Physicists confirm effective wave growth theory in space

Peer-Reviewed Publication

NAGOYA UNIVERSITY

 

IMAGE: WHISTLER-MODE WAVE MAGNETIC FIELD (BLUE ARROWS WITH SPIRAL) PROPAGATING ALONG THE MAGNETIC FIELD (PURPLE) INTERACTING WITH ELECTRONS (RED) PASSING THROUGH IT. view more 

CREDIT: UNIVERSITY OF TOKYO

A team from Nagoya University in Japan has observed, for the first time, the energy transferring from resonant electrons to whistler-mode waves in space. Their findings offer direct evidence of previously theorized efficient growth, as predicted by the non-linear growth theory of waves. This should improve our understanding of not only space plasma physics but also space weather, a phenomenon that affects satellites. 

When people imagine outer space, they often envision it as a perfect vacuum. In fact, this impression is wrong because the vacuum is filled with charged particles. In the depths of space, the density of charged particles becomes so low that they rarely collide with each other. Instead of collisions, the forces related to the electric and magnetic fields filling space, control the motion of charged particles. This lack of collisions occurs throughout space, except for very near to celestial objects, such as stars, moons, or planets. In these cases, the charged particles are no longer traveling through the vacuum of space but instead through a medium where they can strike other particles. 

Around the Earth, these charged-particle interactions generate waves, including electromagnetic whistler-mode waves, which scatter and accelerate some of the charged particles. When diffuse auroras appear around the poles of planets, observers are seeing the results of an interaction between waves and electrons. Since electromagnetic fields are so important in space weather, studying these interactions should help scientists predict variations in the intensity of highly energetic particles. This might help protect astronauts and satellites from the most severe effects of space weather.  

A team comprising Designated Assistant Professor Naritoshi Kitamura and Professor Yoshizumi Miyoshi of the Institute for Space and Earth Science (ISEE) at Nagoya University, together with researchers from the University of Tokyo, Kyoto University, Tohoku University, Osaka University, and Japan Aerospace Exploration Agency (JAXA), and several international collaborators, mainly used data obtained using low-energy electron spectrometers, called Fast Plasma Investigation-Dual Electron Spectrometers, on board NASA’s Magnetospheric Multiscale spacecraft. They analyzed interactions between electrons and whistler-mode waves, which were also measured by the spacecraft. By applying a method of using a wave particle interaction analyzer, they succeeded in directly detecting the ongoing energy transfer from resonant electrons to whistler-mode waves at the location of the spacecraft in space. From this, they derived the growth rate of the wave. The researchers published their results in Nature Communications. 

The most important finding was that the observed results were consistent with the hypothesis that non-linear growth occurs in this interaction. “This is the first time anybody has directly observed the efficient growth of waves in space for the wave-particle interaction between electrons and whistler-mode waves,” explains Kitamura. “We expect that the results will contribute to research on various wave-particle interactions and to also improve our understanding of the progress of plasma physics research. As more specific phenomena, the results will contribute to our understanding of the acceleration of electrons to high energies in the radiation belt, which are sometimes called ‘killer electrons’ because they inflict damage on satellites, as well as the loss of high-energy electrons in the atmosphere, which form diffuse auroras.” 

//Funding// 

This work was supported by Grant-in-Aid for Scientific Research (17H06140, 18H03727, 21K13979) from Japan Society for the Promotion of Science. 

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JOURNAL

Nature Communications

DOI

10.1038/s41467-022-33604-2 

ARTICLE TITLE

Direct observations of energy transfer from resonant electrons to whistler-mode waves in magnetosheath of Earth

NASA missions find ‘jetlets’ could power the solar wind

Peer-Reviewed Publication

NASA/GODDARD SPACE FLIGHT CENTER

 

IMAGE: IN THE CENTER, A GOLD, ROTATING SUN. GOLD AND BLACK SWIRLS ACROSS THE SURFACE OF THE SUN. AROUND THE EDGES, STREAMS OF GOLDEN SOLAR PARTICLES ESCAPE THE STAR, INTO SPACE. A COMPOSITE VIDEO FROM NASA’S SOLAR DYNAMICS OBSERVATORY AND NOAA’S GEOSTATIONARY OPERATIONAL ENVIRONMENTAL SATELLITE – R SERIES SOLAR ULTRAVIOLET IMAGER INSTRUMENT SHOWS SMALL-SCALE JETLET ACTIVITY AT THE BASE OF THE SOLAR CORONA, OR THE SUN’S UPPER ATMOSPHERE, AND ITS EXTENSION TO HIGHER ALTITUDES. THIS CAN BE SEEN IN THE WAVY STRUCTURES EMANATING FROM THE SURFACE OF THE SUN. THE OBSERVATIONS WERE MADE OVER THE COURSE OF APPROXIMATELY 10 HOURS ON APRIL 28, 2021. view more 

CREDIT: NASA/SDO/GOES-R

Scientists with NASA’s Parker Solar Probe mission have uncovered significant new clues about the origins of the solar wind – a continual stream of charged particles released from the Sun that fills the solar system.

Observations from multiple space and ground-based observatories show the solar wind could be largely fueled by small-scale jets, or “jetlets,” at the base of the corona – the Sun’s upper atmosphere. This finding is helping scientists better understand the 60-year-old mystery of what heats and accelerates the solar wind.

“This new data shows us how the solar wind gets going at its source,” said Nour Raouafi, the study lead and the Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “You can see the flow of the solar wind rising from tiny jets of million-degree plasma all over the base of the corona. These findings will have a huge impact on our understanding of the heating and acceleration of the coronal and solar wind plasma.”

Understanding the solar wind is fundamental to our understanding of our solar system and others throughout the universe – and is the primary science goal of the Parker Solar Probe mission. Made of electrons, protons, and heavier ions, the solar wind courses through the solar system at roughly 1 million miles per hour. When the solar wind interacts with Earth’s magnetic field, it can create stunning auroras as well as disruptions in GPS and communications systems. Over time, the solar wind, and stellar winds in other solar systems, can also affect the composition and evolution of planetary atmospheres – even influencing planets’ habitability. 

Strength in Numbers

At Earth, the solar wind is usually a constant breeze. Scientists have therefore been looking for a steady source at the Sun that could continually power the solar wind. However, the new findings – accepted for publication in the Astrophysical Journal and published on the ArXiv, an online preprint site – show the solar wind might be largely energized and fueled by individual jetlets that are intermittently erupting into the lower part of the corona. Though each jetlet is relatively small – just a few hundred miles long – their collective energy and mass could be enough to create the solar wind.

“This result implies that essentially all of the solar wind is likely released intermittently, becoming a steady flow in much the same way that the individual clapping sounds in an auditorium become a steady roar as an audience applauds,” said Craig DeForest, a solar physicist at the Southwest Research Institute in Boulder, Colorado, and coauthor on the new paper. “This changes the paradigm for how we think about certain aspects of the solar wind.” 

Jetlets, which were first observed over a decade ago, are known to be caused by a process known as magnetic reconnection, which occurs as magnetic field lines become tangled and explosively realign. Reconnection is a common process in charged gases called plasmas and is found across the universe from the Sun to near-Earth space to around black holes. In the solar corona, reconnection creates these short-lived jets of plasma that pass energy and material into the upper corona, which escape across the solar system as the solar wind.

To study the jetlets and magnetic fields, scientists primarily used observations from the Solar Dynamics Observatory (SDO) and the Geostationary Operational Environmental Satellite-R Series’ Solar Ultraviolet Imager (GOES-R/SUVI) instrument, as well as high-resolution magnetic field data from the Goode Solar Telescope at the Big Bear Solar Observatory in California. The whole study was driven by a phenomenon first observed by Parker Solar Probe called switchbacks – magnetic zig-zag structures in the solar wind. The combination of observations from many viewpoints, along with the high resolution of those views and Parker Solar Probe’s up-close observations, helped the scientists understand the collective behavior of the jetlets.

“Previously, we could not detect enough such events to explain the observed amount of mass and energy streaming from the Sun,” said Judy Karpen, coauthor on the paper and heliophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But the improved resolution of the observations and meticulous data processing enabled the new findings.” 

The observations showed that jetlets are present in the lower solar atmosphere across the entire Sun. This makes them a tenable driver for the constant solar wind, as opposed to other phenomena that wax and wane with the 11-year cycle of solar activity, such as solar flares and coronal mass ejections. Furthermore, the scientists calculated that the energy and mass produced by the jetlets could provide most, if not all, of the amount of energy and mass seen in the solar wind.

A Breakthrough Decades in the Making

The solar wind was first proposed in the late 1950s by the visionary scientist Eugene Parker, namesake of the Parker Solar Probe. In 1988, Parker proposed the corona could be heated by “nanoflares,” tiny explosions on the solar atmosphere. Parker's theory eventually became a leading candidate to explain the heating and acceleration of the solar wind.

“The tiny reconnection events we observed are, in a way, what Eugene Parker proposed over three decades ago,” Raouafi said. “I am convinced that we are on the right path toward understanding the solar wind and coronal heating.”

Continued observations from Parker Solar Probe and other instruments such as NASA’s Polarimeter to Unify the Corona and Heliosphere, or PUNCH, and the Daniel K. Inouye Solar Telescope, will help scientists confirm whether jetlets are the main source of solar wind. 

“The findings make it much easier to explain how the solar wind is accelerated and heated,” DeForest said. “We’re not finished with the puzzle yet, but this is a major step forward for understanding a central mystery of solar physics.”

Parker Solar Probe was developed as part of NASA’s Living With a Star program to explore aspects of the Sun-Earth system that directly affect life and society. The Living With a Star program is managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland, for NASA’s Science Mission Directorate in Washington. The Johns Hopkins Applied Physics Laboratory designed, built, manages, and operates the spacecraft.

NASA's TESS discovers planetary system’s second earth-size world

Reports and Proceedings

NASA/GODDARD SPACE FLIGHT CENTER

 

IMAGE: NEWLY DISCOVERED EARTH-SIZE PLANET TOI 700 E ORBITS WITHIN THE HABITABLE ZONE OF ITS STAR IN THIS ILLUSTRATION. ITS EARTH-SIZE SIBLING, TOI 700 D, CAN BE SEEN IN THE DISTANCE. view more 

CREDIT: NASA/JPL-CALTECH/ROBERT HURT

Using data from NASA’s Transiting Exoplanet Survey Satellite, scientists have identified an Earth-size world, called TOI 700 e, orbiting within the habitable zone of its star – the range of distances where liquid water could occur on a planet’s surface. The world is 95% Earth’s size and likely rocky.

Astronomers previously discovered three planets in this system, called TOI 700 b, c, and d. Planet d also orbits in the habitable zone. But scientists needed an additional year of TESS observations to discover TOI 700 e.

“This is one of only a few systems with multiple, small, habitable-zone planets that we know of,” said Emily Gilbert, a postdoctoral fellow at NASA’s Jet Propulsion Laboratory in Southern California who led the work. “That makes the TOI 700 system an exciting prospect for additional follow up. Planet e is about 10% smaller than planet d, so the system also shows how additional TESS observations help us find smaller and smaller worlds.”

Gilbert presented the result on behalf of her team at the 241st meeting of the American Astronomical Association in Seattle. A paper about the newly discovered planet was accepted by The Astrophysical Journal Letters.

TOI 700 is a small, cool M dwarf star located around 100 light-years away in the southern constellation Dorado. In 2020, Gilbert and others announced the discovery of the Earth-size, habitable-zone planet d, which is on a 37-day orbit, along with two other worlds.

The innermost planet, TOI 700 b, is about 90% Earth’s size and orbits the star every 10 days. TOI 700 c is over 2.5 times bigger than Earth and completes an orbit every 16 days. The planets are probably tidally locked, which means they spin only once per orbit such that one side always faces the star, just as one side of the Moon is always turned toward Earth.

TESS monitors large swaths of the sky, called sectors, for approximately 27 days at a time. These long stares allow the satellite to track changes in stellar brightness caused by a planet crossing in front of its star from our perspective, an event called a transit. The mission used this strategy to observe the southern sky starting in 2018, before turning to the northern sky. In 2020, it returned to the southern sky for additional observations. The extra year of data allowed the team to refine the original planet sizes, which are about 10% smaller than initial calculations.

“If the star was a little closer or the planet a little bigger, we might have been able to spot TOI 700 e in the first year of TESS data,” said Ben Hord, a doctoral candidate at the University of Maryland, College Park and a graduate researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But the signal was so faint that we needed the additional year of transit observations to identify it.”

TOI 700 e, which may also be tidally locked, takes 28 days to orbit its star, placing planet e between planets c and d in the so-called optimistic habitable zone.

Scientists define the optimistic habitable zone as the range of distances from a star where liquid surface water could be present at some point in a planet’s history. This area extends to either side of the conservative habitable zone, the range where researchers hypothesize liquid water could exist over most of the planet’s lifetime. TOI 700 d orbits in this region.

Finding other systems with Earth-size worlds in this region helps planetary scientists learn more about the history of our own solar system.

Follow-up study of the TOI 700 system with space- and ground-based observatories is ongoing, Gilbert said, and may yield further insights into this rare system.

“TESS just completed its second year of northern sky observations,” said Allison Youngblood, a research astrophysicist and the TESS deputy project scientist at Goddard. “We’re looking forward to the other exciting discoveries hidden in the mission’s treasure trove of data.”

TESS is a NASA Astrophysics Explorer mission led and operated by Massachusetts Institute of Technology in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts; MIT’s Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

Planetary defense and science will advance with new radar on green bank telescope

With less power than a microwave, prototype produced highest resolution images of Moon ever captured from Earth

Reports and Proceedings

GREEN BANK OBSERVATORY

With a transmitter less powerful than a microwave oven, a team of scientists and engineers used the National Science Foundation's Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA) to make the highest-resolution radar images of the Moon ever collected from the ground, paving the way for a next-generation radar system to study planets, moons, and asteroids in the Solar System.

The National Radio Astronomy Observatory (NRAO), Green Bank Observatory (GBO), and Raytheon Intelligence & Space (RIS) are designing a high-power, next generation planetary radar system for the GBT, the world’s largest fully steerable radio telescope. The prototype of this system produced some of the highest resolution planetary radar images ever captured from Earth.

A low-power radar transmitter, with up to 700 watts of output power at 13.9 GHz, designed by RIS was tested on the GBT, aimed at the Moon’s surface, and radar echoes were received with NRAO’s ten 25-meter VLBA antennas. An image of the Tycho crater was captured with 5-meter resolution, showing unprecedented detail of the Moon’s surface from Earth. “It’s pretty amazing what we’ve been able to capture so far, using less power than a common household appliance,” emphasizes Patrick Taylor, radar division head for GBO and NRAO.

Design work continues for the flagship system, a 500 kilowatt, Ku-band (13.7 GHz) planetary radar for the GBT using the VLBA and the future Next Generation Very Large Array (ngVLA) as receivers. This high-power system would have nearly 1000 times the output power and several times the waveform bandwidth (up to 600 MHz) allowing for even higher resolution imaging.

A system like this will serve in the frontline of planetary defense, able to detect, track, and characterize potentially hazardous objects that may be on a crash course with Earth. “In our tests, we were able to zero in on an asteroid 2.1 million kilometers away from us—more than 5 times the distance from the Earth to the Moon. The asteroid is about a kilometer in size, which is large enough to cause global devastation should there be an impact,” adds Taylor, “With the high-power system, we could study more objects much further away. When it comes to developing strategies for possible impacts, having more warning time is everything.” These capabilities recently came in handy to support NASA’s Double Asteroid Redirection Test (DART) mission, with GBT data confirming that the impact of NASA’s DART spacecraft with an asteroid had indeed altered its course in the first demonstration of asteroid deflection technology. 

Astronomers also will find this tool useful for astrometry, imaging, and physical and dynamical characterization of solar system objects for planetary science. In the near term, integration of a medium-power, Ku-band transmitter (of at least 10 kW) would develop an end-to-end system at GBO/NRAO for real-time radar observations and lay the foundation for the flagship high-power system.

The GBT’s new radar capabilities will introduce a tool that astronomy has not had before, collecting data at higher resolutions and at wavelengths not previously available. NRAO and GBO are also developing advanced data reduction and analysis tools that have not been available before. Shares Taylor, “At NRAO and GBO, we have a long history of participation in planetary radar studies, and we look forward to adding new capabilities to the GBT and VLBA to produce a next-generation radar system that will serve as valuable tool for researchers in planetary science and planetary defense.”

The Green Bank Observatory is a major facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

ICYMI

Astronomers find the most distant stars in our galaxy halfway to Andromeda

A search for variable stars called RR Lyrae has found some of the most distant stars in the Milky Way’s halo a million light years away

Reports and Proceedings

UNIVERSITY OF CALIFORNIA - SANTA CRU

 

IMAGE: THIS ILLUSTRATION SHOWS THE MILKY WAY GALAXY'S INNER AND OUTER HALOS. A HALO IS A SPHERICAL CLOUD OF STARS SURROUNDING A GALAXY. view more 

CREDIT: NASA, ESA, AND A. FEILD (STSCI)

Astronomers have discovered more than 200 distant variable stars known as RR Lyrae stars in the Milky Way’s stellar halo. The most distant of these stars is more than a million light years from Earth, almost half the distance to our neighboring galaxy, Andromeda, which is about 2.5 million light years away.

The characteristic pulsations and brightness of RR Lyrae stars make them excellent “standard candles” for measuring galactic distances. These new observations allowed the researchers to trace the outer limits of the Milky Way’s halo.

“This study is redefining what constitutes the outer limits of our galaxy,” said Raja GuhaThakurta, professor and chair of astronomy and astrophysics at UC Santa Cruz. “Our galaxy and Andromeda are both so big, there’s hardly any space between the two galaxies.”

GuhaThakurta explained that the stellar halo component of our galaxy is much bigger than the disk, which is about 100,000 light years across. Our solar system resides in one of the spiral arms of the disk. In the middle of the disk is a central bulge, and surrounding it is the halo, which contains the oldest stars in the galaxy and extends for hundreds of thousands of light years in every direction.

“The halo is the hardest part to study because the outer limits are so far away,” GuhaThakurta said. “The stars are very sparse compared to the high stellar densities of the disk and the bulge, but the halo is dominated by dark matter and actually contains most of the mass of the galaxy.”

Yuting Feng, a doctoral student working with GuhaThakurta at UCSC, led the new study and is presenting their findings in two talks at the American Astronomical Society meeting in Seattle on January 9 and 11.

According to Feng, previous modeling studies had calculated that the stellar halo should extend out to around 300 kiloparsecs or 1 million light years from the galactic center. (Astronomers measure galactic distances in kiloparsecs; one kiloparsec is equal to 3,260 light years.) The 208 RR Lyrae stars detected by Feng and his colleagues ranged in distance from about 20 to 320 kiloparsecs.

“We were able to use these variable stars as reliable tracers to pin down the distances,” Feng said. “Our observations confirm the theoretical estimates of the size of the halo, so that’s an important result.”

The findings are based on data from the Next Generation Virgo Cluster Survey (NGVS), a program using the Canada-France-Hawaii Telescope (CFHT) to study a cluster of galaxies well beyond the Milky Way. The survey was not designed to detect RR Lyrae stars, so the researchers had to dig them out of the dataset. The Virgo Cluster is a large cluster of galaxies that includes the giant elliptical galaxy M87.

“To get a deep exposure of M87 and the galaxies around it, the telescope also captured the foreground stars in the same field, so the data we used are sort of a by-product of that survey,” Feng explained.

According to GuhaThakurta, the excellent quality of the NGVS data enabled the team to obtain the most reliable and precise characterization of RR Lyrae at these distances. RR Lyrae are old stars with very specific physical properties that cause them to expand and contract in a regularly repeating cycle.

“The way their brightness varies looks like an EKG—they’re like the heartbeats of the galaxy—so the brightness goes up quickly and comes down slowly, and the cycle repeats perfectly with this very characteristic shape,” GuhaThakurta said. “In addition, if you measure their average brightness, it is the same from star to star. This combination is fantastic for studying the structure of the galaxy.”

The sky is full of stars, some brighter than others, but a star may look bright because it is very luminous or because it is very close, and it can be hard to tell the difference. Astronomers can identify an RR Lyrae star from its characteristic pulsations, then use its observed brightness to calculate how far away it is. The procedures are not simple, however. More distant objects, such as quasars, can masquerade as RR Lyrae stars.

“Only astronomers know how painful it is to get reliable tracers of these distances,” Feng said. “This robust sample of distant RR Lyrae stars gives us a very powerful tool for studying the halo and testing our current models of the size and mass of our galaxy.”

This study is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/IRFU, at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii.

ALMA scientists find pair of black holes dining together in nearby galaxy merger

Peer-Reviewed Publication

NATIONAL RADIO ASTRONOMY OBSERVATORY

 

IMAGE: SCIENTISTS USING THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY (ALMA) TO LOOK DEEP INTO THE HEART OF THE PAIR OF MERGING GALAXIES KNOWN AS UGC 4211 DISCOVERED TWO BLACK HOLES GROWING SIDE BY SIDE, JUST 750 LIGHT-YEARS APART. THIS ARTIST’S CONCEPTION SHOWS THE LATE-STAGE GALAXY MERGER AND ITS TWO CENTRAL BLACK HOLES. THE BINARY BLACK HOLES ARE THE CLOSEST TOGETHER EVER OBSERVED IN MULTIPLE WAVELENGTHS. view more 

CREDIT: ALMA (ESO/NAOJ/NRAO); M. WEISS (NRAO/AUI/NSF)

While studying a nearby pair of merging galaxies using the Atacama Large Millimeter/submillimeter Array (ALMA)— an international observatory co-operated by the U.S. National Science Foundation’s National Radio Astronomy Observatory (NRAO)— scientists discovered two supermassive black holes growing simultaneously near the center of the newly coalescing galaxy. These super-hungry giants are the closest together that scientists have ever observed in multiple wavelengths. What’s more, the new research reveals that binary black holes and the galaxy mergers that create them may be surprisingly commonplace in the Universe. The results of the new research were published today in The Astrophysical Journal Letters, and presented in a press conference at the 241st meeting of the American Astronomical Society (AAS) in Seattle, Washington.

At just 500 million light-years away from Earth in the constellation Cancer, UGC4211 is an ideal candidate for studying the end stages of galaxy mergers, which occur more frequently in the distant Universe, and as a result, can be difficult to observe. When scientists used the highly sensitive 1.3mm receivers at ALMA to look deep into the merger’s active galactic nuclei— compact, highly luminous areas in galaxies caused by the accretion of matter around central black holes— they found not one, but two black holes gluttonously devouring the byproducts of the merger. Surprisingly, they were dining side-by-side with just 750 light-years between them.

“Simulations suggested that most of the population of black hole binaries in nearby galaxies would be inactive because they are more common, not two growing black holes like we found,” said Michael Koss, a senior research scientist at Eureka Scientific and the lead author of the new research. 

Koss added that the use of ALMA was a game-changer, and that finding two black holes so close together in the nearby Universe could pave the way for additional studies of the exciting phenomenon. “ALMA is unique in that it can see through large columns of gas and dust and achieve very high spatial resolution to see things very close together. Our study has identified one of the closest pairs of black holes in a galaxy merger, and because we know that galaxy mergers are much more common in the distant Universe, these black hole binaries too may be much more common than previously thought.” 

If close-paired binary black hole pairs are indeed commonplace, as Koss and the team posit, there could be significant implications for future detections of gravitational waves.

Ezequiel Treister, an astronomer at Universidad Católica de Chile and a co-author of the research said, “​​There might be many pairs of growing supermassive black holes in the centers of galaxies that we have not been able to identify so far. If this is the case, in the near future we will be observing frequent gravitational wave events caused by the mergers of these objects across the Universe.”

Pairing ALMA data with multi-wavelength observations from other powerful telescopes like Chandra, Hubble, ESO’s Very Large Telescope, and Keck added fine details to an already-compelling tale. “Each wavelength tells a different part of the story. While ground-based optical imaging showed us the whole merging galaxy, Hubble showed us the nuclear regions at high resolutions. X-ray observations revealed that there was at least one active galactic nucleus in the system,” said Treister. “And ALMA showed us the exact location of these two growing, hungry supermassive black holes. All of these data together have given us a clearer picture of how galaxies such as our own turned out to be the way they are, and what they will become in the future.” 

So far, scientists have mostly studied only the earliest stages of galaxy mergers. The new research could have a profound impact on our understanding of the Milky Way Galaxy’s own impending merger with the nearby Andromeda Galaxy. Koss said, “The Milky Way-Andromeda collision is in its very early stages and is predicted to occur in about 4.5 billion years. What we’ve just studied is a source in the very final stage of collision, so what we’re seeing presages that merger and also gives us insight into the connection between black holes merging and growing and eventually producing gravitational waves.”

"This fascinating discovery shows the power of ALMA and how multi-wavelength astronomy can generate important results that expand our understanding of the universe, including black holes, active galactic nuclei, galaxy evolution and more," says Joe Pesce, NSF program director for the National Radio Astronomy Observatory. "With the advent of gravitational wave detectors, we have an opportunity to expand our observational powers even further by combining all these capabilities. I don't think there's really a limit to what we can learn."

About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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JOURNAL

The Astrophysical Journal Letters

ARTICLE TITLE

UGC 4211: A confirmed dual AGN in the local universe at 230 pc nuclear separation

ARTICLE PUBLICATION DATE

9-Jan-2023

Black Holes Dining Together in [VIDEO] | EurekAlert! Science News Releases

The pair of merging galaxies known as UGC 4211 are harboring one big secret: a pair of black holes that are dining together, gobbling up the gas and dust around them. Scientists found and confirmed the existence of the pair— which are just 750 light-years apart— with observations from multiple research projects and telescopes: the Dark Energy Camera Legacy Survey (DECalS) on the Blanco 4 meter telescope at Cerro Tololo Inter-American Observatory (CTIO), the Multi-Unit Spectroscopic Explorer (MUSE) on ESO's Very Large Telescope (VLT), the Keck Observatory, and the Atacama Large Millimeter/submillimeter Array (ALMA). Observing the galaxies in multiple wavelengths helped scientists to see that there was more than a merger going on between the pair.

CREDIT

ALMA (ESO/NAOJ/NRAO), M. Koss/Eureka Scientific et al

Schematic representation of the most important stages and critical physical mechanisms driving the merger of two supermassive black holes and their corresponding representative time and spatial scales.

CREDIT

José Utreras/Ezequiel Treister, Center for Astrophysics and Associated Technologies (CATA); Michael Koss (Eureka Scientific), et al.

Hydrogen masers reveal new secrets of a massive star to ALMA scientists

Scientists used the unique hydrogen radio recombination lines on MWC 349A to reveal hidden collimated jets

Reports and Proceedings

NATIONAL RADIO ASTRONOMY OBSERVATORY

 

IMAGE: SCIENTISTS STUDYING MASERS— NATURALLY OCCURRING LASERS THAT AMPLIFY MICROWAVE RADIO EMISSIONS— AROUND THE MASSIVE STAR MWC 349A DISCOVERED A 500 KM/S JET OF MATERIAL LAUNCHING OUT OF THE STAR’S GAS DISK FROM WITHIN THE WINDS THAT ARE FLOWING AWAY FROM THE STAR. THE BIGGER SURPRISE IS THAT THE JET MAY BE CAUSED BY MAGNETIC FORCES. THIS ARTIST’S CONCEPTION SHOWS A ZOOMED IN VIEW OF MWC 349A AND ITS SURROUNDING DISK OF GAS AND DUST THAT ARE BEING SHAPED BY THE WINDS AND HIGH-SPEED JET. view more 

CREDIT: ALMA (ESO/NAOJ/NRAO), M. WEISS (NRAO/AUI/NSF)

While using the Atacama Large Millimeter/submillimeter Array (ALMA) to study the masers around oddball star MWC 349A scientists discovered something unexpected: a previously unseen jet of material launching from the star’s gas disk at impossibly high speeds. What’s more, they believe the jet is caused by strong magnetic forces surrounding the star. The discovery could help researchers to understand the nature and evolution of massive stars and how hydrogen masers are formed in space. The new observations were presented today in a press conference at the 241st meeting of the American Astronomical Society (AAS) in Seattle, Washington.

Located roughly 3,900 light-years away from Earth in the constellation Cygnus, MWC 349A’s unique features make it a hot spot for scientific research in optical, infrared, and radio wavelengths. The massive star— roughly 30 times the mass of the Sun— is one of the brightest radio sources in the sky, and one of only a handful of objects known to have hydrogen masers. These masers amplify microwave radio emissions, making it easier to study processes that are typically too small to see. It is this unique feature that allowed scientists to map MWC 349A’s disk in detail for the first time.

“A maser is like a naturally occurring laser,” said Sirina Prasad, an undergraduate research assistant at the Center for Astrophysics | Harvard & Smithsonian (CfA), and the primary author of the paper. “It’s an area in outer space that emits a really bright kind of light. We can see this light and trace it back to where it came from, bringing us one step closer to figuring out what’s really going on.” 

Leveraging the resolving power of ALMA’s Band 6, developed by the US National Science Foundation’s National Radio Astronomy Observatory (NRAO), the team was able to use the masers to uncover the previously unseen structures in the star’s immediate environment. Qizhou Zhang, a senior astrophysicist at CfA, and the project’s principal investigator added, “We used masers generated by hydrogen to probe the physical and dynamic structures in the gas surrounding MWC 349A and revealed a flattened gas disk with a diameter of 50 au, approximately the size of the Solar System, confirming the near-horizontal disk structure of the star. We also found a fast-moving jet component hidden within the winds flowing away from the star.” 

The observed jet is ejecting material away from the star at a blistering 500 km per second. That’s akin to traveling the distance between San Diego, California and Phoenix, Arizona in the literal blink of an eye. According to researchers, it is probable that a jet moving this fast is being launched by a magnetic force. In the case of MWC 349A, that force could be a magnetohydrodynamic wind— a type of wind whose movement is dictated by the interplay between the star’s magnetic field and gases present in its surrounding disk.

“Our previous understanding of MWC 349A was that the star was surrounded by a rotating disk and photo-evaporating wind. Strong evidence for an additional collimated jet had not yet been seen in this system. Although we don’t yet know for certain where it comes from or how it is made, it could be that a magnetohydrodynamic wind is producing the jet, in which case the magnetic field is responsible for launching rotating material from the system,” said Prasad. “This could help us to better understand the disk-wind dynamics of MWC 349A, and the interplay between circumstellar disks, winds, and jets in other star systems.”

About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

 About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The massive star MWC 349A is one of the brightest radio sources in the sky. But, at 3,900 light-years away from Earth, scientists needed help to see what’s really going on, and in this case, to discover a jet of material blasting out from the star’s gas disk at 500 km/s. Previously hidden amongst the winds flowing out from the star, the jet was discovered using the combined resolving power of ALMA’s Band 6 (right) and Band 7 (left), and hydrogen masers— naturally occurring lasers that amplify microwave radio emissions, shown here in this ALMA science image. The revelation may help scientists to better understand the nature and evolution of massive stars.

CREDIT

ALMA (ESO/NAOJ/NRAO), S. Prasad/CfA

Researchers develop AI method for mapping planets

Peer-Reviewed Publication

JACOBS UNIVERSITY BREMEN GGMBH

 

IMAGE: EXAMPLES OF MARTIAN PIT LANDFORMS POSSIBLY CONNECTED TO CAVES. view more 

CREDIT: NASA/JPL-CALTECH/UARIZONA/PDS GEOSCIENCES NODE'S ORBITAL DATA EXPLORER FOR MARS DATA ACCESS

Creating geological maps of planetary surfaces such as Mars is a complex process. From data collection to data analysis to publication in different formats – the production of maps is based on a time-consuming, multi-step process. Deep Learning techniques, which use artificial neural networks to analyze data sets, can significantly improve the production process, as broadly shown in both scientific literature and applications. However, until now, open-source, ready-to-use, and highly customizable toolsets for planetary mapping were never released.

"We were interested in designing a simple, out-of-the-box tool that can be customized and used by many," said Giacomo Nodjoumi. The PhD candidate in the research group of Angelo Rossi, Professor of Earth and Planetary Science at Constructor University, was key to developing "DeepLandforms.” The program is open and available for further optimization, and showcases an inexpensive, fast, and simple approach to mapping planets in outer space.

The scientists demonstrated the results that can be achieved with the help of the software for planetary mapping with a specific landform on Mars, which resembles lava tubes on Earth. Geological maps are an important tool in planetary exploration, because they also serve as a basis for possible explorations by robots or humans.

Link to Article:
DeepLandforms: A Deep Learning Computer Vision toolset applied to a prime use case for mapping planetary skylights

www.constructor.university

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JOURNAL

Earth and Space Science

DOI

10.1029/2022EA002278 

Astronomers spotted unusual stellar explosion rich in oxygen and magnesium

Peer-Reviewed Publication

UNIVERSITY OF TURKU

A study led from the University of Turku, Finland, discovered a supernova explosion that expands our understanding of the later life stages of massive stars.

Supernova explosions are produced at the deaths of massive stars. The elements seen in a supernova reflect the composition of the dying star at the time of explosion.

“Stars are glowing balls of gas of mostly hydrogen, the lightest element in nature. They shine by fusing atomic nuclei together to create heavier elements and energy,” explains Academy of Finland Research Fellow Hanindyo Kuncarayakti from the Department of Physics and Astronomy at the University of Turku, Finland.

Massive stars, which have around 8 times the mass of the Sun or more, contain structures similar to an onion, with layers of different elements inside them. As we go deeper inside a star, we encounter layers of subsequently heavier elements than hydrogen, such as helium, then carbon, oxygen, and so on.

“During its lifetime, a star may lose some, or even most, of its mass. The most common way is through ejecting streams of particles, a process known as stellar winds, which occur also in the Sun. Some stars lose their mass very vigorously, and may completely strip all of their hydrogen envelope. As a result, the inner layers may become exposed. The mass lost by the star may remain in the vicinity of the star, creating circumstellar matter,” says Kuncarayakti.

Astronomers have previously identified supernovae with circumstellar matter rich in hydrogen, as well as those rich in helium. Very recently, only in 2021, researchers have discovered supernovae with carbon-oxygen circumstellar matter. These different kinds of objects represent a sequence of stellar envelope stripping and the accumulation of stripped matter around the star, starting from the lightest and outermost element – hydrogen.

A team led by Academy Research Fellow Kuncarayakti has discovered a supernova that possibly extends our understanding of this sequence where massive stars lose their mass.  Supernova (SN) 2021ocs was observed in a survey using the 8.2-m European Southern Observatory (ESO) Very Large Telescope (VLT) in Chile. 

"The spectrum looked like nothing we have seen before. It had strong features of oxygen and magnesium, and the object was unusually long-lasting and blue,” Kuncarayakti describes.

These observations suggest that the oxygen-magnesium-rich expanding gas from the explosion of SN 2021ocs could be crashing into circumstellar matter. Such circumstellar matter could have been formed by the precursor star via mass loss only around 1,000 days prior to the supernova explosion. As such, the observations act like a time machine, probing the dying star's activities shortly before the final explosion.

“By observing new types of supernovae, we gain valuable information about the later stages of life of massive stars. This, on the other hand, creates new challenges for our theories on stars’ evolution,” says Professor of Astronomy Seppo Mattila from the University of Turku who also participated in the study.

In addition to Kuncarayakti and Mattila, researchers Takashi Nagao, Claudia Gutierrez and Rubina Kotak from the University of Turku contributed to the study.

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JOURNAL

The Astrophysical Journal Letters

DOI

10.3847/2041-8213/aca672 

ARTICLE TITLE

Late-time H/He-poor Circumstellar Interaction in the Type Ic Supernova SN 2021ocs: An Exposed Oxygen–Magnesium Layer and Extreme Stripping of the Progenitor