- Attachment: Stephan’s Quintet Galaxies
- The merging galaxies had filaments and streams of stars interconnecting them as the merger was occurring. All 5 galaxies appeared to be about the same size and the same distance away.
- When astronomers first began to measure the distance of the galaxy merger they created great controversy. The technique was to use the redshift of the spectrum of hydrogen. Some got a redshift of 658 nanometers for hydrogen spectrum at 656.3 nanometers. A redshift of 1.7 nanometers. Other measurements got 670.6 nanometers for a redshift of 14.3 nanometers.
- The ratio of the amount of redshift to the wavelength at rest is to the receding velocity is to the speed of light.
------------- shift in wavelength / wavelength = receding velocity / speed of light.
-------------- 1.7 nanometers / 656.3 nanometers = receding velocity / 3*10^5 kilometers / second.
------------- Receding velocity = 780 kilometers per second
------------- Receding velocity = 1,740,000 miles per hour
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-------------- 14.3 nanometers / 656.3 nanometers = receding velocity / 3*10^5 kilometers / second.
------------- Receding velocity = 6540 kilometers per second
------------- Receding velocity = 14,600,000 miles per hour
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- That is 8.5 times faster velocity for some measurements versus others. Astronomers began to loose faith in the redshift method of measuring distances. The Universe is expanding at 47,000 miles per hour per million lightyears distance.
- Distance = 1,740,000 miles per hour / 47,000 miles per hour per million lightyears
- Distance = 37 million lightyears.
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- Distance = 14,600,000 miles per hour / 47,000 miles per hour per million lightyears
- Distance = 310 million lightyears.
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- These galaxies could not be merging and be that far apart, or, the redshift measurements for distance can not be working?
- See the Hubble Space Telescope attached. One of the galaxies has all the bright stars shining as pin points of light. The other 4 galaxies are somewhat blurred because of the 8 times greater distance. It just happened that the 5th galaxy was in our direct line of sight and was 8 times smaller. The interconnecting filaments were an optical illusion.
- However, further study confirmed that the other 4 galaxies were truly colliding and would eventually end up as a giant merger in an elliptical galaxy. The strange interconnecting filaments were caused by giant intergalactic shockwave caused by one galaxy falling into the center of the group at 300,000,000 miles per hour. The shockwave is so big itself is larger than the Milky Way Galaxy. The shockwave is similar to a sonic boom except it is in interstellar gas rather than in air.
- The shockwave was detected by an X-ray Space telescope. The X-rays are emitted by gas heated to millions of degrees. This created another controversy. How could we be measuring the spectrum of molecular hydrogen within the shockwave. This measurement was measured with an Infrared Space telescope. Molecular hydrogen is a very fragile molecule and would easily be ionized or destroyed by a shockwave.
- What astronomers learned was that the shockwave produced a turbulence creating many smaller shocks which in turn created pockets in which the molecular hydrogen could survive. This is very interesting because it is the molecular hydrogen that is the seeds for the birth of new stars.
- Most recently the Infrared Space telescope has discovered as set of 4 other galaxies that are extremely “red”. See the image attached from Hubble Space Telescope. Hubble’s image is not so bright in visible red light, however, the infrared image is 60 times brighter in the longer wavelengths. Galaxies can appear red for several reasons:
------------------- (1) They might be very dusty
------------------- (2) They might be very old stars that have lost their high temperature brilliance.
------------------- (3) They might be very distant and the expansion of the Universe has stretched their brilliant starlight into longer and longer wavelengths. and redder and redder colors.
- All three reasons apply to these 4 distant galaxies that are 13,000,000,000 lightyears away. This proves that galaxies existed within less than 1,000,000,000 years after the Big Bang. Stephan’s Quintet gives us some theories of how molecular hydrogen could survive these galactic collisions to form new stars. The further distance we see the further back in time we go. These images are the childhood of stars in a galactic nursery. We are just beginning to trace their evolution into today’s understanding of the Cosmos we see. An announcement will be made soon, stay tuned.
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(1) Also see Review #1240 Stephan’s Quinter Merging Galaxies
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