Paccagnella, A.A.PaccagnellaVulcani, BenedettaBenedettaVulcaniPOGGIANTI, Bianca MariaBianca MariaPOGGIANTIMORETTI, ALESSIAALESSIAMORETTIFritz, J.J.FritzGULLIEUSZIK, MARCOMARCOGULLIEUSZIKCouch, W.W.CouchBETTONI, DanielaDanielaBETTONICava, A.A.CavaD'Onofrio, M.M.D'OnofrioFasano, G.G.Fasano2020-05-082020-05-0820160004-637Xhttp://hdl.handle.net/20.500.12386/24651The star formation quenching depends on environment, but a full understanding of what mechanisms drive it is still missing. Exploiting a sample of galaxies with masses {M}<SUB>*</SUB>\gt {10}<SUP>9.8</SUP>{M}<SUB>☉ </SUB>, drawn from the WIde-field Nearby Galaxy-cluster Survey (WINGS) and its recent extension OMEGAWINGS, we investigate the star formation rate (SFR) as a function of stellar mass (M{}<SUB>*</SUB>) in galaxy clusters at 0.04\lt z\lt 0.07. We use non-member galaxies at 0.02 < z < 0.09 as a field control sample. Overall, we find agreement between the SFR-M{}<SUB>*</SUB> relation in the two environments, but detect a population of cluster galaxies with reduced SFRs, which is rare in the field. These transition galaxies are mainly found within the cluster virial radius (R<SUB>200</SUB>), but they impact on the SFR-M{}<SUB>*</SUB> relation only within 0.6R<SUB>200</SUB>. The ratio of transition to pure star-forming galaxies strongly depends on environment, being larger than 0.6 within 0.3R<SUB>200</SUB> and rapidly decreasing with distance, while it is almost flat with M<SUB>*</SUB>. As galaxies move downward from the SFR-M{}<SUB>*</SUB> main sequence, they become redder and present older luminosity- and mass-weighted ages. These trends, together with the analysis of the star formation histories, suggest that transition galaxies have had a reduced SFR for the past 2-5 Gyr. Our results are consistent with the hypothesis that the interaction of galaxies with the intracluster medium via strangulation causes a gradual shut down of star formation, giving birth to an evolved population of galaxies in transition from being star forming to becoming passive.STAMPAenArticle10.3847/2041-8205/816/2/L252-s2.0-84954307555000369370500007https://iopscience.iop.org/article/10.3847/2041-8205/816/2/L252016ApJ...816L..25PFIS/05 - ASTRONOMIA E ASTROFISICA