Molecular Environment and an X-ray Spectroscopy of Supernova Remnant Kesteven 78

TL;DR

This study explores the molecular environment and X-ray properties of supernova remnant Kesteven 78, revealing interactions with molecular clouds, shock signatures, and estimating the remnant's age and progenitor mass.

Contribution

It provides new insights into the SNR's interaction with molecular clouds and detailed X-ray spectral analysis, advancing understanding of its environment and evolution.

Findings

SNR Kes78 interacts with molecular clouds at 81 km/s

X-ray emission from underionized plasma (~1.5 keV)

Remnant age estimated at about 6 kyr

Abstract

We investigate the molecular environment of the Galactic supernova remnant (SNR) Kesteven 78 and perform an XMM-Newton X-ray spectroscopic study for the northeastern edge of the remnant. SNR Kes78 is found to interact with the molecular clouds (MCs) at a systemic local standard of rest velocity of 81km/s. At around this velocity, the SNR appears to contact a long molecular strip in the northeast and a large cloud in the east as revealed in the 13CO line, which may be responsible for the radio brightness peak and the OH maser, respectively. The 12CO-line bright region morphologically matches the eastern bright radio shell in general, and the SNR is consistent in extent with a CO cavity. Broadened 12CO line profiles discerned in the eastern maser region and the western clumpy molecular arc and the elevated 12CO J=2-1/J=1-0 ratios along the SNR boundary may be signatures of shock perturbation in the molecular gas. The SNR-MC association places the SNR at a kinematic distance of 4.8 kpc. The X-rays arising from the northeastern radio shell are emitted by underionized hot (~1.5 keV), low-density (~0.1 cm^{-3}) plasma with solar abundance, and the plasma may be of intercloud origin. The age of the remnant is inferred to be about 6 kyr. The size of the molecular cavity in Kes78 implies an initial mass around 22Msun for the progenitor.