Despite several high profile missions to find an Earth-like planet orbiting a Sun-like star, astronomers have failed to find one. Now the Chinese are launching their own space telescope to hunt for Earth 2.0.

Aleksandr Kukharskiy/Shutterstock

The Kepler Space Telescope made some of the most exciting discoveries in astronomy. Launched in 2009, the telescope observed 13 million stars until 2018, when it was de-activated.

During that time, Kepler discovered over 2600 planets orbiting other stars. Some were entirely unlike anything in our Solar System, forcing astronomers to invent two new classes of planet. One or two of Kepler’s discoveries even orbit in the habitable zone of their parent star, albeit around red dwarf stars that are rather different from our Sun. This was hugely exciting because this temperate region in which liquid water can exist has conditions thought crucial for the existence of life.

But for all that, Kepler ultimately failed. Its mission was to find another Earth, in other words an Earth-like planet orbiting a Sun-like star. But in nearly a decade of observations, Kepler found not a single Earth 2.0.

That was partly because Sun-like stars turned out to be noisier than expected and so required longer observation times. But also because in 2013, two of the observatory’s four reaction wheels broke down, making long-term observations impossible. As a result, astronomers have yet to find an alien Earth.

Scanning the Heavens

That could now change thanks to a Chinese mission called Earth 2.0 due to be launched in 2026. This mission will scan the heavens for Earth-like planets orbiting Sun-like stars with instruments designed to cope with the star-noise that Kepler unexpectedly discovered.

The team involves some 300 scientists and engineers from over 40 institutions, most in China. And this week, the collaboration published a detailed description of the mission on the arXiv.

One problem for any space observatory is to cover as a wide a field-of-view as possible while minimizing the cost and weight of the spacecraft. The Chinese team solved this problem by avoiding the cost and weight of a single giant telescope.

Instead, the spacecraft will carry six smaller 30cm telescopes that together will observe a similar area of sky as Kepler, which had a 1.4-meter mirror. These telescopes will look for the characteristic changes in star brightness as a planet passes in front of it.

The spacecraft will also carry a seventh telescope designed to look for microlensing events in which the gravitational field of a star focuses the light from a distant star behind it, temporarily brightening it. By studying the pattern of brightness, astronomers can tell if the star has an orbiting planet.

This seventh instrument will also be able to spot free floating planets, thereby helping to cast some light on these strange, lonely objects.

Data Firehose

The Chinese team’s plan is to launch Earth 2.0 to the L2 Lagrange point, one of several regions of space where the Earth and Moon’s gravitational fields are in balance, and away from Earth’s potential interference. L2 is a popular choice for observatories and home to several past and present, such as the Herschel Space Observatory and the James Webb Space Telescope. The Earth 2.0 spacecraft will orbit L2 over the course of 4 years, sending back some 169 Gb of data every day.

That raises the prospect of some mouth-watering discoveries. “Simulations show that the transit survey will be able to detect ∼ 29,000 new planets, including ∼ 4,900 Earth-sized planets,” the team say. That means the mission should detect between and 10 and 20 Earth 2.0s by 2030.

The discovery of the first Earth 2.0 is likely to be one of the defining moments in the history of astronomy. It is likely to create huge interest in the nature of these planets, the make-up of their atmospheres and the potential presence of water. Then there will be the search for biomarkers suggesting the presence of life, molecules like methane and oxygen, and the characteristic light absorption patterns of photosynthesis. Beyond that will be the search for technosignatures that might indicate the presence of a civilization, signals such as industrial pollutants like chlorofluorocarbons and even narrowband radio transmissions.

Of course, Earth 2.0 isn’t the only mission capable of spotting an alien Earth. Several others have the capability, such as ESA’s Plato mission which will also be launched in 2026. But these will have to be luckier than Earth 2.0 to be successful.

That sets the scene for an exciting international race to discover an “other Earth” and the beginning of a new era in the study of potentially habitable planets.

Reference:

• ET White Paper — To Find the First Earth 2.0: https://arxiv.org/abs/2206.06693

RELATED VIDEOS, selected and posted by peter2011

{ https://astronomy.com/ }

09-08-2022 om 18:48 geschreven door peter  

UFOs – Ultra-red Flattened Objects – revealed by Webb

09-08-2022 om 18:28 geschreven door peter  

New faint, distant and cold brown dwarf discovered

by Tomasz Nowakowski , Phys.org

Using the James Webb Space Telescope (JWST), an international team of astronomers have detected a new faint, distant, and cold brown dwarf. The newly found object, designated GLASS-JWST-BD1, turns out to be about 31 times more massive than Jupiter. The discovery was detailed in a paper published July 29 on arXiv.org.

Brown dwarfs are intermediate objects between planets and stars. Astronomers generally agree that they are substellar objects occupying the mass range between 13 and 80 Jupiter masses. One subclass of brown dwarfs (with effective temperatures between 500 and 1,500 K) is known as T dwarfs, and represents the coolest and least luminous substellar objects so far detected.

Studies of T dwarfs could help astronomers better understand objects near the disputed planet/star boundary, for instance, giant exoplanets. However, although many brown dwarf have been detected to date, T dwarfs are not so common, as only about 400 such objects have been identified.

Now, a group of astronomers led by Mario Nonino of the Astronomical Observatory of Trieste in Italy, reports the finding of a new brown dwarf that is most likely of T dwarf subclass. The discovery was made as part of the Through the Looking GLASS (GLASS-JWST) project—a JWST Early Release Science (ERS) program targeting the massive galaxy cluster Abell 2744 with JWST's Near-Infrared Spectrograph (NIRSPEC) and Near-Infrared Imager and Slitless Spectrograph (NIRISS).

"We present the serendipitous discovery of a late T-type brown dwarf candidate in JWST NIRCam observations of the Early Release Science Abell 2744 parallel field. The discovery was enabled by the sensitivity of JWST at 4 µm wavelengths and the panchromatic 0.9–4.5 µm coverage of the spectral energy distribution," the researchers wrote in the paper.

According to the study, GLASS-JWST-BD1 has a mass of about 31.43 Jupiter masses and an effective temperature of some 600 K. The age of this brown dwarf was estimated to be 5 billion years.

Comparison with theoretical models suggest that GLASS-JWST-BD1 is a late-type T dwarf. Its distance was measured to be between 1,850 and 2,350 light years, in a direction perpendicular to the Galactic plane. The results indicate that this object is likely a member of the Galactic thick disk or halo population.

The astronomers noted that further observations of GLASS-JWST-BD1 are required in order to confirm its T-dwarf nature. In particular, kinematic or chemical abundance data are needed to get more insights into the properties of this object.

In concluding remarks, the authors of the paper underlined how their discovery demonstrates the capability of JWST to investigate distant low-mass Galactic stellar and substellar objects.

"The large estimated distance of GLASS-JWST-BD1 confirms the power of JWST to probe the very low-mass end of the stellar and substellar mass function in the Galactic thick disk and halo, enabling exploration of metallicity dependence on low-mass star formation and the evolution of brown dwarf atmospheres," the scientists wrote.

• Astronomers detect substellar companion of HD 47127

{ https://phys.org/ }

09-08-2022 om 17:53 geschreven door peter  

CAUGHT IN A SOLAR STORM ON THE WAY TO MARS

BY: AAS NOVA 

A chance alignment between Earth and a Mars-bound spacecraft has given us a rare glimpse into the movement of high-energy particles from the Sun.

A chance alignment between Earth and a Mars-bound spacecraft has given us a rare glimpse into the movement of high-energy particles from the Sun. The data from this event can help researchers understand the radiation environment near Mars — a key factor in planning crewed missions to our neighboring planet and beyond.

ENERGETIC PARTICLE PARADE

Illustration of energetic particles being ejected by the Sun.
NASA’s Goddard Space Flight Center Conceptual Image Lab

The space between the planets in our solar system is filled with a wispy sea of charged particles that flow out from the Sun’s atmosphere. This particle population is augmented by cosmic rays — speedy protons and atomic nuclei accelerated in extreme environments across the universe — which ebb and flow against the 11-year solar activity cycle. This undulating particle background is punctuated by bursts of high-energy particles from the Sun, which can be unleashed suddenly in violent solar storms.

Spacecraft that venture out from the protection of Earth’s magnetic field must navigate this ocean of particles and weather solar storms. And if we someday wish to send astronauts to other planets, we’ll need to know how high-energy solar particles, which pose a risk to the health of astronauts and electronic systems alike, travel through the solar system.

WHEN SPACECRAFT ALIGN

Location of Tianwen-1 (TW-1) relative to Solar Orbiter (SolO), Parker Solar Probe (PSP), and STEREO-A (STA), Earth, and Mars. The black arrow marks the location of the active region that launched the solar storm.
Adapted from Fu et al. 2022

In a new publication, a team led by Shuai Fu (Macau University of Science and Technology), Zheyi Ding (China University of Geosciences), and Yongjie Zhang (Chinese Academy of Sciences) studied the high-energy solar particles produced in an event in November 2020, when the Sun emitted a solar flare and a massive explosion of solar plasma called a coronal mass ejection.

This event coincided with a chance alignment of multiple spacecraft along the same solar magnetic field line. This alignment meant that several spacecraft near Earth and the Tianwen-1 spacecraft en route to Mars measured the same burst of energetic particles millions of miles apart, providing a rare opportunity to study how energetic particles from the Sun travel through space along magnetic field lines.

DIFFUSION AND EVOLUTION

Comparison of proton fluence (number of particles collected per unit area) measured by spacecraft at Earth (blue) and by Tianwen-1 at 1.39 au (red). The time increases from (a) to (h). The spectra at Earth and at Tianwen-1 “break” or bend at roughly the same energy, suggesting that there is little evolution as the particles travel outward. Click to enlarge.
Fu et al. 2022

By comparing the timing of measurements from Tianwen-1 to those from three spacecraft near Earth, the team discerned that the magnetic field line that connected the spacecraft did not connect back to the origin of the particles. This means that the particles must have traveled, or diffused, across magnetic field lines to reach the spacecraft.

In addition, the team found that the shape of the particle energy distribution remained the same at moderate and high energies as the particles traveled between Earth and Tianwen-1’s location at 1.39 au. This suggests that the shape of the energy distribution is determined earlier, at the time the particles are accelerated to high energies, rather than as the particles travel through space.

The November 2020 event marked the first solar energetic particle event observed by Tianwen-1, but surely not the last. The spacecraft will continue to monitor high-energy particles from its station in Mars orbit as the solar cycle revs up, collecting valuable data for understanding the radiation environment around Mars and planning future missions.

CITATION

• “First Report of a Solar Energetic Particle Event Observed by China’s Tianwen-1 Mission in Transit to Mars,” Shuai Fu et al 2022 ApJL 934 L15. doi:10.3847/2041-8213/ac80f5

• This post originally appeared on AAS Nova, which features research highlights from the journals of the American Astronomical Society.

Solar Storm-Hunting Spaceship Looking for a Name, Submissions Accepted ...

SVS: Solar Wind Strips the Martian Atmosphere

{ https://skyandtelescope.org/ }

09-08-2022 om 17:18 geschreven door peter  

Was a UFO accidentally filmed during an ARD live broadcast recording of a wildfire in eastern Germany? 

The video footage appears to show a high speed cylindrical object flying by in the background. 

The object has no obvious signs of propulsion and no wings, also it can't be a bird either since we don't see flapping wings. Maybe an insect flying close to the camera? But can an insect fly that speed? What could it be? 

Original ARD video footage, see UFO at about 3.42 minutes.

  

{ http://ufosightingshotspot.blogspot.com/ }

09-08-2022 om 16:31 geschreven door peter  

UFO fireball in the western skies looking from Anza, California 6-Aug-2022

This bright UFO was seen and recorded in the sky above Anza, California on 6th August 2022.

Witness report: 

I saw a fireball in the sky that changed colors from red to orange and changed in size. I was able to get a video of it on my iPhone 13. There was also a small white light that blinked intermittently on the left of it. The red object seemed to have control of the power like a jet engine going on and off. It hovered for a while and then it just disappeared.

{https://www.latest-ufo-sightings.net/ }

09-08-2022 om 14:36 geschreven door peter  

Astronomers Discover A Disappearing Space Object That Turns On And Off Every 20 Minutes And Sends Highly-Polarized Radio Signals

According to a research paper published in Nature, astronomers detected a “really weird” object 4,000 lightyears distant from Earth. Every other minute, the object vanishes from view and produces a massive burst of radio waves three times an hour.

Tyrone O’Doherty, a Curtin University student, first noticed the enigmatic object while scanning the sky in rural Western Australia. “It’s exciting that the source I identified last year has turned out to be such a peculiar object,” stated O’Doherty in a press statement.

The object, which the scientists claim is unlike anything else they’ve observed, emits a tremendous beam of radiation that, every 20 minutes, shines brightly in the sky. It also spins and vanishes every minute.

Scientists refer to space objects that “turn” on and off in the night sky as “transients”.

“When studying transients, you’re watching the death of a massive star or the activity of the remnants it leaves behind,” said Dr. Gemma Anderson, an ICRAR-Curtin astrophysicist and co-author of the work.

Slower transients, such as supernovae, might arrive in a matter of days and last for several months. Fast transients, such as neutron stars, “flash” on and off many times per second. However, transients between those two speeds are uncommon, and the current discovery is “really weird” and “completely unexpected.” according to the researchers.

“It was kind of spooky for an astronomer because there’s nothing known in the sky that does that,” said astrophysicist Dr. Natasha Hurley-Walker, who headed the research team. “And it’s really close to us – about 4000 lightyears distant. It’s there in our galaxy’s backyard.”

Hurley-Walker characterized the enigmatic object as being smaller than the sun yet brilliant, radiating highly polarized radio waves three times an hour. These radio pulses imply that it has an “extremely strong” magnetic field, which may correspond to a previously anticipated astrophysical object that has never been verified to exist. Scientists refer to the hypothetical item as an “ultra-long period magnetar.”

“It’s a type of slowly spinning neutron star that has been predicted to exist theoretically,” Hurley-Walker explained. “However, no one anticipated to immediately discover one like this since they were not thought to be that brilliant. It converts magnetic energy to radio waves considerably more efficiently than anything else we’ve seen previously.”

-

Astronomers believe it is a rare sort of neutron star or a collapsing white dwarf, but they need to examine it again to establish if it is a fluke or a new type of space object.

{https://astronomyscience.vercel. }

09-08-2022 om 01:41 geschreven door peter  

Researchers have uncovered a source of oxygen that may have influenced the evolution of life before the advent of photosynthesis.

Scientists at Newcastle University have discovered a source of oxygen deep in the Earth’s crust that may have influenced the evolution of life before the advent of photosynthesis.

The pioneering research project uncovered a mechanism that can generate hydrogen peroxide from rocks during the movement of geological faults. The study was led by Newcastle University’s School of Natural and Environmental Sciences and published today (August 8) in the journal Nature Communications.

While hydrogen peroxide in high concentrations can be harmful to life, it can also provide a useful source of oxygen to microbes. This additional source of oxygen may have influenced the early evolution, and possibly even origin, of life in hot environments on the early Earth before the evolution of photosynthesis.

In tectonically active regions, the movement of the Earth’s crust not only generates earthquakes but also riddles the subsurface with cracks and fractures. These are lined with highly reactive rock surfaces containing many imperfections, or defects. Water can then filter down and react with these defects on the newly fractured rock.

Master’s student Jordan Stone simulated these conditions in the laboratory by crushing granite, basalt, and peridotite – rock types that would have been present in the early Earth’s crust. These were then added to water at varying temperatures under well-controlled oxygen-free conditions.

The research investigates a source of reactive oxygen associated with geological faulting; a potential oxygen source prior to cyanobacteria oxygenating the Earth’s atmosphere. This reactive oxygen may have had a role in the evolution of life from an oxygen-free to an oxygenated world and contributed to prebiotic chemistry in subsurface fractures prior to the origin of life.

Credit: Jon Telling / Jordan Stone / Newcastle University

The experiments revealed that substantial amounts of hydrogen peroxide – and as a result, potentially oxygen – were only generated at temperatures close to the boiling point of water. Importantly, the temperature of hydrogen peroxide formation overlaps the growth ranges of some of the most heat-loving microbes on Earth called hyperthermophiles, including evolutionary ancient oxygen-using microbes near the root of the Universal Tree of Life.

Lead author Jordan Stone, who conducted this research as part of his Master of Research in Environmental Geoscience, said: “While previous research has suggested that small amounts of hydrogen peroxide and other oxidants can be formed by stressing or crushing of rocks in the absence of oxygen, this is the first study to show the vital importance of hot temperatures in maximizing hydrogen peroxide generation.”

Lead author Jordan Stone, who conducted this research as part of his MRes in Environmental Geoscience at Newcastle University, UK, sets up one of the experiments.

Credit: Jon Telling / Jordan Stone / Newcastle University

Principal Investigator Dr. Jon Telling, Senior Lecturer, added: “This research shows that defects on crushed rock and minerals can behave very differently to how you would expect more ‘perfect’ mineral surfaces to react. All these mechanochemical reactions need to generate hydrogen peroxide, and therefore oxygen, is water, crushed rocks, and high temperatures, which were all present on the early Earth before the evolution of photosynthesis and which could have influenced the chemistry and microbiology in hot, seismically active regions where life may have first evolved.”

Reference:

• “Tectonically-driven oxidant production in the hot biosphere” 8 August 2022, Nature Communications.
  DOI: 10.1038/s41467-022-32129-y
• The work was supported through grants from the Natural Environmental Research Council (NERC) and the UK Space Agency. A major new follow-up project led by Dr. Jon Telling, funded by NERC, is underway to determine the significance of this mechanism for supporting life in the Earth’s subsurface.

{ https://scitechdaily.com/ }

08-08-2022 om 23:33 geschreven door peter  

NASA's 'Helical Engine' could reach 99% the speed of light

When it comes to space, there's a problem with our human drive to go all the places and see all the things. A big problem. It's, well, space. It's way too big. Even travelling at the maximum speed the Universe allows, it would take us years to reach our nearest neighbouring star.

But another human drive is finding solutions to big problems. And that's what NASA engineer David Burns has been doing in his spare time. He's produced an engine concept that, he says, could theoretically accelerate to 99 percent of the speed of light - all without using propellant.

He's posted it to the NASA Technical Reports Server under the heading "Helical Engine", and, on paper, it works by exploiting the way mass can change at relativistic speeds - those close to the speed of light in a vacuum. It has not yet been reviewed by an expert.

But while this concept is fascinating, it's definitely not going to break physics anytime soon. As a thought experiment to explain his concept, Burns describes a box with a weight inside, threaded on a line, with a spring at each end bouncing the weight back and forth. In a vacuum - such as space - the effect of this would be to wiggle the entire box, with the weight seeming to stand still, like a gif stabilized around the weight.Overall, the box would stay wiggling in the same spot - but if the mass of the weight were to increase in only one direction, it would generate a greater push in that direction, and therefore thrust.

According to the principle of the conservation of momentum - in which the momentum of a system remains constant in the absence of any external forces - this should be not completely possible.

But! There's a special relativity loophole. Hooray for special relativity! According to special relativity, objects gain mass as they approach light speed. So, if you replace the weight with ions and the box with a loop, you can theoretically have the ions moving faster at one end of the loop, and slower at the other.

But Burns' drive isn't a single closed loop. It's helical, like a stretched out spring - hence "helical engine".

"The engine accelerates ions confined in a loop to moderate relativistic speeds, and then varies their velocity to make slight changes to their mass. The engine then moves ions back and forth along the direction of travel to produce thrust," he wrote in his abstract.

"The engine has no moving parts other than ions traveling in a vacuum line, trapped inside electric and magnetic fields."

It sounds really nifty, right? And it is - in theory. But it's not without significant practical problems.

According to New Scientist, the helical chamber would have to be pretty large. Around 200 metres (656 feet) long and 12 metres (40 feet) in diameter, to be precise.

And it would need to generate 165 megawatts of energy to produce 1 newton of thrust. That's the equivalent of a power station to produce the force required to accelerate a kilogram of mass per second squared. So a lot of input for a teeny tiny output. It is horribly inefficient.

Burns notes the efficiency problem in his presentation, and also adds that his work hasn't been reviewed by experts, and there may be errors in his maths. We don't exactly have the blueprints for a fully functional space travel engine here.

What we do have is a piece of groundwork that could be used to develop such an engine. What we have is a dream of the stars.

RELATED VIDEOS, selected and posted by peter2011

{https://blog.sci-nature.com/ }

08-08-2022 om 22:20 geschreven door peter  

China launches mysterious reusable 'test spacecraft' to Earth orbit

08-08-2022 om 21:53 geschreven door peter  

US Space Force tests robot dogs to patrol Cape Canaveral

08-08-2022 om 21:33 geschreven door peter  

Curious Kids: Is it possible to see what is happening in distant solar systems now?

08-08-2022 om 20:46 geschreven door peter  

The physics of accretion: How the universe pulled itself together

Material from an accretion disk swirls around the young star FU Orionis in this artist’s concept.

NASA/JPL-Caltech

Accretion is one of the most fundamental processes in the cosmos. It is a universal phenomenon triggered by gravity, and the process by which bits of matter accumulate and coalesce with more bits of matter. It works inexorably on all scales to attract and affix smaller things to bigger things, from the tiniest dust grains to supermassive black holes. 

Accretion creates everything there is: galaxies, stars, planets, and eventually, us. It is the reason the universe is filled with a whole bunch of somethings instead of a whole lot of nothing.

The fact that matter tends to glom together may seem intuitive. But to scientists, accretion remains a mysterious topic, filled with unanswered questions.

For instance: Why do some stellar nurseries form a few massive stars instead of lots of smaller ones? What causes so much accreting material to ultimately fall inward onto its central object, instead of just circling it forever? And how do space rocks ultimately stick together to form planets instead of just bouncing off each other? No one knows the definitive answers to any of these questions yet, but there are some theories gaining traction — and evidence.

The Taurus Molecular Cloud is a vast star-forming region threaded by a network of filaments. It was captured here by the European Space Agency’s Herschel Space Observatory, which operated from 2009 to 2013.

ESA/Herschel/NASA/JPL-Caltech, CC BY-SA 3.0 IGO; Acknowledgement: R. Hurt (JPL-Caltech)

All objects great and small

Accretion is the inevitable result of gravitational forces operating on all scales, and on all types of material — gas, dust, plasma, even dark matter. Gravity makes matter accrete. And when matter accretes, it forms objects. Thus, accretion and formation are very closely related in astronomy: The former can be considered an aspect of the latter. 

The Soviet scientist Otto Schmidt devised the first accretion model of planetary formation in 1944, and his countryman Viktor Safronov fleshed out the mathematics of accretion in 1969. The underlying principles of gravitational attraction have since been applied to the formation of stars and even galaxies. The discovery of quasars and compact X-ray sources in the 1960s, using optical, radio, and X-ray observations, set the field in motion.

But the true renaissance began a decade ago, when the Atacama Large Millimeter/submillimeter Array (ALMA), an array of 66 radio telescopes in Chile, came online. With the ability to study distant, cool objects in detail came the data necessary to understand the process of accretion in a variety of circumstances. Seeing accretion in action promised to be a game-changer.

Today, ALMA and other advanced telescopes are observing numerous objects of different sizes and stages of evolution: galaxy groups, molecular clouds, stellar nurseries, protostars, planetary disks, black holes, and many more. We now know that whether on scales of kilometers or light-years, accretion operates on the same broad principles. The particular mechanisms remain mysterious, but the veil is beginning to lift.

The reason that the gas in a molecular cloud can accrete into a star may be due to magnetohydrodynamics (MHD), the physics of how magnetic fields interact with hot ionized gas.

Interstellar space and everything in it is permeated by a weak magnetic field. Normally, this background magnetic field has no effect on a cold, dense cloud of gas and dust.

But this changes when a collapsing cloud heats up and begins to generate plasma. Because plasma is electrically charged, it is linked to the magnetic field: As it moves, it drags the magnetic field lines with it. As the cloud collapses further and begins to form an accretion disk, the magnetic field becomes wound up by the disk’s rotation. The magnetic field also becomes stronger as the field lines bunch together.

All of these magnetic field lines then act as highways for plasma to escape the strong magnetic field: Following the field lines, the charged particles zip away from the accretion disk into space. This MHD wind carries angular momentum away from the disk — and this, astronomers suspect, helps the cloud collapse into a star.

---

The Giant GRB Ring is a suspected superstructure — a collection of nine gamma-ray bursts (immensely powerful stellar explosions) arranged in a loose ring that spans 5.6 billion light-years, as shown in this artist’s concept.

Pablo Carlos Budassi/Wikimedia Commons/CC BY-SA 4.0

Stellar nurseries at the crossroads

The largest structures in the universe are groups of galaxies that are gravitationally bound to each other. We are not yet able to see them, but peculiar arrangements of objects have been interpreted as evidence of such superstructures. They are given various names according to their observed shapes, such as arcs, rings, or walls.

The observable portions of superstructures consist mostly of molecular clouds of gas millions of light-years across. Over the eons, these diffuse regions are perturbed by a variety of effects: the chaotic motions of the galaxies within them, the winds thrown by quasar jets, the passing wakes of rotating black holes, and blasts from supernovae. Here and there, a confluence of gas and dust will become dense enough that gravity takes over and a domino effect begins, as more and more mass is drawn into a conglomeration, where a star-forming region is born.

The mechanics of these stellar nurseries, from which hundreds or thousands of stars are created, are not completely understood. Sometimes a region containing a few hundred solar masses of dense gas and dust will form 100 Sun-like stars. Other times a few massive stars will also appear. This difference is of particular interest to astronomers because massive stars can alter the evolution of a galaxy. What guides the seemingly random accretion process on these vast scales?

One theory posits that there are “filaments of flowing gas, which thread through these clusters,” says Todd Hunter, an astronomer at the National Radio Astronomy Observatory. Astronomers are starting to see evidence of these filaments. “They fragment and intersect at certain places, especially in the center of clusters,” says Hunter. “And where they meet is where protostars have access to a lot of gas on a short timescale” — which feeds the formation of massive stars.

The accretion disk that surrounds the elliptical galaxy M87 feeds its central supermassive black hole (SMBH) and relativistic jet in this artist’s concept.

ESO/M. Kornmesser

These objects are called infrared dark clouds, and they are very large, very cold objects that were difficult to detect and resolve until recently. The first observations were made with the Infrared Space Observatory in 1996. It was a serendipitous find, made during the first detailed survey of stellar populations in the galactic plane. Nowadays these regions are studied in detail with ALMA and the Submillimeter Array in Hawaii, which are more sensitive and have higher resolution at submillimeter wavelengths where cold molecular gas is easiest to detect.

These facilities have allowed astronomers to map the gas flows they believe provide the necessary supply for the growth of massive stars. One survey, published in The Astrophysical Journal in 2019, identified hundreds of protostellar and prestellar core candidates in a particular region and studied how they affect each other. The researchers suggest a kind of “competitive accretion” process takes place, alongside what they call “global hierarchical collapse” — where chaotic gravitational forces cause a series of collapses within collapses, with small-scale events happening later and faster than large-scale events. This process works over a couple of million years, eventually transforming a diffuse cloud of starless cores into a flattened disk of protostars.

A widening gyre

Where there is gravity and matter, there will also be accretion. Infalling matter forms a swirling accretion disk. This gravitational gyre forms because the infalling material — like everything else in the universe — had some motion and angular momentum before becoming caught up by an object’s gravity. The laws of physics state that angular momentum must be conserved — so, to fall into a star, black hole, or other object, material must lose its angular momentum first. It cannot be simply sucked toward the core along a straight line. Instead, it forms a flattened structure called an accretion disk.

At just 450 light-years away, the Taurus Molecular Cloud is an ideal place to search for accretion disks. Two examples are the young stars HL Tauri (bright blue, at upper center left) and V1213 Tauri (lower right). The latter is hidden by an accretion disk, though the star partly illuminates the disk above and below it. The visible disk and the jets comprise the object HH 30.

ESA/Hubble and NASA; Acknowledgement: Judy Schmidt

The closer the material is carried to the center, the faster it spins. (Physicists often use the metaphor of a figure skater to demonstrate this effect; when the skater pulls their arms in, they spin faster.) There’s just a small problem: For material to actually fall onto the core, it must slow down and eventually come to a stop. But how can this happen when the closer it gets, the faster it moves? Why doesn’t it just swirl around forever? What dissipates the angular momentum, allowing gravity to win the tug-of-war?

There are two prevailing theories. “The old idea is that disks are turbulent, and this turbulence generates a kind of viscosity,” or friction within a fluid, says Ilaria Pascucci, an astrophysicist and planetary scientist at the University of Arizona in Tucson. In this scenario, the disk is full of eddies, which means the gas particles don’t orbit smoothly. As inner material accelerates, it drags the material outside of it along for the ride, like a jar of molasses being stirred. “The viscosity redistributes angular momentum outward, enabling disk gas close in to accrete,” says Pascucci.

This turbulence-viscosity model of disk accretion was first suggested around 40 years ago. But astronomers have never really been able to make the numbers add up. The models required disks to be stickier and more viscous than turbulence could probably account for.

Then, in the last decade, an overlooked characteristic of accretion disks — magnetic fields — started to show promise. “What if the angular momentum is not redistributed in the disk, but extracted through winds?” Pascucci says.

The ghostly halo we see in the groundbreaking image of an SMBH from the Event Horizon Telescope is the hot, glowing plasma in the accretion disk surrounding it.

Event Horizon Telescope Collaboration

Star-forming regions have magnetic fields running through them. While they do not affect neutral gas, particles that have been heated and ionized have an electric charge and will tend to follow these magnetic field lines. As the large-scale clouds collapse under their own gravity, these magnetic field lines also become twisted and tangled. And if magnetic field lines are somehow bent outward, anchored to plasma that remains outside the collapsing cloud, plasma that is zipping along the magnetic field might be able to overcome gravity and accelerate away from the disk. Astronomers call these outflows magnetohydrodynamic (MHD) winds, and they could carry away angular momentum. This would enable the leftover disk material to fall onto the forming protostar.

Both observations and simulations seem to point toward the MHD wind hypothesis. The best evidence so far for an MHD wind is a 2021 study in The Astrophysical Journal of an active young star, where astronomers have measured how high the wind appears to sustain itself as it flows away from the disk. Measuring how powerful these winds are — and therefore how much angular momentum they carry away — will be the next major task in testing the theory.

Disk worlds

At the same time a star is forming, so are the planets that will orbit it. Both star formation and planet formation happen within disks via accretion. As gas and dust swirls around the star, delineations begin to appear in the disk. Astronomers saw this for the first time in 2014 in a young star called HL Tauri. This observation, made using ALMA, was a major advancement in our understanding of how planets form.

In a nascent planetary system, the congregation of matter depends on lots of different factors. Turbulence, magnetic fields, and the play of viscosity between gas and dust may cause a kind of traffic jam that eventually congeals to form protoplanets. Closer in, most of the gas gets consumed by the star, leaving rocky material and heavy metals, which form terrestrial planets.

In 2014, the ALMA radio telescope revealed distinctive gaps in HL Tauri’s accretion disk. They mark regions where planets are accreting and sweeping up material.

ALMA (ESO/NAOJ/NRAO)

But there is a long-standing question about how rocky bodies accrete, involving a concept called the bouncing barrier. Electrostatic forces cause small grains to stick together and larger planetesimals are attracted to each other by gravity. But how does a particle become a planet? Models show that objects in that middle range between tiny and massive just tend to bounce off each other. So how do amassing objects overcome this barrier to growth?

One theory is that the particles experience a drag force as they move through gas in the disk. “There’s a strong interaction between solid particles and the gas in the disk,” says James Stone, an astrophysicist at Princeton University. “This causes clumps to form, which over time can produce larger and larger objects.”

So far, this protoplanetary evolution mechanism, called streaming instability, seems to be a promising way to grow things from centimeter to kilometer sizes. The most intriguing part of the theory is that the gas is the crucial component: Without it, dust in the disk couldn’t coalesce to form planetesimals. But there is not yet direct evidence.

The hope is that within a decade or two, we will have seen lots of planets at different stages of formation. This will stand in as a kind of time-lapse and we can judge how well predictions of prevailing hypotheses, like streaming instability, match up to actual exoplanets. This ambitious venture received a kickstart in 2021 with the discovery of the youngest planet ever observed: 2M0437b. The discovery image, taken by the Subaru Telescope on Mauna Kea in Hawaii, shows a world still glowing hot from energy released during its formation, meaning it just recently (astronomically speaking) finished accreting. The study, led by Eric Gaidos of the University of Hawai’i, also fills in our picture of how quickly planetary systems form, because the star is only about 2.5 million years old.

Supercomputer simulations reveal the turbulent and hierarchical dynamics of collapsing infrared dark clouds (IRDCs), forming filaments within filaments. In the densest regions of this simulation, shown in red, molecular clouds are forming cores that will become massive stars.

Richard Klein, Lawrence Livermore National Laboratory; Pak Shing Li, University of California, Berkeley; Tim Sandstrom, NASA Ames Research Center

Gathering dust

Every star grows up on its own schedule. The protostar stage is like a star’s volatile teen years. When its accretion disk stabilizes and material stops falling into the core, it becomes a main sequence star. There may still be a debris disk and the planets around might still be figuring out where they orbit, but accretion has largely stopped. That doesn’t mean there won’t be any more accretion in the star’s future, though. Depending on its mass, when fusion ceases, it will then transition into either a white dwarf, a neutron star, or a black hole, all of which can form accretion disks of their own.

The supply for this new disk can come from a variety of sources. Compact objects, like white dwarfs and black holes, may siphon gas from a companion star. A white dwarf may also pull in material that it puffed off in the earlier red giant phase. And when black holes grow and merge to become the supermassive black holes (SMBHs) at the centers of galaxies, they draw material from the vast roaming stars, clouds, and nebulae within the galaxy itself.

As material from the disk falls into the central object — whether a star, planet, or singularity — it releases energy in the form of radiation. The disk itself also radiates as it swirls around the gravity well and heats up, with different factors like viscosity, friction, and speed making some parts hotter than others. The stronger the draw of the central object, the more powerful the radiation emitted, as gas can be transformed into plasma. The groundbreaking 2019 image of the supermassive black hole at the center of the galaxy M87 is not of the hole itself, but of the black hole’s shadow on the charged plasma swirling around it.

A black hole gains mass from everything it accretes over time. But while we understand how Sun-sized black holes form, we don’t know how SMBHs got as big as they are. For example, the SMBH at the center of the Whirlpool Galaxy (M51) in Canes Venatici has a mass equivalent to 1 million Suns. There is no way for a single small, stellar-mass black hole to accrete enough material to grow this large at the universe’s current age.

“It’s one of the biggest mysteries of black hole research,” says Joanna Piotrowska, a graduate student at Cambridge University. The laws of physics limit how quickly an object can accrete matter, called the Eddington limit. Above that limit, the radiation from the accretion disk is so intense, it blows material away — preventing more accretion from happening. “The mass of [SMBHs] exceeds what is expected from continuous accretion at the Eddington limit over the lifetime of our universe,” says Piotrowska.

One proposed solution is that SMBHs were big to start with. Perhaps in the early universe, even before the first stars, there were molecular clouds with just the right conditions to collapse straight away into singularities. The James Webb Space Telescope might be able to shed some light on this dark topic when it comes online this year. It was designed especially to see the first galaxies and stars, and those primordial formations could help us to understand the initial distribution of potential collapsible matter.

IRDCs appear as shadows splayed across the bright mid-infrared background of the Milky Way, as seen in this false-color image from NASA’s Spitzer Space Telescope. Though they are some of the darkest objects in the sky, these ultracold and dense clouds give birth to the brightest, most massive stars in the galaxy.

NASA/JPL-Caltech

And that’s not all ...

It’s tempting to picture accretion as a peaceful, gradual, and constructive process, like erosion in reverse. It can certainly take time to get going. But the methods by which an accretor gains mass can be quite quick and chaotic. Recently, observers have seen what they call accretion bursts around protostars — instances of extreme instability in a disk, where large amounts of material suddenly plunge into the star. Hunter recently observed this on NGC 6334 I, a protostar cluster in the Cat’s Paw Nebula (NGC 6334) in the constellation Scorpius, using the Stratospheric Observatory for Infrared Astronomy (or SOFIA). He theorizes that a high proportion of the total accretion of some stars — up to 50 percent — may actually happen in this way.

08-08-2022 om 18:07 geschreven door peter  

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08-08-2022 om 17:21 geschreven door peter  

Dwarf Galaxies Found Without Influence From Dark Matter

Ask astronomers about dark matter and one of the things they talk about is that this invisible, mysterious “stuff” permeates the universe. In particular, it exists in halos surrounding most galaxies. The mass of the halo exerts a strong gravitational influence on the galaxy itself, as well as on others in the neighborhood. That’s pretty much the standard view of dark matter and its influence on galaxies. However, there are problems with the idea of those halos. Apparently, some oddly shaped dwarf galaxies exist that look like they have no halos. How could this be? Do they represent an observationally induced challenge to the prevailing ideas about dark matter halos?

Finding Perturbed Dwarf Galaxies

In the so-called “Standard Model” of cosmology, shells or halos of dark matter protect galaxies from the gravitational influence of nearby galactic neighbors. However, when astronomers at the University of Bonn and Saint Andrews in Scotland looked in the nearby Fornax Cluster, which lies some 62 million light-years away from us, they saw something strange. It contains a number of dwarf galaxies with distorted, perturbed shapes. This is odd, especially if they should be surrounded by dark matter halos.

Let’s take a quick look at dwarf galaxies. They’re small and faint and usually found riding along in galaxy clusters or near much larger companions. The Milky Way Galaxy has a coterie of dwarf galaxies around it,. It is, in fact, cannibalizing ones such as the Sagittarius Dwarf Spheroidal. Interestingly, recent studies show that at least one of the dwarf galaxies near ours, an ancient one called Tucana II, has an astoundingly massive dark matter halo.

So, what’s happening in Fornax that’s different? There, dwarf galaxies could be “disturbed” by gravitational tides from nearby larger ones in the cluster. Tides happen when gravity from one body pulls differently on different parts of another body. These are similar to tides on Earth when the Moon pulls more strongly on the side of Earth that faces it.

The distorted shapes of the dwarf galaxies seen by the team indicate a problem with our understanding of dark matter. “Such perturbations in the Fornax dwarfs are not expected according to the Standard Model,” said Pavel Kroupa, Professor at the University of Bonn and Charles University in Prague. “This is because, according to that model, the dark matter halos of these dwarfs should partly shield them from tides raised by the cluster.”

Dwarf galaxy NGC1427A, part of the Fornax galaxy cluster.

(ESO)

Explaining Distorted Dwarf Galaxies

Kroupa and Ph.D. student Elena Ascencio analyzed observations of the perturbed dwarfs in Fornax. They wanted to understand the extent of gravitational distortions these galaxies show and what causes them. The expected levels of distortion depend on a couple of factors. One is the internal characteristics of the dwarf galaxy. In addition, their distance to the center of the cluster is important. That’s where gravitational influences are much stronger. As a rule, galaxies with large sizes but not many stars could be easily disturbed by strong gravitational tides. The same is true for galaxies closer to the core of the cluster.

The team members compared what they saw in the cluster with observations made by the VLT Survey Telescope at the European Southern Observatory. Asencio pointed out that what they found seems to point to problems with the Standard Model. “The comparison showed that, if one wants to explain the observations in the standard model,” she said, “the Fornax dwarfs should already be destroyed by gravity from the cluster center even when the tides it raises on a dwarf are sixty-four times weaker than the dwarf’s own self-gravity.”

Not only is this counter-intuitive, she said, it also contradicts previous studies. The team also found that the force needed to disturb a dwarf galaxy is about the same as its self-gravity.

What Does This Mean for the Standard Model?

The research team points out that it’s difficult to explain these perturbed, disturbed shapes of the dwarf galaxies in Fornax if they’re surrounded by dark matter. In other words, they shouldn’t be misshapen if they do have halos. Yet, there they are with disturbed-looking shapes. That means that there are no dark matter halos around those galaxies.

Obviously, if what the astronomers found is confirmed, then the Standard Model needs some tweaking. And, there is at least one alternative explanation for the strange galaxy shapes. It’s called the MOND model (short for Modified Newtonian Dynamics). It suggests that Newton’s law of universal gravitation should be modified to account for the observed properties of galaxies. It could be applied to explain why misshapen galaxies look the way they do.

According to Hongsheng Zhao, a member of the research team from the University of Saint Andrews, finding disturbed dwarfs without dark matter halos is a major challenge to the current view. It states that galaxies have halos. It appears not all of them do, he points out. “Our results have major implications for fundamental physics,” he said. “We expect to find more disturbed dwarfs in other clusters, a prediction which other teams should verify”.

For More Information

• No trace of dark matter halos
• The distribution and morphologies of Fornax Cluster dwarf galaxies suggest they lack dark matter
• Modified Newtonian Dynamics

The post Dwarf Galaxies Found Without Influence From Dark Matter appeared first on Universe Today.

Source: 

• https://www.universetoday.com/157056/dwarf-galaxies-found-without-influence-from-dark-matter/

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08-08-2022 om 17:02 geschreven door peter  

Ancient records and religious texts describe multiple "Gods" (aka extraterrestrials) creating humanity in a series of genetic experiments and warring among themselves over who would be dominant in influencing Earth's future. 

The world's oldest known creation story, Sumer's Enuma Elish, and other ancient texts introduce the different creator Gods and how they formed grand assemblies to resolve their differences over the destiny of humanity. 

This new video is the official trailer/short film for the "World Religions and Extraterrestrial Contact" webinar to be held on August 13. In addition to the above issues, the trailer discusses the rise and fall of Atlantis in relation to creator Gods/extraterrestrials alarmed over humanity's rapid technological development. 

Finally, this short film covers the return of the creator Gods (Elohim/Anunnaki) to our solar system and what this means for us today.

  

{ http://ufosightingshotspot.blogspot.com/ }

08-08-2022 om 16:29 geschreven door peter  

Stationary blinking UFO over Boynton, Florida 31-May-2022

This blinking unidentified flying object was filmed above the sea near Boynton in Florida. This happened on 31st May 2022.

Witness report: 

Here’s the 12 minutes video of various times during the 45 + minute sighting. However, please study this at 10 minutes and 35 seconds into the video above when a very large Ufo streaks across the screen from top right to bottom left quadrant!

So, let’s use logic. This craft flew at least 2 1/2 miles over the sea (which is a VERY conservative estimate because it really appears to have gone over the horizon which is 35 miles away). Theirs 3,600 seconds in one hour. IF this craft only went 2 1/2 miles in 1/10 th of a second – that would put the speed of the Ufo at 90,000 per hour!

However, if it’s gone out of sight over the horizon (35 miles) in 1/10 th of a second , using the same equation…(3,600 seconds in one hour) that would put the speed of the Ufo at an Astounding 1,260,000 mph!!

RECENT UFO-VIDEOS FLORIDA, selected and posted by peter2011

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08-08-2022 om 16:00 geschreven door peter  

Kosmisch overgewicht: waarom sterren, planeten en manen rond zijn

08-08-2022 om 01:42 geschreven door peter  

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08-08-2022 om 01:25 geschreven door peter  

Future Space Travelers May Follow Cosmic Lighthouses

For centuries, lighthouses helped sailors navigate safely into harbor. Their lights swept across the water, cutting through fog and darkness, guiding mariners around dangerous obstacles and keeping them on the right path. In the future, space explorers may receive similar guidance from the steady signals created by pulsars.

Scientists and engineers are using the International Space Station to develop pulsar-based navigation using these cosmic lighthouses to assist with wayfinding on trips to the Moon under NASA’s Artemis program and on future human missions to Mars.

Pulsars, or rapidly spinning neutron stars, are the extremely dense remains of stars that exploded as supernovas. They emit X-ray photons in bright, narrow beams that sweep the sky like a lighthouse as the stars spin. From a great distance they appear to pulse, hence the name pulsars.

An X-ray telescope on the exterior of the space station, the Neutron star Interior Composition Explorer or NICER, collects and timestamps the arrival of X-ray light from neutron stars across the sky. Software embedded in NICER, called the Station Explorer for X-ray Timing and Navigation Technology or SEXTANT, is using the beacons from pulsars to create a GPS-like system. This concept, often referred to as XNAV, could provide autonomous navigation throughout the solar system and beyond.

“GPS uses precisely synchronized signals. Pulsations from some neutron stars are very stable, some even as stable as terrestrial atomic clocks in the long term, which makes them potentially useful in a similar way,” says Luke Winternitz, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The stability of the pulses allows highly accurate predictions of their time of arrival to any reference point in the solar system. Scientists have developed detailed models that predict precisely when a pulse would arrive at, for example, the center of Earth. Timing the arrival of the pulse to a detector on a spacecraft, and comparing that to when it is predicted to arrive at a reference point, provides information for navigating far beyond our planet.

“Navigation information provided by pulsars does not degrade by moving away from Earth since pulsars are distributed throughout our Milky Way galaxy,” says SEXTANT team member Munther Hassouneh, navigation technologist.  

“It effectively turns the ‘G’ in GPS from Global to Galactic,” adds team member Jason Mitchell, director of the Advanced Communications and Navigation Technology Division in NASA’s Space Communication and Navigation Program. “It could work anywhere in the solar system and even carry robotic or crewed systems beyond the solar system.”

Pulsars also can be observed in the radio band but, unlike radio waves, X-rays are not delayed by matter in space. Additionally, detectors for X-rays can be more compact and smaller than radio dishes.

But because X-ray pulses are very weak, a system must be robust enough to collect a signal sufficient for navigating. NICER’s large collection area makes it nearly ideal for XNAV research. A future XNAV system could be made smaller, trading size for longer collection time.

“NICER is roughly the size of a washing machine, but you could dramatically reduce its size and volume,” Mitchell says. “For example, it would be interesting to fit an XNAV telescope into a small satellite that could independently navigate the asteroid belt and characterize primitive solar system bodies.”

As published in a 2018 paper, SEXTANT already has successfully demonstrated real-time pulsar-based navigation aboard the space station. It also studied the use of pulsars for time-keeping and clock synchronization and is helping expand the catalog of pulsars to use as reference points for XNAV.

The SEXTANT team also includes Samuel Price, Sean Semper and Wayne Yu at Goddard; Naval Research Lab partners Paul Ray and Kent Wood; and NICER principal investigator Keith Gendreau and science lead Zaven Arzoumanian.

The team now is studying the possibility of using XNAV autonomous navigation as a technique on NASA’s Gateway platform, to study support for crewed missions to Mars.

These kinds of experiments could bring cosmic lighthouses to guide spacecraft to their destinations another step closer to reality.

• For daily updates, follow @ISS_Research, Space Station Research and Technology News or our Facebook. Follow the ISS National Lab or information on its sponsored investigations. For opportunities to see the space station pass over your town, check out Spot the Station.

Melissa Gaskill

International Space Station Program Research Office

Johnson Space Center

{ https://www.nasa.gov/ }

08-08-2022 om 01:04 geschreven door peter