What is a nebula? If you don’t already know the answer, consider reading our article, “20 Interesting Nebula Facts”. Now, assuming that you know what a nebula is or you have just acquired the knowledge, it is time to build up on the same and learn 20 interesting Boomerang Nebula facts. In this article, we will try to find out why this nebula is called by that name, where is it located, what makes this nebula so unique and so on… Ready? Let us start then!

Interesting Boomerang Nebula Facts: 1-5

1. It is the coolest object that scientists have found till date in our visible universe.

2. So just how cold is it? In case you didn’t know, there is something called absolute zero, which is clocked at -273°C. Boomerang Nebula has a temperature of -272°C – just 1 degree above the absolute zero.

3. This nebula is a planetary nebula and it sits in Centaurus constellation, which in turn sits at a distance of 5,000 light years from our very own earth.

Good to know:

What really is a planetary nebula? A planetary nebula is nothing but a chunk of expanding gas that is released after a star’s outer layers blow off when the star has no left-over fuel for burning. The star will usually sit at the center of the nebula and can be seen as a glowing object, which is the inner central part of the star. Not all stars will explode to form nebulae. Despite their name – Planetary Nebulae – they are not really related to planets. They get the name because they appear like large planets. Planetary nebulae are not long-lived. They will usually survive for several tens of thousands of years. That’s long you think? Well, talk of cosmic scales, that’s like a few seconds because a star can survive for billions of years.

4. As we said, the Boomerang Nebula is very, really very cold. But did you know, it is actually colder than the cooling leftovers, that were left behind by the Big Bang. Those leftovers are found everywhere in this universe and they have a temperature of -270°C.

5. ALMA telescope or Atacama Large Millimeter/submillimeter Array telescope is the one that was used for measuring the temperature of this nebula.

Interesting Boomerang Nebula Facts: 6-10

6. The Boomerang Nebula glows and is visible but this glow is actually caused by the central white dwarf star’s light which gets reflected by the dust grains present in the nebula’s gas.

7. This simply means that the Boomerang Nebula is very young because, in older planetary nebulae, it is the ultraviolet rays emitted by the central white dwarf stars that make the gasses of the nebulae glow brightly. The white dwarf of the Boomerang Nebula is yet to reach that stage where it will emit ultraviolet radiations.

8. The Boomerang Nebula gets its name from the asymmetric shape that is visible using the optical telescopes based on the ground.

9. When this nebula was first spotted using ground telescopes, scientists or researchers actually found that the shape of the nebula actually looked a little distorted. However, Hubble Space Telescope swung its camera towards the nebula back in 2003 and discovered that the nebula looked more like an hourglass when viewed in visible wavelengths.

10. Hubble then viewed the nebula a number of times and so did several other telescopes. A new mystery emerged and then it was resolved. The fact is that planetary nebulae do have the shape of bow tie or hourglass in general but that happens only and only when gas from the central star is ejected at high speed.

Interesting Boomerang Nebula Facts: 11-15

11. What really happens is that material jet released by the central star punches through gas surrounding the star when it was a red giant. This creates holes in the gas and gives the bow tie shape.

12. If that’s what would have happened in case of Boomerang Nebula, scientists could have easily seen the bow tie shape at wavelengths that are cooler. However, when ALMA (which is known to have the highest resolution of all telescopes at submillimeter wavelength) was used it was found that the molecules of carbon dioxide in the gas cloud of the Boomerang Nebula formed hourglass shape but in the inner parts. In case you didn’t know, carbon dioxide molecules shine brightly in submillimeter wavelength.

13. Moving away from the inner parts of the nebula, the carbon dioxide molecules formed rounder shape.

14. In addition to that, grains of dust present around the central star were actually masking visible wavelength of light emitted out by the star. These dust grains can also be seen in millimeter wavelength. This masking of light by these dust grains also gave the nebula an hourglass shape. But if these dust grains weren’t there, the nebula is actually a round gas cloud. This was revealed in 2013.

15. Thus, the name Boomerang Nebula that was given by Mike Scarrott and Keith Taylor in 1980 after they used an optical ground-based telescope located in Australia, is not really a suitable name. The more fitting name would have been Bow Tie Nebula. Scarrott and Taylor observed a slight asymmetry in the lobes of the nebula and they thought it has a curved shape like that of a boomerang.

Interesting Boomerang Nebula Facts: 16-20

16. Researchers in NASA say that the central white dwarf of the Boomerang Nebula has lost nearly 1.5 times solar mass in previous 1,500 years.

17. The nebula’s central star uses bipolar outflow – a process for ejecting its mass.

18. The reason why the Boomerang Nebula is so cold is that the gas ejected from the central white dwarf star is expanding outside at a very rapid speed of 102 miles per second or 164 kilometers per second. This allows the gas to lose its heat. It works on the same principle as that of refrigerators where expanding gas allows cooling.

19. The Boomerang Nebula’s bow tie shape, according to NASA researchers, is caused by winds blowing at a speed of 500,000 kilometers per hour. It is this wind that blows of the ultra-cold gas away from the dying star situated at the center of the nebula.

20. The telescope that measured the temperature of the nebula is based in Chile. It is a Swedish telescope known as 15-meter ESO Submillimetre Telescope. Nyman and Sahai were the two astronomers who calculated the temperature.

Sources: 1, 2, 3, 4, 5

Image sources: 1, 2

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