It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, September 20, 2024
SPACE / COSMOLOGY
Magnifying deep space through the “carousel lens”
A newly discovered cluster-scale strong gravitational lens, with a rare alignment of seven background lensed galaxies, provides a unique opportunity to study cosmology.
DOE/Lawrence Berkeley National Laboratory
image:
The Carousel Lens, as seen through the Hubble Space Telescope.
In a rare and extraordinary discovery, researchers have identified a unique configuration of galaxies that form the most exquisitely aligned gravitational lens found to date. The Carousel Lens is a massive cluster-scale gravitational lens system that will enable researchers to delve deeper into the mysteries of the cosmos, including dark matter and dark energy.
“This is an amazingly lucky ‘galactic line-up’ – a chance alignment of multiple galaxies across a line-of-sight spanning most of the observable universe,” said David Schlegel, a co-author of the study and a senior scientist in Berkeley Lab’s Physics Division. "Finding one such alignment is a needle in the haystack. Finding all of these is like eight needles precisely lined up inside that haystack."
The Carousel Lens is an alignment consisting of one foreground galaxy cluster (the ‘lens’) and seven background galaxies spanning immense cosmic distances and seen through the gravitationally distorted space-time around the lens. In the dramatic image below:
The lensing cluster, located 5 billion light years away from Earth, is shown by its four brightest and most massive galaxies (indicated by La, Lb, Lc, and Ld), and these constitute the foreground of the image.
Seven unique galaxies (numbered 1 through 7), appear through the lens. These are located far beyond, at distances from 7.6 to 12 billion light years away from Earth, approaching the limit of the observable universe.
Each galaxy’s repeated appearances (indicated by each number’s letter index, e.g., a through d) show differences in shape that are curved and stretched into multiple “fun house mirror” iterations caused by the warped space-time around the lens.
Of particular interest is the discovery of an Einstein Cross – the largest known to date – shown in galaxy number 4’s multiple appearances (indicated by 4a, 4b, 4c, and 4d). This rare configuration of multiple images around the center of the lens is an indication of the symmetrical distribution of the lens’ mass (dominated by invisible dark matter) and plays a key role in the lens-modeling process.
Light traveling from far-distant space can be magnified and curved as it passes through the gravitationally distorted space-time of nearer galaxies or clusters of galaxies. In rare instances, a configuration of objects aligns nearly perfectly to form a strong gravitational lens. Using an abundance of new data from the Dark Energy Spectroscopic Instrument (DESI)Legacy Imaging Surveys, recent observations from NASA’s Hubble Space Telescope, and the Perlmutter supercomputer at the National Energy Research Scientific Computing Center (NERSC), the research team built on their earlier studies (in May 2020 and Feb 2021) to identify likely strong lens candidates, laying the groundwork for the current discovery.
“Our team has been searching for strong lenses and modeling the most valuable systems,” explains Xiaosheng Huang, a study co-author and member of Berkeley Lab’s Supernova Cosmology Project, and a professor of physics and astronomy at the University of San Francisco. “The Carousel Lens is an incredible alignment of seven galaxies in five groupings that line up nearly perfectly behind the foreground cluster lens. As they appear through the lens, the multiple images of each of the background galaxies form approximately concentric circular patterns around the foreground lens, as in a carousel. It’s an unprecedented discovery, and the computational model generated shows a highly promising prospect for measuring the properties of the cosmos, including those of dark matter and dark energy.”
The study also involved several Berkeley Lab student researchers, including the lead author, William Sheu, an undergraduate student intern with DESI at the beginning of this study, now a PhD student at UCLA and a DESI collaborator.
The Carousel Lens will enable researchers to study dark energy and dark matter in entirely new ways based on the strength of the observational data and its computational model.
“This is an extremely unusual alignment, which by itself will provide a testbed for cosmological studies,” observes Nathalie Palanque-Delabrouille, director of Berkeley Lab’s Physics Division. “It also shows how the imaging done for DESI can be leveraged for other scientific applications,” such as investigating the mysteries of dark matter and the accelerating expansion of the universe, which is driven by dark energy.
Hubble Space Telescope image of the Carousel Lens, taken in two 10-minute exposures, one using an optical filter and another using an infrared filter. The “L” indicators near the center (La, Lb, Lc, and Ld) show the most massive galaxies in the lensing cluster, located 5 billion light years away. Seven unique galaxies (numbered 1 through 7) – located an additional 2.6 to 7 billion light years beyond the lens – appear in multiple, distorted “fun-house mirror” iterations (indicated by each number’s letter index, e.g., a through d), as seen through the lens.
Credit
William Sheu (UCLA) using Hubble Space Telescope data.
Lawrence Berkeley National Laboratory (Berkeley Lab) is committed to delivering solutions for humankind through research in clean energy, a healthy planet, and discovery science. Founded in 1931 on the belief that the biggest problems are best addressed by teams, Berkeley Lab and its scientists have been recognized with 16 Nobel Prizes. Researchers from around the world rely on the lab’s world-class scientific facilities for their own pioneering research. Berkeley Lab is a multiprogram national laboratory managed by the University of California for the U.S. Department of Energy’s Office of Science.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.
NJIT researchers awarded NSF grant to develop AI-powered solar eruption forecasting system
News Release New Jersey Institute of Technology
NJIT researchers have been awarded a $593,864 National Science Foundation grant to develop a new AI system for more quickly and accurately predicting when explosive space weather events on the Sun will strike, from solar flares to coronal mass ejections (CMEs).
The three-year project, led by Yan Xu at NJIT's Institute for Space Weather Sciences (ISWS) and Jason Wang at the university’s Ying Wu College of Computing, will develop AI-powered space weather forecasting capabilities that could offer solar researchers a new window into the complex magnetic processes in regions of the Sun's atmosphere that trigger such eruptions, and to this point, have rarely been observed.
According to the researchers, the new AI-powered forecasting system — called SolarDM — could boost early-warning detection of these eruptive events on Earth by days, while offering vital insights to the space weather science community as activity on our nearest star ramps up over the course of the current 11-year solar cycle, which began in 2019.
“Major solar eruptions are powered by magnetic processes taking place in the solar corona, where we’ve lacked critical data due to poor observation conditions and insufficient instruments,” said Xu, the project’s principal investigator and research professor at NJIT’s Center for Solar-Terrestrial Research. “Observations of the atmospheric layer underneath are crucial to study 3D magnetic fields. SolarDM’s data insights potentially give us a way to map the magnetic landscape of this region, allowing us to better predict these powerful eruptions."
Solar physicists have long studied the structure and evolution of magnetic fields in the corona (the Sun’s upper atmosphere). The breaking and reconnecting of these field lines are known to power explosive events capable of disrupting technologies on Earth, such as satellite operations.
However, challenges persist in observing the magnetic field conditions in the second layer of the Sun’s atmosphere, the chromosphere, a rarely visible region positioned above the lowest layer of the star’s atmosphere, the photosphere.
To address this, the NJIT team is leveraging advanced artificial intelligence to generate synthetic vector magnetograms — computer-generated images of magnetic field dynamics in both the photosphere and chromosphere — providing critical data that could shed light on the precursors to solar eruptions.
The SolarDM AI system will be trained using simulations of the Sun's magnetic field and observational data from NSF's Synoptic Optical Long-term Investigations of the Sun (SOLIS) — one of the world’s most advanced solar telescopes for long-term monitoring of the Sun, currently stationed at NJIT’s Big Bear Solar Observatory. In addition, data from NASA’s missions will be used to augment the training set.
“Due to the differences between the instruments on board the ground-based and space-borne observatories, it is extremely challenging to obtain high-quality alignments of the data needed for training and testing the AI system,” explained Wang. “The forecast horizon of state-of-the-art solar eruption forecasting systems is 24 hours. If successful, with SolarDM’s generated vector magnetograms, it is expected that the new AI system can extend the forecast horizon from 24 hours to three days.”
Ultimately, Xu and Wang say the AI modeling system will use the data not only to predict when and where eruptions are likely to occur across millions of miles of the solar atmosphere, but it will also explain why it has arrived at those conclusions.
“Insights into why the AI model is making its forecasts could significantly enhance our understanding of the underlying physics that are behind these powerful events,” noted Xu.
The NJIT project, "AI-Driven Generation of Vector Magnetograms in the Chromosphere and Photosphere with Application to Explainable Solar Eruption Predictions," will run from Sept. 15, 2024, to Aug. 31, 2027, as part of a broader wave of funding by NSF's Collaborations in Artificial Intelligence and Geosciences (CAIG) program.
The 25 NSF-CAIG projects — each integrating AI approaches with aspects of geoscience research — aim to enhance our understanding of complex Earth systems, improve natural hazard forecasting, and inform decision-making in the face of climate change, while driving the development of innovative AI techniques and expanding educational opportunities.
Credit: NASA SVS/Ernie Wright and Michaela Garrison
New NASA research reveals a process to generate extremely accurate eclipse maps, which plot the predicted path of the Moon’s shadow as it crosses the face of Earth. Traditionally, eclipse calculations assume that all observers are at sea level on Earth and that the Moon is a smooth sphere that is perfectly symmetrical around its center of mass. As such, these calculations do not take into account different elevations on Earth or the Moon’s cratered, uneven surface.
For slightly more accurate maps, people can employ elevation tables and plots of the lunar limb — the edge of the visible surface of the Moon as seen from Earth. However, now eclipse calculations have gained even greater accuracy by incorporating lunar topography data from NASA’s LRO (Lunar Reconnaissance Orbiter) observations.
Using LRO elevation maps, NASA visualizer Ernie Wright at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, created a continuously varying lunar limb profile as the Moon’s shadow passes over the Earth. The mountains and valleys along the edge of the Moon’s disk affect the timing and duration of totality by several seconds. Wright also used several NASA data sets to provide an elevation map of Earth so that eclipse observer locations were depicted at their true altitude.
The resulting visualizations show something never seen before: the true, time-varying shape of the Moon’s shadow, with the effects of both an accurate lunar limb and the Earth’s terrain.
“And people ask, why does it look like a potato instead of a smooth oval? The short answer is that the Moon isn’t a perfectly smooth sphere.”
The mountains and valleys around the edge of the Moon change the shape of the shadow. The valleys are also responsible for Baily’s beads and the diamond ring, the last bits of the Sun visible just before and the first just after totality.
Wright is lead author of a paper published Sept. 19 in The Astronomical Journal that reveals for the first time exactly how the Moon’s terrain creates the umbra shape. The valleys on the edge of the Moon act like pinholes projecting images of the Sun onto the Earth’s surface.
The umbra is the small hole in the middle of these projected Sun images, the place where none of the Sun images reach.
The edges of the umbra are made up of small arcs from the edges of the projected Sun images.
This is just one of several surprising results that have emerged from the new eclipse mapping method described in the paper. Unlike the traditional method invented 200 years ago, the new way renders eclipse maps one pixel at a time, the same way 3D animation software creates images. It’s also similar to the way other complex phenomena, like weather, are modeled in the computer by breaking the problem into millions of tiny pieces, something computers are really good at, and something that was inconceivable 200 years ago.
A Raster-oriented Method for Creating Eclipse Maps
Article Publication Date
19-Sep-2024
Viewed from behind the Moon, the Sun images projected by lunar valleys on the Moon’s edge fall on the Earth’s surface in a flower-like pattern with a hole in the middle, forming the umbra shape.
Credit
NASA SVS/Ernie Wright
Volcanoes may help reveal interior heat on Jupiter moon
Cornell University
ITHACA, N.Y. – By staring into the hellish landscape of Jupiter’s moon Io – the most volcanically active location in the solar system – Cornell University astronomers have been able to study a fundamental process in planetary formation and evolution: tidal heating.
“Tidal heating plays an important role in the heating and orbital evolution of celestial bodies,” said Alex Hayes, professor of astronomy. “It provides the warmth necessary to form and sustain subsurface oceans in the moons around giant planets like Jupiter and Saturn.”
“Studying the inhospitable landscape of Io’s volcanoes actually inspires science to look for life,” said lead author Madeline Pettine, a doctoral student in astronomy.
By examining flyby data from the NASA spacecraft Juno, the astronomers found that Io has active volcanoes at its poles that may help to regulate tidal heating – which causes friction – in its magma interior.
“The gravity from Jupiter is incredibly strong,” Pettine said. “Considering the gravitational interactions with the large planet’s other moons, Io ends up getting bullied, constantly stretched and scrunched up. With that tidal deformation, it creates a lot of internal heat within the moon.”
Pettine found a surprising number of active volcanoes at Io’s poles, as opposed to the more-common equatorial regions. The interior liquid water oceans in the icy moons may be kept liquefied by tidal heating, Pettine said.
In the north, a cluster of four volcanoes – Asis, Zal, Tonatiuh, one unnamed and an independent one named Loki – were highly active and persistent with a long history of space mission and ground-based observations. A southern group, the volcanoes Kanehekili, Uta and Laki-Oi demonstrated strong activity.
The long-lived quartet of northern volcanoes concurrently became bright and seemed to respond to one another. “They all got bright and then dim at a comparable pace,” Pettine said. “It’s interesting to see volcanoes and seeing how they respond to each other.
This research was funded by NASA’s New Frontiers Data Analysis Program and by the New York Space Grant.
Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere
Beijing Zhongke Journal Publising Co. Ltd.
image:
Illustration of the magnetic field configuration in the meridian plane under high BIMF and PSW conditions (a) and under low BIMF and PSW conditions (b). The tail current sheet is oriented perpendicular to the meridian plane. The red line indicates the position of the bow shock. Note that the shape of bow-shock is larger during low BIMF and PSW.
This study is led by Postdoctoral researcher Jiawei Gao from IGGCAS. Unlike Earth, Mars lacks a global dipolar magnetic field; the planet does have locally distributed crustal magnetic fields. Mars is exposed to the solar wind, which carries the Interplanetary Magnetic Field (IMF) that interacts with Mars’ highly conductive ionosphere, resulting in an induced magnetosphere. This study, recently featured on the front cover of Earth and Planetary Physics, reveals how the Red Planet's magnetic field responds to solar winds, providing key insights into atmospheric escape processes and Mars' climatic evolution.
An intriguing aspect of this emerging scenario is the question: How do variations in upstream solar wind conditions impact the topology of the low-altitude induced magnetic field on Mars? The induced field topology exhibits statistical variation in response to solar conditions, such as the IMF’s strength and direction, solar wind dynamic pressure, and solar extreme ultraviolet (EUV) flux, which vary with solar seasons. Given that the historical solar wind is believed to have been denser and faster than today’s conditions, normal solar wind conditions in the past may have resembled today’s extreme dynamic pressure events, such as those during coronal mass ejections (CMEs) and in co-rotating interaction regions (CIRs).
Depending on the solar conditions experienced by Mars in the past, the draped magnetic field may have routinely penetrated deep into the ionosphere, potentially leading to significantly higher rates of ionospheric escape to space for early Mars compared to the present day. Therefore, understanding how solar conditions influence the Martian ionospheric magnetic field, especially the penetration depth of the IMF, is crucial for elucidating the past history of Mars’s ion escape processes.
Using MAVEN data from November 2014 to May 2023, this research have investigated the distribution of magnetic field residuals in the Martian nightside ionosphere under four upstream solar wind drivers: the intensity of the IMF, solar wind dynamic pressure, solar extreme ultraviolet (EUV) flux, and Martian seasons. The key finding is: The magnetic field residuals in the Martian ionosphere show significant positive correlation with the intensity of the IMF and solar wind dynamic pressure; they are weakly correlated with EUV flux and Martian seasons. Specifically, the IMF can reach the 100−200 km altitude range under high and medium the intensity of the IMF and solar wind dynamic pressure.
"Our research not only advances our knowledge of Mars' present magnetic environment but also opens a window into its atmospheric past. By understanding how Mars' atmosphere responded to a more active early Sun, we can better conjecture the planet’s capacity to have supported life, enriching our quest for uncovering Mars' ancient secrets." Dr. Gao says.
See the article:
Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere
Influence of upstream solar wind on magnetic field distribution in the Martian nightside ionosphere
Study: Early dark energy could resolve cosmology’s two biggest puzzles
In the universe’s first billion years, this brief and mysterious force could have produced more bright galaxies than theory predicts
Massachusetts Institute of Technology
A new study by MIT physicists proposes that a mysterious force known as early dark energy could solve two of the biggest puzzles in cosmology and fill in some major gaps in our understanding of how the early universe evolved.
One puzzle in question is the “Hubble tension,” which refers to a mismatch in measurements of how fast the universe is expanding. The other involves observations of numerous early, bright galaxies that existed at a time when the early universe should have been much less populated.
Now, the MIT team has found that both puzzles could be resolved if the early universe had one extra, fleeting ingredient: early dark energy. Dark energy is an unknown form of energy that physicists suspect is driving the expansion of the universe today. Early dark energy is a similar, hypothetical phenomenon that may have made only a brief appearance, influencing the expansion of the universe in its first moments before disappearing entirely.
Some physicists have suspected that early dark energy could be the key to solving the Hubble tension, as the mysterious force could accelerate the early expansion of the universe by an amount that would resolve the measurement mismatch.
The MIT researchers have now found that early dark energy could also explain the baffling number of bright galaxies that astronomers have observed in the early universe. In their new study, reported in the Monthly Notices of the Royal Astronomical Society, the team modeled the formation of galaxies in the universe’s first few hundred million years. When they incorporated a dark energy component only in that earliest sliver of time, they found the number of galaxies that arose from the primordial environment bloomed to fit astronomers’ observations.
“You have these two looming open-ended puzzles,” says study co-author Rohan Naidu, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “We find that in fact, early dark energy is a very elegant and sparse solution to two of the most pressing problems in cosmology.”
The study’s co-authors include lead author and Kavli postdoc Xuejian (Jacob) Shen, and MIT professor of physics Mark Vogelsberger, along with Michael Boylan-Kolchin at the University of Texas at Austin, and Sandro Tacchella at the University of Cambridge.
Big city lights
Based on standard cosmological and galaxy formation models, the universe should have taken its time spinning up the first galaxies. It would have taken billions of years for primordial gas to coalesce into galaxies as large and bright as the Milky Way.
But in 2023, NASA’s James Webb Space Telescope (JWST) made a startling observation. With an ability to peer farther back in time than any observatory to date, the telescope uncovered a surprising number of bright galaxies as large as the modern Milky Way within the first 500 million years, when the universe was just 3 percent of its current age.
“The bright galaxies that JWST saw would be like seeing a clustering of lights around big cities, whereas theory predicts something like the light around more rural settings like Yellowstone National Park,” Shen says. “And we don’t expect that clustering of light so early on.”
For physicists, the observations imply that there is either something fundamentally wrong with the physics underlying the models or a missing ingredient in the early universe that scientists have not accounted for. The MIT team explored the possibility of the latter, and whether the missing ingredient might be early dark energy.
Physicists have proposed that early dark energy is a sort of antigravitational force that is turned on only at very early times. This force would counteract gravity’s inward pull and accelerate the early expansion of the universe, in a way that would resolve the mismatch in measurements. Early dark energy, therefore, is considered the most likely solution to the Hubble tension.
Galaxy skeleton
The MIT team explored whether early dark energy could also be the key to explaining the unexpected population of large, bright galaxies detected by JWST. In their new study, the physicists considered how early dark energy might affect the early structure of the universe that gave rise to the first galaxies. They focused on the formation of dark matter halos — regions of space where gravity happens to be stronger, and where matter begins to accumulate.
“We believe that dark matter halos are the invisible skeleton of the universe,” Shen explains. “Dark matter structures form first, and then galaxies form within these structures. So, we expect the number of bright galaxies should be proportional to the number of big dark matter halos.”
The team developed an empirical framework for early galaxy formation, which predicts the number, luminosity, and size of galaxies that should form in the early universe, given some measures of “cosmological parameters.” Cosmological parameters are the basic ingredients, or mathematical terms, that describe the evolution of the universe.
Physicists have determined that there are at least six main cosmological parameters, one of which is the Hubble constant — a term that describes the universe’s rate of expansion. Other parameters describe density fluctuations in the primordial soup, immediately after the Big Bang, from which dark matter halos eventually form.
The MIT team reasoned that if early dark energy affects the universe’s early expansion rate, in a way that resolves the Hubble tension, then it could affect the balance of the other cosmological parameters, in a way that might increase the number of bright galaxies that appear at early times. To test their theory, they incorporated a model of early dark energy (the same one that happens to resolve the Hubble tension) into an empirical galaxy formation framework to see how the earliest dark matter structures evolve and give rise to the first galaxies.
“What we show is, the skeletal structure of the early universe is altered in a subtle way where the amplitude of fluctuations goes up, and you get bigger halos, and brighter galaxies that are in place at earlier times, more so than in our more vanilla models,” Naidu says. “It means things were more abundant, and more clustered in the early universe.”
“A priori, I would not have expected the abundance of JWST’s early bright galaxies to have anything to do with early dark energy, but their observation that EDE pushes cosmological parameters in a direction that boosts the early-galaxy abundance is interesting,” says Marc Kamionkowski, professor of theoretical physics at Johns Hopkins University, who was not involved with the study. “I think more work will need to be done to establish a link between early galaxies and EDE, but regardless of how things turn out, it’s a clever — and hopefully ultimately fruitful — thing to try.”
“We demonstrated the potential of early dark energy as a unified solution to the two major issues faced by cosmology. This might be an evidence for its existence if the observational findings of JWST get further consolidated,” Vogelsberger concludes. “In the future, we can incorporate this into large cosmological simulations to see what detailed predictions we get.”
This research was supported, in part, by NASA and the National Science Foundation.
###
Written by Jennifer Chu, MIT News
Paper: “Early Galaxies and Early Dark Energy: A Unified Solution to the Hubble
Tension and Puzzles of Massive Bright Galaxies revealed by JWST”
Gravity map of Mars. The red circles show prominent volcanoes on Mars and the black circles show impact crates with a diameter larger than a few 100 km. A gravity high signal is located in the volcanic Tharsis Region (the red area in the centre right of the image), which is surrounded by a ring of negative gravity anomaly (shown in blue).
Studies of gravity variations at Mars have revealed dense, large-scale structures hidden beneath the sediment layers of a lost ocean. The analysis, which combines models and data from multiple missions, also shows that active processes in the martian mantle may be giving a boost to the largest volcano in the Solar System, Olympus Mons. The findings have been presented this week at the Europlanet Science Congress (EPSC) in Berlin by Bart Root of Delft University of Technology (TU Delft).
Mars has many hidden structures, such as ice deposits, but the features discovered in the northern polar plains are a mystery because they are covered with a thick and smooth sediment layer believed to deposited on ancient seabed.
“These dense structures could be volcanic in origin or could be compacted material due to ancient impacts. There are around 20 features of varying sizes that we have identified dotted around the area surrounding the north polar cap – one of which resembles the shape of a dog,” said Dr Root. “There seems to be no trace of them at the surface. However, through gravity data, we have a tantalising glimpse into the older history of the northern hemisphere of Mars.”
Dr Root and colleagues from TU Delft and Utrecht University used tiny deviations in the orbits of satellites to investigate the gravity field of Mars and find clues about the planet’s internal mass distribution. This data was fed into models that use new observations from NASA’s Insight mission on the thickness and flexibility of the martian crust, as well as the dynamics of the planet’s mantle and deep interior, to create a global density map of Mars.
The density map shows that the northern polar features are approximately 300-400 kg/m3 denser than their surroundings. However, the study has also revealed new insights into the structures underlying the huge volcanic region of Tharsis Rise, which includes the colossal volcano, Olympus Mons.
Although volcanoes are very dense, the Tharsis area is much higher than the average surface of Mars, and is ringed by a region of comparatively weak gravity. This gravity anomaly is hard to explain by looking at differences in the martian crust and upper mantle alone. The study by Dr Root and his team suggests that a light mass around 1750 kilometres across and at a depth of 1100 kilometres is giving the entire Tharsis region a boost upwards. This could be explained by huge plume of lava, deep within the martian interior, travelling up towards the surface.
“The NASA InSight mission has given us vital new information about the hard outer layer of Mars. This means we need to rethink how we understand the support for the Olympus Mons volcano and its surroundings,” said Dr Root. “It shows that Mars might still have active movements happening inside it, affecting and possibly making new volcanic features on the surface.”
Dr Root is part of the team proposing the Martian Quantum Gravity (MaQuls) mission, which aims to use technology developed for missions like GRAIL and GRACE on the Moon and Earth respectively to map in detail the gravity field of Mars.
“Observations with MaQuIs would enable us to better explore the subsurface of Mars. This would help us to find out more about these mysterious hidden features and study ongoing mantle convection, as well as understand dynamic surface processes like atmospheric seasonal changes and the detection of ground water reservoirs,” said Dr Lisa Wörner of DLR, who presented on the MaQuIs mission at EPSC2024 this week.
Map highlighting the dense gravitational structures in the northern hemisphere.
Map highlighting the dense gravitational structures in the northern hemisphere. The regions denoted by the black lines are high mass anomalies that do not show any correlation with geology and topography. These hidden subsurface structures are covered by sediments from an old ocean. Their origin is still a mystery and a dedicated gravity mission, like MaQuIs, is needed to reveal their nature.
Credit
Root et a
Super-Jupiter from the Great Bear
Nicolaus Copernicus University in Torun
image:
Artist's vision of a cold super-Jupiter in the HD 118203 system. It is an extremely massive gas planet orbiting its star in an orbit six times that of Earth. Astronomers believe it has very low temperatures
The scientists behind the discovery are from the Nicolaus Copernicus Univeristy Institute of Astronomy: dr habil. Gracjan Maciejewski, NCU Prof., prof. dr habil. Andrzej Niedzielski, prof. dr habil. Krzysztof Goździewski and a fifth-year astronomy student, Julia Sierzputowska. In collaboration with researchers from Spain and the United States, including Prof. Aleksander Wolszczan, they described the cosmic finding in the prestigious scientific journal "Astronomy & Astrophysics".
An inconspicuous star with a massive planet
We are dealing with an extremely massive exoplanet - as much as eleven times the mass of Jupiter, the largest planet in our Solar System. It orbits its parent star in 14 years, and is six astronomical units away from it (the astronomical unit [a.u.] is a conventional measure of distance used in astronomy, the average distance between the Earth and the Sun. It is 149,597,870.7 km. For example: The Moon is 0.026 a.u. from the Earth, while Jupiter is 5.2 a.u. from the Sun).
- We cannot see a planet, but we can spot the star around which it orbits - with a small telescope as small as 10 cm. The star's physical parameters are similar to those of the Sun. The data indicate that it is 20 percent more massive and twice as large as the Sun. Interestingly, it has already completed the stage of evolution that the Sun is currently in; it has a backyard '5 billion years behind it. We can therefore estimate that this is also the age of the entire planetary system,' explains dr habil. Gracjan Maciejewski, NCU Prof., leader of the research group from the NCU Institute of Astronomy. - It is located on the northern side of the sky in the Great Bear constellation and bears the designation HD 118203, because it was first listed in Henry Draper's stellar catalogue under this number. The telescope used to make the observations for this catalogue more than a century ago is now located in our observatory in Piwnice, near Torun.
The Draper telescope is one of the world's first astrographs, or photographic recorders of celestial sphere phenomena. It was built in 1891 as a 'memorial' to the prematurely deceased American spectroscopic physicist Henry Draper, with which his wife Anna Maria supported the Harvard Observatory's ambitious programme, led by Edward C. Pickering, to develop a catalogue of photographic and photovisual brightnesses of stars and their spectral classification. More than 60,000 photometric and spectral images of the sky were taken with this telescope in Cambridge, and it contributed so much to Pickering's intention that the compiled inventory containing almost a quarter of a million stars was called the Henry Draper catalogue. The 'HD' star designations are still used today and are familiar to all astronomers around the world.
How did Draper's astrograph find its way to Piwnice? In autumn 1947, the construction of the first observatory pavilion of the NCU Astronomical Observatory with a rotating dome of five metres in diameter began. Two years later, an astrograph sent from Cambridge stood there and, after the necessary adaptations, began regular observational work.
Today this interesting monument, unique in the world, has become an attraction for visitors to the NCU Institute of Astronomy in Piwnice.
Patience pays off
For nearly 20 years, astronomers have known that the star HD 118203 orbits a fairly massive planet. In 2006, the first gas giant was discovered, with a mass of two Jupiter masses, orbiting the star in a tight orbit in just six days.
Doppler observations, however, indicated that this was not the end of the story, that there might be another planet out there. Therefore, we immediately included this system in our observational programmes,' says Prof. Andrzej Niedzielski, co-author of the discovery. – At first, as part of the Torun-Pennsylvania exoplanet research programme, conducted in collaboration with Professor Aleksander Wolszczan, we tracked the object with one of the largest optical instruments on Earth, the nine-metre Hobby-Eberly Telescope in Texas.
The results were so promising that the Torunians, with collaborators from Spain, continued observations of the star in the Canary Islands, using the Italian Galileo telescope. This observatory was equipped with the best instrumentation designed to discover planets.
- However, eight years of research have not provided an answer as to what type of an object it is, ' adds Prof. Niedzielski.
It took another seven years for astronomers in Torun to obtain indisputable evidence that they were dealing with a planet.
Patience pays off,' says Prof. Maciejewski. - The new observations collected in March 2023 proved crucial in determining the planet's orbital parameters. Moreover, because it takes a planet several years to orbit its star, we were able to combine our Doppler observations with available astrometric measurements to unambiguously determine its mass. This allowed us to build a complete model of this planetary system and study its dynamical behaviour.
Before that, however, it was necessary to make sure that there were no more planets hiding in the system. This task was undertaken by Julia Sierzputowska, a student of astronomy.
I analysed photometric observations obtained with the Transiting Exoplanet Survey Satellite space telescope, showing that there were no other planets around HD 118203 larger than twice the size of Earth, and therefore not massive enough to be relevant for studying the dynamics of the system.
Planetary tandem
It turned out that the astronomers had discovered a hierarchical planetary system.
It is a peculiar configuration in which one planet forms a tight pair with its star, and a second planet orbits the pair in an orbit wide enough to, as it were, form another pair with the first one,' explains Prof. Krzysztof Goździewski, who conducted detailed numerical studies of the system's dynamics.
Both planets are massive and orbit in rather elongated orbits. Despite this, their mutual gravitational influence does not destabilise the system on a scale of millions of years.
- We have shown that this is due to effects arising from the general theory of relativity. If it were not for these effects, the planets would behave like jittery springs, constantly changing the shape of their orbits and their orientation in space,' adds Prof. Goździewski.
Cosmic answers
Astronomers admit that knowledge of the formation and evolution of planetary systems still hides many fundamental unknowns. Hierarchical systems like HD 118203, of which only a dozen are known, allow them to probe hypotheses for the formation of massive planets.
An interesting question is about the paths of development of such planetary configurations,' says Prof. Maciejewski. - Although from our point of view - inhabitants of the Solar System - they are quite 'exotic', learning about systems with massive gaseous planets seems important so that we can get to know our nearest, 'astronomical backyard'.
- Our work does not end. We are still conducting observations and analysing data - there are chances for further planetary discoveries,' says Prof Niedzielski. - It is gratifying that we manage to involve students and doctoral students in this interesting and important research.
Henry Draper's Astrograph (1891)
The Draper telescope is one of the world's first astrographs, or photographic recorders of celestial sphere phenomena. It was built in 1891 as a 'memorial' to the prematurely deceased American spectroscopic physicist Henry Draper, with which his wife Anna Maria supported the Harvard Observatory's ambitious programme, led by Edward C. Pickering, to develop a catalogue of photographic and photovisual brightnesses of stars and their spectral classification. More than 60,000 photometric and spectral images of the sky were taken with this telescope in Cambridge, and it contributed so much to Pickering's intention that the compiled inventory containing almost a quarter of a million stars was called the Henry Draper catalogue. The 'HD' star designations are still used today and are familiar to all astronomers around the world.
How did Draper's astrograph find its way to Piwnice (Poland)? In autumn 1947, the construction of the first observatory pavilion of the NCU Astronomical Observatory with a rotating dome of five metres in diameter began. Two years later, an astrograph sent from Cambridge stood there and, after the necessary adaptations, began regular observational work.
Today this interesting monument, unique in the world, has become an attraction for visitors to the NCU Institute of Astronomy in Piwnice.
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