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

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 classica molecular dynamics simulation code.At the same time,we consider the effect of temperature on the evolution 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,70Si_(3)C_(3),and 121Si_(3)C_(3) models have clear characteristic peaks of infrared spectra responding at 5,8.6,11.3,15,19,and 37μm.

Observation of HⅠaround three Satellite Galaxies of M31 with FAST:AndromedaⅡ,NGC 205,and NGC 185

With the exceptional sensitivity of the Five-hundred-meter Aperture Spherical radio Telescope,we conducted observations of the neutral hydrogen(HⅠ)in the circumgalactic medium of Andromeda’s(M31)satellite galaxies,specifically AndromedaⅡ,NGC 205,and NGC 185.Initially,three drift scans were executed for these satellites,with a detection limit of 4×10^(18)cm^(-2)(approximately 1.88×10^(3)M_Θof HⅠmass),followed by a more in-depth scan of a specific region.We discovered a C-shaped HⅠarc structure sharing a position and line-of-sight velocity similar to a stellar ring structure around AndromedaⅡ,hinting at a potential connection with AndromedaⅡ.In the context of NGC 205,we identified two mass concentrations in the northeast direction,which could be indicative of tidal streams resulting from the interaction between this galaxy and M31.These new lumps discovered could be very helpful in solving the missing interstellar medium problem for NGC 205.Observations regarding NGC 185are consistent with previous studies,and we did not detect any additional HⅠmaterial around this galaxy.These observational results enhance our understanding of the evolution of these satellite galaxies and provide insight into their historical interactions with the galaxy M31.

Molecular Gas Distribution around the Supernova Remnant G40.5-0.5

The distribution of dense molecular gas around the supernova rem- nant G40.5-0.5 has been investigated by radio spectroscopic observations in the CO （J=1 - 0） transition. The molecular gas is found to extend over the entire region of G40.5-0.5. A molecular shell, with a diameter of ～ 26′, coincides with the ionized gas as revealed by the cm-radio observations. This coincidence, along with the velocity discontinuity following the shell, provides direct evidence for interaction between the ionized gas and the dense molecular gas. No clear evidence for cosmic-ray accelera- tion can be identified from this SNR as previously suggested, due to positional uncertainty in relating the SNR shell defined by CO to the EGRET gamma-ray sources, GRO J1904＋06, from the gamma-ray observations.