G107.0+9.0: a new large optically bright, radio, and X-Ray faint galactic supernova remnant in Cepheus
Robert A. Fesen, Kathryn E. Weil, J. C. Raymond, Laurent Huet, Martin Rusterholz, Dennis di Cicco, David Mittelman, Sean Walker, Marcel Drechsler, Sheldon Faworski
Abstract
ABSTRACT Wide-field H α images of the Galactic plane have revealed a new supernova remnant (SNR) nearly 3 deg in diameter centred at l = 107.0, b = +9.0. Deep and higher resolution H α and [O iii] 5007 Å images show dozens of H α filaments along the remnant’s northern, western, and southwestern limbs, but few [O iii] bright filaments. The nebula is well detected in the H α Virginia Tech Spectral-Line Survey images, with many of its brighter filaments even visible on Digital Sky Survey images. Low-dispersion spectra of several filaments show either Balmer dominated, non-radiative filaments, or the more common SNR radiative filaments with [S II]/H α ratios above 0.5, consistent with shock-heated line emission. Emission line ratios suggest shock velocities ranging from ≤70 km s−1 along its western limb to ≃ 100 km s−1 along its northwestern boundary. While no associated X-ray emission is seen in ROSAT images, faint 1420 MHz radio emission appears coincident with its western and northern limbs. Based on an analysis of the remnant’s spatially resolved H α and [O iii] emissions, we estimate the remnant’s distance at ∼1.5−2.0 kpc implying a physically large (dia. = 75−100 pc) and old (90−110 × 103 yr) SNR in its post-Sedov radiative phase of evolution expanding into a low-density interstellar medium (n0 = 0.05−0.2 cm−3) and lying some 250−300 pc above the Galactic plane.