Breakthrough Listen, a privately funded project seeking evidence of extraterrestrial intelligence, has started operations on the MeerKAT radio telescope array in South Africa. Over the next two years, the team will search over a million nearby stars, expanding the number of targets observed by a factor of 1000.
“I am very excited to be able to conduct a search for technosignatures using one of the most sensitive telescopes in the world,” says Breakthrough Listen’s MeerKAT Project Scientist, Dr. Cherry Ng. “MeerKAT will provide us with the ability to detect a transmitter akin to Earth’s brightest radio beacons out to a distance of 250 light years.”
There are about 260,000 stars within that range. For stars further away, the search becomes more difficult, but there is still a chance of detecting signals from distant sources.
The Search for Extraterrestrial Intelligence (SETI) has the unenviable position of rarely receiving government research funding. NASA has largely avoided SETI research since the cancellation of its planned High Resolution Microwave Survey back in 1993. SETI’s (sometimes unfair) association with conspiracy theories occasionally overshadows its potential to answer one of the biggest questions humanity can ask: are we alone in the Universe?
But private funding from billionaires Julia and Yuri Milner have given SETI a boost in recent years.
Breakthrough Listen operates using the Green Bank Telescope in the USA and the Parkes Telescope in Australia, among others. MeerKAT is the latest addition. MeerKAT’s array of 64 dishes can see an area of sky 50 times bigger than the Green Bank telescope, making it an exceptional tool for surveying broad swaths of the nearby galactic neighborhood.
Importantly, Breakthrough Listen’s software on MeerKAT enables them to operate in ‘commensal mode,’ meaning they piggyback onto the telescope and can carry out their search for technosignatures without interfering with the observing time of other astronomers.
Aerial photo of part of the MeerKAT array. Credit: South African Radio Astronomy Observatory (SARAO).
“Such a large field of view typically contains many stars that are interesting technosignature targets,” says Breakthrough Listen’s Principal Investigator Dr. Andrew Siemion. “Our new supercomputer enables us to combine signals from the 64 dishes to get high resolution scans of these targets with excellent sensitivity, all without impacting the research of other astronomers who are using the array.”
One of the first targets Breakthrough Listen will observe with MeerKAT is Proxima Centauri, a nearby star with two known rocky planets in the habitable zone.
Astronomers have competing opinions regarding whether there are technological civilizations out there to find. One camp suggests that if they were out there, we would have seen them already. That is the premise of the Fermi Paradox, which proposes that life is likely common elsewhere in the Universe, so it is strange we’ve yet to see any yet. The famous Drake equation, formulated in 1961, tries to mathematically distill the Fermi paradox into concrete probabilities for finding life elsewhere.
The Drake equation. N = the number of civilizations in the Milky Way galaxy with which communication might be possible; R? = rate of star formation in our Galaxy; fp = the number of stars that have planets; ne = the number of planets that could support life per star; fl = the number of planets that actually develop life; fi = the number of planets with intelligent life; fc = the fraction of civilizations that release detectable technosignatures; L = the length of time that those civilizations release detectable signals.
So far, there are no signs of ET. The occasional oddity, like the ‘Wow! signal’ in 1977, have failed to be repeated in follow-up studies. These oddities are, at best, inconclusive hints that something else is out there. Alternatively, they often prove to be signals from elsewhere on Earth, misunderstood as extraterrestrial in origin.
The premise of Breakthrough Listen is that if we don’t look, we won’t get an answer. MeerKAT’s powerful capabilities will make that search more thorough. Only time will tell what they find, or don’t find.
Featured Image: Artist’s impression of the MeerKAT telescope in South Africa, and the Breakthrough Listen compute cluster, scanning the sky for possible signals (represented as binary codes) from extraterrestrial intelligence. Credit: Danielle Futselaar / Breakthrough Listen / SARAO.
The best images from Artemis so far. More spacecraft are going to the Moon. Researchers have simulated a wormhole. China now has six people on board its space station. All this and more space news in this week’s Space Bites.
Stunning Images from Artemis I
As the Artemis I mission continues on its journey around the Moon, NASA releases new images and videos from its voyage. We got a fantastic new video that shows many more views of the launch. You see the perspective from the rocket and see the moment when its twin solid rocket boosters detach and fly away. Read deeper into this newsletter because NASA released a second supercut that’s even better.
The Moon’s south pole is becoming the focus of lunar exploration, and for a good reason: there are probably valuable deposits of water ice. NASA will soon launch a new Cubesat mission to figure out how much water ice is frozen inside the permanently shadowed craters at the Moon’s south pole. The Lunar Flashlight is equipped with an infrared laser that will fire into the craters as it flies overhead, measuring the reflected light that bounces back. Future astronauts could live off the land from what it finds.
NASA has awarded a $57.2 million contract to a Texas-based company called Icon to develop infrastructure for the Moon. This goes under Phase III of NASA’s Small Business Innovation Research (SBIR) program. Icon develops 3D-printing tech that should be able to use regolith to build structures like landing pads and habitats from the material that can be found on the Moon.
Scientists Simulate a Quantum Wormhole
I’m sure you’ve already heard about this story, but if not, here goes. Scientists have created a quantum computing experiment that allows them to study the dynamics of wormholes – theoretical shortcuts through spacetime. They didn’t make an actual wormhole; they just simulated it on a quantum computing system that calculates how it would work if it were possible to create theoretical “negative matter.” The researchers hope their work will uncover ways to integrate gravity with quantum mechanics.
The James Webb Space Telescope teamed up with the Keck Observatory to capture new images of Saturn’s moon Titan. Even though Saturn is over 1.5 billion km away, Webb and Keck could see its hazy atmosphere and even clouds made from methane that forms over its northern region. The telescopes observed the moon in infrared, penetrating the thick clouds on Titan to show surface features obscured in visible light.
It’s time for another fantastic picture from the James Webb Space Telescope. This time you’re looking at galaxy NGC 1566, seen face-on. The image was captured using JWST’s Mid-Infrared Instrument (MIRI) and then processed by Judy Schmidt. The reddish areas in the image contain regions of star formation, and the bright core indicates that it’s a Seyfert galaxy with an actively feeding supermassive black hole.
A Black Hole Consumed a Star and Released the Light of a Trillion Suns
Astronomers were using an all-sky survey of the northern night sky when they noticed an extremely bright flash in the sky. Follow-up observations revealed that this flash was probably a blast of radiation emitted by a star as a supermassive black hole consumed it. This is known as a tidal disruption event, where a star is torn apart piece by piece by a black hole. According to the researchers, the black hole is feasting on about half a solar mass of stellar material each year, releasing these bright flashes each time.
SpaceX continues to test its new fully reusable SuperHeavy booster to help carry Starship into orbit. This week they fired up 11 of its Raptor 2 engines in a test that lasted 13 seconds. Once again, nothing exploded, which is always good news. Elon Musk said the next test would last 20 seconds with a filled oxygen tank. After that will be another static fire test, and if that’s successful, we’ll see an orbital launch attempt.
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Globular clusters are densely-packed collections of stars bound together gravitationally in roughly-shaped spheres. They contain hundreds of thousands of stars. Some might contain millions of stars.
Sometimes globular clusters (GCs) kick stars out of their gravitational group. How does that work?
There are a few things that can cause GCs to eject stars. Gravitational scattering, supernovae, tidal disruption events, and physical collisions could all be responsible. Whatever’s behind it, the gradual ejection of stars from GCs is an established phenomenon.
The evidence for stellar ejection from GCs is in the tidal tails that stream out from them.
Palomar 5 is a globular cluster being torn apart by the Milky Way. Palomar 5 is the white blob at the center, and the orange is streams of stars. The yellow line with arrows represents the cluster’s orbit around the Milky Way. Image Credit: Odenkirchen, Grebel, et al. 2002/Sloan Digital Sky Survey
“Recent exquisite kinematic data from the Gaia space telescope has revealed numerous stellar streams in the Milky Way (MW) and traced the origin of many to specific MWGCs, highlighting the need for further examination of stellar escape from these clusters,” the authors write. This study is the first of a series, and the authors examine all the escape mechanisms and how each one contributes to GC star loss.
GCs are some of the oldest stellar associations in the Milky Way. Individual GC stars are also older and have lower metallicity than the Milky Way’s general population. Nearly all galaxies host GCs, and in spiral galaxies like ours, the GCs are mostly found in the halo. The Milky way hosts more than 150 of them. Astronomers used to think that stars in a GC form from the same molecular cloud, but now they know that that’s not true. GCs contain stars of different ages and metallicities.
GCs are different from their cousins, the open clusters (OCs). OCs are most often found in the disks of spiral galaxies, have more heavy elements, and are less dense and also smaller than GCs. OCs have only a few thousand stars, and there are more than 1100 of them in the Milky Way.
NGC 6441 is one of the most luminous and massive globular clusters in the Milky Way. Image Credit: ESA/Hubble & NASA, G. Piotto
GCs are unique, and astronomers consider them tracers of galactic evolution. Thanks largely to the ESA’s Gaia spacecraft, we know more about GCs. Gaia helped reveal the presence of numerous stellar streams coming from the Milky Way’s globular clusters. As the authors explain in their paper, “These drawn-out associations of stars on similar orbits are likely debris from disrupted dwarf galaxies and their GCs, shorn off by Galactic tides during accretion by the MW (Milky Way.)”
Gaia did more than spot these streams. It was able to connect some streams to specific GCs. “Gaia’s exquisite kinematic data has firmly tied the origins of ~10 especially thin streams to specific MWGCs,” the authors write. The Palomar 5 GC and its streams are well-known examples. The streams are excellent tracers of the Milky Way’s evolution. (Palomar 5 gained even more notoriety in astronomy recently when a 2021 paper found more than 100 black holes in its center.)
Observations of these types of tails, both from stars ejected from GCs, and from interacting and merging galaxies, are an extremely active area of research. There are many astounding images of these interactions. But as the authors point out, “… the theoretical study of stellar escape from GCs has a longer history.” Astronomers have come up with different mechanisms for these escapes, and this paper starts with a review of each one.
Artist’s impression of the thin stream of stars torn from the Phoenix globular cluster, wrapping around our Milky Way (left). Red giant stars make up a significant portion of the stream and helped astronomers map it. Credit: James Josephides (Swinburne Astronomy Productions) and the S5 Collaboration.
The authors divide escape mechanisms into two categories: Evaporation and Ejection. Evaporation is gradual, while ejection is more abrupt. The following are brief descriptions of each of the ejection methods, beginning with the Evaporation category.
Two-Body Relaxation: the motions of each body induce granular perturbations that create exchanges in energy and momentum in the bodies. Over time, stars can be ejected from GCs.
Cluster mass loss: stars lose mass over time, and that can affect the gravitational binding that holds stars in the cluster.
Sharply time-dependent tides: MWGCs orbit the Milky Way in eccentric and inclined orbits. The galactic tide will be stronger at some points in the orbit. The changing gravity can allow stars to exit the GCs.
The second broad category is Ejection. These are events typically involving single stars that are ejected rapidly and dramatically.
Strong Encounters: a close passage between two or more bodies that provides a strong enough kick to eject a star.
(Near)-Contact Recoil: encounters so close that tides, internal stellar processes, and/or relativistic effects are relevant. This includes collisions and gravitational waves.
Stellar Evolution Recoil: This includes the powerful forces unleashed when a star goes supernova, for example, or when a black hole or neutron star is formed.
Since there was no way to go and observe a statistically significant number of GC ejections, the team of researchers took what data was available and performed simulations. They used what’s called the CMC Cluster Catalog.
The study is concerned with the two types of GCs: non-core collapsed and core-collapsed. They’re different from each other and are a fundamental property of GCs, so the team simulated both types.
Core collapse in GCs occurs when the more massive stars in a GC encounter less massive stars. This creates a dynamic process that, over time, drives some stars out of the center of the GC towards the outside. This creates a net loss of kinetic energy in the core, so the remaining stars in the GCs core take up less space, creating a collapsed core.
This figure from the study shows the number of escaped single stars and stellar objects for the archetypal core-collapse GCs and non-core-collapse GCs. The x-axis is unlabelled but measures time in Gyrs. Each black marker is two Gyrs. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. The plotted lines are colour coded according to the legend at the top. As the figure shows, most ejected stars are main-sequence stars, mirroring the population of the GCs themselves. Image Credit: Weatherford et al. 2022.
An important astronomical principle plays a role in the team’s results. Two-body relaxation is a fundamental aspect of stellar associations that has far-reaching effects. It’s a complicated topic, but it basically describes the ways that stars in stellar associations, such as GCs, interact gravitationally and share kinetic energy with each other. It shows that star-to-star interactions drive GCs to evolve during the lifetime of the galaxy they’re attached to.
Not surprisingly, the researchers found that two-body relaxation plays a powerful role. That conclusion lines up with the established theory. “Consistent with longstanding theory and numerical modelling, we find that two-body relaxation in the cluster core dominates the overall escape rate,” they write.
This figure from the study shows binary compact objects ejected in the simulation. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.
They also found that “… central strong encounters involving binaries contribute especially high-speed
ejections, as do supernovae and gravitational wave-driven mergers.” This also lines up with other research.
This figure from the study shows binary objects containing a compact object and a main-sequence or giant star ejected from GCs. The number of objects is on the y-axis, and time in two-Gyr increments is on the x-axis. Dashed lines are results from core-collapsed GCs, while solid lines are non-core-collapsed GCs. Image Credit: Weatherford et al. 2022.
But one of their results is new. It concerns three-body binary formation (3BBF.) 3BBF is when three bodies collide to form a new binary object. “We have also shown for the first time that three-body binary formation plays a significant role in the escape dynamics of non-core-collapsed GCs typical of those in the MW. BHs are an essential catalyst for this process,” they write. “3BBF dominates the rate of present-day high-speed ejections over any other mechanism,” they explain, as long as significant numbers of BHs remain in the GCs core. 3BBFs also produce a significant number of hypervelocity stars.
In their conclusion, the authors explain that “… this study provides a broad sense of the escape mechanisms and demographics of escapers from GCs,” while also noting that the results are “not immediately comparable to Gaia observations.” That’s why this work is the first in a series of papers. In their follow-up paper, they intend to integrate the trajectories of escaped stars and construct their velocity distributions to reproduce tidal tails. After that work, they hope that they’ll have a clearer understanding of how stars escaping from GC contribute to galactic evolution.
In a third paper, they intend to “… identify likely past members (‘extratidal candidates’) of specific MWGCs and directly compare the mock ejecta from our cluster models to the Gaia data.” This will get closer to some of the core questions surrounding GCs and the Milky Way’s evolution: how do stellar streams form? How many BHs are there in GCs? What role do supernovae play?
“Ultimately, we hope to better understand stellar stream formation and, in an ideal case, leverage the new
observables from Gaia to better constrain uncertain properties about MWGCs, such as BH content, SNe kicks, and the initial mass function, which affect ejection velocities and the cluster evaporation rate.”
The ESA’s Gaia spacecraft doesn’t make a lot of headlines in regular media because it doesn’t take gorgeous images. But as this study shows, its contribution to important topics like galactic evolution can’t be overstated. (Those who know, know.) Artist’s impression of the ESA’s Gaia Observatory. Credit: ESA
This study is an interesting look at how a number of natural phenomena all contribute to galactic evolution. The evolution of individual stars, how individual stars interact gravitationally and how they form binary objects, the tidal interactions between globular clusters and their host galaxies, two-body relaxation, and even three-body binary formation. Throw in supernovae and hypervelocity stars.
Each one of these topics can form the basis of an entire career in astrophysics. It’s easy to see why follow-up studies are needed. Once they’re completed, we’ll have a much better picture of how galaxies, specifically our own Milky Way, evolve.
Artemis I is now on day seventeen of its mission, having just completed its distant retrograde orbit burn. This maneuver has placed the uncrewed Orion spacecraft (loaded with mannequins and sensors) on its way back to Earth. In honor of this historic mission that has traveled farther than any spacecraft in history, NASA has released a second supercut video of footage from the mission. The 1-minute, 36-second video includes highlights from the maiden launch of the Space Launch System (SLS) rocket and the Orion spacecraft making its circumlunar flight and looking back at the Earth-Moon system.
As NASA described in the description that accompanied the video’s release:
“Cameras on NASA’s Space Launch System (SLS) rocket and Orion spacecraft give us amazing views of our adventure around the Moon. See up close views of the Moon from external cameras as well as the view from inside the capsule.”
In the first minute, we see the launch, the separation of the solid rocket boosters, the launch abort system, and the second stage at various speeds (2x normal to close to 250x). We then see the Orion spacecraft deploying its four foldable solar arrays and snapshots of it floating through space and looking back at Earth. Next up, we see the Moon as Orion closes in on it, makes its closest approach and looks back to spot the lunar surface and Earth in the distance. Some snapshots from inside the spacecraft and many close-up pictures of the far side of the Moon (showing the cratered surface) follow.
The interior snapshots show the spacecraft connecting with the Callisto technology demonstrator that became active on Day Two of the mission (November 17th). The video closes with Orion’s most distant views of Earth and the Moon, which show just how far it has reached into deep space. These pieces of footage highlight the accomplishments of the mission and the importance of the spaceflight systems involved. They also underline what is special about the Artemis Program and the mission architecture that will send astronauts back to the Moon for the first time since the end of the Apollo Era.
“Orion is the only spacecraft capable of carrying humans from Earth on Artemis missions to deep space and bringing them back to Earth from the vicinity of the Moon,” NASA states. “SLS is the most powerful rocket in the world and the only rocket capable of launching Orion with astronauts and their supplies on Artemis missions to the Moon.”
Planetary scientists have greatly anticipated using the James Webb Space Telescope’s infrared vision to study Saturn’s enigmatic moon Titan and its atmosphere. The wait is finally over and the results are spectacular. Plus, JWST had a little help from one of its ground-based observatory friends in helping to decode some strange features in the new images. Turns out, JWST had just imaged a rare event on Titan: clouds.
In these new images, the white areas near the top of Titan are clouds, likely made from methane. The clouds appear to have formed over Titan’s northern region, known to have lakes made of liquid hydrocarbons.
Images of Saturn’s moon Titan, captured by the James Webb Space Telescope’s NIRCam instrument Nov. 4, 2022. Left: Image using F212N, a 2.12-micron filter sensitive to Titan’s lower atmosphere. The bright spots are prominent clouds in the northern hemisphere. Right: Color composite image using a combination of NIRCam filters: Blue=F140M (1.40 microns), Green=F150W (1.50 microns), Red=F200W (1.99 microns), Brightness=F210M (2.09 microns). Several prominent surface features are labeled: Kraken Mare is thought to be a methane sea; Belet is composed of dark-colored sand dunes; Adiri is a bright albedo feature. Image credit: NASA, ESA, CSA, A. Pagan (STScI). Science: Webb Titan GTO Team.
Titan’s nitrogen-rich atmosphere covers the moon like a shroud, as it is 50% denser than Earth’s atmosphere and visible light cannot penetrate it. But astronomers have figured out ingenious ways to see through the atmosphere – using radar, infrared techniques, and other tricks (more on that later), enabling them to see details in Titan’s atmosphere and amazingly, even down to surface to see features like dunes, as well as the hydrocarbon rivers and lakes. While astronomers have been able to detect clouds in Titan’s atmosphere since 1995, according to planetary scientist Sarah Hörst, it’s rare and Titan can go years and years without detectable clouds.
For JWST to see them at its first go at Titan is remarkable – with maybe a little luck thrown in.
“What a wake-up this morning (Paris time)! Lots of alerts in my mailbox! I went directly to my computer and started at once to download the data. At first glance, it is simply extraordinary! I think we’re seeing a cloud!” JWST Solar System GTO Project Lead Heidi Hammel, from the Association of Universities for Research in Astronomy (AURA), had a similar reaction: “Fantastic! Love seeing the cloud and the obvious albedo markings. So looking forward to the spectra! Congrats, all!!! Thank you!”
The team quickly called in colleagues at the Keck Telescope on Mauna Kea in Hawai’i to perform follow-up observations. A series of Keck images taken about 30 and 54 hours after JWST’s showed similar clouds — likely the same ones — but slightly displaced because of the moon’s rotation relative to Earth.
“We were concerned that the clouds would be gone when we looked at Titan one and two days later with Keck, but to our delight there were clouds at the same positions, looking like they might have changed in shape,” said Imke de Pater, a UC Berkeley Professor of the Graduate School, in a press release.
The astronomers cautioned, however, that since clouds are not long-lasting on Titan or Earth, so those seen on November 4 by JWST may not be the same as those seen on November 7 by Keck.
Evolution of clouds on Titan over 30 hours between Nov. 4 and Nov. 6, as seen by near-infrared cameras on the James Webb Space Telescope (top) and Keck Telescope. Titan’s trailing hemisphere seen here is rotating from left (dawn) to right (evening) as seen from Earth and the sun. Cloud A appears to be rotating into view, while Cloud B appears to be either dissipating, or moving behind Titan’s limb. Clouds are not long-lasting on Titan or Earth, so those seen on Nov. 4 may not be the same as those seen on Nov. 6. (Image credit: NASA/STScI/Keck Observatory/Judy Schmidt)
Titan is the only moon in the Solar System with a dense atmosphere and the only planetary body other than Earth that currently has surface features like rivers, lakes and seas. Unlike Earth, however, the liquid on Titan’s surface is composed of hydrocarbons including methane and ethane, not water.
The new and continued observations of Titan from JWST, combined with those from Earth-bound telescopes, will help astronomers understand the weather patterns on Titan. Additionally, the upcoming mission to this moon, scheduled for launch in 2027 called Dragonfly, will also provide more insights. Dragonfly has a multirotor lander and will assess the habitability of Titan’s unique environment.
For some additional info on how astronomers use every trick the book to see through Titan’s thick atmosphere — and how clouds were first seen on that moon — the Planet Dr, Sarah Hörst has a great thread on Twitter explaining it all:
The science team that used JWST to study Titan are still working through their data, and so these observations are still a work in progress, and the team stressed their work has not yet been through the peer-review process.
When a flash of light appears somewhere in the sky, astronomers notice. When it appears in a region of the sky not known to host a stellar object that’s flashed before, they really sit up and take notice. In astronomical parlance, objects that emit flashing light are called transients.
Earlier this year, astronomers spotted a transient that flashed with the light of a trillion Suns.
In this case, it was the Zwicky Transient Facility (ZTF) that spotted the flash. The ZTF is an all-sky survey aimed at the northern night sky. It’s hosted at the Palomar Observatory, and it’s a systematic study using an extremely wide-field optical light camera to scan the entire northern sky every two days. It’s part of what’s known as Time-Domain Astronomy, the study of astronomical objects that change over time.
The Zwicky Transient Facility is housed at California Institute of Technology’s Palomar Observatory. Image: CIT/Palomar Observatory.
When the ZTF spots a new transient in the sky, other astronomers are alerted. The ZTF isn’t suited to studying objects in detail. It just finds them and then passes the baton to other facilities that are better suited for observing astronomical objects in greater detail. In this case, a whole group of facilities took part.
Hubble Space Telescope observations in optical and infrared combined with data from the Jansky Very Large Array pinpointed the flash’s precise location. The European Southern Observatory’s (ESO) Very Large Telescope (VLT) determined that it was 8.5 billion light-years away. Observational data from other facilities followed, giving astronomers a picture of the flash across a wide swath of the electromagnetic spectrum.
As the title tells us, the transient light source was a jet of matter emitted from a supermassive black hole (SMBH) at 99.9% of the speed of light. The light signal has a name, AT 2022cmc, and the SMBH responsible for it is halfway across the Universe. What caused it? Something extraordinary, according to lead author Pasham.
“This particular event was 100 times more powerful than the most powerful gamma-ray burst afterglow. It was something extraordinary.”
Dheeraj Pasham, lead author, Kavli Institute
A behemoth supermassive black hole (SMBH) at the heart of a distant galaxy is responsible. The SMBH is swallowing a star that got too close. This is called a Tidal Disruption Event (TDE) and it’s the first one observed since 2011. It’s also the first one spotted in optical light, and the 78th one that ZTF has detected.
AT 2022cmc is the most distant TDE ever seen, and also the brightest. Gamma Ray Bursts (GRB) are the brightest objects in the Universe, second only to the Big Bang. So it’s natural to assume that the event was a GRB. But it wasn’t. The jet’s high x-ray luminosity helped rule that out.
There’s a lot of information in this figure from the study. Take note of the black and grey area in the lower right. It shows the TDE’s luminous x-ray emissions. Their strength and duration ruled out a Gamma Ray Burst as the cause of the flash. Image Credit: Pasham et al. 2022
“This particular event was 100 times more powerful than the most powerful gamma-ray burst afterglow,” lead author Pasham said in a press release. “It was something extraordinary.”
The TDE just happened to point its searing jet of material directly at Earth, like a flashlight shone right in our eyes. Rough calculations showed that the jet was as bright as a trillion Suns.
The jetted tidal disription event AT2022cmc was first observed in the ZTF optical data and was followed by 21 other astronomical facilities that saw it shine in X-ray, UV, infrared and radio. Image credit: Zwicky Transient Facility/R.Hurt (Caltech/IPAC)
The Universe is full of transient events, but observing TDEs is still rare. It helps when the jet is aimed right at Earth, as it was in this case. But when a SMBH consumes a star that got too close, it doesn’t always emit jets. TDEs like this one give astronomers an opportunity to learn more about the SMBHs that cause them.
“The last time scientists discovered one of these jets was well over a decade ago,” said Michael Coughlin, an assistant professor of astronomy at the University of Minnesota Twin Cities and co-lead on the paper. “From the data we have, we can estimate that relativistic jets are launched in only 1% of these destructive events, making AT2022cmc an extremely rare occurrence. In fact, the luminous flash from the event is among the brightest ever observed.”
This schematic from the paper illustrates the team’s proposed scenario behind the TDE. For a detailed explanation, see the study. Image Credit: Pasham et al. 2022
Supermassive Black Holes are, obviously, extraordinarily huge. The most massive ones are several billions of times more massive than the Sun. Even in astronomy, a subject known for large numbers, something several billion times more massive than our star is almost incomprehensible.
But as it turns out, even something that large can’t eat a star in one bite. It’s taking its time devouring the star. The jet was probably emitted during an intermittent ‘feeding frenzy,’ according to Pasham. “It’s probably swallowing the star at the rate of half the mass of the sun per year,” Pasham estimates. “A lot of this tidal disruption happens early on, and we were able to catch this event right at the beginning, within one week of the black hole starting to feed on the star.”
This artist’s impression illustrates how it might look when a star approaches too close to a black hole, where the star is squeezed by the intense gravitational pull of the black hole. Some of the star’s material gets pulled in and swirls around the black hole forming the disc that can be seen in this image. In rare cases, such as this one, jets of matter and radiation are shot out from the poles of the black hole. Image Credit: ESO/M.Kornmesser
Astronomers can’t yet see the galaxy that emitted it. The jet’s light is so powerful that it’s outshining its host galaxy. But astronomers think that once the jet dims they’ll be able to spot the galaxy with the Hubble and the James Webb Space Telescope.
That might lead them partway to answering an important question: All SMBHs are bound to eat stars, why do so few of them emit jets? Observations show that the ones that emit these types of jets are likely spinning rapidly. The rotation helps power these ultraluminous jets.
The rapid rotation might be only one factor, perhaps the factor that’s easiest to observe. But it does bring researchers one step closer to understanding the awesome forces at work in SMBHs.
“We know there is one supermassive black hole per galaxy, and they formed very quickly in the universe’s first million years,” says co-author Matteo Lucchini, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “That tells us they feed very fast, though we don’t know how that feeding process works. So, sources like a TDE can actually be a really good probe for how that process happens.”
What astrophysicists need, is to find more of these jets, TDEs, and SMBHs. They’ll probably get their wish in the near future.
“Scientists can use AT2022cmc as a model for what to look for and find more disruptive events from distant black holes.”
Igor Andreoni, Department of Astronomy at UMD and NASA Goddard Space Flight Center
With facilities like the Vera Rubin Observatory coming online soon, we’re bound to spot more transients like AT2022cmc. The Vera Rubin should see first light in 2023, and will perform a synoptic survey that will image the entire visible night sky every few nights. One of its four science goals is to find transients and notify other observatories for follow-up observations. And it should find a lot of them.
“Our new search technique helps us to quickly identify rare cosmic events in the ZTF survey data. And since ZTF and upcoming larger surveys such as Vera Rubin’s LSST scan the sky so frequently, we can now expect to uncover a wealth of rare, or previously undiscovered cosmic events and study them in detail,” says Igor Andreoni, a postdoctoral associate in the Department of Astronomy at UMD and NASA Goddard Space Flight Center.
“Astronomy is changing rapidly,” Andreoni said. “More optical and infrared all-sky surveys are now active or will soon come online. Scientists can use AT2022cmc as a model for what to look for and find more disruptive events from distant black holes. This means that more than ever, big data mining is an important tool to advance our knowledge of the universe.”
Gone are the days when professional astronomers spend long cold nights looking into the eyepiece of their telescopes. If we still relied on those efforts, we’d likely never even see a TDE. Automated sky surveys are becoming more and more prevalent, covering larger swaths of the sky than astronomers can, and doing it more diligently. They never get tired, get sick, or take holidays.
But facilities like them generate an enormous amount of data, which Andreoni alluded to. The Vera Rubin Observatory is expected to take 200,000 pictures each year of its ten-year run. That means that it’ll generate 1.2 petabytes of data each year, far more data than astronomers will be able to handle. It’ll be up to AI and machine learning to deal with all that data.
The Zwicky Transient Facility served as a prototype for the Vera Rubin. But while the ZTF found 78 TDEs since its inception, the Vera Rubin will dwarf those results. Nobody’s certain how many TDEs it’ll find, but the observatory is expected to generate hundreds of alerts per second, and each one will be a transient of some sort.
Some of those will be TDEs, and as more detections roll in, astronomers will do follow-up observations with other facilities.
“We expect many more of these TDEs in the future,” said Lucchini. “Then we might be able to say, finally, how exactly black holes launch these extremely powerful jets.”
SpaceX is at it again! Yesterday (November 29th), the company conducted another static fire test with the Booster 7 (BN7) prototype at its Starbase in Boca Chica, Texas. The test began at 02:42 p.m. EST (11:42 a.m. PST) and saw eleven of the BN7’s thirty-three Raptor 2 engines fire for 13 seconds. While static fire tests have been the norm these past few months, this latest might be the prelude to the orbital test flight Musk has been hinting at for close to a year. News of the successful test was shared via Twitter, while NASA Spaceflight (NSF) shared footage of the test via Youtube.
The last time SpaceX conducted a static fire test with the BN7 was on November 17th, when fourteen of its Raptor 2 engines were fired for thirteen seconds. Before that, SpaceX conducted a test on September 19th, where the BN7 fired seven Raptor 2 engines for about seven seconds. These tests came after many months of stacking and unstacking and repeatedly revised estimates of when the orbital test flight may occur. Musk previously indicated it might fly in May, July, and sometime in November.
Booster 7 completed a long-duration static fire test of 11 Raptor 2 engines on the orbital launch pad at Starbase pic.twitter.com/fFnKR00XNo
But after the September 19th test, Musk offered a more detailed assessment of when the Starship could be ready to go to space. After sharing NASA Spaceflight’s footage of the test via Twitter, NSF Managing Editor Chris Bergin and Musk got into a brief conversation. When Bergin asked Musk when the orbital flight might happen, he replied, “Next test is ~20 sec firing with max oxygen fill to test autogenous pressurization, possibly one more static fire, then orbital launch attempt.” In short, Musk claims that another static fire is likely to follow this one, followed by an orbital flight.
While Musk did not indicate when that might happen, it’s a safe bet that it won’t take place before 2023. If successful, the flight test will make the Starship and Super Heavy the most powerful launch system in history. The title used to be held by the Saturn V rocket that took the Apollo astronauts to the Moon and is currently held by NASA’s Space Launch System (SLS). The SLS earned this title after launching from the Kennedy Space Center in Florida at 01:47 a.m. EST on November 16th (10:47 p.m. PST, November 15th)
The Artemis I mission has subsequently established a new record for the farthest distance ever achieved by a spacecraft. The uncrewed Orion vehicle also took some amazing photographs of the Moon and the Earth-Moon system in the process. NASA has already contracted with SpaceX to provide the Human Landing System (HLS) for the Artemis III mission, which is currently scheduled for 2025. This historic mission will see astronauts land on the lunar surface for the first time since the Apollo Era.
According to NASA’s mission architecture, the Artemis III crew will launch aboard an Orion spacecraft atop an SLS rocket and fly to the Moon, where they will rendezvous with the Starship HLS in lunar orbit. The crew will then transfer to the HLS, land on the Moon, and conduct surface operations before launching again to return to their Orion spacecraft (and then return home). The SLS will have to give up the title of “most powerful rocket” after a few short months but will remain a vital part of the Artemis Program.
And be sure to check the SNF’s footage of the latest static fire test of the BN7 below:
