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Black holes, quasars & supernova: The most astounding phenomenon in outer space
Everything you wanted to know about black holes, supernova, and quasars but were afraid to ask.
In the vast outreach of space, there exist cosmic events so unbelievably strange and powerful, they’ve changed the way we view the universe and ourselves in it. The inhuman distances make dimensional and spatial comparison difficult to accomplish. But that hasn’t stopped us from looking out into the stars and trying to make sense of it all. Over the past nearly three decades, we’ve used the Hubble Space Telescope to look out into the universe.
Current estimates for some time have pointed to there being some 100 - 200 billion galaxies in our observable universe. Some astrophysicists believe that this could be underselling the real estate of the cosmos and think that there could actually be 2 trillion galaxies in total. Either way, the observable universe as we know it is unfathomably big, and that’s without taking into account string theory and other possible dimensions. Within this great universe nestled in the heart of faraway galaxies and outer rims of places millions upon billions of light years away, we look into some of the most fascinating phenomena in outer space. The quasar pistons that fire off from the mysterious black hole engines of your universe, cascading and dying stars that shine brighter than a whole galaxy for a few universal moments; these are the giants of the macrocosm.
Black holes and the quasar blast
Black holes are objects that have an incredible amount of mass and density, so much that not even light can escape the confines of its gravity. The theory of black holes’ existence has been around for nearly two centuries. While it’s still impossible to directly see a black hole, the advent of space telescopes with special tools allowed us to detect them. We’re able to find black holes due to the effects of gravitational attraction on the stars and planets around them. Scientists have proved that there is most likely a supermassive black hole at the center of every galaxy.
Black holes come in varying sizes. Some can be as small as a single atom, but its mass as dense as a mountain range. Stellar black holes are around the mass of our Sun, these are usually created when a large star explodes in a supernova. Supermassive black holes are many million times the mass of the Sun.
One of the latest natures of black holes to be discovered was the blast of star-like objects emitting from galactic centers. This is the quasar, which is a jetlike stream of energy in epic proportion compared to other space objects around it. These two occurrences in the universe go hand-in-hand. Hubble has been able to get a better grasp on both supermassive black holes and quasars. Some black holes are 3 billion times the mass of the Sun with equally powerful quasars jets and glowing discs of material surrounding it. European Space Agency (ESA) astronomer Duccio Macchetto stated that:
"Hubble provided strong evidence that all galaxies contain black holes millions or billions of times heavier than our sun. This has quite dramatically changed our view of galaxies. I am convinced that Hubble over the next ten years will find that black holes play a much more important role in the formation and evolution of galaxies than we believe today. Who knows, it may even influence our picture of the whole structure of the Universe...?"
For a long time, one of the most perplexing questions in astrophysics was the mechanism behind quasars which are intrinsically linked with these black holes. Short for “quasi-stellar radio source,” a quasar is one of the brightest known objects in the universe. Some are believed to produce 10 to 100 times more energy than the entire Milky Way in a space confined to the size of our solar system.
A majority of quasars are billions of lightyears away from earth and are monitored by measuring the spectrum of their light. While we don’t know the exact operations behind a quasar, we do have a few ideas. Current scientific consensus leads to astronomers to agreeing that quasars are produced by supermassive black holes which are consuming the matter around them. As the matter is sucked into the hole and spins around, large amounts of radiation in the form of x-rays, visible light rays, gamma rays and radio waves are blasted off. This type of churning chaotic friction created by the gravitational pull and stresses then erupts and the escaping energy forms the quasar. The connections between quasars and black holes are intrinsically linked. Supernovas are also responsible for the creation of black holes. The way that all of this adds up is slowly coming together as scientists and astronomers put the cosmic pieces in their place.
Historical discoveries of quasars and supernova
Quasars were discovered in 1963 by Caltech astronomer Maarten Schmidt, this discovery was instrumental in supporting the Big Bang theory. Schmidt spotted the first quasar while working at the Mt. Palomar Observatory. It was at first mistaken for a star as it was billions of light years away. Thanks to the telescopes at Mount Palomar at this time and the advances in radio astronomy, the universe was beginning to become a lot bigger of a place –nearly increasing tenfold at the time.
Maarten Schmidt was studying radio waves emitting from something called Source 3C 273. He thought it peculiar that the radio signals seemed to be coming from a star. The spectrum produced bright spectral lines and hydrogen gas emissions that were shifting into different wavelengths. Redshift and blueshift describe how lights shift towards different wavelengths to determine if the objects are moving closer or further away from us.
Hubble's Law states that:
“An object with that red shift must be located billions of light-years away. It must be brighter than a million galaxies to appear as bright as a star at that great distance.”
This would lead to 3C 273 becoming known as the first quasar. Following this discovery, many more quasars throughout the universe would be found – some even further away than 3C 273. As we gazed back in time, scientists garnered further evidence for the big bang and were able to chart out the history of younger galaxies in the early universe.
But this wasn’t the first time that distant objects in the night sky were mistaken for stars. Various times in human history, even before the telescope was invented – humans discovered supernova which they mistook for regular stars.
A supernova is an exceedingly bright start that lasts for only a moment in time. It is the end of a star’s life. A supernova can briefly outshine a whole galaxy and produce more energy than the Sun in a matter of moments. NASA considers the supernova to be the largest explosion that takes place in space.
One of the first recorded supernovas was logged in 185 A.D. by Chinese astronomers. It’s currently called the RCW 86. According to their records, the star stayed in the sky for eight months. There have been a total of seven recorded supernovas before telescopes according to the Encyclopedia Britannica.
One famous supernova that we know today as the Crab Nebula, was seen throughout the world around 1054. Korean astronomers recorded this explosion in their records and Native Americans may have been inspired by it according to their rock paintings dated to that time. The supernova was so bright that it could be seen during the day.
The term supernova was first used in the 1930s, by Walter Baade and Fritz Zwicky when they witnessed an exploding star called S ANdromedae or SN 1885A.
A supernova is the death of a star and there are a whole lot of stars in the universe. On average, it’s predicted that a supernova occurs once every 50 years in a galaxy like the Milky Way. That means that a star is likely exploding every second somewhere in the universe.
How a star dies depends on the size of it. For example, the Sun isn’t large enough to explode and become a supernova at the end of its lifetime. It will, on the other hand, grow into a red giant at the end of its lifetime in a couple of billion years. Stars go supernova accordingly to their mass, there are two types of ways a star can do this.
Type I Supernova: A star gathers matter from nearby neighbors and causes a runaway nuclear reaction which ignites its explosion.
Type II Supernova: A star runs out of nuclear fuel and then collapses upon itself, usually causing a black hole.
Scientists are getting better at witnessing these types of events. In 2008, astronomers witnessed the initial act of the explosion. For years they’d predicted an outburst of X-rays, which was confirmed as they watched the evolution of the explosion right from the start.
As our telescopes grow larger and become more advanced, we will be able to dive into the secrets and intricacies that these phenomenon display. They may be distant but are important to understanding the pillars and foundations of what holds up our universe.
"You dream about these kinds of moments when you're a kid," said lead paleontologist David Schmidt.
- The triceratops skull was first discovered in 2019, but was excavated over the summer of 2020.
- It was discovered in the South Dakota Badlands, an area where the Triceratops roamed some 66 million years ago.
- Studying dinosaurs helps scientists better understand the evolution of all life on Earth.
David Schmidt, a geology professor at Westminster College, had just arrived in the South Dakota Badlands in summer 2019 with a group of students for a fossil dig when he received a call from the National Forest Service. A nearby rancher had discovered a strange object poking out of the ground. They wanted Schmidt to take a look.
"One of the very first bones that we saw in the rock was this long cylindrical bone," Schmidt told St. Louis Public Radio. "The first thing that came out of our mouths was, 'That kind of looks like the horn of a triceratops.'"
After authorities gave the go-ahead, Schmidt and a small group of students returned this summer and spent nearly every day of June and July excavating the skull.
Credit: David Schmidt / Westminster College
"We had to be really careful," Schmidt told St. Louis Public Radio. "We couldn't disturb anything at all, because at that point, it was under law enforcement investigation. They were telling us, 'Don't even make footprints,' and I was thinking, 'How are we supposed to do that?'"
Another difficulty was the mammoth size of the skull: about 7 feet long and more than 3,000 pounds. (For context, the largest triceratops skull ever unearthed was about 8.2 feet long.) The skull of Schmidt's dinosaur was likely a Triceratops prorsus, one of two species of triceratops that roamed what's now North America about 66 million years ago.
Credit: David Schmidt / Westminster College
The triceratops was an herbivore, but it was also a favorite meal of the Tyrannosaurus rex. That probably explains why the Dakotas contain many scattered triceratops bone fragments, and, less commonly, complete bones and skulls. In summer 2019, for example, a separate team on a dig in North Dakota made headlines after unearthing a complete triceratops skull that measured five feet in length.
Michael Kjelland, a biology professor who participated in that excavation, said digging up the dinosaur was like completing a "multi-piece, 3-D jigsaw puzzle" that required "engineering that rivaled SpaceX," he jokingly told the New York Times.
Morrison Formation in Colorado
James St. John via Flickr
The Badlands aren't the only spot in North America where paleontologists have found dinosaurs. In the 1870s, Colorado and Wyoming became the first sites of dinosaur discoveries in the U.S., ushering in an era of public fascination with the prehistoric creatures — and a competitive rush to unearth them.
Since, dinosaur bones have been found in 35 states. One of the most fruitful locations for paleontologists has been the Morrison formation, a sequence of Upper Jurassic sedimentary rock that stretches under the Western part of the country. Discovered here were species like Camarasaurus, Diplodocus, Apatosaurus, Stegosaurus, and Allosaurus, to name a few.
|Credit: Nobu Tamura/Wikimedia Commons|
As for "Shady" (the nickname of the South Dakota triceratops), Schmidt and his team have safely transported it to the Westminster campus. They hope to raise funds for restoration, and to return to South Dakota in search of more bones that once belonged to the triceratops.
Studying dinosaurs helps scientists gain a more complete understanding of our evolution, illuminating a through-line that extends from "deep time" to present day. For scientists like Schmidt, there's also the simple joy of coming to face-to-face with a lost world.
"You dream about these kinds of moments when you're a kid," Schmidt told St. Louis Public Radio. "You don't ever think that these things will ever happen."
Are "humanized" pigs the future of medical research?
The U.S. Food and Drug Administration requires all new medicines to be tested in animals before use in people. Pigs make better medical research subjects than mice, because they are closer to humans in size, physiology and genetic makeup.
In recent years, our team at Iowa State University has found a way to make pigs an even closer stand-in for humans. We have successfully transferred components of the human immune system into pigs that lack a functional immune system. This breakthrough has the potential to accelerate medical research in many areas, including virus and vaccine research, as well as cancer and stem cell therapeutics.
Existing biomedical models
Severe Combined Immunodeficiency, or SCID, is a genetic condition that causes impaired development of the immune system. People can develop SCID, as dramatized in the 1976 movie “The Boy in the Plastic Bubble." Other animals can develop SCID, too, including mice.
Researchers in the 1980s recognized that SCID mice could be implanted with human immune cells for further study. Such mice are called “humanized" mice and have been optimized over the past 30 years to study many questions relevant to human health.
Mice are the most commonly used animal in biomedical research, but results from mice often do not translate well to human responses, thanks to differences in metabolism, size and divergent cell functions compared with people.
Nonhuman primates are also used for medical research and are certainly closer stand-ins for humans. But using them for this purpose raises numerous ethical considerations. With these concerns in mind, the National Institutes of Health retired most of its chimpanzees from biomedical research in 2013.
Alternative animal models are in demand.
Swine are a viable option for medical research because of their similarities to humans. And with their widespread commercial use, pigs are met with fewer ethical dilemmas than primates. Upwards of 100 million hogs are slaughtered each year for food in the U.S.
In 2012, groups at Iowa State University and Kansas State University, including Jack Dekkers, an expert in animal breeding and genetics, and Raymond Rowland, a specialist in animal diseases, serendipitously discovered a naturally occurring genetic mutation in pigs that caused SCID. We wondered if we could develop these pigs to create a new biomedical model.
Our group has worked for nearly a decade developing and optimizing SCID pigs for applications in biomedical research. In 2018, we achieved a twofold milestone when working with animal physiologist Jason Ross and his lab. Together we developed a more immunocompromised pig than the original SCID pig – and successfully humanized it, by transferring cultured human immune stem cells into the livers of developing piglets.
During early fetal development, immune cells develop within the liver, providing an opportunity to introduce human cells. We inject human immune stem cells into fetal pig livers using ultrasound imaging as a guide. As the pig fetus develops, the injected human immune stem cells begin to differentiate – or change into other kinds of cells – and spread through the pig's body. Once SCID piglets are born, we can detect human immune cells in their blood, liver, spleen and thymus gland. This humanization is what makes them so valuable for testing new medical treatments.
We have found that human ovarian tumors survive and grow in SCID pigs, giving us an opportunity to study ovarian cancer in a new way. Similarly, because human skin survives on SCID pigs, scientists may be able to develop new treatments for skin burns. Other research possibilities are numerous.
The ultraclean SCID pig biocontainment facility in Ames, Iowa. Adeline Boettcher, CC BY-SA
Pigs in a bubble
Since our pigs lack essential components of their immune system, they are extremely susceptible to infection and require special housing to help reduce exposure to pathogens.
SCID pigs are raised in bubble biocontainment facilities. Positive pressure rooms, which maintain a higher air pressure than the surrounding environment to keep pathogens out, are coupled with highly filtered air and water. All personnel are required to wear full personal protective equipment. We typically have anywhere from two to 15 SCID pigs and breeding animals at a given time. (Our breeding animals do not have SCID, but they are genetic carriers of the mutation, so their offspring may have SCID.)
As with any animal research, ethical considerations are always front and center. All our protocols are approved by Iowa State University's Institutional Animal Care and Use Committee and are in accordance with The National Institutes of Health's Guide for the Care and Use of Laboratory Animals.
Every day, twice a day, our pigs are checked by expert caretakers who monitor their health status and provide engagement. We have veterinarians on call. If any pigs fall ill, and drug or antibiotic intervention does not improve their condition, the animals are humanely euthanized.
Our goal is to continue optimizing our humanized SCID pigs so they can be more readily available for stem cell therapy testing, as well as research in other areas, including cancer. We hope the development of the SCID pig model will pave the way for advancements in therapeutic testing, with the long-term goal of improving human patient outcomes.
Adeline Boettcher earned her research-based Ph.D. working on the SCID project in 2019.
Satellite imagery can help better predict volcanic eruptions by monitoring changes in surface temperature near volcanoes.
- A recent study used data collected by NASA satellites to conduct a statistical analysis of surface temperatures near volcanoes that erupted from 2002 to 2019.
- The results showed that surface temperatures near volcanoes gradually increased in the months and years prior to eruptions.
- The method was able to detect potential eruptions that were not anticipated by other volcano monitoring methods, such as eruptions in Japan in 2014 and Chile in 2015.
How can modern technology help warn us of impending volcanic eruptions?
One promising answer may lie in satellite imagery. In a recent study published in Nature Geoscience, researchers used infrared data collected by NASA satellites to study the conditions near volcanoes in the months and years before they erupted.
The results revealed a pattern: Prior to eruptions, an unusually large amount of heat had been escaping through soil near volcanoes. This diffusion of subterranean heat — which is a byproduct of "large-scale thermal unrest" — could potentially represent a warning sign of future eruptions.
Conceptual model of large-scale thermal unrestCredit: Girona et al.
For the study, the researchers conducted a statistical analysis of changes in surface temperature near volcanoes, using data collected over 16.5 years by NASA's Terra and Aqua satellites. The results showed that eruptions tended to occur around the time when surface temperatures near the volcanoes peaked.
Eruptions were preceded by "subtle but significant long-term (years), large-scale (tens of square kilometres) increases in their radiant heat flux (up to ~1 °C in median radiant temperature)," the researchers wrote. After eruptions, surface temperatures reliably decreased, though the cool-down period took longer for bigger eruptions.
"Volcanoes can experience thermal unrest for several years before eruption," the researchers wrote. "This thermal unrest is dominated by a large-scale phenomenon operating over extensive areas of volcanic edifices, can be an early indicator of volcanic reactivation, can increase prior to different types of eruption and can be tracked through a statistical analysis of little-processed (that is, radiance or radiant temperature) satellite-based remote sensing data with high temporal resolution."
Temporal variations of target volcanoesCredit: Girona et al.
Although using satellites to monitor thermal unrest wouldn't enable scientists to make hyper-specific eruption predictions (like predicting the exact day), it could significantly improve prediction efforts. Seismologists and volcanologists currently use a range of techniques to forecast eruptions, including monitoring for gas emissions, ground deformation, and changes to nearby water channels, to name a few.
Still, none of these techniques have proven completely reliable, both because of the science and the practical barriers (e.g. funding) standing in the way of large-scale monitoring. In 2014, for example, Japan's Mount Ontake suddenly erupted, killing 63 people. It was the nation's deadliest eruption in nearly a century.
In the study, the researchers found that surface temperatures near Mount Ontake had been increasing in the two years prior to the eruption. To date, no other monitoring method has detected "well-defined" warning signs for the 2014 disaster, the researchers noted.
The researchers hope satellite-based infrared monitoring techniques, combined with existing methods, can improve prediction efforts for volcanic eruptions. Volcanic eruptions have killed about 2,000 people since 2000.
"Our findings can open new horizons to better constrain magma–hydrothermal interaction processes, especially when integrated with other datasets, allowing us to explore the thermal budget of volcanoes and anticipate eruptions that are very difficult to forecast through other geophysical/geochemical methods."