大样本恒星演化研究组知识库

Context. Since NGC300 is a bulgeless, isolated low-mass galaxy and it has not experienced radial migration during its evolution history, it can be treated as an ideal laboratory to test the simple galactic chemical evolution model. 

Aims. Our main aim is to investigate the main properties of the star formation history (SFH) of NGC-00 and compare its SFH with that of M33 to explore the common properties and differences between these two nearby low-mass systems. 

Methods. We construct a simple chemical evolution model for NGC-00, assuming its disk forms gradually from continuous accretion of primordial gas and including the gas-outflow process. The model allows us to build a bridge between the SFH and observed data of NGC-00, in particular, the present-day radial profiles and global observed properties (e. g., cold gas mass, star formation rate, and metallicity). By means of comparing the model predictions with the corresponding observations, we adopt the classical chi(2) methodology to find out the best combination of free parameters a, b, and b(out). 

Results. Our results show that by assuming an inside-out formation scenario and an appropriate outflow rate, our model reproduces well most of the present-day observational values. The model not only reproduces well the radial profiles, but also the global observational data for the NGC-00 disk. Our results suggest that NGC-00 may experience a rapid growth of its disk. Through comparing the best-fitting, model-predicted SFH of NGC-00 with that of M 33, we find that the mean stellar age of NGC-00 is older than that of M 33 and there is a recent lack of primordial gas infall onto the disk of NGC-00. Our results also imply that the local environment may play a key role in the secular evolution of galaxy disks.