Wispy remains of a supernova explosion hide a possible ‘survivor.’ Of all the varieties of exploding stars, the ones called Type Ia are perhaps the most intriguing. Their predictable brightness lets astronomers measure the expansion of the universe, which led to the discovery of dark energy. Yet the cause of these supernovae remains a mystery. Do they happen when two white dwarf stars collide? Or does a single white dwarf gorge on gases stolen from a companion star until bursting? If the second theory is true, the normal star should survive. Astronomers used the Hubble Space Telescope to search the gauzy remains of a Type Ia supernova in a neighboring galaxy called the Large Magellanic Cloud. They found a sun-like star that showed signs of being associated with the supernova. Further investigations will be needed to learn if this star is truly the culprit behind a white dwarf’s fiery demise.
This supernova remnant is located 160,000 light-years from Earth. The actual supernova remnant is the irregular shaped dust cloud, at the upper center of the image. The gas in the lower half of the image and the dense concentration of stars in the lower left are the outskirts of a star cluster.
Image credit: NASA, ESA and H.-Y. Chu (Academia Sinica, Taipei)
“But there’s one killer move that stars have that makes carbon a loser in the cosmic equation: when a star is massive enough to initiate carbon fusion – a requirement for generating a type II supernova – the process that turns carbon into oxygen goes almost to full completion, creating significantly more oxygen than carbon by time the star is ready to explode.”
When the Universe was first born, all we had was hydrogen and helium, with a trace amount of lithium and absolutely nothing else. 13.8 billion years later, hydrogen is still #1 in the Universe and helium is still #2, but lithium isn’t close to #3 anymore: more than two dozen elements have passed it. The key? Stars! Over billions of years, nuclear fusion in the cores of stars have built up all the naturally occurring elements we know of in the periodic table. You might think that since three heliums can fuse together to make carbon, that would be the third most common element in the Universe. And it’s close: carbon comes in at #4. But another element has it beat.
“Every star will someday run out of fuel in its core, bringing an end to its run as natural source of nuclear fusion in the Universe. While stars like our Sun will fuse hydrogen into helium and then – swelling into a red giant – helium into carbon, there are other, more massive stars which can achieve hot enough temperatures to further fuse carbon into even heavier elements. Under those intense conditions, the star will swell into a red supergiant, destined for an eventual supernova after around 100,000 years or so. And the brightest red supergiant in our entire night sky? That’s Betelgeuse, which could go supernova at any time.”
One of the most sobering cosmic truths is that every star in the Universe will someday run out of fuel and die. Once its core fuel is exhausted, all it can do is contract under its own gravitational pull, fusing heavier and heavier elements until it can go no further. Only the most massive stars, capable of continuing to fuse carbon (and even heavier elements) will ever create the Universe’s ultimate cataclysmic event: a Type II, or core collapse, supernova. Stars that are fusing carbon (and up) appear to us today as red supergiants, and the brightest red supergiant as seen from Earth is Betelgeuse. Sometime in the next 100,000 years or so, Betelgeuse will go supernova. When it does, it will emit incredible amounts of radiation, become intrinsically brighter than a billion suns and and be easily visible from Earth during the day. But that’s not all.
The Nearest Supernova Of Our Lifetime Turns 30, And Still Shines
“The supernova light brightened and then dimmed, but the surrounding gas, blown off from the supergiant, remains illuminated by radiation.
As shockwaves from the explosion move outwards, they collide with interstellar material, producing brightening rings of material.”
In February of 1987, the first light from a supernova some 168,000 light years away was observed on Earth. It became the closest supernova to be observed since the invention of the telescope. As a result, it’s taught us more about massive star death, ejecta and supernova remnant evolution than any other object in the Universe. Illuminated outer rings showcase ejection events that occurred prior to the final death of the star; continued brightening teach us the rate of expansion of the supernova remnant; the lack of a neutron star at the core teaches us about the power of dust to obscure even radio light from this object. Perhaps most interestingly, neutrinos were observed from this supernova, arriving nearly three hours before the light did, confirming that they move through a star unimpeded, unlike light.