White dwarfs(WDs)are the final stage for most low and intermediate mass stars,which play an important role in understanding stellar evolution and galactic history.Here we performed an asteroseismological analysis on T...White dwarfs(WDs)are the final stage for most low and intermediate mass stars,which play an important role in understanding stellar evolution and galactic history.Here we performed an asteroseismological analysis on TIC 231277791 based on 10 independent modes reported by Romero et al.Two groups of modes were identified with frequency splitting:mode identification_1 with one l=1,m=0 mode,two l=2,m=0 modes,and three l=1 or 2,m=0 modes,and mode identification_2 with one l=1,m=0 mode,three l=2,m=0 modes,and one l=1 or 2,m=0 mode.The rotation period is derived to be 41.64±2.73 hr for TIC 231277791.We established a large sample(7,558,272)of DAV star models using the White Dwarf Evolution Code(WDEC;2018,v16),resulting of optimal models with model_1(mode identification_1):M_(*)=0.570±0.005 M⊙,Teff=11300±10 K,-log(MH/M_(*))=9.15±0.01,-log(M_(He)/M_(*))=4.94±0.01,andσrms=0.06 s,and model_2(mode identification_2):M_(*)=0.720±0.005 M⊙,Teff=1910±10 K,-log(M_(H)/M_(*))=6.11±0.01,-log(M_(He)/M_(*))=3.09±0.01,andσrms=0.04 s.The central oxygen abundances are 0.71(optimal model_1)and 0.72(optimal model_2),respectively,which are consistent with the results of stellar structure and evolution theory.展开更多
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,spectr...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.展开更多
基金supported by the International Centre of Supernovae,Yunnan Key Laboratory(No.202302AN36000101)supported by the Yunnan Province Youth Talent Project(2019-182)。
文摘White dwarfs(WDs)are the final stage for most low and intermediate mass stars,which play an important role in understanding stellar evolution and galactic history.Here we performed an asteroseismological analysis on TIC 231277791 based on 10 independent modes reported by Romero et al.Two groups of modes were identified with frequency splitting:mode identification_1 with one l=1,m=0 mode,two l=2,m=0 modes,and three l=1 or 2,m=0 modes,and mode identification_2 with one l=1,m=0 mode,three l=2,m=0 modes,and one l=1 or 2,m=0 mode.The rotation period is derived to be 41.64±2.73 hr for TIC 231277791.We established a large sample(7,558,272)of DAV star models using the White Dwarf Evolution Code(WDEC;2018,v16),resulting of optimal models with model_1(mode identification_1):M_(*)=0.570±0.005 M⊙,Teff=11300±10 K,-log(MH/M_(*))=9.15±0.01,-log(M_(He)/M_(*))=4.94±0.01,andσrms=0.06 s,and model_2(mode identification_2):M_(*)=0.720±0.005 M⊙,Teff=1910±10 K,-log(M_(H)/M_(*))=6.11±0.01,-log(M_(He)/M_(*))=3.09±0.01,andσrms=0.04 s.The central oxygen abundances are 0.71(optimal model_1)and 0.72(optimal model_2),respectively,which are consistent with the results of stellar structure and evolution theory.
基金provided by the National Development and Reform Commissionthe support of the National Natural Science Foundation of China(NSFC,11803004)+2 种基金Yunnan Province Youth Talent Project(2019182)the support by NSFC through grant No.12203011Yunnan provincial Department of Science and Technology through grant No.202101BA070001-261。
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.
