In 1054 A.D. , Chinese astronomers noted a new star in the sky. It shone so brightly that folks could see it in the daytime. But the star was temporary. In fact, it was not a new star at all but an old star that exploded. This nebula is the result of that explosion. M1 is a supernova remnant. It is one of the coolest deep sky objects in the heavens.
Why so cool? Well, first, this is one of the few deep sky objects whose origin was observed by human beings, and it's been growing ever since. Most objects in the sky change very slowly by our time scale, but not this one. In fact, some amateur astronomers have observed changes in M1 in their own images over time.
Second, M1 is not just a supernova remnant. It is the home of what is left of the star that exploded. The core of the supernova did not have enough mass to become a black hole, so it stopped just short of that and became a neutron star. Within it, gravity's power has overcome the forces that create space within atoms, crushing the elements away. What is left is a ball of neutrons only 15-18 miles wide that contains more mass than the Sun! Pretty heavy stuff!
But there is more. The neutron star and its interactions with its immediate environment produce more than just visible light. Radio waves, x-rays, and gamma rays all stream out of the center of M1. See NASA's combined optical and x-ray image of the center of M1
here. The neutron star's intense radiation causes this to happen.
Even more remarkably, the neutron star is spinning very quickly. It's strong electromagnetic field concentrates the radio waves into pulses that tick like a clock in space. When astronomers first heard it, its regularity suggested that astronomers were receiving a signal from aliens. But theorists later determined how a neutron star could produce such pulses. We call such a spinning neutron star a pulsar.
The pulsar itself is visible in this image. At the center of the nebula are two stars, easily visible next to each other. The pulsar is the dimmer of the two, on the right. We may not have a picture of a black hole yet, but we have images of the next closest thing. How cool is that?
This image is a combination of (1) a stack of frames taken through an H-alpha filter with (2) a short color image I took a year ago through the same telescope. I have simply slapped the color over the H-alpha image. Here is the H-alpha alone:
Here is the capture data for the H-alpha image:
Telescope: Orion 254mm f/4.7 Newtonian and RCC I
Camera and Exposure: SXVF-H9 (H-alpha: 10x900"), T-shirt flats
Filter: Astronomik 12nm Ha
Guiding: SX Lodestar and SX OAG
Mount: Takahashi NJP
Software: Nebulosity, Maxim DL, Registar, Photoshop CS3
Location: The Woodlands, TX
The color data is described
here.
