Silicon Isotopic Abundance Ratio along different Galactocentric Distance

The abundance ratios of 28Si, 29Si, and 30Si provide valuable constraints for Galactic Chemical Evolution (GCE) models. We report simultaneous observations of the 28SiO, 29SiO, and 30SiO 4–3 lines toward 51 massive star-forming regions, conducted with the IRAM 30 m telescope. Detections were achieved in 46, 25, and 24 sources for 28SiO, 29SiO, and 30SiO, respectively. Based on the largest sample of silicon isotope ratios to date, the relationships between 28Si/30Si, 28Si/29Si, and 29Si/30Si ratios, and Galactocentric distance (DGC), are presented. No clear trend between these ratios and (DGC) is found. On the other hand, the abundance ratios of 28Si/30Si and 29Si/30Si, show a positive correlation, which implies that nucleosynthesis of 29Si and 30Si is closely related.