Extended envelopes around Galactic Cepheids

We aim to investigate the IR excess of 45 MW Cepheids combining different observables constrain presence CSE. used SPIPS algorithm, a robust implementation parallax-of-pulsation method that combines photometry, angular diameter, stellar effective temperature, and RV measurements in global modelling pulsation. obtained new photometric at mid-IR with VLT/VISIR complemented literature data. then compared mean magnitude from 0.5$\mu$m 70$\mu$m atmosphere models infer excess, which we attribute report least 29% our sample have detected excess. estimated 0.08mag K 0.13mag N. Other possibly but they were rejected due their low detection level single-star model. do not see any correlation between pulsation period as previously suspected for Cepheids, rather constant trend. also find CO absorption CSE, confirms features reported are mostly photospheric. No bias caused by CSE is on average distance estimates analysis fitted colour evolution stage. fraction an likely produced Longer exhibit greater than short periods observations theoretical dusty-wind models. mechanisms such free-free emission, among others, may be origin formation. show fitting leads Galaxy.