摘要
Based on the large field multicolor observations ofBeijing-Arizona-Taiwan-Connecticut (BATC) program, we obtain the spectral energy distribution (SED)for individual regions of M81. We study the structure and evolution of M81 with an evolutionarypopulation synthesis (EPS) model, PEGASE. We find that the exponentially deceasing star formationrate (SFR) with star formation scale 3 Gyr (hereafter Exp, τ = 3 Gyr) gives the best agreementbetween the model predictions and the observed SEDs. We then obtain the structure, age distributionand evolutionary history of M81. There is a clear age gradient between the central and outerregions. The populations in the central regions are older than 7 Gyr, those in the outer regions areyounger, at about 4.5 Gyr. The youngest components in the spiral arms have ages of about 2.5 Gyr orless.
Based on the large field multicolor observations ofBeijing-Arizona-Taiwan-Connecticut (BATC) program, we obtain the spectral energy distribution (SED)for individual regions of M81. We study the structure and evolution of M81 with an evolutionarypopulation synthesis (EPS) model, PEGASE. We find that the exponentially deceasing star formationrate (SFR) with star formation scale 3 Gyr (hereafter Exp, τ = 3 Gyr) gives the best agreementbetween the model predictions and the observed SEDs. We then obtain the structure, age distributionand evolutionary history of M81. There is a clear age gradient between the central and outerregions. The populations in the central regions are older than 7 Gyr, those in the outer regions areyounger, at about 4.5 Gyr. The youngest components in the spiral arms have ages of about 2.5 Gyr orless.
基金
Supported by the National Natural Science Foundation of China
