TL;DR
- Researchers have been shedding light on the enigmatic ‘spiders from Mars’, providing the first physical evidence that these unique features on the planet’s surface can be formed by the sublimation of CO2 ice.
- What would a volcano — and its lava flows — look like on a planetary body made primarily of metal? A pilot study offers insights into ferrovolcanism that could help scientists interpret landscape features on other worlds.
- Scientists have discovered a vast, previously unknown reservoir of new aromatic material in a cold, dark molecular cloud by detecting individual polycyclic aromatic hydrocarbon molecules in the interstellar medium for the first time, and in doing so are beginning to answer a three-decades-old scientific mystery: how and where are these molecules formed in space? The more than a dozen PAHs may hold clues as to the formation of comets, asteroids, stars, and even planets.
- The stormy, centuries-old maelstrom of Jupiter’s Great Red Spot was shaken but not destroyed by a series of anticyclones that crashed into it over the past few years, according to a new study.
- Astronomers have now directly measured winds in Jupiter’s middle atmosphere. By analyzing the aftermath of a comet collision from the 1990s, the researchers have revealed incredibly powerful winds, with speeds of up to 1450 kilometers an hour, near Jupiter’s poles. They could represent a ‘unique meteorological beast in our Solar System’.
- In this largest-ever survey of nascent stars to date, researchers are finding that gas-clearing by a star’s outflow may not be as important in determining its final mass as conventional theories suggest.
- A radio telescope located in outback Western Australia has observed a cosmic phenomenon with a striking resemblance to a jellyfish.
- Astronomers using the VLA took advantage of the gravitational lensing provided by a distant cluster of galaxies to detect an even more-distant galaxy that probably is the faintest radio-emitting object ever found.
- In the universe, galaxies are distributed along extremely tenuous filaments of gas millions of light years long separated by voids, forming the cosmic web. Astronomers have captured an image of several filaments in the early universe, revealing the unexpected presence of billions of dwarf galaxies in the filaments.
- Using light from the Big Bang, an international team led by Cornell University and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory has begun to unveil the material which fuels galaxy formation.
- NASA and SpaceX sign agreement on spaceflight safety.
- Space Force to launch fifth SBIRS satellite in May.
- Redwire to go public through a SPAC merger.
- Upcoming industry events. And more!
Space industry in numbers
Last summer, the Space Foundation published the second-quarter findings of its 2019 issue of The Space Report, revealing that:
- The global space economy grew 8.1% in 2018 to USA 414.75 billion, exceeding USD 400 billion for the first time.
- Global launches in 2018 increased by 46% over the number of launches a decade ago.
- Global launches in 2018 exceeded 100 for the first time since 1990.
Analysts at Morgan Stanley and Goldman Sachs have predicted that economic activity in space will become a multi-trillion-dollar market in the coming decades. Morgan Stanley’s Space Team estimates that the roughly USD 350 billion global space industry could surge to over USD 1 trillion by 2040.
Source: Satellite Industry Association, Morgan Stanley Research, Thomson Reuters. *2040 estimates
Space industry news
NASA and SpaceX sign agreement on spaceflight safety
Space Force to launch fifth SBIRS satellite in May
Redwire to go public through a SPAC merger
BlackSky strikes deal with Rocket Lab to launch eight more satellites in 2021
Space M&A boom appears right on time
Sky Perfect JSAT orders first Airbus satellite
ABL Space Systems raises $170 million
Arianespace launches 36 more OneWeb satellites
ESA awards €10.45 million to two UK launch startups
Italy’s Leaf Space to establish U.S. office
Is there still space for export credit agencies?
SpaceX marks anniversary of first launch with Starlink mission
Ingenuity helicopter prepares for first flight on Mars
NASA to offer funding for initial studies of commercial space stations
Bluestaq wins $280 million Space Force contract to expand space data catalog
Global Eagle Entertainment completes Chapter 11 restructuring
With CAS500, South Korea launches journey toward private-led satellite development
NanoAvionics to take on larger microsatellite market
Lockheed Martin signs agreement with Omnispace to explore 5G in space
Can you still spell space without SPAC?
Sure, you can spell SPAC. But what is it?
MDA files to go public
Rocket Lab launches smallsat rideshare mission
Rogers feeling optimistic about Space Force procurement efforts
Download the March 15 issue of SpaceNews Magazine
A little love from the Air Force can put a space business on the map
Airbus nets first commercial GEO order of 2021 with Eutelsat replacement satellite
Soyuz launch marks first full-commercial mission of Russia’s GK Launch Services
Pixxel raises seed round for hyperspectral satellites
Decommissioned NOAA weather satellite breaks up
Space exploration
The formation of araneiforms by carbon dioxide venting and vigorous sublimation dynamics under martian atmospheric pressure
by Lauren Mc Keown, J. N. McElwaine, M. C. Bourke, M. E. Sylvest, M. R. Patel in Scientific Reports
Researchers at Trinity College Dublin have been shedding light on the enigmatic “spiders from Mars,” providing the first physical evidence that these unique features on the planet’s surface can be formed by the sublimation of CO2 ice.
Spiders, more formally referred to as araneiforms, are strange-looking negative topography radial systems of dendritic troughs; patterns that resemble branches of a tree or fork lightning. These features, which are not found on Earth, are believed to be carved into the Martian surface by dry ice changing directly from solid to gas (sublimating) in the spring. Unlike Earth, Mars’ atmosphere comprises mainly of CO2 and as temperatures decrease in winter, this deposits onto the surface as CO2 frost and ice.
The Trinity team, along with colleagues at Durham University and the Open University, conducted a series of experiments funded by the Irish Research Council and Europlanet at the Open University Mars Simulation Chamber, under Martian atmospheric pressure, in order to investigate whether patterns similar to Martian spiders could form by dry ice sublimation.
Dr Lauren McKeown, who led this work during her PhD at Trinity and is now at the Open University, said:
“This research presents the first set of empirical evidence for a surface process that is thought to modify the polar landscape on Mars. Kieffer’s hypothesis [explained below] has been well accepted for over a decade, but until now, it has been framed in a purely theoretical context.
“The experiments show directly that the spider patterns we observe on Mars from orbit can be carved by the direct conversion of dry ice from solid to gas. It is exciting because we are beginning to understand more about how the surface of Mars is changing seasonally today.”
The research team drilled holes in the centres of CO2 ice blocks and suspended them with a claw similar to those found in arcades, above granular beds of different grain sizes. They lowered the pressure inside a vacuum chamber to Martian atmospheric pressure (6mbar) and then used a lever system to place the CO2 ice block on the surface.
They made use of an effect known as the Leidenfrost Effect, whereby if a substance comes in contact with a surface much hotter than its sublimation point, it will form a gaseous layer around itself. When the block reached the sandy surface, CO2 turned directly from solid to gas and material was seen escaping through the central hole in the form of a plume.
In each case, once the block was lifted, a spider pattern had been eroded by the escaping gas. The spider patterns were more branched when finer grain sizes were used and less branched when coarser grain sizes were used. This is the first set of empirical evidence for this extant surface process.
Dr Mary Bourke, of Trinity’s Department of Geography, who supervised the PhD research, said:
“This innovative work supports the emergent theme that the current climate and weather on Mars has an important influence not only on dynamic surface processes, but also for any future robotic and/or human exploration of the planet.”
The main hypothesis proposed for spider formation (Kieffer’s hypothesis) suggests that in spring, sunlight penetrates this translucent ice and heats the terrain beneath it. The ice will sublimate from its base, causing pressure to build up and eventually the ice will rupture, allowing pressurised gas to escape through a crack in the ice. The paths of the escaping gas will leave behind the dendritic patterns observed on Mars today and the sandy/dusty material will be deposited on top of the ice in the form of a plume.
However, until now, it has not been known if such a theoretical process is possible and this process has never been directly observed on Mars.
Additionally, the researchers observed that when CO2 blocks were released and allowed to sublimate within the sand bed, sublimation was much more vigorous than expected and material was thrown all over the chamber.
This observation will be useful in understanding models of other CO2 sublimation-related processes on Mars, such as the formation of lateral Recurring Diffusive Flows surrounding linear dune gullies on Mars.
The methodology used can be refocused to study the geomorphic role of CO2 sublimation on other active Martian surface feature formation — and indeed, can pave the way for further research on sublimation processes on other planetary bodies with no/scant atmospheres like Europa or Enceladus.
Imagining and constraining ferrovolcanic eruptions and landscapes through large-scale experiments
by A. Soldati, J. A. Farrell, R. Wysocki, J. A. Karson in Nature Communications
What would a volcano — and its lava flows — look like on a planetary body made primarily of metal? A pilot study from North Carolina State University offers insights into ferrovolcanism that could help scientists interpret landscape features on other worlds.
Volcanoes form when magma, which consists of the partially molten solids beneath a planet’s surface, erupts. On Earth, that magma is mostly molten rock, composed largely of silica. But not every planetary body is made of rock — some can be primarily icy or even metallic.
“Cryovolcanism is volcanic activity on icy worlds, and we’ve seen it happen on Saturn’s moon Enceladus,” says Arianna Soldati, assistant professor of marine, earth and atmospheric sciences at NC State and lead author of a paper describing the work. “But ferrovolcanism, volcanic activity on metallic worlds, hasn’t been observed yet.”
Enter 16 Psyche, a 140-mile diameter asteroid situated in the asteroid belt between Mars and Jupiter. Its surface, according to infrared and radar observations, is mainly iron and nickel. 16 Psyche is the subject of an upcoming NASA mission, and the asteroid inspired Soldati to think about what volcanic activity might look like on a metallic world.
“When we look at images of worlds unlike ours, we still use what happens on Earth — like evidence of volcanic eruptions — to interpret them,” Soldati says. “However, we don’t have widespread metallic volcanism on Earth, so we must imagine what those volcanic processes might look like on other worlds so that we can interpret images correctly.”
Soldati defines two possible types of ferrovolcanism: Type 1, or pure ferrovolcanism, occurring on entirely metallic bodies; and Type 2, spurious ferrovolcanism, occurring on hybrid rocky-metallic bodies.
In a pilot study, Soldati and colleagues from the Syracuse Lava Project produced Type 2 ferrovolcanism, in which metal separates from rock as the magma forms.
“The Lava Project’s furnace is configured for melting rock, so we were working with the metals (mainly iron) that naturally occur within them,” Soldati says. “When you melt rock under the extreme conditions of the furnace, some of the iron will separate out and sink to the bottom since it’s heavier. By completely emptying the furnace, we were able to see how that metal magma behaved compared to the rock one.”
The metallic lava flows travelled 10 times faster and spread more thinly than the rock flows, breaking into a myriad of braided channels. The metal also traveled largely beneath the rock flow, emerging from the leading edge of the rocky lava.
The smooth, thin, braided, widely spread layers of metallic lava would leave a very different impression on a planet’s surface than the often thick, rough, rocky flows we find on Earth, according to Soldati.
“Although this is a pilot project, there are still some things we can say,” Soldati says. “If there were volcanoes on 16 Psyche — or on another metallic body — they definitely wouldn’t look like the steep-sided Mt. Fuji, an iconic terrestrial volcano. Instead, they would probably have gentle slopes and broad cones. That’s how an iron volcano would be built — thin flows that expand over longer distances.”
An HST Survey of Protostellar Outflow Cavities: Does Feedback Clear Envelopes?
by Nolan M. Habel, S. Thomas Megeath, Joseph Jon Booker, William J. Fischer, Marina Kounkel, Charles Poteet, Elise Furlan, Amelia Stutz, P. Manoj, John J. Tobin, Zsofia Nagy, Riwaj Pokhrel, Dan Watson in The Astrophysical Journal
Though our galaxy is an immense city of at least 200 billion stars, the details of how they formed remain largely cloaked in mystery.
Scientists know that stars form from the collapse of huge hydrogen clouds that are squeezed under gravity to the point where nuclear fusion ignites. But only about 30 percent of the cloud’s initial mass winds up as a newborn star. Where does the rest of the hydrogen go during such a terribly inefficient process?
It has been assumed that a newly forming star blows off a lot of hot gas through lightsaber-shaped outflowing jets and hurricane-like winds launched from the encircling disk by powerful magnetic fields. These fireworks should squelch further growth of the central star. But a new, comprehensive Hubble survey shows that this most common explanation doesn’t seem to work, leaving astronomers puzzled.
Researchers used data previously collected from NASA’s Hubble and Spitzer space telescopes and the European Space Agency’s Herschel Space Telescope to analyze 304 developing stars, called protostars, in the Orion Complex, the nearest major star-forming region to Earth. (Spitzer and Herschel are no longer operational).
In this largest-ever survey of nascent stars to date, researchers are finding that gas-clearing by a star’s outflow may not be as important in determining its final mass as conventional theories suggest. The researchers’ goal was to determine whether stellar outflows halt the infall of gas onto a star and stop it from growing.
Instead, they found that the cavities in the surrounding gas cloud sculpted by a forming star’s outflow did not grow regularly as they matured, as theories propose.
“In one stellar formation model, if you start out with a small cavity, as the protostar rapidly becomes more evolved, its outflow creates an ever-larger cavity until the surrounding gas is eventually blown away, leaving an isolated star,” explained lead researcher Nolan Habel of the University of Toledo in Ohio.
“Our observations indicate there is no progressive growth that we can find, so the cavities are not growing until they push out all of the mass in the cloud. So, there must be some other process going on that gets rid of the gas that doesn’t end up in the star.”
A Star is Born
During a star’s relatively brief birthing stage, lasting only about 500,000 years, the star quickly bulks up on mass. What gets messy is that, as the star grows, it launches a wind, as well as a pair of spinning, lawn-sprinkler-style jets shooting off in opposite directions. These outflows begin to eat away at the surrounding cloud, creating cavities in the gas.
Popular theories predict that as the young star evolves and the outflows continue, the cavities grow wider until the entire gas cloud around the star is completely pushed away. With its gas tank empty, the star stops accreting mass — in other words, it stops growing.
To look for cavity growth, the researchers first sorted the protostars by age by analyzing Herschel and Spitzer data of each star’s light output. The protostars in the Hubble observations were also observed as part of the Herschel telescope’s Herschel Orion Protostar Survey.
Then the astronomers observed the cavities in near-infrared light with Hubble’s Near-infrared Camera and Multi-object Spectrometer and Wide Field Camera 3. The observations were taken between 2008 and 2017. Although the stars themselves are shrouded in dust, they emit powerful radiation which strikes the cavity walls and scatters off dust grains, illuminating the gaps in the gaseous envelopes in infrared light.
The Hubble images reveal the details of the cavities produced by protostars at various stages of evolution. Habel’s team used the images to measure the structures’ shapes and estimate the volumes of gas cleared out to form the cavities. From this analysis, they could estimate the amount of mass that had been cleared out by the stars’ outbursts.
“We find that at the end of the protostellar phase, where most of the gas has fallen from the surrounding cloud onto the star, a number of young stars still have fairly narrow cavities,” said team member Tom Megeath of the University of Toledo. “So, this picture that is still commonly held of what determines the mass of a star and what halts the infall of gas is that this growing outflow cavity scoops up all of the gas. This has been pretty fundamental to our idea of how star formation proceeds, but it just doesn’t seem to fit the data here.”
Jupiter’s Great Red Spot: strong interactions with incoming anticyclones in 2019
by A. Sánchez‐Lavega, A. Anguiano‐Arteaga, P. Iñurrigarro, E. Garcia‐Melendo, J. Legarreta, R. Hueso, J. F. Sanz‐Requena, S. Pérez‐Hoyos, I. Mendikoa, M. Soria, J. F. Rojas, M. Andrés‐Carcasona, A. Prat‐Gasull, I. Ordoñez‐Extebarria, J.H. Rogers, C. Foster, S. Mizumoto, A. Casely, C.J. Hansen, G.S. Orton, T. Momary, G. Eichstädt in Journal of Geophysical Research: Planets
The stormy, centuries-old maelstrom of Jupiter’s Great Red Spot was shaken but not destroyed by a series of anticyclones that crashed into it over the past few years.
The smaller storms cause chunks of red clouds to flake off, shrinking the larger storm in the process. But the new study found that these disruptions are “superficial.” They are visible to us, but they are only skin deep on the Red Spot, not affecting its full depth.
“The intense vorticity of the [Great Red Spot], together with its larger size and depth compared to the interacting vortices, guarantees its long lifetime,” said Agustín Sánchez-Lavega, a professor of applied physics at the Basque Country University in Bilbao, Spain, and lead author of the new paper. As the larger storm absorbs these smaller storms, it “gains energy at the expense of their rotation energy.”
The Red Spot has been shrinking for at least the past 150 years, dropping from a length of about 40,000 kilometers (24,850 miles) in 1879 to about 15,000 kilometers (9,320 miles) today, and researchers still aren’t sure about the causes of the decrease, or indeed how the spot was formed in the first place. The new findings show the small anticyclones may be helping to maintain the Great Red Spot.
Timothy Dowling, a professor of physics and astronomy at the University of Louisville who is a planetary atmospheric dynamics expert not involved in the new study, said that “it’s an exciting time for the Red Spot.”
Stormy collisions
Before 2019, the larger storm was only hit by a couple of anticyclones a year while more recently it was hit by as many as two dozen a year. “It’s really getting buffeted. It was causing a lot of alarm,” Dowling said.
Sánchez-Lavega and his colleagues were curious to see whether these relatively smaller storms had disturbed their big brother’s spin.
The iconic feature of the gas giant sits near its equator, dwarfing earthly concepts of a big bad storm for at least 150 years since its first confirmed observation, though observations in 1665 may have been from the same storm. The Great Red Spot is about twice the diameter of Earth and blows at speeds of up to 540 kilometers (335 miles) per hour along its periphery.
“The [Great Red Spot] is the archetype among the vortices in planetary atmospheres,” said Sánchez-Lavega, adding that the storm is one of his “favorite features in planetary atmospheres.”
Cyclones like hurricanes or typhoons usually spin around a center with low atmospheric pressure, rotating counter-clockwise in the northern hemisphere and clockwise in the southern, whether on Jupiter or Earth. Anticyclones spin the opposite way as cyclones, around a center with high atmospheric pressure. The Great Red Spot is itself an anticyclone, though it is six to seven times as big as the smaller anticyclones that have been colliding with it. But even these smaller storms on Jupiter are about half the size of the Earth, and about 10 times the size of the largest terrestrial hurricanes.
Sánchez-Lavega and his colleagues looked at satellite images of the Great Red Spot for the past three years taken from the Hubble Space Telescope, the Juno spacecraft in orbit around Jupiter and other photos taken by a network of amateur astronomers with telescopes.
Devourer of storms
The team found the smaller anticyclones pass through the high-speed peripheral ring of the Great Red Spot before circling around the red oval. The smaller storms create some chaos in an already dynamic situation, temporarily changing the Red Spot’s 90-day oscillation in longitude, and “tearing the red clouds from the main oval and forming streamers,” Sánchez-Lavega said.
“This group has done an extremely careful, very thorough job,” Dowling said, adding that the flaking of red material we see is akin to a crème brûlée effect, with a swirl apparent for a few kilometers on the surface that doesn’t have much impact on the 200-kilometer (125-mile) depth of the Great Red Spot.
The researchers still don’t know what has caused the Red Spot to shrink over the decades. But these anticyclones may be maintaining the giant storm for now.
“The ingestion of [anticyclones] is not necessarily destructive; it can increase the GRS rotation speed, and perhaps over a longer period, maintain it in a steady state,” Sánchez-Lavega said.
First direct measurement of auroral and equatorial jets in the stratosphere of Jupiter
by T. Cavalié, B. Benmahi, V. Hue, R. Moreno, E. Lellouch, T. Fouchet, P. Hartogh, L. Rezac, T. K. Greathouse, G. R. Gladstone, J. A. Sinclair, M. Dobrijevic, F. Billebaud, C. Jarchow in Astronomy & Astrophysics
Using the Atacama Large Millimeter/submillimeter Array (ALMA), in which the European Southern Observatory (ESO) is a partner, a team of astronomers has directly measured winds in Jupiter’s middle atmosphere for the first time. By analysing the aftermath of a comet collision from the 1990s, the researchers have revealed incredibly powerful winds, with speeds of up to 1450 kilometres an hour, near Jupiter’s poles. They could represent what the team have described as a “unique meteorological beast in our Solar System.”
Jupiter is famous for its distinctive red and white bands: swirling clouds of moving gas that astronomers traditionally use to track winds in Jupiter’s lower atmosphere. Astronomers have also seen, near Jupiter’s poles, the vivid glows known as aurorae, which appear to be associated with strong winds in the planet’s upper atmosphere. But until now, researchers had never been able to directly measure wind patterns in between these two atmospheric layers, in the stratosphere.
Measuring wind speeds in Jupiter’s stratosphere using cloud-tracking techniques is impossible because of the absence of clouds in this part of the atmosphere. However, astronomers were provided with an alternative measuring aid in the form of comet Shoemaker-Levy 9 , which collided with the gas giant in spectacular fashion in 1994. This impact produced new molecules in Jupiter’s stratosphere, where they have been moving with the winds ever since.
A team of astronomers, led by Thibault Cavalié of the Laboratoire d’Astrophysique de Bordeaux in France, have now tracked one of these molecules — hydrogen cyanide — to directly measure stratospheric “jets” on Jupiter. Scientists use the word “jets” to refer to narrow bands of wind in the atmosphere, like Earth’s jet streams.
“The most spectacular result is the presence of strong jets, with speeds of up to 400 metres per second, which are located under the aurorae near the poles,” says Cavalié. These wind speeds, equivalent to about 1450 kilometres an hour, are more than twice the maximum storm speeds reached in Jupiter’s Great Red Spot and over three times the wind speed measured on Earth’s strongest tornadoes.
“Our detection indicates that these jets could behave like a giant vortex with a diameter of up to four times that of Earth, and some 900 kilometres in height,” explains co-author Bilal Benmahi, also of the Laboratoire d’Astrophysique de Bordeaux. “A vortex of this size would be a unique meteorological beast in our Solar System,” Cavalié adds.
Astronomers were aware of strong winds near Jupiter’s poles, but much higher up in the atmosphere, hundreds of kilometres above the focus area of the new study, which is published today in Astronomy & Astrophysics. Previous studies predicted that these upper-atmosphere winds would decrease in velocity and disappear well before reaching as deep as the stratosphere. “The new ALMA data tell us the contrary,” says Cavalié, adding that finding these strong stratospheric winds near Jupiter’s poles was a “real surprise.”
The team used 42 of ALMA’s 66 high-precision antennas, located in the Atacama Desert in northern Chile, to analyse the hydrogen cyanide molecules that have been moving around in Jupiter’s stratosphere since the impact of Shoemaker-Levy 9. The ALMA data allowed them to measure the Doppler shift — tiny changes in the frequency of the radiation emitted by the molecules — caused by the winds in this region of the planet. “By measuring this shift, we were able to deduce the speed of the winds much like one could deduce the speed of a passing train by the change in the frequency of the train whistle,” explains study co-author Vincent Hue, a planetary scientist at the Southwest Research Institute in the US.
In addition to the surprising polar winds, the team also used ALMA to confirm the existence of strong stratospheric winds around the planet’s equator, by directly measuring their speed, also for the first time. The jets spotted in this part of the planet have average speeds of about 600 kilometres an hour.
The ALMA observations required to track stratospheric winds in both the poles and equator of Jupiter took less than 30 minutes of telescope time. “The high levels of detail we achieved in this short time really demonstrate the power of the ALMA observations,” says Thomas Greathouse, a scientist at the Southwest Research Institute in the US and co-author of the study. “It is astounding to me to see the first direct measurement of these winds.”
“These ALMA results open a new window for the study of Jupiter’s auroral regions, which was really unexpected just a few months back,” says Cavalié. “They also set the stage for similar yet more extensive measurements to be made by the JUICE mission and its Submillimetre Wave Instrument,” Greathouse adds, referring to the European Space Agency’s JUpiter ICy moons Explorer, which is expected to launch into space next year.
Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering
by Brett A. Mcguire, Ryan A. Loomis, Andrew M. Burkhardt, Kin Long Kelvin Lee, Christopher N. Shingledecker, Steven B. Charnley, Ilsa R. Cooke, Martin A. Cordiner, Eric Herbst, Sergei Kalenskii, Mark A. Siebert, Eric R. Willis, Ci Xue, Anthony J. Remijan, Michael C. Mccarthy in Science
Scientists have discovered a vast, previously unknown reservoir of new aromatic material in a cold, dark molecular cloud by detecting individual polycyclic aromatic hydrocarbon molecules in the interstellar medium for the first time, and in doing so are beginning to answer a three-decades-old scientific mystery: how and where are these molecules formed in space?
“We had always thought polycyclic aromatic hydrocarbons were primarily formed in the atmospheres of dying stars,” said Brett McGuire, Assistant Professor of Chemistry at the Massachusetts Institute of Technology, and the Project Principal Investigator for GOTHAM, or Green Bank Telescope (GBT) Observations of TMC-1: Hunting Aromatic Molecules. “In this study, we found them in cold, dark clouds where stars haven’t even started forming yet.”
Aromatic molecules, and PAHs — shorthand for polycyclic aromatic hydrocarbons — are well known to scientists. Aromatic molecules exist in the chemical makeup of human beings and other animals, and are found in food and medicines. As well, PAHs are pollutants formed from the burning of many fossil fuels and are even amongst the carcinogens formed when vegetables and meat are charred at high temperatures. “Polycyclic aromatic hydrocarbons are thought to contain as much as 25-percent of the carbon in the universe,” said McGuire, who is also a research associate at the Center for Astrophysics | Harvard & Smithsonian (CfA). “Now, for the first time, we have a direct window into their chemistry that will let us study in detail how this massive reservoir of carbon reacts and evolves through the process of forming stars and planets.”
Scientists have suspected the presence of PAHs in space since the 1980s but the new research, detailed in nine papers published over the past seven months, provides the first definitive proof of their existence in molecular clouds. To search out the elusive molecules, the team focused the 100m behemoth radio astronomy GBT on the Taurus Molecular Cloud, or TMC-1 — a large, pre-stellar cloud of dust and gas located roughly 450 light-years from Earth that will someday collapse in on itself to form stars — and what they found was astonishing: not only were the accepted scientific models incorrect, but there was a lot more going on in TMC-1 than the team could have imagined.
“From decades of previous modeling, we believed that we had a fairly good understanding of the chemistry of molecular clouds,” said Michael McCarthy, an astrochemist and Acting Deputy Director of CfA, whose research group made the precise laboratory measurements that enabled many of these astronomical detections to be established with confidence. “What these new astronomical observations show is these molecules are not only present in molecular clouds, but at quantities which are orders of magnitude higher than standard models predict.”
McGuire added that previous studies revealed only that there were PAH molecules out there, but not which specific ones. “For the last 30 years or so, scientists have been observing the bulk signature of these molecules in our galaxy and other galaxies in the infrared, but we couldn’t see which individual molecules made up that mass. With the addition of radio astronomy, instead of seeing this large mass that we can’t distinguish, we’re seeing individual molecules.”
Much to their surprise, the team didn’t discover just one new molecule hiding out in TMC-1. Detailed in multiple papers, the team observed 1-cyanonaphthalene, 1-cyano-cyclopentadiene, HC11N, 2-cyanonaphthalene, vinylcyanoacetylene, 2-cyano-cyclopentadiene, benzonitrile, trans-(E)-cyanovinylacetylene, HC4NC, and propargylcyanide, among others. “It’s like going into a boutique shop and just browsing the inventory on the front-end without ever knowing there was a back room. We’ve been collecting little molecules for 50 years or so and now we have discovered there’s a back door. When we opened that door and looked in, we found this giant warehouse of molecules and chemistry that we did not expect,” said McGuire. “There it was, all the time, lurking just beyond where we had looked before.”
McGuire and other scientists at the GOTHAM project have been “hunting” for molecules in TMC-1 for more than two years, following McGuire’s initial detection of benzonitrile in 2018. The results of the project’s latest observations may have ramifications in astrophysics for years to come. “We’ve stumbled onto a whole new set of molecules unlike anything we’ve previously been able to detect, and that is going to completely change our understanding of how these molecules interact with each other. It has downstream ramifications,” said McGuire, adding that eventually these molecules grow large enough that they begin to aggregate into the seeds of interstellar dust. “When these molecules get big enough that they’re the seeds of interstellar dust, these have the possibility then to affect the composition of asteroids, comets, and planets, the surfaces on which ices form, and perhaps in turn even the locations where planets form within star systems.”
The discovery of new molecules in TMC-1 also has implications for astrochemistry, and while the team doesn’t yet have all of the answers, the ramifications here, too, will last for decades. “We’ve gone from one-dimensional carbon chemistry, which is very easy to detect, to real organic chemistry in space in the sense that the newly discovered molecules are ones that a chemist knows and recognizes, and can produce on Earth,” said McCarthy. “And this is just the tip of the iceberg. Whether these organic molecules were synthesized there or transported there, they exist, and that knowledge alone is a fundamental advance in the field.”
Before the launch of GOTHAM in 2018, scientists had cataloged roughly 200 individual molecules in the Milky Way’s interstellar medium. These new discoveries have prompted the team to wonder, and rightly so, what’s out there. “The amazing thing about these observations, about this discovery, and about these molecules, is that no one had looked, or looked hard enough,” said McCarthy. “It makes you wonder what else is out there that we just haven’t looked for.”
This new aromatic chemistry that scientists are finding isn’t isolated to TMC-1. A companion survey to GOTHAM, known as ARKHAM — A Rigorous K/Ka-Band Survey Hunting for Aromatic Molecules — recently found benzonitrile in multiple additional objects. “Incredibly, we found benzonitrile in every single one of the first four objects observed by ARKHAM,” said Andrew Burkhardt, a Submillimeter Array Postdoctoral Fellow at the CfA and a co-principal investigator for GOTHAM. “This is important because while GOTHAM is pushing the limit of what chemistry we thought is possible in space, these discoveries imply that the things we learn in TMC-1 about aromatic molecules could be applied broadly to dark clouds anywhere. These dark clouds are the initial birthplaces of stars and planets. So, these previously invisible aromatic molecules will also need to be thought about at each later step along the way to the creation of stars, planets, and solar systems like our own.”
A radio telescope located in outback Western Australia has observed a cosmic phenomenon with a striking resemblance to a jellyfish
An Australian-Italian team used the Murchison Widefield Array (MWA) telescope to observe a cluster of galaxies known as Abell 2877.
Lead author and PhD candidate Torrance Hodgson, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) in Perth, said the team observed the cluster for 12 hours at five radio frequencies between 87.5 and 215.5 megahertz.
“We looked at the data, and as we turned down the frequency, we saw a ghostly jellyfish-like structure begin to emerge,” he said. “This radio jellyfish holds a world record of sorts. Whilst it’s bright at regular FM radio frequencies, at 200 MHz the emission all but disappears. No other extragalactic emission like this has been observed to disappear anywhere near so rapidly.”
This uniquely steep spectrum has been challenging to explain. “We’ve had to undertake some cosmic archaeology to understand the ancient background story of the jellyfish,” said Hodgson.
“Our working theory is that around 2 billion years ago, a handful of supermassive black holes from multiple galaxies spewed out powerful jets of plasma. This plasma faded, went quiet, and lay dormant. Then quite recently, two things happened — the plasma started mixing at the same time as very gentle shock waves passed through the system. This has briefly reignited the plasma, lighting up the jellyfish and its tentacles for us to see.”
The jellyfish is over a third of the Moon’s diameter when observed from Earth, but can only be seen with low-frequency radio telescopes.
“Most radio telescopes can’t achieve observations this low due to their design or location,” said Hodgson.
The MWA — a precursor to the Square Kilometre Array (SKA) — is located at CSIRO’s Murchison Radio-astronomy Observatory in remote Western Australia.
The site has been chosen to host the low-frequency antennas for the SKA, with construction scheduled to begin in less than a year.
Professor Johnston-Hollitt, Mr Hodgson’s supervisor and co-author, said the SKA will give us an unparalleled view of the low-frequency Universe.
“The SKA will be thousands of times more sensitive and have much better resolution than the MWA, so there may be many other mysterious radio jellyfish waiting to be discovered once it’s operational. We’re about to build an instrument to make a high resolution, fast frame-rate movie of the evolving radio Universe. It will show us from the first stars and galaxies through to the present day,” she said. “Discoveries like the jellyfish only hint at what’s to come, it’s an exciting time for anyone seeking answers to fundamental questions about the cosmos.”
The VLA Frontier Fields Survey: Deep, High-resolution Radio Imaging of the MACS Lensing Clusters at 3 and 6 GHz
by I. Heywood, E. J. Murphy, E. F. Jiménez-Andrade, L. Armus, W. D. Cotton, C. DeCoursey, M. Dickinson, T. J. W. Lazio, E. Momjian, K. Penner, I. Smail, O. M. Smirnov in arXiv.org
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The VLA Frontier Field Survey: A Comparison of the Radio and UV/optical size of 0.3≲z≲3 star-forming galaxies
by E. F. Jiménez-Andrade, E. J. Murphy, I. Heywood, I. Smail, K. Penner, E. Momjian, M. Dickinson, L. Armus, T. J. W. Lazio in arXiv.org
Radio telescopes are the world’s most sensitive radio receivers, capable of finding extremely faint wisps of radio emission coming from objects at the farthest reaches of the universe. Recently, a team of astronomers used the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to take advantage of a helping hand from nature to detect a distant galaxy that likely is the faintest radio-emitting object yet found.
The discovery was part of the VLA Frontier Fields Legacy Survey, led by NRAO Astronomer Eric Murphy, which used distant clusters of galaxies as natural lenses to study objects even farther away. The clusters served as gravitational lenses, using the gravitational pull of the galaxies in the clusters to bend and magnify light and radio waves coming from the more-distant objects.
In this composite, a VLA radio image is superimposed on a visible-light image from the Hubble Space Telescope. The prominent red-orange objects are radio relics — large structures possibly caused by shock waves — inside the foreground galaxy cluster, called MACSJ0717.5+3745, which is more than 5 billion light-years from Earth.
Detailed VLA observations showed that many of the galaxies in this image are emitting radio waves in addition to visible light. The VLA data revealed that one of these galaxies, shown in the pullout, is more than 8 billion light-years distant. Its light and radio waves have been bent by the intervening cluster’s gravitational-lensing effect.
The radio image of this distant galaxy, called VLAHFF-J071736.66+374506.4, has been magnified more than 6 times by the gravitational lens, the astronomers said. That magnification is what allowed the VLA to detect it.
“This probably is the faintest radio-emitting object ever detected,” said Ian Heywood, of Oxford University in the UK. “This is exactly why we want to use these galaxy clusters as powerful cosmic lenses to learn more about the objects behind them.”
“The magnification provided by the gravitational lens, combined with extremely sensitive VLA imaging, gave us an unprecedented look at the structure of a galaxy 300 times less massive than our Milky Way at a time when the universe was less than half its current age. This is giving us valuable insights on star formation in such low-mass galaxies at that time and how they eventually assembled into more massive galaxies,” said Eric Jimenez-Andrade, of NRAO.
The MUSE Extremely Deep Field: The cosmic web in emission at high redshift
by R. Bacon, D. Mary, T. Garel, J. Blaizot, M. Maseda, J. Schaye, L. Wisotzki, S. Conseil, J. Brinchmann, F. Leclercq, V. Abril-Melgarejo, L. Boogaard, N. F. Bouché, T. Contini, A. Feltre, B. Guiderdoni, C. Herenz, W. Kollatschny, H. Kusakabe, J. Matthee, L. Michel-Dansac, T. Nanayakkara, J. Richard, M. Roth, K. B. Schmidt, M. Steinmetz, L. Tresse, T. Urrutia, A. Verhamme, P. M. Weilbacher, J. Zabl, S. L. Zoutendijk in Astronomy & Astrophysics
Although the filaments of gas in which galaxies are born have long been predicted by cosmological models, we have so far had no real images of such objects. Now for the first time, several filaments of the ‘cosmic web’ have been directly observed using the MUSE (1) instrument installed on ESO’s Very Large Telescope in Chile. These observations of the early Universe, 1 to 2 billion years after the Big Bang, point to the existence of a multitude of hitherto unsuspected dwarf galaxies. Carried out by an international collaboration led by the Centre de Recherche Astrophysique de Lyon (CNRS/Université Lyon 1/ENS de Lyon), also involving the Lagrange laboratory (CNRS/Université Côte d’Azur/Observatoire de la Côte d’Azur) (2).
The filamentary structure of hydrogen gas in which galaxies form, known as the cosmic web, is one of the major predictions of the model of the Big Bang and of galaxy formation. Until now, all that was known about the web was limited to a few specific regions, particularly in the direction of quasars, whose powerful radiation acts like car headlights, revealing gas clouds along the line of sight. However, these regions are poorly representative of the whole network of filaments where most galaxies, including our own, were born. Direct observation of the faint light emitted by the gas making up the filaments was a holy grail which has now been attained by an international team headed by Roland Bacon, CNRS researcher at the Centre de Recherche Astrophysique de Lyon (CNRS/Université Lyon 1/ENS de Lyon).
The team took the bold step of pointing ESO’s Very Large Telescope, equipped with the MUSE instrument coupled to the telescope’s adaptive optics system, at a single region of the sky for over 140 hours. Together, the two instruments form one of the most powerful systems in the world. The region selected forms part of the Hubble Ultra-Deep Field, which was until now the deepest image of the cosmos ever obtained. However, Hubble has now been surpassed, since 40% of the galaxies discovered by MUSE have no counterpart in the Hubble images.
After meticulous planning, it took eight months to carry out this exceptional observing campaign. This was followed by a year of data processing and analysis, which for the first time revealed light from the hydrogen filaments, as well as images of several filaments as they were one to two billion years after the Big Bang, a key period for understanding how galaxies formed from the gas in the cosmic web. However, the biggest surprise for the team was when simulations showed that the light from the gas came from a hitherto invisible population of billions of dwarf galaxies spawning a host of stars (3). Although these galaxies are too faint to be detected individually with current instruments, their existence will have major consequences for galaxy formation models, with implications that scientists are only just beginning to explore.
Notes:
(1) MUSE, which stands for Multi Unit Spectroscopic Explorer, is a 3D spectrograph designed to explore the distant Universe. The construction of the instrument was led by the Centre de Recherche Astrophysique de Lyon (CNRS/Université Claude Bernard-Lyon 1/ENS de Lyon).
(2) Other French laboratories involved: Laboratoire d’Astrophysique de Marseille (CNRS/Aix-Marseille Université/CNES), Institut de Recherche en Astrophysique et Planétologie (CNRS/Université Toulouse III — Paul Sabatier/CNES).
(3) Until now, theory predicted that the light came from the diffuse cosmic ultraviolet background radiation (very weak background radiation produced by all the galaxies and stars) which, by heating the gas in the filaments, causes them to glow.
Atacama Cosmology Telescope: Modeling the gas thermodynamics in BOSS CMASS galaxies from kinematic and thermal Sunyaev-Zel’dovich measurements
by Stefania Amodeo, Nicholas Battaglia, Emmanuel Schaan, Simone Ferraro, Emily Moser, Simone Aiola, Jason E. Austermann, James A. Beall, Rachel Bean, Daniel T. Becker, Richard J. Bond, Erminia Calabrese, Victoria Calafut, et al. in Physical Review D
Using light from the Big Bang, an international team led by Cornell University and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory has begun to unveil the material which fuels galaxy formation.
“There is uncertainty on the formation of stars within galaxies that theoretical models are unable to predict,” said lead author Stefania Amodeo, a Cornell postdoctoral researcher in astronomy in the College of Arts and Sciences, who now conducts research at the Observatory of Strasbourg, France. “With this work, we are providing tests for galaxy formation models to comprehend galaxy and star formation.”
Proto galaxies are always full of gas and when they cool, the galaxies start to form, said senior author Nick Battaglia, assistant professor of astronomy at Cornell. “If we were to just do a back-of-the-envelope calculation, gas should turn into stars,” he said. “But it doesn’t.”
Galaxies are inefficient when they manufacture stars, Battaglia said. “About 10% of the gas — at most — in any given galaxy gets turned into stars,” he explained, “and we want to know why.”
The scientists can now check their longtime theoretical work and simulations, by looking at microwave observations with data and applying a 1970s-era mathematical equation. They’ve looked at data from Atacama Cosmology Telescope (ACT) — which observes the Big Bang’s static-filled cosmic microwave background (CMB) radiation — and search for the Sunyaev-Zel’dovich effects. That combination of data enables the scientists to map out the material around that indicate the formation of galaxies in various stages.
“How do galaxies form and evolve in our universe?” Battaglia said. “Given the nature of astronomy, we can’t sit and watch a galaxy evolve. We use various telescopic snapshots of galaxies — and each has its own evolution — and we try and stitch that information together. From there, we can extrapolate Milky Way formation.”
Effectively, the scientists are using the cosmic microwave background — remnants of the Big Bang — as a backlit screen that is 14 billion years old to find this material around galaxies.
“It’s like a watermark on a bank note,” said co-author Emmanuel Schaan, the Chamberlain postdoctoral fellow at the Lawrence Berkeley National Laboratory. “If you put it in front of a backlight then the watermark appears as a shadow. For us, the backlight is the cosmic microwave background. It serves to illuminate the gas from behind, so we can see the shadow as the CMB light travels through that gas.”
Together with Simone Ferraro, divisional fellow at Lawrence Berkeley, Schaan led the measurement part of the project.
“We’re making these measurements of this galactic material at distances from galaxy centers never before done,” Battaglia said. “These new observations are pushing the field.”
Top: comparison of the best-fit gas density (left) and thermal pressure (right) profiles (blue curves and 2σ bands) with the related profiles from two cosmological simulations: (magenta) and Illustris/TNG (orange and green), and a NFW profile (black). For the pressure profile, researchers also show the Planck 2013 best fit (maroon dotted line). They show average profiles, where each halo contribution is weighted by its mass according to the mass probability density function of the CMASS catalog used in this work, and at the same redshift (z=0.55). They select red galaxies from TNG and show both stellar mass- (orange) and halo mass-weighted average profiles. The vertical grey lines enclose the range where they measure the kSZ and the tSZ. Middle: projected density and pressure profiles, for comparison purposes. Bottom: comparison of the profiles projected into the kSZ (left) and tSZ (right) observable space with the measurements by in the ACT f150 band (blue points and 1σ error bars). The projections of the simulated and the NFW profiles account for the convolution with the ACT beam and the aperture photometry filtering. The black dashed curve shows the NFW profile truncated at the virial radius. The tSZ simulated profiles also include the dust correction from the ACT+Herschel measurements (2σ).
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