PHANGS-JWST First Results: Duration of the early phase of massive star formation in NGC628 by Jaeyeon Kim et al. on Wednesday 30 November

The earliest stages of star formation, when young stars are still deeply

embedded in their natal clouds, represent a critical phase in the matter cycle

between gas clouds and young stellar regions. Until now, the high-resolution

infrared observations required for characterizing this heavily obscured phase

(during which massive stars have formed, but optical emission is not detected)

could only be obtained for a handful of the most nearby galaxies. One of the

main hurdles has been the limited angular resolution of the Spitzer Space

Telescope. With the revolutionary capabilities of the JWST, it is now possible

to investigate the matter cycle during the earliest phases of star formation as

a function of the galactic environment. In this Letter, we demonstrate this by

measuring the duration of the embedded phase of star formation and the implied

time over which molecular clouds remain inert in the galaxy NGC628 at a

distance of 9.8Mpc, demonstrating that the cosmic volume where this measurement

can be made has increased by a factor of $>100$ compared to Spitzer. We show

that young massive stars remain embedded for $5.1_{-1.4}^{+2.7}$Myr

($2.3_{-1.4}^{+2.7}$Myr of which being heavily obscured), representing

$\sim20\%$ of the total cloud lifetime. These values are in broad agreement

with previous measurements in five nearby ($D < 3.5$Mpc) galaxies and

constitute a proof of concept for the systematic characterization of the early

phase of star formation across the nearby galaxy population with the

PHANGS-JWST survey.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.15698v1