Results 11 to 20 of about 434 (137)
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 +2 more
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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 +6 more
wiley +1 more source
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.
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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 +7 more
wiley +1 more source
300: An ACA 870 μm Continuum Survey of Orion Protostars and Their Evolution
The Astrophysical Journal, 2023 We present an 870 μ m continuum survey of 300 protostars from the Herschel Orion Protostar Survey using the Atacama Compact Array (ACA). These data measure protostellar flux densities on envelope scales ≤8000 au (20″) and resolve the structure of ...
Samuel Federman +13 more
doaj +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 +4 more
wiley +1 more source
Magnetic Effects Promote Supermassive Star Formation in Metal-enriched Atomic-cooling Halos
The Astrophysical Journal, 2023 Intermediate-mass black holes (with ≥10 ^5 M _⊙ ) are promising candidates for the origin of supermassive black holes (with ∼10 ^9 M _⊙ ) in the early universe (redshift z ∼ 6).
Shingo Hirano +2 more
doaj +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 +3 more
wiley +1 more source
Security and Communication Networks, Volume 2022, Issue 1, 2022., 2022 At present, the health monitoring system of world sports events uses the system's on‐site information or periodic test information to evaluate the health of the system. In order to make the data more accurate, the application of cloud computing is necessary.
Rui Feng, Ning Chang, Muhammad Arif
wiley +1 more source
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 +4 more
openaire +3 more sources