Lessons from the massive relic NGC 1277: Remaining <i>in situ</i>star formation in the cores of massive galaxies

ABSTRACT Near-ultraviolet (NUV) spectroscopic studies have suggested that passively evolving massive, early-type galaxies host sub-one per cent fractions of young stars in their innermost regions. We shed light on the origin these by analysing NGC 1277, a widely studied nearby prototypical massive compact relic galaxy. These are rare survived without experiencing significant size evolution via accretion and mergers since formation at high redshift. obtain spectrum UV range within central 1 kpc region 1277. compare carefully selected set optical NUV line-strengths to model predictions with star histories characteristic galaxies. find 0.8 mass fraction centre similar found Given limited history results favour an intrinsic, situ, process triggering later epochs. Our suggest general constraint amount cores This should be assumed as upper limit for stellar contribution galaxies, there might present other contributions from evolved stars.