Progenitor Constraint with Circumstellar Material for the Magnetar-hosting Supernova Remnant RCW 103

Abstract Stellar winds blown out from massive stars (≳10 M ⊙ ) contain precious information on the progenitor itself, and in this context most important elements are carbon (C), nitrogen (N), oxygen (O), which produced by CNO cycle H-burning layer. Although their X-ray fluorescence lines expected to be detected swept-up shock-heated circumstellar materials supernova remnants, those of C N have been particularly difficult detect so far. Here, we present high-resolution spectroscopy young magnetar-hosting remnant RCW 103 with Reflection Grating Spectrometer board XMM-Newton report detection vii Ly α (0.50 keV) line for first time. By comparing obtained abundance ratio O (N/O = 3.8 ± 0.1) various stellar evolution models, show that is likely a low mass (10–12 medium rotation velocity (≲100 km s −1 ). The results also rule possibility dynamo effects (≥35 as mechanism forming associated magnetar 1E 161348−5055. Our method useful estimating parameters future missions microcalorimeters such XRISM Athena.