Supernova Remnant & Star Cluster


Supernova Remnant & Star Cluster in Gemini

A bubble of glowing gas blows away from an ancient dying star, next to a cluster of new stars in Gemini.

This image, from a week ago, captures contrasting stages in the life of a star.

At left is a crescent-shaped bubble of gas called IC 443, or the Jellyfish Nebula, billowing away from the site of an ancient supernova explosion, when a giant star ended its life in a blast thousands of years ago. Estimates put its age as between 3,000 and 30,000 years.

At upper right is the bright open star cluster, Messier 35, a gathering of hundreds of comparatively new stars at the beginning of their lives. M35 lies 2,800 light years away, close enough that its stars are nicely resolved in my photo and in any small telescope. M35 is one of the showpieces of the winter northern sky.

Just below M35 you can see a fuzzy glow. It’s another star cluster, NGC 2158. However, its great distance of 11,000 light years makes it appear as a small, partially-resolved glow, a nice contrast in clusters near and far.

IC 443 Supernova Remnant in Gemini

This image focuses on IC 443, sitting between the stars Eta (right) and Mu Geminorum. The field is filled with other faint nebulosity, all part of the cycle of star birth and death.

– Alan, December 7, 2014 / © 2014 Alan Dyer

Snapshots of Starlife


IC 443 Jellyfish Nebula & M35 (92mm 6D)

This one image frames examples of both the beginning and end points of a star’s life.

I shot this last night, February 6, 2013, capturing a field in the constellation of Gemini the twins. At upper right is the showpiece star cluster known as Messier 35. It’s a collection of fairly young stars still hanging around together after forming from a cloud of interstellar gas tens of millions of years ago. M35 lies about 2,800 light years from Earth, on the other side of the spiral arm we live in. Just below M35 you can see another smaller and denser cluster. That’s NGC 2158, about five times farther away from us, thus its smaller apparent size. Both are objects that represent the early stages of a star’s life.

At lower left is an object known as the Jellyfish Nebula, for obvious reasons. The official name is IC 443. It’s the expanding remains of a star that blew up as a supernova anywhere from 3,000 to 30,000 years ago. What’s left of the star’s core can still be detected as a spinning neutron star. You need a radio telescope to see that object, but the blasted remains of the star’s outer layers can be seen through a large backyard telescope as a shell of gas. It is expanding into the space between stars – the interstellar medium – ploughing into other gas clouds. The shockwave from its collision with other nebulas may trigger those clouds to collapse and form clusters of new stars. And so it goes in the Galaxy.

For this portrait of stellar lifestyles, I used a 92mm apochromatic refractor and a new Canon 6D camera, one that has had its sensor filter modified to accept a greater range of deep red light emitted by hydrogen nebulas. The image is actually a stack of 12 exposures with an accumulated exposure time of 80 minutes.

– Alan, February 7, 2013 / © 2013 Alan Dyer

Chariot of the Sky


Auriga the Charioteer rides high across the northern winter sky these nights. This is a wide-field image I took last week of the constellation that now shines overhead from northern latitudes.

My image takes in all of Auriga, the pentagon-shaped charioteer of Roman mythology, as well as the feet of Gemini the twins, spanning a wide area of the winter Milky Way. Sprinkled along this bit of Milky Way you can see a few clusters of stars. They include four of the best open star clusters in the catalogue of Charles Messier: M35 in Gemini at bottom, and M36, M37 and M38 in Auriga at centre, all wonderful targets for a small telescope. Some of these targets lie in the next spiral arm out from the one we live in.

The star colours show up nicely here, with the brightest star at top appearing a little off white. That’s Capella, 42 light years away and classified as a type G “yellow” star not unlike our own Sun in temperature but much larger – a giant star. Indeed, it is really two yellow-giant stars in close orbit around each other. It’s interesting that Capella doesn’t really show up as yellow. Just like our Sun does to our eyes, Capella appears white because it still emits such a broad range of colours that even though its peak energy does fall in the yellow part of the spectrum, all the other colours remain strong enough that the star looks white to our eyes. Remember, our eyes evolved under the light of a type G star to see all the colours of the spectrum from red to blue.

Only the cool red giant stars take on a yellow or orange hue to our eyes, and to the camera. You can see a few in this image, as well as hot blue stars. The pinky red bits are nebulas in the Milky Way – clouds of hydrogen gas emitting deep red light.

When we look in this direction in the Milky Way we are looking out toward the edge of our Galaxy, exactly opposite the galactic centre.

– Alan, February 21, 2012 / © 2012 Alan Dyer