Astronomy at a distance: Nebulae
Nebulae are birthplaces of stars and spectacular sights to behold. But you don’t need a powerful telescope to experience these ‘Stellar Nurseries’, as postgraduate researcher Jack McCleery explains.
A nebula is a collection of gas and dust which floats around in space. Their name comes from the Latin for ‘cloud’, which is what astronomers first described them as when they noticed these blurry patches in the sky. They are formed at the end of stars’ lives, but it is from nebulae that new stars are born.
When stars like our Sun run out of fuel near the end of their lives, they shed their outer layers of gas. As this gas expands, the star's exposed core will begin to light it up; these are known as Planetary Nebulae. Stars much more massive than our Sun, however, have violent explosive deaths known as a Supernova. Most of the star’s guts are expelled out into the surrounding space at extreme speeds during this event. The resulting nebula is called a Supernova Remnant.
After Nebulae are formed, over time some parts will begin to clump together and material around this clump will condense into a new ball of gas. Eventually, so much material will have condensed that this ball will ignite and a new star will have been born. Many stars can be formed from a single nebulae, and that’s why they are also often referred to as ‘Stellar Nurseries’.
There are thousands of nebulae in the night sky, many of which are very difficult to see. Let's have a look at some you can see over the next few months, with a pair of binoculars or a small telescope. As added help for finding these, you could download a sky map app on your phone which can direct you to these very easily.
For help with finding some of the constellations mentioned, you can find advice in the article on Constellations.
The Orion Nebula is one of the most famous nebulae and can even be seen with the naked eye. You’ll need to be quick to catch this one just after sunset as at this time of year Orion sets shortly after night falls. You can find it almost due south of the middle star in Orion's belt, halfway to his feet, where it’ll almost look like a blurry star. A closer look with binoculars or a telescope and you might be able to pick out the four brightest stars in the centre; these are referred to as The Trapezium. These are young stars born in this nebula, and are responsible for most of the beautiful glow.
- What you’ll need: Only your eyes! The Orion Nebula is special because of how easy it is to see. It’ll look even more fantastic with binoculars or a telescope though. Even with typical light pollution or a full moon you should be able to see it. Here’s a guide to help find it.
Lying to the East of Orion is the Rosette Nebula, located in the constellation Monoceros, the Unicorn. To the naked eye this will look like a misty red patch, however, a closer look with telescopes with special filters can reveal a much more vibrant picture. Stretching 130 light years in diameter, this is a massive nebula with thousands of young stars within it. At the centre is a cluster of stars known as Caldwell 50, which contains some stars which are only five million years old (yes, 'only' - five million years is quite young in astronomy).
- What you’ll need: Maybe just your eyes/some binoculars. Depending on the light pollution in your area, you may be able to pick this one out with your eyes alone on a moonless night. Binoculars or a telescope will greatly enhance the experience though. Try this guide for help finding it.
Found in Vulpecula - the little fox - the Dumbbell Nebula is a bright Planetary Nebula and can be seen fairly easily with binoculars. Discovered in 1828 by John Herschel, he compared its lobed shape to that of a dumbbell, and since then the name has stuck. To the naked eye it will appear white on the sky, but the two ends of the dumbell will still be clear. At the centre of the nebula is a stellar remnant known as a White Dwarf, which is about 55% the mass of our Sun but only the size of the Earth. It is also one of the largest White Dwarfs known.
- What you’ll need: Definitely binoculars. You won’t be able to see this one without aid, and it’s best to try in an area with as little light pollution as you can get to. This guide will help you find it.
This is a difficult one for you to try on a moonless night, or if you can get away from light polluted areas, with a pair of binoculars at least. Located in Ursa Major - The Great Bear - the Owl Nebula was originally named because of its two dark patches that resemble owl eyes. Made of three shells, the outermost shell is not symmetric like the other two, which is what creates the two dark patches as observed from Earth. Don’t be upset if you can’t get this one, it is a tough one but worth the effort. This is another Planetary Nebula with a White Dwarf about 60% the mass of our Sun at its centre.
- What you’ll need: Binoculars, or preferably a small telescope. This one’s tough, you want there to be no moonlight and as little light pollution as possible. With binoculars you should be able to make it out its shape, a telescope will be needed to make out the owl eyes, though. Here’s a guide to find it.
How did you do? Most nebulae are known to be difficult to see but they are very worth the effort. Be sure to look up others that you might be able to see come autumn and winter, as they have their own individual qualities.
21 May 2020
The Astronomy and Astrophysics group at Warwick is interested in a huge range of scales across the Universe: planetary systems, how they form, live and die; stars, stellar binaries and and the exotic physical processes that they allow us to explore; as well as the transient events which mark the end of stellar lifetimes and the galaxies stars inhabit across the Universe. The group started in September 2003 and is both an observational and theoretical group. The group makes use of a wide range of ground-based telescopes, such as ESO's Very Large Telescope (VLT) in Chile and the Isaac Newton Group of telescopes (ING) in the Canary Islands, or the Atacama Large Millimetre Array (ALMA), as well as space telescopes such as NASA's Chandra and ESA's XMM-Newton X-ray observatories and the Hubble Space Telescope. The Warwick astro group partners in the four large spectroscopic surveys (DESI, SDSS-V, WEAVE, and 4MOST) that will start operations throughout 2020-2021.
Images - credit NASA:
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