Credit: www.space.com
Anyone up for a fried egg?
Astronomers use The Very Large Telescope (VLT) to take a picture of a giant star which is classified as a super rare type called the yellow supergiant. It is the most detailed picture and is the first time to see two layers of dust around the supergiant. The star and its dust are so similar to a fried egg that astronomers give its a nickname, "Fried Egg nebular."
Actually, it has an official name, IRAS 17163-3907, which is much harder to remember. It has a diameter of around a thousand time of solar diameter. It is approximately 13000 light years from earth which makes it the nearest yellow supergiant up until now. And from the recent study, it shines around 5 times of solar luminosity.
It is pretty luminous in infrared but no one knew before that it is a yellow supergiant. The image is taken by the infrared camera, VISIR, on VLT. This is the first picture that clearly shows two layers of dust around the star.
If the Fried Egg nebular were at the Sun position in our solar system, Earth would be inside the star itself and Jupiter would be slightly above the surface. The nebular that is even bigger would take in all planets and dwarf planets including asteroids that are beyond Neptune. The nebula would have a radius of around 10000 AU.
The yellow supergiant is at its most active stage. It just "excreted" mass of 4 times of solar mass within a hundred years. Substances excreted from the star form the double layer of the nebular which is composed of silicate and some gases.
These activities also show that the star should "die" in a big explosion in near future. It could be the next supernova in our galaxy. Supernova will send out rare chemicals to its neighbor space and the shock wave could form new stars.
Credit: www.thegeekbook.com
The photo of VLT during a sunset
Cool!
ReplyDelete113000 lightyears... that's about 35 kiloparsecs (kpc). That's pretty far for an object in our own Galaxy! We are about 8 kpc from the center of our Galaxy, and there's much more going on inside that radius than outside. Is it definitely inside our galaxy?
What qualities of the VLT allowed it to take such an impressive image? Was it using any special instruments? What is the angular size of a 10,000 AU nebula at a distance of 113000 lightyears, and how does that compare to the diffraction limit of the VLT?
You are right about the distance. It's the typo. The distance should be 13000 lightyears instead of 113000 lightyears. With the correct distance, it is about 4 kpc from Earth which is well within our Galaxy.
ReplyDeleteNow, the angular size of the nebula is 2*arctan(5000 AU/13000 ly) which is roughly 2.5 arc seconds. Since the nebula is most luminous in infrared, in calculation for diffraction limit, lambda is around 800 nm. The aperture of VLT is 8.2 so the diffraction limit is around 0.025 arc seconds which is 100 times smaller than the angular size of the object.