Detection of ca II absorption triplet in a circumnuclear H II region of ngc 3310

Abstract

We have obtained long slit spectrophotometry across NGC 3310, a lurninous galaxy with cucumnuclear bursts of star formation, covering the spectral range from λ3650 to 9700 Å. In one giant star-forrning region, the near-IR Ca II absorption lines (a signature of young supergiants) was detected with a strength similar to that of the nuclear region. This is, to our knowledge, the first detection of the IR Ca II triplet in an extragalactic giant H li region and confirms theoretical predictions that, after some 4 Myr, red supergiants should appear in bursts of star formation.