiology. Of particular interest for understanding primordial water transport are the unequilibrated ordinary chondrites (UOCs), which have ...
Helen Grant, Romain Tartèse, Rhian Jones, Laurette Piani, Yves Marrocchi, Ashley King, Thomas Rigaudier   +6 more
wiley   +1 more source

Loading of Amino Acids onto RNA in a Putative RNA‐Peptide World

Angewandte Chemie International Edition, Volume 62, Issue 21, May 15, 2023., 2023
The loading of RNAs with amino acids constitutes the first step toward RNA‐based peptide synthesis in a putative prebiotic RNA‐peptide world. The efficient loading of RNA strands incorporating N‐methylcarbamoyl nucleotides with a series of amino acids is reported. The loaded RNA strands also underwent RNA‐based amino acid transfer reactions.
Johannes N. Singer, Felix M. Müller, Ewa Węgrzyn, Christina Hölzl, Hans Hurmiz, Chuyi Liu, Luis Escobar, Thomas Carell   +7 more
wiley   +1 more source

The grain size distribution of matrix in primitive chondrites

Meteoritics &Planetary Science, Volume 58, Issue 5, Page 688-704, May 2023., 2023
Abstract The matrix of primitive chondrites is composed of submicron crystals embedded in amorphous silicates. These grains are thought to be the remains of relatively unprocessed dust from the inner regions of the protoplanetary disk. The matrix of primitive meteorites is often compared to chondritic porous interplanetary dust particles (CP‐IDPs ...
E. Vaccaro, P. Wozniakiewicz, I. A. Franchi, N. Starkey, S. S. Russell   +4 more
wiley   +1 more source

Lifetime of the Outer Solar System Nebula From Carbonaceous Chondrites

Journal of Geophysical Research: Planets, Volume 127, Issue 7, July 2022., 2022
Abstract The evolution and lifetime of protoplanetary disks (PPDs) play a central role in the formation and architecture of planetary systems. Astronomical observations suggest that PPDs evolve in two timescales, accreting onto the star for up to several million years (Myr) followed by gas dissipation within ≲1 Myr. Because solar nebula magnetic fields
Cauê S. Borlina, Benjamin P. Weiss, James F. J. Bryson, Philip J. Armitage   +3 more
wiley   +1 more source

NONSTEADY ACCRETION IN PROTOSTARS [PDF]

The Astrophysical Journal, 2009
Observations indicate that mass accretion rates onto low-mass protostars are generally lower than the rates of infall to their disks; this suggests that much of the protostellar mass must be accreted during rare, short outbursts of rapid accretion. We explore when protostellar disk accretion is likely to be highly variable. While constant $α$ disks can
Zhu, Zhaohuan, Hartmann, Lee, Gammie, Charles   +2 more
openaire   +2 more sources