G299.2−2.9, is a faint and filamentary supernova remnant (SNR) located in the constellation Norma, roughly 16,000 light-years from Earth. This SNR is the result of a Type Ia supernova — the thermonuclear explosion of a white dwarf, that occurred thousands of years ago, leaving behind this expanding shell of shocked gas and energized interstellar material.
The remnant spans about 15 arcminutes across, corresponding to a physical diameter of nearly 70 light-years. Its asymmetric appearance and unusually bright outer shell suggest that the explosion occurred in a non-uniform environment, likely near the edge of a dense molecular cloud. Unlike more symmetrical remnants like Tycho or SN 1006, G299.2−2.9 is strongly shaped by its surroundings.
This image combines narrowband hydrogen-alpha and oxygen-III data with RGB stars, highlighting the faint, wispy structure of the shock front. The red filaments trace ionized hydrogen, while the bluish filaments show doubly ionized oxygen — both glowing as the shockwave continues to sweep through the interstellar medium.
G299.2−2.9 is not commonly imaged in visible light due to its low surface brightness and remote location, making this capture a relatively rare view of an ancient, isolated Type Ia remnant.
Imaged in HOO RGB on my Planewave CDK 700 at Observatorio El Sauce, Chile.
Image acquisition and processing: Mike Selby