Protoplanetary discs around sun-like stars live longer when the metallicity is low

Previous Hubble Space Telescope (HST) observations of the star-forming cluster NGC 346 in the Small Magellanic Cloud (SMC) had revealed a large population of pre-main sequence (PMS) candidates, characterised by Hα excess emission in their photometry. However, without access to spectroscopy, the nature of these objects remained unclear. Using the NIRSpec instrument on board JWST, we studied a sample of these stars, with masses in the range ∼ 0.9 − 1.8 M⊙, effective temperatures (Teff) in the range 4, 500−8, 000 K, and PMS ages between ∼ 0.1 and 30 Myr. We compared their properties with those of a number of normal main sequence (MS) objects with similar stellar parameters. Here we present the first spectra of solar-mass stars in the metal-poor SMC (Z = 1/8Z⊙) and discuss the physical properties of ten representative sources with good signal-to-noise ratio. The observations convincingly demonstrate that even the oldest of these PMS candidates are still accreting gas with typical rates of ∼ 10−8 M⊙ yr−1 for stars older than ∼ 10 Myr. Remarkably, the spectra also reveal near-infrared excess and molecular hydrogen excitation lines, both of which attest to the presence of long-lived discs around these stars. A reanalysis of the HST observations considering the effects of photometric incompleteness and patchy extinction provides a lower limit of 36 % to the accreting disc fraction for PMS stars older than 10 Myr. Taken together, these findings have profound implications for our understanding of the formation of stars and planetary systems in low-metallicity environments similar to those in place at Cosmic Noon.