- 2996 - NEBULAE - Jewel Bug, math - Hubble's Wide Field Camera observed the nebulae in 2019 and 2020 using its full, panchromatic capabilities. Astronomers have been using emission line images from near-ultraviolet to near-infrared light to learn more about their properties.
----------------------------------- 2996 - NEBULAE - Jewel Bug , math
- The picture above is of the Jewel Bug Nebula (NGC 7027) captured by the Hubble Space Telescope in 2019 and released in 2020.
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- The red, green, blue image shows extinction due to dust, as inferred from the relative strength of two hydrogen emission lines, as red; emission from sulfur, relative to hydrogen, as green; and emission from iron as blue.
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Hubble's Wide Field Camera observed the nebulae in 2019 and 2020 using its full, panchromatic capabilities. Astronomers have been using emission line images from near-ultraviolet to near-infrared light to learn more about their properties. The studies were first-of-their-kind panchromatic imaging surveys designed to understand the formation process and test models of binary-star-driven planetary nebula.
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- These pictures allow astronomers to see the effect of the dying central star in how it's shedding and shredding its ejected material. They are able to see that material that the central star has tossed away is being dominated by ionized gas, where it's dominated by cooler dust, and even how the hot gas is being ionized, whether by the star's UV or by collisions caused by its present, fast winds.
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- Other images of the Butterfly Nebula are confirming that the nebula was ejected only about 2,000 years ago and that the S-shaped iron emission that helps give it the "wings" of gas may be even younger.
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- Surprisingly, they found that astronomers had previously believed they had located the nebula's central star, it was actually a star not associated with the nebula that is much closer to Earth than the nebula.
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- The ongoing analysis of the Jewel Bug Nebula is built on a 25-year baseline of measurements dating back to early Hubble imaging. The nebula retains large masses of molecular gas and dust despite harboring a hot central star and displaying high excitation states.
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- There are molecular tracers of ultraviolet and X-ray light that continue to shape the nebula.
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- The width of the entire image is 5 light years. If the elliptical ring near the center is actually a circular ring seen at a tilted angle, what is the radius of this ring in: light years? And kilometers? (Note: 1 light year = 5.9 trillion kilometers).
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- The scale of this image can be found using a millimeter ruler. When printed, the image is about 70 mm. The scale is then 5 lightyears / 70 millimeters = 0.071 ly/mm. The radius of the ring will be the maximum radius of the elliptical ring, which you can see by drawing a circle on a piece of paper and tilting it so it looks like an ellipse.
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- On the image, the length of the major axis of the ellipse is 10 mm, so the radius of the circle is 5 mm.
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- Using the scale of the image we get 5 mm x 0.071 ly/mm = 0.36 light years.
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- The radius in kilometers is just 0.36 ly x 5.9 trillion km/1 ly = 2.1 trillion km.
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- The high-energy particles that make-up the ring were created near the neutron star at the center of the ring. If they are traveling at a speed of 95% the speed of light, to the nearest day, how many days did it take for the particles to reach the edge of the ring? (Speed of light = 300,000 km/s)
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- Time = distance/speed, so for s = 0.95x300,000 km/s = 285,000 km/s, and d = 2.1 trillion km, we get T = 2,100,000,000,000 / 285,000 = 7,368,421 seconds. Converting to days: 7,368,421 seconds x (1 hour/3600 sec) x (1 day/24 hours) = 85.28 days. To the nearest day, this is 85 days.
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- Suppose the pulsar ejected the particles and was visible to astronomers on Earth as a burst of light from the central neutron star 'dot'. If the astronomers wanted to see the high-energy particles from this ejection reach the ring and change its shape, how long would they have to wait for the ring to change after seeing the burst of light?
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- They would have to wait 85 days after seeing the burst of light because light travels faster than the matter in the particles.
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- Another way to appreciate how much faster light travels, calculate the number of days it would take for the pulse of light to reach the ring, compared to the 85 days taken by the particles. The light pulse would take 2.1 trillion km/300,000 km/s = 7 million seconds or about 81 days.
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- So astronomers would have to wait 81 days to see whether the light pulse affects the ring, and then another 4 days for the particles to arrive. It is in the math.
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January 23, 2021 NEBULAE - Jewel Bug , math 2996
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