- 2953 - ETA CATENAE - an exploding star? Astronomers using NASA's “Far Ultraviolet Spectroscopic Explorer” satellite made the first direct detection of a companion star of Eta Carinae. Eta Carinae is one of the most massive and unusual stars in the Milky Way galaxy. The detection was made possible by the high temperature of the companion star and the unique sensitivity of the satellite at the shortest ultraviolet wavelengths.
--------------- Husband and wife decide who does what;
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- A man said to his wife one day, "I don't know how
you can be so stupid and so beautiful all at the same time.
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"The wife responded, "Allow me to explain.
God made me beautiful so you would be attracted to
me;
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God made me stupid so I would be attracted to you!
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- A man and his wife were having an argument about who
should brew the coffee each morning.
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The wife said, "You should do it because you get up
first, and then we don't have to wait as long to get our
coffee.
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The husband said, "You are in charge of cooking
around here and you should do it, because that is your job, and I
can just wait for my coffee."
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Wife replies, "No, you should do it, and besides, it
is in the Bible that the man should do the coffee."
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Husband replies, "I can't believe that, show me."
So she fetched the Bible, and opened the New
Testament and showed him at the top of several pages, that it indeed says
...........
"HEBREWS"
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----------------------------- 2953 - ETA CATENAE - an exploding star
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- Eta Carinae is an unstable star thought to be rapidly approaching the final stage of its life. It is clearly visible from the southern hemisphere and has been the subject of intense studies for decades.
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- This mysterious star is located about 7,500 light-years from Earth in the star constellation Carina. Scientists thought a companion star in orbit around Eta Carinae might explain some of its strange properties, but researchers lacked direct evidence a companion star existed.
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- Evidence that Eta Carinae might be a double star system was inferred from a repeating pattern of changes in visual, X-ray, radio and infrared light over approximately 5 light years radius. Astronomers thought a second star in a 5 light year orbit around Eta Carinae might cause the repeated changes in its light.
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- The strongest indirect evidence supporting the double star theory is that once every 5 light years, the X-rays coming from the system disappear for about three months. Eta Carinae is too cool to generate X-rays, but it continuously blasts a flow of gas into space as a stellar wind at about 300 miles per second.
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- If its companion has a similar wind, their stellar winds would collide with enough force to generate the X-rays. This collision region must lie somewhere between the two stars.
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- As Eta Carinae moves in its orbit, it passes in front of the region where the winds collide, as viewed from Earth. When this occurs, Eta Carinae eclipses the X-rays once every 5 light years, causing them to disappear.
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- The last X-ray eclipse began on June 29, 2003. The 5 light year orbit places the companion star only about 10 times farther from Eta Carinae than Earth is from the sun. Eta Carinae is too far away for telescopes to distinguish two stars in such a close orbit.
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- Another way to find evidence of a double-star system would be to detect the light of the second star, which in this case is much fainter than Eta Carinae. Several scientists searched for light from Eta Carinae's companion using ground-based telescopes, but none have succeeded.
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- Because the companion is thought to be much hotter than Eta Carinae, astronomers reasoned it should be brighter at shorter wavelengths like ultraviolet light. However, it still escaped detection when it was searched for using the ultraviolet capabilities of the Hubble Space Telescope.
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- Finally the companion could be seen at even shorter ultraviolet wavelengths than Hubble. Astronomers observed the far-ultraviolet light from Eta Carinae with the satellite on June 10, 17 and 27, 2003, right before the expected X-ray eclipse.
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- The disappearance of far ultraviolet light so close to the X-ray eclipse implies when Eta Carinae eclipsed the X-rays, it also eclipsed the companion star. The far-ultraviolet light observed prior to the eclipse was from the hotter companion, because Eta Carinae is too cool to emit much far-ultraviolet light.
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- This far ultraviolet light comes directly from Eta Carinae's companion star, the first direct evidence that it exists. The companion star is much hotter than Eta Carinae, settling a long-standing mystery about this important star.
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- Here is some history on this exploding star. 170 years ago, Eta Carinae, one of the brightest, most massive stars in the Milky Way, erupted with a titanic blast, releasing almost as much energy as a supernova explosion and becoming at one point the second brightest star in the night sky. Somehow, the star survived the “Great Eruption”, providing an intriguing mystery for astronomers.
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- Light from the outburst has rebounded, or “echoed,” off interstellar dust and has only now reached Earth, researchers have found the original explosion created a huge 10-solar-mass cloud of debris expanding 20 times faster than expected more than 20,000,000 miles per hour, fast enough to travel from Earth to Pluto in just a few days.
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- Velocities that high are seen in the aftermath of supernova explosions, but not in events that leave a star intact. These really high velocities in a star that seems to have had a powerful explosion, but somehow the star survived. The easiest way to do this is with a shock wave that exits the star and accelerates material to very high speeds.
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- Researchers first detected the light echoes from Eta Carinae in 2003, initially using telescopes at the Cerro Tololo Inter-American Observatory in Chile. Using the larger Magellan telescopes and the Gemini South Observatory, also in Chile, the researchers collected spectra to determine the velocity of the expanding debris.
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- The data did not jibe with accepted ideas about stellar evolution. Massive stars normally die when their cores run out of nuclear fuel. When the outward pressure of fusion-generated energy suddenly stops, gravity takes over and the core collapses, generating a tremendous shock wave that blows the outer layers of the star into space.
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- Depending on the original mass, the core becomes a compact neutron star or a black hole. In the case of Eta Carinae’s eruption, some process must have produced a supernova-like shockwave that came just shy of the energy needed to destroy the star. What might have happened?
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- Eta Carinae likely started out as a triple star system with two massive stars orbiting close together and a third star farther away. When the more massive of the two closely orbiting suns neared the end of its life, it began to expand, allowing the slightly less massive star to suck in an enormous amount of material.
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- That less massive star could swell to about 100 solar masses, in the process stripping away the dying sun’s outer atmosphere and leaving an exposed helium core about 30 times more massive than the Sun.
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- From stellar evolution, there is a firm understanding that more massive stars live their lives more quickly and less massive stars have longer lifetimes. So the hot companion star seems to be further along in its evolution, even though it is now a much less massive star than the one it is orbiting. That doesn’t make sense without a transfer of mass.
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- That mass transfer would have changed the gravitational architecture of the system, allowing the helium-core star to move away from its huge partner, so far, in fact, that it eventually interacted with the outer third star, kicking it inward. That star finally crashed into the supermassive star at the heart of the triple system in a cataclysmic merger f the three stars.
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- In its initial stages, ejected material moved relatively slowly as the two stars spiralled closer and closer together. When the stars finally merged, debris was blown away 100 times faster, catching up and ramming into the slower-moving material and generating the light seen in Eta Carinae’s eruption.
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- The helium-core star, meanwhile, ended up in an elliptical orbit that carries it through the giant central star’s outer atmosphere every five-and-a-half years, generating X-rays and shock waves.
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- The now-binary star system shines five million times brighter than the Sun with two enormous, symmetrical lobes of expanding debris expanding to either side. The large star will likely exhaust its nuclear fuel in the near future, astronomically speaking, and explode as a supernova.
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- So, now you know the story of an exploding star. Here are some more reviews on this star:
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- 1731 - Learn more about astronomy by using more of the electromagnetic spectrum. Here are 2 views of galaxies and stars using X-rays and Radio waves converted to light waves.
- 1347 - What is the Next Supernova to Go Boom? The biggest supernova recorded was in 2006. It was 250,000,000 lightyears away. The picture is a star ready to blow. It is 8,000 lightyears away.
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- 775 - Eta Carinae Supernova? Press Democrat May 8, 2007, headlines: “Supernova awes astronomers”. Suprenova SN 2006gy was an exploding star 5 times brighter and more powerful than astronomers have ever seen before. Fortunately, it was 240,000,000 light years away and that is how long ago it exploded. The light got here last September but what amazes astronomers is that it is still as bright.
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- 49 - 409 - Eta Carinae - The biggest, brightest star.
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December 26, 2020 ETA CATENAE - an exploding star? 2953
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