Recent Optical Studies of Supernova Remnants

Abstract

Although supernova remnants (SNRs) have been studied the longest time at optical wavelengths, such investigations continue to provide new information and insights into the properties of Galactic and extragalactic SNRs. One reason for this is that optical SNR research can provide data not easily obtainable at other wavelengths. For example, optical studies of SNRs can yield kinematic data (proper motions and radial velocities), gas temperatures and densities, plus elemental abundances relative to hydrogen and helium — information that is at present either difficult or impossible to derive from radio, infrared, or X-ray data. Optical studies also permit the investigation of SNRs over a wide-range of ionization states; from Fe I in S Andromedae (SN 1885; FESEN, HAMILTON, and SAKEN [17]) to [Fe X] and [Fe XIV] in Puppis A, IC 443, and the Cygnus Loop (TESKE and PETRE [37,38]; BROWN, WOODGATE, and PETRE [3]; TESKE and KIRSHNER [36]). Finally, while it is true that only about 25% of the 160 known Galactic SNRs have been detected optically, this list does include the six youngest Galactic remnants known: SN 1006, SN 1054 (the Crab Nebula), SN 1181 (3C58), SN 1572 (Tycho’s SN), SN 1604 (Kepler’s SN), and Cas A (≈ 1680).