In January 2004, NASA rovers Spirit and Opportunity (aka “Oppy”) landed in two completely different locations on Mars. Their missions were only designed to last 90 sols (approximately 90 Earth days), but they exceeded these parameters, and then some. While Spirit lasted until 2010, Opportunity lasted another astonishing eight years, when it sent its last transmission to Earth in June 2018. During its more than 14-year tenure on the Red Planet, not only did Opportunity gain celebrity status as being the longest serving planetary robotic explorer in history, but it helped reshape our understanding of Mars’ present and past. Now with the help of Amazon Studios and available on Amazon Video, we can re-live the adventure of this incredible rover with Good Night Oppy.
This incredible film gives in-depth and very emotional interviews with the many scientists and engineers responsible for sending the most successful rover to another world, with fantastic narration of the rover’s voices by the extremely talented, Angela Bassett.
“At the beginning, there’s nothing,” Dr. Steve Squyres, Principal Investigator on the Mars Exploration Rover Mission (MER) which comprised Spirit and Oppy, narrates the opening of the film as the viewer is taken on a gorgeous computer animated flyover of the Red Planet. “There’s no concept of a robot explorer crawling across the surface of another world. And, then gradually, you start to think, you start to act, you start to build, and those machines come to life.”
Dr. Squyres, along with other scientists and engineers associated with the mission, tell the story of getting the mission approved, building the rovers, and their personals and professional journeys throughout the course of the mission itself. These incredible interviews include Dr. Jennifer Trosper (MER Project System Engineer and Mission Manager), Rob Manning (MER Lead Systems Engineer), Ashley Stroupe (MER Rover Driver), Kobie Boykins (MER Mechanical Engineer), and Dr. Abigail Fraeman (MER Deputy Project Scientist), and many more.
The film follows all their incredible journeys from two years prior to launch and throughout the course of the entire mission. We get to see them overcome adversity as they tackle one obstacle after another, not just to get the rovers launched, but the mechanical and scientific concerns they encountered after landing on Mars. We see their jubilation as they play wakeup songs for the rovers, watch as these brave robotic pioneers traverse a Martian landscape, and their responses of wonder when they discover that dust devils are responsible for cleaning the rover’s solar panels, that ultimately allow them to operate far longer than initially expected.
As the mission progresses, they begin to make bets on how long the rovers will last, but this excitement slowly diminishes over time as the rovers begin experiencing mechanical failures. Eventually, Spirit meets its end after becoming stuck in sand, and while Oppy continued for several more years, it eventually perishes when a global dust storm prevents the rover from receiving the adequate sunlight necessary to keep it powered. In the end, when the reality hits that Oppy won’t be phoning home, some of the team tearfully describe the experience as like losing a loved one.
Good Night Oppy isn’t just about examining the exploration of other planets, but the exploration of the unbreakable bond between humans and our robotic counterparts, the latter of which are responsible for doing the exploring themselves. It’s a beautiful and heartwarming story of adversity, excitement, and loss. If you want to know what it’s like to work on a NASA mission with all the emotional ups and downs, watch Good Night Oppy on Amazon Video.
Exoplanets have become quite the sensation over the last decade-plus, with scientists confirming new exoplanets on a regular basis thanks to NASA’s Kepler and TESS missions, along with the James Webb Space Telescope recently examining exoplanet atmospheres, as well. It’s because of these discoveries that exoplanet science has turned into an exciting field of intrigue and wonder, but do the very same scientists who study these wonderful and mysterious worlds have their own favorite exoplanets? As it turns out, four such exoplanet scientists, sometimes referred to as “exoplaneteers”, were kind enough to share their favorites with Universe Today!
“My favorite is actually a system of exoplanets: the HR 8799 system,” said Dr. Theodora Karalidi, who is an assistant professor in the Department of Physics at the University of Central Florida. “The system has four planets that are giant and are still warm enough and far enough from their parent star so that we can see them with our telescopes. Seeing the planets rotating around their parent star is fascinating.”
HR 8799 is located approximately 130 light-years from Earth within the constellation Pegasus, whose planets—HR 8799 b, HR 8799 c, HR 8799 d, and HR 8799 e—were discovered using the direct imaging method, with b, c, and d being discovered in 2008, and e being discovered in 2010. All four exoplanets range from 8 to 10 times as massive as Jupiter, and all orbit well beyond its parent star’s HZ.
Artist rendition of HR 8799 b observed from the surface of a potential nearby moon. (Credit: NASA/European Space Agency/G. Bacon (Space Telescope Science Institute)
“I love lots of exoplanets and am not good at choosing favorites, but I suppose I’d have to pick Kepler-9d because I discovered it!” Dr. Darin Ragozzine, who is an associate professor in the Department of Physics and Astronomy at Brigham Young University, proudly exclaimed. “The Kepler Team was working actively on Kepler-9, and I had the idea to check for additional signals and out popped Kepler-9d. It’s my only personal planet discovery, though I have been involved with many others!”
After its discovery using what’s known as the transit method in 2010, Dr. Ragozzine was also the lead author of a 2018 historical piece on the Kepler-9 system, which is located approximately 2,049 light-years from Earth. As stated, the exoplanet that Dr. Ragozzine discovered is Kepler-9d, which is hypothesized to be a rocky planet just over 3 times as massive as the Earth. While this sounds intriguing for the prospects for life, Kepler-9d orbits well inside the habitable zone (HZ) of its parent star, and far closer than Mercury with an orbital period of only 1.6 days.
“I love HD 20782 b,” said Dr. Stephen Kane, who is a Professor of Planetary Astrophysics with dual roles in the Department of Earth and Planetary Sciences and the Department of Physics and Astronomy at the University of California, Riverside. “It is the most eccentric known exoplanet (e = 0.97!!), and so is an incredible giant wrecking ball that gets so close to its star that they almost touch!”
HD 20782 b is known as a highly eccentric exoplanet that is located approximately 117 light-years from Earth, meaning its orbit is incredibly elongated and actually travels in and out of its star’s HZ during the course of one orbit. It was discovered in 2006 using the radial velocity method, is slightly more massive than Jupiter, and takes more than one and a half years to orbit its star. A short clip of HD 20782 b’s orbit was provided by Dr. Kane and can be found here.
The final favorite exoplanet in our journey isn’t a specific exoplanet or exoplanetary system, but a specific type of exoplanet known as pulsar planets, which as the name implies, are exoplanets orbiting pulsars, and are incredibly rare. These exoplanets are a favorite of Dr. Alex Wolszczan, who is an Evan Pugh University Professor in the Department of Astronomy and Astrophysics at Penn State University, saying they’re his favorite not just because he discovered them.
Artist rendition of the PSR B1257+12. (Credit: NASA/JPL-Caltech/R. Hurt)
“They are the first confirmed exoplanets, and that discovery carried with it the prediction that planets should be common around all kinds of stars, which is exactly what we have found out over the last 30 years,” explains Dr. Wolszczan.
The discovery Dr. Wolszczan refers to happened in 1992 with two exoplanets in a system known as PSR B1257+12 located approximately 1,950 light-years from Earth, and were found using the pulsar timing method, with a third exoplanet being confirmed in 1994. While this seems intriguing enough, pulsar planets would not be a good place to look for life due to the intense levels of radiation emanating from the pulsar itself.
What are your favorite exoplanets, exoplanetary systems, or types of exoplanets?
When it comes to “on the ground” exploration of Mars, rovers make pretty good advance scouts. From Pathfinder to Perseverance, we’ve watched as these semi-autonomous robots do what human explorers want to do in the future. Now, engineers are studying ways to expand rover exploration on Mars. One thing they’re thinking about: communication satellite constellations for Mars surface navigation.
The current generation of Mars rovers landed in easily accessible places. Other Martian regions, such as the poles, or Valles Marineris, remain pretty much untouched. That’s partly because they’re difficult to reach and their weather conditions present challenges. The poles hold a lot of clues to the Martian climate system. Although one cap is known to be mostly water ice, both caps could contain (or be hiding) additional water either in underground lakes or frozen beneath the caps. This is a commodity that any future Mars explorers will need to tap into for survival and other operations. All of these reasons make the polar regions a prime target for future rovers.
Chasma Boreale is a long, flat-floored valley that cuts deep into Mars’ north polar ice cap. Its walls rise about 1,400 meters (4,600 feet) above the floor. Where the edge of the ice cap has retreated, sheets of sand are emerging that accumulated during earlier ice-free climatic cycles. This scene combines images taken during the period from December 2002 to February 2005 by NASA’s Mars Odyssey orbiter. Surface features like this are interesting targets for future Mars rovers. Image Credit: NASA/JPL-Caltech/ASU
Today, orbiters around Mars do the heavy lifting of communications between Earth and the Red Planet. But future exploration requires more flexible communications systems, particularly if we’re going to study the polar regions. So, imagine this scenario: NASA or another agency wants to send a fleet of rovers to Mars’s polar caps. Distance complicates communications from the ground to the rovers for their every move. Light-travel times of many minutes could make it very hard to navigate in “real-time” situations. The solution is to deploy satellite constellations that can “see” the polar regions and help the rovers navigate more accurately.
Small Satellites to the Rescue
A team of engineers led by Ph.D. student Serena Molli at the Department of Mechanical and Aerospace Engineering at the Sapienza University of Rome did a concept study of small satellite (smallsat) constellations at Mars. Their objective is to design one that is almost completely autonomous and can handle the relative and absolute positioning of its nodes around the planet. The constellation should support navigation for other probes, such as objects in the Entry, Descent, and Landing (EDL) phase, as well as landers, rovers, or orbiters. Nodes would communicate with each other via an inter-satellite link (ISL) and with the rovers and other installations on the surface.
In an upcoming paper, Molli and the team outline models for two such constellations. They focus on systems that don’t need constant updates from Earth. Each uses five satellites to communicate with each other and the surface. Depending on their orbital configuration, they could give nearly constant coverage of the polar regions.
“We achieved excellent performance with this autonomous navigation system without the need for AI programming, Molli explained. “The onboard software relies on dedicated orbit determination theory and algorithms, adapted to face the challenge of the novel autonomous navigation system. However, the onboard orbit determination software may benefit from updates. The system allows for those. What we need is a sufficiently powerful onboard computer and periodic contacts to Earth, both for health checks of the system, improved orbit determination, and, if necessary, software upgrades.”
Navigating Mars
The team’s proposed navigation systems are based on smallsats currently in design at the Italian aerospace engineering group Argotec. They’re working on a proposed microsatellite-based “internet of the Moon” system called ANDROMEDA. The systems Molli’s team propose have the required ISL technology that fosters communication between satellite nodes. This was used previously for terrestrial and planetary geodesy, most notably with the GRACE and GRAIL missions.
Applying it to Mars requires a lot of data about the planet in order to make the system work efficiently. “In our work, we exploit the previous knowledge of the Martian gravitational field from missions such as MRO (Mars Reconnaissance Orbiter) and MGS (Mars Global Surveyor),” said Molli. “This allows the spacecraft of the constellation to determine its position autonomously or with a sporadic link with Earth, depending on the altitude of the orbits and consequently on the effects of the gravity gradients on the spacecraft dynamic.”
Small Satellites at other Worlds
The team points out that these smallsat constellations come with low development and launch costs and short development times. They also offer flexibility in mission implementation. That’s because multiple systems can be launched simultaneously with dedicated launches or as secondary payloads of larger missions. If this all pans out at Mars, it’s possible that similar satellite systems could be used on other worlds in the solar system. However, those come with great unknowns.
“There are several challenges to deploying this navigation system on other planets and moons,” said Molli. “The environmental conditions are quite different: radiation fields, a different thermal environment, etc. Therefore, the hardware must be adapted to cope with the moon’s environment. In addition, the knowledge of the gravity field and rotational state of those bodies may not be known at the required levels to perform precise positioning.”
The first test of such a system will begin at Mars as spacecraft teams plan polar missions. So, the development of small satellite constellations is crucial. Not only will they help in the exploration of Mars, but eventually could pave the way for similar constellations around worlds beyond the Red Planet.
For the first time, scientists have created a quantum computing experiment for studying the dynamics of wormholes — that is, shortcuts through spacetime that could get around relativity’s cosmic speed limits.
“We found a quantum system that exhibits key properties of a gravitational wormhole, yet is sufficiently small to implement on today’s quantum hardware,” Caltech physicist Maria Spiropulu said in a news release. Spiropulu, the Nature paper’s senior author, is the principal investigator for a federally funded research program known as Quantum Communication Channels for Fundamental Physics.
Don’t pack your bags for Alpha Centauri just yet: This wormhole simulation is nothing more than a simulation, analogous to a computer-generated black hole or supernova. And physicists still don’t see any conditions under which a traversable wormhole could actually be created. Someone would have to create negative energy first.
Columbia theoretical physicist Peter Woit warned against making too much of a to-do over the research.
“The claim that ‘Physicists Create a Wormhole’ is just complete bullshit, with the huge campaign to mislead the public about this a disgrace, highly unhelpful for the credibility of physics research in particular and science in general,” he wrote on his blog, which is called Not Even Wrong.
The main aim of the research was to shed light on a concept known as quantum gravity, which seeks to unify the theories of general relativity and quantum mechanics. Those two theories have done an excellent job of explaining how gravity works and how the subatomic world is structured, respectively, but they don’t match up well with each other.
One of the big questions focuses on whether wormhole teleportation might follow the principles that are behind quantum entanglement. That quantum phenomenon is better understood, and it’s even been demonstrated in the real world, thanks to Nobel-winning research: It involves linking subatomic particles or other quantum systems in a way that allows for what Albert Einstein called “spooky action at a distance.”
Spiropulu and her colleagues, including principal authors Daniel Jafferis and Alexander Zlokapa, created a computer model that applies the physics of quantum entanglement to wormhole dynamics. Their program was based on a theoretical framework known as the Sachdev-Ye-Kitaev model, or SYK.
The big challenge was that the program had to be executed on a quantum computer. Google’s Sycamore quantum processing chip was just powerful enough to take on the task, with an assist from conventional machine learning tools.
“We employed [machine] learning techniques to find and prepare a simple SYK-like quantum system that could be encoded in the current quantum architectures and that would preserve the gravitational properties,” Spiropulu said. “In other words, we simplified the microscopic description of the SYK quantum system and studied the resulting effective model that we found on the quantum processor.”
The researchers inserted a quantum bit, or qubit, of encoded information into one of two entangled systems — and then watched the information emerge from the other system. From their perspective, it was as if the qubit passed between black holes through a wormhole.
“It took a really long time to arrive at the results, and we surprised ourselves with the outcome,” said Caltech researcher Samantha Davis, one of the study’s co-authors.
The team found that the wormhole simulation allowed information to flow from one system to the other when the computerized equivalent of negative energy was applied, but not when positive energy was applied instead. That matches what theorists would expect from a real-world wormhole.
As quantum circuits become more complex, the researchers aim to conduct higher-fidelity simulations of wormhole behavior — which could lead to new twists in fundamental theories.
“The relationship between quantum entanglement, spacetime, and quantum gravity is one of the most important questions in fundamental physics and an active area of theoretical research,” Spiropulu said. “We are excited to take this small step toward testing these ideas on quantum hardware and will keep going.”
In addition to Jafferis, Zlokapa, Spiropulu and Davis, the authors of the Nature paper, titled “Traversable Wormhole Dynamics on a Quantum Processor,” include Joseph Lykken, David Kolchmeyer, Nikolai Lauk and Hartmut Neven.
A sleeping giant of a volcano woke up this past week on the Big Island of Hawaii. Mauna Loa, which last erupted in the early 1980s, has been rattling the island with earthquakes for weeks. Finally, on November 27th, the mountain opened up. Not only did residents see this eruption, but NASA and NOAA satellites captured an infrared view of it.
The bright glow of the eruption was visible to NASA and NOAA satellites orbiting hundreds of miles above the surface. The image above was acquired at 2:25 a.m. local time (12:25 UTC) on November 28 by the “day-night band” of the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-NASA Suomi NPP satellite. For comparison, the image above shows the same area on October 29, 2022, before the eruption had begun.
The first space-based images show the mountain as it appeared on November 28th. By that time, lava flows had started and stopped in the mountain’s caldera, and fissures and vents had opened up. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-NASA Suomi NPP satellite acquired the first day-night band images (above) at 2:25 a.m. local time (12:25 UTC) on November 28th.
Cloud cover scattered light from the eruption and urban areas and made it look more diffuse. “It also looks like the lava emitted by the eruption was so bright that the sensor was saturated, producing a ‘post-saturation recovery streak’ along the VIIRS scan to the southeast,” noted Simon Carn, a volcanologist at Michigan Tech. “These streaks are only seen over very intense sources of visible radiation.”
The Big Island has several active volcanoes and Mauna Loa is the biggest. It has erupted off and on for thousands of years. Eruptions in the early 1980s sent flows close to the city of Hilo and were visible from atop Mauna Kea. The mountain is a typical shield volcano and rises about four kilometers above sea level. It’s the largest active volcano in the world and covers half the Big Island.
Monitoring Mauna Loa From Space
Geologists constantly study Mauna Loa and other volcanic activity such as the ongoing Kilauea and Pu’u O’o eruptions. Space-based observations provide additional information about how these eruptions affect the atmosphere. “The eruption is effusive rather than explosive, although its initial phase overnight on November 28 was quite energetic and injected some sulfur dioxide to high altitudes, possibly all the way to the tropopause,” said Carn. “That is unusual for this type of eruption.”
In addition to the NASA-NOAA observations, the European Space Agency’s Sentinel-5P satellite detected sulfur dioxide (SO2) from the eruption. Its primary atmospheric sensing instrument is the Tropospheric Monitoring Instrument (TROPOMI) sensor. NASA operates the Ozone Monitoring Instrument (OMI) on the Aura satellite. Both instruments measured the SO2 levels at about 0.2 teragrams. “These sensors measured within 5 minutes of each other in early afternoon and are in excellent agreement despite having different algorithms,” said Nickolay Krotkov, an atmospheric scientist at NASA’s Goddard Space Flight Center. During Mauna Loa’s 1984 eruption, it emitted about 1.2 teragrams of SO2 over a period of three weeks.
Mauna Loa’s Ongoing Eruption
The ground-based images of the current eruption show lava fountains reaching up nearly 200 feet, with lava flows heading out of at least two active fissures. Mauna Loa lies along a feature called the Northeast Rift Zone, which is the most active area on the island. Kilauea and the Pu’u O’o eruption areas are also located along the rift.
At the moment, the flows have not threatened homes, but they should reach the Saddle Road which cuts through the island in a day or two. Geologists at the USGS Hawaiian Volcano Observatory (HVO) continue to monitor the flow as well as earthquake activity. Tremors are continuing, which means that the eruption is likely to go on for some time. Prior to the first eruption, an earthquake swarm served as a wake-up call that something was about to happen.
This image taken from the International Gemini Observatory site on Mauna Kea shows the flow from nearby Mauna Loa. It also captured a rare “lava light pillar” caused by a juxtaposition of light from the eruption, high clouds, and cold temperatures that freeze water crystals in the air. Courtesy International Gemini Observatory/NOIRLab/NSF/AURA
The Big Island is home to a number of observatories at the summit of Mauna Kea. So far, the eruption has not affected their operations. However, the National Solar Observatory’s Mauna Loa GONG facility lost power as the eruptions began, and lava flows blocked the access road. NSO has shut it down temporarily. GONG is the Global Oscillations Network Group and focuses on the internal structure of the Sun using helioseismology. The eruption also affected access to NOAA’s Mauna Loa Observatory (part of the Global Monitoring Laboratory). NOAA shut it down and suspended its data-gathering operations.
Looking Back Through Time
The Hawaiian islands are part of a chain of Pacific volcanoes created as a tectonic plate moved over a hot spot. They began forming some 70 million years ago, and the Big Island contains the youngest of them, called Kama‘ehuakanaloa (formerly called Loihi). It’s forming underwater off the southeast coast of the Big Island. Currently, six volcanoes are active in the whole island chain, including Haleakala on the island of Maui.
For the current eruption, personnel with NASA’s Disasters program are actively monitoring the eruption and are in the process of providing data and imagery to other agencies, including USGS HVO and FEMA. Space-based sensors can monitor the emissions from the volcano and share that data with affected communities on the island.
NASA just released a new supercut of high-resolution video from the Artemis I launch on November 16, 2022. Much of the footage is from cameras attached to the rocket itself, allowing everyone to ride along from engine ignition to the separation of the Orion capsule as it begins its journey to the Moon.
A few highlights:
We first see the rocket on the pad, with NASA pointing out various parts of the Space Launch System. The music swells, anticipation builds
Then the big thrill: seeing the launch from various vantage points, including the rocket itself. Billed as the most powerful rocket in the world, SLS rocks and shakes the ground and the cameras. The killer view comes at about 18 second in: the same view of the liftoff as those iconic Apollo Saturn V launches, seeing the rocket rise from a camera on the side of the gantry.
But nothing beats watching the rocketcam footage of the launchpad receding away as the rocket rises into the heavens.
At about 40 seconds in, the quarter Moon can be seen from the perspective of the rocket – NASA highlights it for you in case you missed it!
At about 50 seconds comes the separation of the boosters, which is so very reminiscent of the space shuttle booster seps, as the two outboard solid rocket boosters are shuttle-derived. The music here is perfect.
At 1:06, the European Service Module panels are jettisoned, and how quickly they tumble away is almost scary.
Through the rest of the stage separations, be on the lookout for the Moon making cameos in several shots.
Finally, we see Orion and the European Service Module heading away.
While the launch footage is stunning, the current views of the Moon and Earth together from Orion as it travels out past the Moon on its distant retrograde orbit have been incredible. NASA now has high-resolution images and video from Monday’s pinnacle, when Orion was more than 268,500 miles (432,000 km) away from Earth, the farthest a “Command-type Module” has ever been from our planet (the Apollo 10 lunar module, nicknamed Snoopy –the Command Module was Charlie Brown — might be still traveling in space at a greater distance from Earth in a heliocentric orbit.)
On flight day 13, Orion reached its maximum distance from Earth during the Artemis I mission when it was 268,563 miles away from our home planet.Credit: NASA.
If you like shiny things, some of the most gorgeous objects in space are globular clusters, with their bright, densely packed collections of gleaming stars. And if you like globular clusters, you’re in luck: two different Hubble images of globular clusters were featured this week by NASA and ESA.
The Hubble telescope basically revolutionized the study of globular clusters, as with ground-based telescopes, it is almost impossible to distinguish the individual stars in globular clusters because they are so densely packed. Hubble been used to study what kind of stars globular clusters are made up of, how they evolve and the role of gravity in these dense systems.
The first image from Hubble, featured by NASA, is this beautiful glittering gathering of stars (above) called Pismis 26, a globular star cluster located about 23,000 light-years away. The cluster is named for Armenian astronomer Paris Pismis who first discovered the cluster in 1959 at the Tonantzintla Observatory in Mexico; and this cluster has the dual name Tonantzintla 2.
Usually, globular clusters consist of stars that are quite old (red and dead), with some of the oldest stars in the Universe. In fact, our resident astrophysicist, Paul Sutter has called globular clusters the “retirement homes for the galaxy.”
Astronomers estimate the age of this particular cluster to be 12 billion years old.
The stars in globular clusters are held together by mutual gravitational attraction. Globular clusters cover a relatively small region in space, with most no more than a couple dozen parsecs across. But each one contains hundreds of thousands, and sometimes millions, of stars. Sutter says that puts the average distance between stars at about 1 light-year, but in their cores the stars pack together over a thousand times more tightly than in our own neighborhood.
Hubble captured this star-studded imageof Ruprecht 106. Credit: ESA/Hubble & NASA, A. Dotter
The second globular cluster image, this one featured by ESA, shows Ruprecht 106. Hubble captured this star-studded image with the Advanced Camera for Surveys (ACS), which was installed on the space telescope by astronauts during a servicing mission in 2002.
Ruprecht 106 contains a bit of a mystery. Even though most of the constituent stars in globular clusters stars likely formed at approximately the same time and location, research with Hubble has shown that is not always true. It turns out that almost all globular clusters contain groups of stars with distinct chemical compositions, which means those groups of stars within the clusters have very slightly different ages or compositions from the rest of the cluster.
However, a handful of globular clusters do not possess these multiple populations of stars, and Ruprecht 106 is a member of that group. Astronomers will likely use the James Webb Space Telescope to study enigmatic clusters like Ruprecht 106 to learn more about the stars and their life cycles.
At least once, you’ve looked up at the night sky and asked the same longstanding question we’ve all asked at least once, “Are we alone?” With all those points of light out there, we can’t be the only intelligent beings in the universe, right? There must be at least one technological civilization aside from us in the great vastness that we call the cosmos.
The astronomer Carl Sagan was famous for his quote in his book and film, Contact, “The universe is a pretty big place. If it’s just us, seems like an awful waste of space.” Yet, for some of us, it’s incredibly hard to fathom that it’s just us in the vast unknown full of so many stars and a growing list of exoplanets being discovered on a near daily basis. However, despite all our endless searching, we’ve so far found no one.
So, what if you found out one day that it is just us? What if in the great cosmos, out of all the planets, stars, and galaxies, we are truly alone? How would you look at the universe? At humanity? At yourself? Would you believe it? Would you stop looking up at the stars entirely? Would you feel disappointed that we’re alone, that we’re truly it, or would you feel a sense of optimism knowing that the longstanding question has finally been answered once and for all?
The film, Ad Astra, showed Roy McBride played by Brad Pitt searching for his father, H. Clifford McBride, played by Tommy Lee Jones, the latter of whom was on a mission at Neptune searching for intelligent life outside of the solar system and in the rest of the universe. In the end, Brad finds his dad alone on the space station orbiting Neptune, only to discover that his father didn’t find anything. No intelligent life anywhere in the universe. He discovered that we’re it.
Throughout the film, Roy was struggling to reconnect with his father and his father was struggling to connect with the universe, and this only serves as an appropriate analogy for our own pursuit of answering the longstanding question. At one point when he’s on Mars, Roy asks himself regarding his father, “I don’t know if I hope to find him or be free of him.” In our own pursuit of trying to answer the longstanding question, what if it’s not that we’re hoping to find intelligent life, but that we’re trying to be free of knowing if there’s intelligent life?
In the end, when Clifford disappointingly tells his son that there’s no one else in the universe and that he’s failed in his mission, Roy doesn’t respond with anger or disappointment, but with optimism, telling his estranged father with a smile, “Dad, you haven’t. Now we know. We’re all we’ve got.” In that moment, it was as if the literal weight of the universe was lifted from Roy’s shoulders knowing that we’re it. After Roy unfortunately leaves his father to die in the void, Roy notes that he can’t wait for the day that his solitude ends, and the film ends with him reconnecting with his wife.
While Roy felt almost relieved to finally know the answer to the longstanding question, it’s important to ask if you’d feel the same way? Because, despite all the hopes of us finding intelligent life elsewhere in the universe, we must face the real possibility that we’re it. That’s it just us, and where do we go from here?
New technologies bring new astronomical insights, which is especially satisfying when they help answer debates that have been ongoing for decades. One of those debates is why exactly the plasma emitted from pulsars “collimates” or is brought together in a narrow beam. While it doesn’t provide a definitive answer to that question, a new paper from an international group of scientists points to a potential solution, but it will require even more advanced technologies.
The paper takes a look at the first quasar ever found. Now known as 3C 273, it was discovered back in 1959 and is several billion light years away from Earth in the direction of the constellation Virgo. It is likely the farthest object amateur astronomers can see if they use a standard telescope. However, that is relatively close for a quasar, so it has been the focal point of dozens of studies regarding these massively powerful objects since its discovery.
One feature that 3C 273 and many other quasars share is that they emit a jet of plasmatized matter out of their core at close to the speed of light. This plasma jet typically extends far past the quasar, a type of supermassive black hole, that created it. So far, in fact, that it typically extends past the bounds of the galaxy surrounding its parent black hole and begins to contribute matter to the intergalactic medium, thereby shaping the formation of new galaxies.
UT video describing a quasar.
During its formation, the beam is brought together, which allows it to travel much further than would otherwise be possible. This would be analogous to a laser, which essentially does the same thing for light by bringing it together into a coherent state and allowing it to travel far distances without disruption.
Scientists have puzzled for years about what brings about this collimation that allows the plasma to travel as far as it does. However, they could never get a good look inside the base of the beam to understand the physics there. These quasars are billions of light years away, so that isn’t that surprising.
But humans are ingenious problem solvers, and a team led by MIT devised a way to leverage some of the best telescopes in the world and make them even more capable than they would be separately. Utilizing a technique called very long baseline interferometry (VLBI), researchers were able to link up six different sets of telescopes, including ALMA, one of the world’s most powerful and a key contributor to this research.
UT video discussing quasar “dust”
Its 66 telescopes, linked with others using the VLBI process, created what is effectively the world’s best interferometer. And the images it, along with its interconnected partners, returned were stunning (see banner picture). However, while these were the highest resolution images of a quasar plasma jet yet, they still weren’t enough to determine what actual physical process was going on.
That next step might require another amazing piece of new tech. Quasars are, after all, black holes, and what better instrument to check out what is going on near a black hole than the Event Horizon Telescope, which famously provided the data to directly image one back in 2017. It measures at higher frequencies than ALMA, allowing researchers to look more closely at the C3 273 jet and those that are farther away, which could prove whether C3 273 is unique or typical of its type.
Coordinating that will take some more doing, but, as one of the paper’s author’s put it in a press release, they already have plenty of “homework” to do with the data collected so far. More technological advances are sure to bring on more spectacular images and maybe a definitive answer to this long-standing question – someday, anyway.
Lead Image:
New detailed images of quasar 3C 273 using the VLBI technique, ranging from the most detailed (far left) to an image from Hubble (far right).
Credit – Hiroki Okino and Kazunori Akiyama; GMVA+ALMA and HSA images: Okino et al.; HST Image: ESA/Hubble & NASA
According to the most widely-accepted theory, planetary systems form from large clouds of dust and gas that form disks around young stars. Over time, these disks accrete to create planets of varying size, composition, and distance from their parent star. In the past few decades, observations in the mid- and far-infrared wavelengths have led to the discovery of debris disks around young stars (less than 100 million years old). This has allowed astronomers to study planetary systems in their early history, providing new insight into how systems form and evolve.
This includes the SpHere INfrared survey for Exoplanets (SHINE) consortium, an international team of astronomers dedicated to studying star systems in formation. Using the ESO’s Very Large Telescope (VLT), the SHINE collaboration recently observed and characterized the debris disk of a nearby star (HD 114082) in visible and infrared wavelengths. Combined with data from NASA’s Transiting Exoplanet Space Satellite (TESS), they were able to directly image a gas giant many times the size of Jupiter (a “Super-Jupiter”) embedded within the disk.
The SPHERE instrument shortly after it was installed on ESO’s VLT Unit Telescope 3. Credit: ESO/J. Girard
As they state in their paper, the team relied on the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on the VLT to take optical and near-IR images of HD 114082, an F-type star (a yellow-white dwarf) located in the Scorpius–Centaurus association – a stellar cluster located about 310 light-years from Earth. Like the 500 stars surveyed by the SHINE team, HD 114082 is a young star surrounded by a protoplanetary debris disk (from which planets form). Observations of these disks in recent decades have shown that they are an integral part of planetary systems:
As Dr. Engler told Universe Today via email, these surveys date back to 1983 and the discovery of the first disk around Vega. Since then, dozens of surveys have been performed in infrared wavelengths and scattered light using space-based telescopes like the Herschel Space Observatory and the venerable Hubble and ground-based telescopes like the Atacama Large Millimeter-submillimeter Array (ALMA), the Gemini Planet Imager (GMI), and SPHERE/VLT. As she explained:
“These studies provided valuable information about the formation and evolution of planetary systems since planets are formed from, reside in, and interact with the dust material. Young debris disks (in the first hundred million years) trace the processes of terrestrial planet formation, and thus studying them helps us to understand the dynamical interaction and evolution of terrestrial planets, in particular the Earth, in the young Solar system.”
Using Sphere, Engler and her team observed HD 114082 in the optical and near-infrared using the angular differential imaging (ADI) and polarimetric differential imaging (PDI) techniques. The former consists of acquiring high-contrast images from an altitude-azimuth telescope while the instrument rotator is off, allowing the instrument and telescope optics to remain aligned and the field of view to rotate relative to the instrument. The latter involves combining different incident polarizations of light and measuring the specific polarization components transmitted or scattered by the object.
Artist’s impression of circumstellar disk of debris around a distant star. Credit: NASA/JPL
Both techniques have been used extensively in the study of circumstellar debris disks and (according to Engler) revealed some interesting things about HD 114082:
“Our images revealed a bright planetesimal belt at a distance of 35 AU from the host star, very similar to the Kuiper belt in the Solar system. The debris belt is inclined at 83° and has a wide inner cavity. The dust particles, which we trace in this observation, have sizes around 5 microns and a relatively high scattering albedo of 0.65; this means they scatter nearly two-thirds of incoming stellar radiation and absorb only one third of it. The scattered light has a relatively low degree of linear polarization with a maximum of 17% which, however, is comparable with the polarization values for cometary dust in the Solar system.”
The team also consulted data from TESS to confirm the presence of a super-Jupiter companion, which was first detected by the observatory in 2021 using transit photometry (aka. the Transit Method). Consistent with this data, Engler and her colleagues confirmed that the planet orbits its parent star at approximately 0.7 AU – about the same distance between Venus and the Sun. Recent observations based on radial velocity measurements confirmed this planet and produced mass estimates about eight times that of Jupiter.
“HD 114082 provides an example for young planetary systems, where the presence of planetary companions to the host star has been inferred from the discovery of a debris disk,” Engler added. “This confirms the theoretical considerations of debris systems as signposts for young planets. Studying this and other similar planetary systems will allow [astronomers] to establish a link between the properties of extrasolar Kuiper belts and planets residing within them.”
Artist’s impression of the super-hot Super-Jupiter WASP-79b located 780 light-years away in the constellation Eridanus. Credit: NASA
The implications of this study go beyond the study of young stars and planetary systems that are still in formation. They are also significant for studying our Solar System, which has some interesting parallels to these protoplanetary environments. Said Engler:
“The direct imaging studies of the last decade show that the circumstellar material in many debris disks is confined to ring-like structures, similar to two debris belts in the Solar system: the Edgeworth-Kuiper belt and the main asteroid belt. The cavities inside the extrasolar Kuiper belts are curved by unseen planets, which leave their imprints in the debris dust distribution, such as warps, clumps and belt eccentricities.”
Lastly, this study demonstrates the growing use and effectiveness of direct imaging studies, which are possible thanks to improved instruments, imaging capability, and data-sharing methods. In the near future, next-generation instruments will allow for even more accurate and detailed direct imagining studies. These include space-based observatories like the JWST and the Nancy Grace Roman Space Telescope and ground-based telescopes like the Extremely Large Telescope (ELT), the Giant Magellan Telescope, and the Thirty Meter Telescope (TMT).
By studying the geometry and asymmetric features in debris disks, astronomers can predict the location and masses of planets that are not yet detectable with current instruments. “Direct imaging makes it possible to study the scattering properties of dust particles around distant stars,” Engler added. “These properties contain information about particle composition, shape, and size, and thus we can gain insights into the composition of the building blocks of exoplanets.”
A team of astronomers has caught glimpses of gas giants forming around a very young star.
The nascent giants are having a chilling effect on their potential siblings.
Planet formation takes place inside an almost impenetrable veil of dust. As our telescopes and instruments become more capable, we’re getting better looks at the process. Much of the detail is still hidden, but researchers at the RIKEN Star and Planet Formation Laboratory are getting glimpses of three gas giants forming around a protostar about 450 light years away.
Many Universe Today readers know the basics of planet formation. It starts with a young star forming inside a molecular cloud and a rotating disk of gas and dust forming around the star. Dust grains in the disk begin to clump together, and larger rocks and boulders form. These boulders become larger and larger in a chaotic process of serial collisions. Over time—millions of years—planetesimals form. The chaotic collisions continue until a protoplanet forms. More and more material collects as the protoplanet becomes more massive.
That rough outline describes how rocky planets form, and a similar process explains how gas giants form. Rocky material forms the core of gas giants, and they accrue more and more gas rather than rock. Eventually, they have deep, massive atmospheres of gas. But this model is informed mostly by theory, not observation. That’s because it’s very difficult to see inside the disks around young stars. Young protostars aren’t energetic enough to clear out the shroud of gas and dust that cloaks them.
Optical light is no use when trying to observe planets forming inside these shrouds. Astronomers rely on wavelengths of light in between infrared and radio waves to examine events inside the thick gas and dust around protostars. This is called millimetre and sub-millimetre radiation, and a team of astronomers put it to good use when they studied a well-known protostar in the Taurus Molecular Cloud, a nearby large star-forming region.
The protostar is called L1527, and the James Webb Space Telescope recently imaged it as part of a separate study. The star is very young, only about 100,000 years old. The star isn’t directly visible due to the thick circumstellar disk surrounding it.
The James Webb Space Telescope revealed features of the protostar L1527 with its Near Infrared Camera (NIRCam), providing insight into the formation of a new star. The disk in the new study is the small dark band in the center of the huge hourglass shape. This new study is based on ALMA and JVLA observations of the same object. Image Credit: NASA, ESA, CSA, and STScI, J. DePasquale (STScI), CC BY-SA 3.0 IGO
In a new study, a team of researchers at RIKEN used data from the Atacama Large Millimetre/sub-millimetre Array (ALMA) and the Jansky Very Large Array (JVLA) to probe the obscuring disk. The formation of planets is one of the foundational aspects of astronomy and has long been hidden from view and only theorized about. Scientists at RIKEN are bringing some of the processes into view.
The disk around L1527 is 80 to 100 times wider than the distance between Earth and the Sun, called an astronomical unit (AU). For comparison, Neptune is 30 AU from the Sun. (The inner main region of our Solar System’s Kuiper Belt ends at about 50 AU, and a second region extends as far as 1,000 AU.)
The disk is unstable, and a part of it appears to be collapsing. The collapsing region is about 20 AU from the protostar, and previous observations showed several clumps, which astronomers interpret as forming planets. This new study contains further observations of the disk and its clumps, including temperatures, and is titled “Formation of Dust Clumps with Sub-Jupiter Mass and Cold Shadowed Region in Gravitationally Unstable Disk around Class 0/I Protostar in L1527 IRS.” It’s published in The Astrophysical Journal, and the lead author is Satoshi Ohashi, a researcher at RIKEN.
“These clumps may be the precursors of gas giant planets since they are massive and dense,” Ohashi said in a press release. Since the protostar is only 100,000 years old, the observations suggest that planetary formation can begin very early in a circumstellar disk.
These images from the study show the dust continuum around L1527 in different ALMA bands. They show the size in AU and the temperature in Kelvin. The disk is viewed nearly edge-on and is elongated in the north-south direction. Image Credit: Ohashi et al. 2022.
The team also measured the temperature in the disk, which is lower further from the young star. That’s to be expected. But the surprising result is what happens in the shadows of the baby gas giants.
In the inner region of the young solar system, close to the star, the temperature is ~193 degrees Celsius, which is warm in astronomical terms. When the team measured the temperature further out, on the far side of the clumps, the temperature was significantly lower at about –263 degrees Celsius. That’s very cold, only 10 degrees above absolute zero.
This image from the study shows the three clumps in the disk, labelled N, C, and S. Previous research found the same objects but classified them as ring or spiral structures in the disk. Image Credit: Ohashi et al. 2022.
That’s a sharp drop and can’t be explained by distance alone, according to the researchers. It implies that the clumps are shading the regions beyond them and affecting what types of objects can form out there. Lead author Ohashi says the temperature drop can affect the composition of objects that form in the outer disk beyond the nascent gas giants.
Dust and gas temperatures are critical aspects of planetary formation. It’s strongly related to a solar system’s frost line, a demarcation between the inner system where terrestrial planets form and the outer system where volatiles like methane, ammonia, and carbon dioxide turn to solids. A solar system’s frost line changes over time. It moves outward as the star becomes more energetic and as the gas and dust clear away, so the formation frost line and the current frost line can be different. In our Solar System, the line has migrated outward since its formation, but in a young system like L1527, the frost line won’t have shifted much.
If the baby gas giants are casting a shadow on regions beyond them, then it’s reasonable to think that different volatiles will condense there compared to unshadowed regions, just as they do beyond the frost line. As a result, planetary atmospheres could be different in shadowed regions, just as if they were on different sides of the frost line.
The observed clumps and the drop in temperatures aren’t the only indications that planets are forming. A 2019 study found different orbital planes between the inner and outer parts of the disk. The outer parts are misaligned with the central star’s equatorial plane. What causes the misalignment?
Previous research showed that gas giants could be causing it via gravitational scattering, or companion stars or even stellar fly-bys could be causing it. But those conclusions came from research into young disks in general, not specifically L1527. This new study refutes those causes and strongly suggests nascent gas planets are the culprit while still acknowledging the ongoing debate.
The researchers concluded that gravitational stability is creating the clumps. The gravitational instability could be caused by spiral arms or by fragmentation of the disk. Other studies have shown that spiral arms can cause instability that leads to clumps. “Spiral arms are commonly observed in gravitationally unstable disks,” the authors write.”We investigated whether spiral arms can be observed as clumps in an edge-on disk, similar to the VLA clumps in the L1527 disk.”
They produced a model of spiral arms that could create the clumps and an edge-on simulated view of the same.
This figure from the study shows the spiral arm model the researchers created to explain the clumps and a simulated edge-on view of it. Image Credit: Ohashi et al. 2022.
Other researchers have investigated the disks around young protostars with ALMA, and this isn’t the first time researchers have found cooler, shadowed regions in their disks. “These results suggest that the shadowing effect may be a common possible structure in the disks as well as the envelopes,” the authors write in their paper.
There’s another possible future where these clumps never become planets. Instead, they could be drawn to the star and accreted, never to become planets at all. “Rather than planet formation, it may also be possible for the VLA clumps to accrete to the central star and cause an accretion burst, such as in the case of FU Orionis,” they write.
FU Orionis is a young stellar object that undergoes accretion outbursts at a rate that increases over a period from several decades to 100 years. The authors found that the clumps around L1527 are sufficiently massive to cause similar outbursts. “The masses of the VLA clumps are sufficient to increase the accretion rate, should these clumps accrete to the central star via migration,” they write. “Thus, the VLA clumps might be the origin of future accretion bursts.”
The authors lean towards the clumps being young gas giants, though they do have one reservation. At the end of their paper, they clearly state a caveat for their conclusions. It’s based on different models for dust surface density and dust opacity, which is an important building block of their conclusions. Studies like these rely on models developed by other researchers, and over time these models become better and better and constrain results more accurately. There are models on top of models.
They acknowledge that the dust model they used isn’t the only model. “If we apply these opacity models, it is only possible for the disk to be gravitationally stable with Q > 2.0 when the dust grains are larger,” they explain. “Although we have suggested that gravitational instability is the likely origin of the substructure <the clumps>, other mechanisms may have created the shadowing effect at r ~ 20 au.”
(Q is short for the Toomre Q parameter – Index. It’s a value that reveals the stability of differentially rotating disks and takes into account thermal pressure, radial velocity, and other factors. It’s constructed so that Q < 1 implies instability.)
The only way to determine the nature of the clumps more accurately is to obtain higher-resolution observations. “Further observations at higher spatial resolution and greater sensitivity are needed to confirm the origin of the substructures,” the authors explain.
In general, the study shows that protostars this young have disks massive enough to generate the gravitational instabilities that lead to planetary formation. “Thus, we suggest that Class 0/I disks can be sufficiently massive to be gravitationally unstable, which might be the origin of gas giant planets in a 20 au radius.”
What effect will these young gas giants have on future planet formation inside their shadows? Can they lower the temperature enough to determine the types of planets that form beyond them?
Jupiter and Saturn are both gas giants. When they were first forming, did they cast shadows that influenced how other planets formed? Image Credit: (L) NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill. (R) NASA, ESA, A. Simon (GSFC), M.H. Wong (University of California, Berkeley) and the OPAL Team
This study is like looking back in time to when our own Solar System formed. Jupiter and Saturn are both gas giants, while the two planets beyond them are not; they’re ice giants. Could young Jupiter and young Saturn have formed first, casting cool shadows that influenced the formation of the icy giants Uranus and Neptune?
Uranus and Neptune are both ice-giant planets. Could Jupiter and Saturn have affected their formation by casting shadows? Image Credits: (L) By NASA – https://ift.tt/su1A3Xj, Public Domain, https://ift.tt/2asH49o. (R) By Justin Cowart – https://ift.tt/y41MCTa, Public Domain, https://ift.tt/fz1bguX
“Our Solar System is also suggested to have formed a shadowed region in the past,” says Ohashi.
Researchers from Ohio State University have come up with a novel method to detect dark matter, based on existing meteor-detecting technology. By using ground-based radar to search for ionization trails, similar to those produced by meteors as they streak through the air, they hope to use the Earth’s atmosphere as a super-sized particle detector. The results of experiments using this technique would help researchers to narrow down the range of possible characteristics of dark matter particles.
The existence of dark matter is pretty well accepted by mainstream physicists. Ever since Lord Kelvin calculated that the mass of all the stars in the Milky Way galaxy was much less than the mass of the galaxy itself, we’ve known that much of the matter in the Universe is not visible to us. As technology has improved, we’ve learned how to detect things that were hidden from visible-light telescopes, but we still can’t account for all the missing matter. We call this missing material “dark matter”, and current estimates say that a full 85% of the mass of the universe is made from dark matter. Most physicists now believe that dark matter is made of an as-yet undiscovered particle.
Dr John Beacom of Ohio State University has proposed an experiment to determine the characteristics of this particle. He wants to adapt the radar technology used to detect and measure meteors as they streak through the atmosphere, using it to look for similar streaks that could indicate a dark matter particle colliding with air molecules. This technique uses radar stations on the ground to detect and measure trails of ionization through the upper atmosphere.
When a meteoroid enters the Earth’s atmosphere, it rams through the air faster than the air itself can move out of the way. This causes the air in front of the meteor to compress and become so hot that it ionizes – individual air molecules collide with each other so hard that they lose electrons. Ionized air not only glows, but it is opaque to radio waves. This causes radar signals to reflect back to earth, allowing meteors to be detected even during the day.
Theoretical physicists have calculated the physical characteristics that dark matter particles could possibly have. Unfortunately, since most of what we know about these particles is that they interact weakly with normal matter (we have so far only detected it at all by it’s gravitational influence), this leaves a wide range of possibilities. Dr Beacom points out that if dark matter particles fall within the larger, heavier end of the range of possibilities, then they would interact with “normal” matter more easily, although these interactions would still be rare.
“One of the reasons dark matter is so hard to detect could be because the particles are so massive,” Beacom said. “If the dark-matter mass is small, then the particles are common, but if the mass is large, the particles are rare.”
If these particles are large, then traditional detectors on the ground might never see them, because the particles are being absorbed by Earth’s atmosphere. But if this happens, then they should have enough energy to produce an ionization trail, similar to what we see with meteors. Meteor-detecting radar installations could therefore be adapted to also search for dark matter particles — essentially turning the entire Earth’s atmosphere into one giant particle detector.
The existence of dark matter was first predicted in 1884 by Lord Kelvin. He had calculated the mass of the Milky Way galaxy, based on the speed at which it rotates, and found that it must be significantly heavier than the combined visible stars. He theorized that most of the galaxy’s mass must be made of “dark” material – things which could not be seen with the telescopes of the time. However, most scientists assumed this meant that there would be a lot of cold gas, dust, exoplanets, and other objects that do not shine with their own light. The phrase “dark matter” was first used to describe these things in a French paper in 1906.
Hubble Space Telescope offers a cosmic cobweb of galaxies and invisible dark matter in the cluster Abell 611. Credit: ESA/Hubble, NASA, P. Kelly, M. Postman, J. Richard, S. Allen
Many other lines of evidence have appeared since then: Fritz Zwicky noticed in the 1930s that galaxies in the Coma cluster move as if the entire cluster was 400 times heavier than the total mass of all its visible members. Early radio astronomers in the 1960s saw that spiral galaxies spin way too fast around their edges – they should simply fly apart, unless there was an additional source of gravity to hold them together. Vera Rubin, Kent Ford, and Ken Freeman made the same discovery shortly after, using newly improved spectrographs to measure the rotational curve of galaxies in visible light. And a series of deep cosmological observations in the 1980s detected gravitational lensing and anisotropies in the Cosmic Microwave Background Radiation (CMBR), adding to the evidence for the existence of dark matter.
It’s worth noting that nobody yet knows whether dark matter particles will actually produce these ionization trails. Detectors built using this technique may never see anything at all. But either result, detections or no detections, would be a good thing. One way or another, an experiment using this detection technique will answer the question: “Are dark matter particles large heavy, and rare? Or are they small, light, and numerous?”
There’s a little galaxy in the Milky Way’s cosmic neighborhood called Leo 1. It’s a dwarf spheroidal that lies less than a million light-years away from us. Surprisingly, it has a supermassive black hole about the same mass as Sagittarius A* in our galaxy. That’s unusual in several ways, and astronomers want to know more about it.
The name of the central supermassive black hole is Leo 1*. The galaxy itself is hard to observe, due to its proximity to the bright star Regulus. Leo 1* is challenging to spot, too. It’s just not bright, even though it is gobbling up material to stay alive. So, astronomers at the Center for Astrophysics | Harvard & Smithsonian, are developing a method to study it and figure out how this monster supermassive black hole could exist in such a small galaxy.
“Black holes are very elusive objects, and sometimes they enjoy playing hide-and-seek with us,” said Fabio Pacucci, lead author of a study published this week. “Rays of light cannot escape their event horizons, but the environment around them can be extremely bright — if enough material falls into their gravitational well. But if a black hole is not accreting mass, instead, it emits no light and becomes impossible to find with our telescopes.”
Leo 1 and its Black Hole
This galaxy’s supermassive black hole’s existence was suggested in 2021 by astronomers who noticed that stars at the heart of Leo 1 were speeding up as they approached. That’s pretty good evidence for a black hole. However, imaging the emissions from any material spiraling into the black hole was impossible. And thus, Leo 1’s black hole remained tantalizingly out of reach.
What makes this supermassive black hole in a dwarf spheroidal such a challenge to understand? Let’s look at its home. Leo 1 is a very “low metal” galaxy, like many other dwarf spheroidals. It has stars, to be sure, but not a lot of gas. Until recently astronomers didn’t think these types of galaxies had central supermassive black holes. That’s because these monsters accrete and grow by feeding on gas and other material that wanders too close. A metal-poor, gas-poor galaxy just doesn’t seem like the right environment for a behemoth like Leo 1 seems to have.
Leo 1 is also a fairly young galaxy. It last went through a star-forming epoch that began some 6 billion years ago and ended about a billion years ago. Star formation gobbles up a lot of gas. In addition, since this galaxy orbits the Milky Way, a close passage may have stripped more gas away. That would have also slowed the star formation rate and robbed the black hole of the fuel it needs. So, that leaves a lot of questions, first among them, if there is a 3-million-solar-mass black hole in Leo 1, how did it get so big? Clearly, it grew from something, and it’s still growing, albeit slowly. Also, since it’s not hugely bright with emissions, how can it be observed?
Observing the Leo 1* Supermassive Black Hole
Pacucci and his research partner, Avi Loeb, suggest using red giant stars as tracers to track the supermassive black hole’s activity. “In our study, we suggested that a small amount of mass lost from stars wandering around the black hole could provide the accretion rate needed to observe it,” Pacucci explained. “Old stars become very big and red — we call them red giant stars. Red giants typically have strong winds that carry a fraction of their mass to the environment. The space around Leo I* seems to contain enough of these ancient stars to make it observable.”
U Camelopardalis, or U Cam for short, is a red giant star nearing the end of its life. It’s losing mass as it dies, and that material is ejected into space. Red giant stars similar to this one, but in Leo 1 are losing mass, too. If they wander too close to Leo 1*, that mass gets caught up in the gravitational pull of the Leo 1* black hole. Emissions from that gas as it gets superheated can be traced, and used to help understand more about this black hole. Credit: ESA/Hubble, NASA and H. Olofsson (Onsala Space Observatory).
It’s an interesting methodology that should allow them to gain more information about the black hole and its environment. It also raises more questions about this supermassive black hole’s very existence. “Observing Leo I* could be groundbreaking,” said Loeb, the co-author of the study. “It would be the second-closest supermassive black hole after the one at the center of our galaxy, with a very similar mass but hosted by a galaxy that is a thousand times less massive than the Milky Way. This fact challenges everything we know about how galaxies and their central supermassive black holes co-evolve. How did such an oversized baby end up being born from a slim parent?”
Most galaxies host central supermassive black holes that are a small percent of their total mass. That’s true of the Milky Way. But, Leo 1* breaks the mold. “In the case of Leo I,” Loeb said, “we would expect a much smaller black hole. Instead, Leo I appears to contain a black hole a few million times the mass of the Sun, similar to that hosted by the Milky Way. This is exciting because science usually advances the most when the unexpected happens.”
Using Radio Telescopes to Probe Leo 1*
While there’s no way to image Leo 1* in visible light, it turns out radio observatories can focus on it. The team has already observed it using the Chandra X-ray Observatory, the Karl Jansky Very Large Array, and the Atacama Large Millimeter Array. Those observations should confirm the existence of the black hole and give some idea of its accretion rate.
