A Sprawling Supernova Remnant
The tattered result of a massive stellar explosion, the Vela supernova remnant sprawls across more than 20 square degrees of the far-southern sky. Taken from Chile with a 180-mm f/2.5 lens and a hydrogen-alpha filter, the image reveals much of the remnant's extensive network of glowing gaseous filaments. The bright stars d and e Velorum are labeled. North is to the upper right. Click on the image to see more of the remnant.
Courtesy Michael Stecker.
When I was making the hit list for my Southern Hemisphere observing run I asked a group of experienced observers whether the Vela supernova remnant (
Vela SNR) could be seen visually. Atlanta-based observer Alex Langoussis replied, "You could spend hours following all the visible filaments." That caught my attention!
The tattered remains of a supernova explosion that took place 20,000 to 30,000 years ago, the Vela SNR sprawls across more than 20 square degrees of sky and is centered roughly at R.A. 8h 36m, Dec. -45°. One night I attempted to see the Vela SNR from a dark site on the western edge of Wollemi National Park with Buckley's fine 14½-inch and an O III filter. I saw only three filaments near the 4th-magnitude star e Velorum. While those three filaments were not particularly difficult, I saw nothing definite in the southern part of the remnant. However, on that night the seeing was so poor that I couldn't split Acrux, even though its two very bright components were only 4.0" apart. What's more, I was exhausted, as the heat and the raucous kookaburras had kept me from getting a good day's sleep, and I was observing in a very uncomfortable position (hunched over on the third step of a ladder for two excruciating hours). These three factors apparently reduced my ability to discern elusive nebulosity. At home I wouldn't have tried to do serious observing when the seeing was that poor, but you can't afford to be choosy when on an observing run in another hemisphere.
German observer Ronald Stoyan used the MegaStar software program to plot the star field around the Vela SNR. He then sketched the parts of the remnant that he was able to see (from Namibia) through a 20-inch f/5 Newtonian telescope with an oxygen-III filter. The labeled stars are a, b, d, and e Velorum. North is up. Click on the image for a larger view.
More can be seen of the Vela SNR under more favorable conditions. Langoussis had "legendary" seeing when he explored the remnant at the 1997 Winter Star Party with an O III filter and his 15-inch f/5 Dobsonian. Observing at 54x he'd "try to follow each individual strand, and try to work [his] way back and catch the next, in order to see everything."
Sky & Telescope contributing editor Sue French had a comparable view with her 4.1-inch f/5.8 refractor. With the obligatory O III filter "large swaths of very complex nebulosity were visible" at 17x, she reports. "The brightest sections lie north and west of e Velorum. A large, detached 'T' of nebulosity lies east of the main, sprawling complex."
Observers in Australia, South Africa, and other lands south of the equator need no encouragement to seek out these remarkable nebulae. But if you live north of the Tropics, I heartily recommend that you pack a portable telescope and observe some of these objects if you head south for a winter vacation.
