than 0.11 dex when the S/N of spectrum continuum is larger than 5. Comparing our mass surface density $\Sigma_*$ with the public MaNGA Pipe3D value added catalog [@Sanchez2016a], we note that our $\Sigma_*$ is systematically lower than the Pipe3D values, with a offset of 0.539 dex with a scatter of 0.22 dex. The offset is likely due to the difference of SSP library and IMF used in Pipe3D and our work. Pipe3D adopt the [@Salpeter1955] IMF, while we use the [@Chabrier2003] IMF, which may cause a offset of 0.24 $\pm$ 0.13 dex [@Sanchez2016a]. For the MaNGA data, the Pipe3D pipeline use 12 SSPs from MIUSCAT library [@Vazdekis2012], covering four stellar ages (0.06, 0.2, 2.0, 17.78 Gyr) and three metallicities (0.0004, 0.02, 0.0331), while we perform the spectrum fiting with 45 SSPs from [@Bruzual2003] model by STARLIGHT, consisting of 15 ages and 3 different metallicities (see Section \[subsec:spec-fitting\]).

We use the ${\hbox{H$\alpha$}}$ emission line luminosity to determine the dust-corrected star formation rate for each spaxel, assuming a [@Chabrier2003] IMF and solar metallicity. The SFR is calculated from ${\hbox{H$\alpha$}}$ luminosity $L({{\hbox{H$\alpha$}}})$ using the relation from @Kennicutt1998: $${\rm SFR(M_{\sun} yr^{-1})} = 4.4 \ \times \ {\rm 10^{-42}} \ {\rm \times \ L({{\hbox{H$\alpha$}}})(erg \ 