Posted with permission from STEAM Register

Lola Gayle, STEAM Register

Low-mass stars like our Sun burn brightly for around 10 billion years, give or take a few. When its time is up, a star will go rogue and become a red giant star, meaning it will grow to more than a hundred times larger than its size.

When our own Sun's time is up, it will no doubt take Earth and the rest of the solar system with it, but that won't even begin to happen for at least another 5 billion years.

When an event like this happens, low-mass stars expel most of their material outward into shells of gas and dust. These shells eventually form some of the most beautiful objects in the universe, called planetary nebulae.

The Calabash Nebula is a spectacular example of what happens in the moments immediately after such a violent cosmic death.

Although this event occurred about 800 years ago, this Hubble Space Telescope image shows the dying star going through a rapid transformation from a red giant to a planetary nebula. The recently ejected material is spat out in opposite directions with immense speed - the gas shown in yellow is moving close to a million kilometers an hour!

Catching this phase of a star's evolution is extremely rare because the entire process happens within the blink of an eye - in astronomical terms that is. Over the next thousand years or so, this nebula is expected to evolve into a fully-fledged planetary nebula.

See Also: Galactic Tug Of War Propels Milky Way Through The Universe

The Calabash Nebula is also technically known by the boring name of OH 231.8+04.2. However, it's also referred to as the Rotten Egg Nebula because it contains a lot of sulfur, an element that, when combined with other elements, smells like a rotten egg. Luckily, however, this nebula is located roughly 5,000 light-years away in the constellation of Puppis.

How Far Is That Dead Star?

There are literally thousands of planetary nebulae in the Milky Way alone, and these are favored targets for professional and amateur astronomers alike. Despite intense study, however, scientists have struggled to measure their distance.

However, in Nov. 2015, a trio of astronomers from the University of Hong Kong figured out a way to more accurately estimate the distance to these cosmic beauties.

Their simple and elegant solution requires only an estimate of the dimming toward the object, the projected size of the object on the sky, and a measurement of how bright the object is. The end result being a ‘surface-brightness relation' scale.

Being able to better measure the distances sizes of these objects will give scientists a far better insight into how these objects form and develop, and how stars as a whole evolve and die.

The same team has since refined their technique. According to the researchers, the newly improved method can provide distances accurate to 20 percent, which is a major advance on previous estimators that can have errors of a factor of two or more.

See Also: Surprises From The Heart Of The Orion Nebula

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