Clues on the presence and segregation of very massive stars in the Sunburst Lyman-continuum cluster at z=2.37

Understand

We report the identification of very massive stars (VMS; mass $> 100$\,\msun) that may be segregated in the center of the young massive star cluster at $z$=2.37 hosted in the lensed galaxy called {\tt Sunburst} galaxy.

• This result is based on two pieces of evidence: (1) VLT/MUSE spectra of several multiple images of the same star cluster show key spectral signatures of VMS, such as the \heii\ broad emission, \nivblue\ emission, and an \niv\ P-Cygni profile.
• In particular, \heii\ is broad ($\sim1610\pm300$ \kms), with an equivalent width of 3\AA,\ and asymmetric profile.
• These features require an extremely young ($\sim2.5$ Myr) stellar population component in which the masses of the stars exceed 100~\msun.