This image is of galaxy Arp148, taken by NASA's Spitzer- and Hubble telescopes. The white circle contains Spitzer data that has been specially processed. It shows infrared light from supernovae hidden by dust. Credit: NASA/JPL-CaltechExploding stars generate dramatic light shows. Spitzer is an infrared telescope that can see through the cloud and give you a better understanding of the frequency of these explosions.Supernovae, the death throes for massive stars and some of the most powerful explosions in all of the universe, would be easy to miss. However, the number of supernovae observed in distant regions of the universe is far less than what astrophysicists predicted.New data from NASA's Spitzer Space Telescope has revealed five new supernovae that were previously unknown. Spitzer observed the universe through infrared light. This light penetrates through dust clouds, blocking optical light. It is the same light that our eyes see, and which supernovae shine brightest.The Spitzer observations of 40 dusty galactic objects were used by the researchers to search for hidden supernovae. (In space dust is a term that refers to grains-like particles having a consistency similar smoke. The study confirmed that supernovae occur as often as scientists expected based on the number of them found in these galaxies. This expectation is based upon scientists' current understandings of how stars evolve. These studies are needed to strengthen or challenge certain aspects of that understanding."These Spitzer results show that optical surveys used for supernova detection have been missing up to half of the stellar eruptions occurring out there in the universe," stated Ori Fox, a scientist from the Space Telescope Science Institute, Baltimore, Maryland. She is the lead author of the new study. It was published in the Monthly Notices of the Royal Astronomical Society. It's very encouraging that Spitzer's supernovae numbers are statistically consistent with theoretical predictions.In the near universe, there is no "supernova discrepancy", which is the difference between the predicted number of supernovae and what has been observed using optical telescopes. These galaxies are less dusty and have a slower rate of star formation. Galaxies in the far reaches of the universe are younger and produce stars at a faster rate, but they also tend to have more dust. This dust scatters and absorbs ultraviolet and optical light, which prevents it from reaching telescopes. Researchers have known for a long time that supernovae missing from the Earth's sky must exist, and they are only undiscovered.Fox stated that "Because our local universe has cooled down a bit from its early years of starmaking, we now see the expected number of supernovae using typical optical searches." Fox stated that supernova detection percentages decrease as we move further away from the cosmic epochs when dustier galaxies predominated.It can be difficult to detect supernovae from such distant distances. Fox's team chose a set of 40 dusty galaxies to search for supernovae at far greater distances. These galaxies are known as luminous or ultra-luminous infrared galactics (LIRGs) and ULIRGs, depending on their location. While the dust in LIRGs or ULIRGs absorbs light from supernovae, it allows for infrared light to pass through these galaxies unimpeded. This makes them easy to detect by telescopes such as Spitzer.When five previously undiscovered supernovae were visible in (infrared), light, the researchers' intuition was correct. Fox stated, "It's testament to Spitzer’s discovery potential that this telescope was able to detect the signal of hidden Supernovae from these dusty galactices."Alex Filippenko (a professor of astronomy from the University of California at Berkeley) said that it was particularly fun for many of our undergraduate students. "They helped us answer the question: "Where have all the supernovae gone?"Spitzer detected supernovae that are "core-collapse supernovae". These supernovae involve giant stars with a minimum of eight times the mass as the Sun. As the stars age, their cores become irony and they no longer have enough energy to resist their gravity, their cores begin to collapse suddenly and devastatingly.Through nuclear fusion, new chemical elements are formed by the intense pressures and high temperatures that resulted from the rapid cave-in. The super-dense cores of collapsing stars eventually burst, causing them to explode and scattering the elements across space. Supernovae can produce heavy elements such as the majority of metals. These elements are essential for the formation of rocky planets like Earth and biological life. Supernova rates are an important indicator of the existence of heavy elements in our universe and star formation models.Fox stated, "If you know how many stars are being formed, you can predict how many will explode." Fox said that if you know how many stars are currently exploding you can predict the number of stars that will form. This relationship is crucial for many areas in astrophysics research.The next-generation telescopes will detect infrared light like Spitzer, such as NASA's Nancy Grace Roman Space Telescope (NASA) and the James Webb Space Telescope (NASA).Fox stated, "Our study has demonstrated that star formation models are more consistent than previously believed with supernova rates." Spitzer's discovery of these supernovae has opened up new possibilities for discoveries using the Webb or Roman space telescopes.Continue reading A massive protocluster merging galaxies, in the early universe
