2025ApJ...978...59C

As one type of blue early-type galaxy, the evolutionary history and fate of star-forming lenticular galaxies (S0s) remain elusive. We selected 134 star-forming S0s from the Sloan Digital Sky Survey IV MaNGA survey and found that they have steep and warped size-mass relations, similar to quiescent S0s and red spirals, indicating that they may have similar gas dissipation scenarios. These galaxies have a higher central stellar mass surface density than normal blue spirals. The radial profiles of D_n4000 and [Mgb/Fe] show that red spirals and quiescent S0s have similar old central populations and high [Mgb/Fe] values, suggesting rapid bulge formation, though red spirals exhibit a steeper gradient possibly due to residual star formation (SF) in outer regions. In contrast, star-forming S0s exhibit profiles between quiescent S0s/red spirals and normal blue spirals, with relatively flat D_n4000 and [Mgb/Fe] gradients. More long-term SF history causes normal blue spirals to have very flat D_n4000 and [Mgb/Fe] profiles, and the majority of them (79% ± 5%) have a Sérsic index of <2. We also found that the halo mass of star-forming S0s resembles that of quiescent S0s/red spirals, with 82% ± 5% exceeding the critical mass (M_halo = 10¹²M_⊙h^–1). To supplement previous H I detection of star-forming S0s covered by H IMaNGA, we obtained new observations for H I emission from 41 star-forming S0s in our sample using the Five-hundred-meter Aperture Spherical Radio Telescope. We found that the H I mass distribution of star-forming S0s matches that of normal blue spirals, although both star-forming S0s and red spirals are relatively gas-poor, resulting in varying atomic gas depletion times due to different SF levels. Based on these observational results, we discuss the possible evolutionary scenarios of star-forming S0s.