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We present an update of the {\sc MulChem} chemical evolution model applied to the Milky Way Galaxy (Molla et al. submitted), by using the most recent stellar yields for low and intermediate mass stars and for massive stars. We study the role of the type Ia supernova (SN Ia) rate, using 15 different Delay Time Distribution (DTD) prescriptions, depending on the binary star scenario able to create a SN Ia. Simultaneously, 12 tables of yields of elements produced by different explosion mechanisms for SN Ia are explored. The chemical abundances derived from these 180 models, resulting from the combination of different SN Ia yields and DTDs, are analized. The Solar Region results for [Fe/H] and [$\alpha$/Fe] {\sl vs.} stellar age and for [$\alpha$/Fe] {\sl vs.} [Fe/H] (where $\alpha$-elements are O, Mg, Si, S, and Ca) are compared with an extensive observational dataset coming from the most recent surveys and compiled for this work. A $\chi^{2}$ technique is used to look for the best model for reproducing the data set. Finally, we analyse the relative abundances [$\alpha$/Fe] for disc and halo regions of the best model. As in previous works, we find that a significant fraction of type Ia SNe must take place at short delay times in order to reproduce the observations. The large dispersion of data could be explained by a mix of stars located at different spatial regions that moved after their birth. However, a mix of different DTD’s or explosion mechanisms is a likely hypothesis in light of comparison models-data.

We are observing a large sample of stars with MEGARA on GTC through a filler-type OpenTime program obtained in 7 semesters up to now. We summarize our advances done with MEGASTAR, the stellar spectral library we are observing with MEGARA at R=20000 in two setups HR-R around H$\alpha$ and HR-I around CaT. We described our project in García Vargas et al. (2020, MNRAS, 493, 871). We published our first data release in Carrasco et al. (2021, MNRAS, 501, 3568). In our third piece of work (Mollá et al. 2022, MNRAS, submitted) we have determined the stellar parameters (effective temperature, surface gravity and metallicity) of a subsample of the DR1 stars with spectral types later than B2, and we have measured some stellar indices, also giving the first set of {\sc MegaPopStar} evolutionary synthesis models. Next papers will be devoted to the second data release and to the physical parameters determination of the hot stars.