| 1 | The Preliminary Statistical Analysis of LAMOST DR8 Low Resolution AFGK Stars显示文摘We download the Large sky Area Multi-Object fiber Spectroscopic Telescope Data Release 8(LAMOST DR8)low resolution catalog for 6,478,063 AFGK type stars and plot the figures of effective temperature,gravitational acceleration and metal abundance.Some small and medium mass stars are evolved from pre-main sequence or main sequence stage to planetary nebula stage or white dwarf stage by the stellar evolution code MESA.We analyze the observed statistical data and model calculation results,and then obtain some basic conclusions preliminarily.Most red giant and asymptotic giant branch stars with log g less than 0.85 have poor metal abundance.Most hot A type main-sequence stars are metal-rich stars with log g from 3.5 to 4.5.The conclusions are reasonable within a certain error range.The theory of a gap area in the Hertzsprung-Russell diagram for stellar evolutions of medium mass stars is reflected in the statistical plots.The central core hydrogen burning stage and the central core helium burning stage correspond to the peak structures in the statistical plots for gravitational acceleration.The metal abundances among A,F,G and K type stars have a wide distribution.We cannot simply replace the metal abundances of these stars with the metal abundance of the Sun when doing fine research work. | Y.H.Chen G.W.Li H.Shu | 2022 | Research in Astronomy and Astrophysics2022，22，5： | 0 |
| 2 | An Initial Analysis of a Strongly Lensed QSO Candidate Identified by LAMOST显示文摘From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available. | Y.H.Chen M.Y.Tang H.Shu H.Tu | 2023 | Research in Astronomy and Astrophysics2023，23，10： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员