Optical Properties of C-rich ( 12 C, SiC and FeC) Dust Layered Structure of Massive Stars*

Self Cite

Using quantum chemical calculations, we model the pathways for synthesizing adenine and guanine in the gas-phase interstellar environment, surrounded by neutral atomic hydrogen (HI). HI is found active in facilitating a series of fundamental proton transfer processes of organic synthesis, including bond formation, cyclization, dehydrogenation, and H migration. The reactive potential barriers were significantly reduced in the alternative pathways created by HI, leading to a remarkable increase in the reaction rate. The presence of HI also lowered the reactive activation temperature from 757.8 K to 131.5-147.0 K, indicating the thermodynamic feasibility of these pathways in star-forming regions where some of the reactants have been astronomically detected. Our findings suggest that HI may serve as an effective catalyst for interstellar organic synthesis.

Section: Resultsmentioning

confidence: 99%

Catalytic Role of H i in the Interstellar Synthesis of Complex Organic Molecule

Yang

Xie

Liang

et al. 2023

Self Cite

“…The physical parameters of Viaing Vienna Ab−initio Simulation Package (VASP) are set as follows: the energy convergence of the standard is 1 × 10 −6 eV, the Hellmann-Feynman forces of the standard are set to 1 × 10 −2 eV Å −1 , and the vacuum layer is [20-25] Å along the z-direction (Zhang et al 2018;Wu et al 2022). The lattice angles of each dust structure are α = β = γ = 90°.…”

Section: Models and Methodsmentioning

confidence: 99%

“…where n and K are the real and imaginary parts of the emission index, respectively. The use of the ionization state parameter for dust relies on the arbitrary loss of [1-2] electrons from the total number of electrons (Rani et al 2014;Wang et al 2016;Yao et al 2021;Wu et al 2022). In the presence of an electric field, the parameter IDIPOL turns on monopole/dipole and quadrupole corrections for total energy.…”

Section: Models and Methodsmentioning

confidence: 99%

“…here, E and α are the emission intensity and absorption intensity, respectively. The radiant intensity of dust is the flux of radiation produced by the light of a central star that penetrates the dust (Wu et al 2022). Table 1 shows the surface area of the unit structure (ds) and final radius (r d ) of the dust clusters of seven initial structures, and radiation losses are not considered in this article.…”

Section: Ionized Spherical Clusters Of Dustmentioning

confidence: 99%

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Radiation Spectral Analysis of 3D Dust Molecular Clusters (PAHs) and Peptoids under Ionization and Electric Field in ISM

Wu,

Zhu,

Lü

et al. 2023

The polycyclic aromatic hydrocarbons (PAHs), PANHs, and peptoids dustspectral calculations from the interstellar medium (ISM) is important for dust obser vations and theory. Our goal is to calculate the radiation spectrum of spherical PAHsdust clusters in a vacuum containing ionized and applied in the presence of electricfield. And we propose a new simple computational model to calculate the size of three dimensional (3D) spherical dust clusters formed by different initial dust structures. By Vienna Ab−initio Simulation Package (VASP) code, the density functional theory (DFT) with the generalized approximation (GGA) was used to calculate the electron density gradient and obtain the radiation spectrum of dust. When the radius of spherical dust clusters is ∼ [0.009−0.042] µm, the dust radiation spectrum agrees well with the Z=0.02mMMP stellar spectrums, and the PAHs radiation spectrum of NGC 4676 at wavelengths of (0-5] µm and (5-10] µm, respectively. In the ionized state, the N-PAH, C10H9N, 2(C4H4)1+, and peptoids 4(CHON), (C8H10N2O5)1+ dust clusters at 3.3 µm, while the 2(C22H21N3O2)1+, 4(CHON) dust clusters at 5.2 µm have obvious peaks. There is a characteristic of part of PAHs and peptoids clusters radiation at the near-infrared wavelength of 2 µm. However, especially after applying an electric field to the dust, the emission spectrum of the dust increase significantly in the radiation wavelength range [3-10]µm. Consequently, the dust clusters of PAHs, PANHs, and peptoids of the radius size ∼[0.009−0.042] µm are likely to exist in the ISM.

“…Second, the dust grains are grown to macroscopic size by adding small monomers entities (Siess et al 2022). In Figure 1, the initial structure of the 121Si 3 C 3 models comes from the work of Wu et al (2022). Si 3 C 3 was chosen because it is the smallest cluster with a three-dimensional structure (see Gobrecht et al (2017)), so we could study the spectra of the low-end clusters.…”

Section: Sic and Sio Molecular Dynamics And Spectral Calculations For...mentioning

confidence: 99%

Dust Condensation of SiC, SiO in Asymptotic Giant Branch Stellar Winds-SiC Spectrum

Wu,

Zhu,

Lü

et al. 2024

We have chosen the Large Scale Atomic/Molecular Massively ParallelSimulator (LAMMPS) code to calculate the coalescence of silicon carbide (SiC), siliconoxide dust (SiO) in the AGB stellar wind. LAMMPS is a classical molecular dynamics(MD) simulation code. At the same time, we consider the effect of temperature on the evo lution of molecular dynamics. We also calculated the temperature change of non-sphericalSiC, SiO dust coalescence. The condensation temperature range of SiC dust in the AGBstellar wind is [300-500]k and [900-1100]k for SiO. Finally, the infrared spectrum of SiCwas calculated using Gaussian 16 software. The 77SiC, 70Si3C3, and 121Si3C3 modelshave clearly characteristic peaks of infrared spectra responding at 5, 8.6, 11.3, 15, 19, and37 µm.