Simulations are great tools for astrophysics, we can model everything from our (cosmic) backyard to things outside the Milky Way galaxy — and the universe itself. Now we have a new example of simulated star formation.
A group of scientists from several American universities developed a numerical simulation called STARFORGE (STAR FORmation in Gaseous Environments). STARFORGE is a 3D simulation of star formation, it is the first to provide the visual of an entire gas cloud. It’s also the first simulation to include complex physical parameters into its code.
Producing stars is complicated (both in the real life, and in simulations), and in order to create more accurate reproductions, STARFORCE considers a long list of physical phenomena, not just gravity but also thermodynamics and stellar dynamics. Perhaps the most important physical input to the simulation is magnetohydrodynamics — which describes how an extremely hot ionized gas, a star in this case, behaves.
The best example of what STARFORGE can do is the massive giant molecular cloud named ‘The Anvil of Creation’ by the team. In the video you can see the time evolution in Mega years of the stars forming in the middle of the gas. As the stars appear, you will notice the white marbles popping in the screen, some emit massive yellow jets, those jets emanating from them. The stunning detail of the simulation is great to look at even without knowing exactly what’s going on.
It is also possible to simulate supernovae with the algorithm. The team assumes every star with 8 times the mass of the Sun can go supernova, and STARFORGE will help them explore the phenomenon and how it is affected by various parameters. The simulation can be carried out until it reaches the supernova remnant stage.
To get an idea of how important this study is, consider the Hubble Space Telescope observed the supernova in NGC 2525 for an entire year (from February 2018 to February 2019) just to get a timelapse of the dim phenomenon — and observation tools like Hubble are limited. With simulations like STARFORGE, scientists can study the evolution of stars and supernovae remnants in less time and with much better resolution.
Credits: ESA/Hubble & NASA, M. Kornmesser, M. Zamani, A. Riess and the SH0ES team.
With STARFORGE, the team also observed an interesting effect in star formation. According to other studies, every time the star forms ejecting jets it is expected that stars lose lots of material that could make up for their total mass. Reasonable, right? The simulation had seen this happening very clearly, and also concluded that this doesn’t change much the global gas where the stars form. A great result for STARFORGE, proving it is a reliable tool for astrophysics.
Using data from the NASA Chandra X-ray Observatory and South African radio telescope MeerKAT, astronomer Daniel Wang detected magnetic threads and plumes emerging from the center of the Milky Way. Turns out, the center of our galaxy is proving to be a prolific zone for this type of phenomenon.
The image depicting the features clearly shows a large number of threads near the galactic center. They are related to nonthermal radio filaments (NTF) — polarized filaments perpendicular to the galaxy and whose origin is still a mystery. The NTFs are the purple lines crossing the galactic center in purple representing the radio emissions.
The images also show bright white objects which — this is cosmic dust detected by X-ray sensors. This isn’t the type of dust you normally see around your house. Specs of cosmic dust are only slightly bigger than a molecule, but that can be enough to act as seeds to form planets and asteroids. The fuzzy glow is a result of the X-ray scattering, which is only possible with a sufficient amount of dust between the source and Chandra.
The most interesting thread is the one called G0.17-0.41. Narrow and vertically oriented with respect to the Milky Way, it emits both radio and X-ray — which may be indicative of a process called magnetic field reconnection. Reconnections happen when magnetic fields connect and then disconnect, which allows a massive energy transfer to happen. This is often a type of space weather phenomenon which occurs after solar flares, magnetic fields form a crossed shape that leads to a separation, then magnetic field lines are separated from the original one.
Large plumes emitted by the galactic center were also observed. The Chandra/MeerKAT plumes have 700 light-years of extension on both sides of the galactic plane, much smaller than the Fermi Bubbles, but farther enough to appear visually disconnected from the galactic center – also a reconnection example.
With this recent discovery, it was also possible to detect several supernovae remnants, as well as neutron stars, and black holes. The most prominent black hole is the Sagittarius A*, our central supermassive black hole. This new view of the galactic could help explain similar features in other galaxies.
If you’ve been following our space articles, you may have come across something called “dark matter”. It’s the most abundant type of matter in the universe — our best models have established that dark matter comprises 84.4% of the matter contained in the known universe — but we still don’t really understand just what it is. Dark matter is something that we know is out there, but we have little idea what it’s made of.
Wait, so how do we know it’s even real?
“Regular” matter (technically called baryonic matter) is made of electrons, protons, and neutrons. Cosmologists define the three particles as baryons –technically speaking, electrons are something else, but that’s beside the point here. Baryons make up gas, gas makes up stars, stars go boom and make planets and other things — including you. Yes, you are made of star stuff — baryonic star stuff, to be precise.
All this is done thanks to the electromagnetic (EM) force that forms chemical bonds, glueing regular atoms together But Dark Matter (DM) plays a different game.
Dark matter doesn’t interact with things the way baryonic matter does. It doesn’t scatter or absorb light, but it still has a gravitational pull. So if there are beings made of dark matter living right here, right now, you probably wouldn’t even know it because the perception of touch is felt when your sensory nerves send the message to your brain, and these nerves work thanks to the EM force.
We can’t touch dark matter, and no optical instruments can detect, so how do we ‘see’ it? Indirectly, for starters. Look for gravity, if there isn’t enough visible mass to explain to explain the gravitational pull felt by a region of the universe, then there something there. Invisible does not mean non-existant. If it weren’t for its gravity effect, there would be little indication of dark matter existing.
The main observational evidence for dark matter is the orbital speeds of stars in the arms of spiral galaxies. If Kepler and Newton were correct, stars’ velocity would decrease with the orbital radius in a specific way. But this was not observed by Vera Rubin and Kent Ford, who tracked this relationship. Instead, Rubin and Ford got a velocity vs radius relation that looked like the stars had a nearly constant behavior from a certain point of the galactic orbit.
This could only be explained if there would be a lot more matter somewhere that we’re not seeing. Something was pulling at these stars gravitationally, and that something is dark matter.
Another important evidence of dark matter comes from galaxy superclusters like 1E 0657-558. Astronomers observed that within this cluster, there are two groups of galaxies placed in a peculiar position to one another.
If you look at the Hubble Space Telescope image below (1st and 2nd), you’ll notice that there are many galaxies on the left and another group on the opposite side. When astronomers observed in X-ray, they concluded that these two clusters collided and left a gas trace of the shock. The faster cluster was like a bullet (it’s even named the Bullet Cluster) passing through the slower one at around 3000–4000 km/s nearly 100-200 million years ago (3rd pic).
Scientists used gravitational lensing to estimate the mass of the objects involved in the collision. They found that the galaxies which hadn’t collided agreed with the weak lensing detections. This indicates those galaxies are ahead of ‘the X-ray evidence’ (below, 1st image). Since dark matter doesn’t interact with nearly anything, in this phenomenon, we see a bunch of mass (blue) moving faster than the gas (purple), barely affecting the baryonic matter (2nd image).
So what is Dark Matter?
Just because we don’t know what dark matter is doesn’t mean we have no idea. In fact, researchers have a few theories and are considering several plausible candidates.
There are three ways to classify dark matter. Cold dark matter describes the formation of the large-scale structure of the universe and is the fundamental component of the matter in the universe. It’s called cold because it moves ‘slowly’ compared to the speed of light.
Weakly interacting massive particles (WIMPs) are the candidates for cold dark matter particles. They supposedly interact via weak nuclear force. The particles which belong to this group are thought to be the lightest particles of the supersymmetric theories. Neutral examples of these particles could have been produced in the early universe, and later participated in the formation of galaxy clusters.
Hot dark matter is the opposite, it moves close to the speed of light. The warm candidate particles are thought to be less interactive than neutrinos.
Another candidate particle for dark matter is the sterile neutrino — a hypothetical particle that interacts only via gravity and not via any of the other fundamental forces. These would be responsible for forming warm dark matter. They also seem to be heavier than the standard neutrino, and have a longer lifetime before they break down.
Neutrinos were thought to be the best candidates for dark matter. Neutrinos are weird particles — they barely interact with things, and even then only gravitationally (which is a weak interaction). Besides, they do not possess electrical charge, which is why they do not interact electromagnetically. However, the neutrino temperature is high and they decouple (stop interacting with other forms of matter) only at relativistic velocities. If dark matter was made of neutrinos, the universe would have looked radically different.
Massive Compact Halo Objects (MACHOs) represent a different type of candidate. They’re no WIMPs at least. They aren’t particles either, but rather brown dwarfs, planets like Jupiter, black holes in galactic haloes. The best possible MACHOs are primordial black holes( PBHs). Different from the ordinary black holes we see in the center of galaxies, PBHs are thought to have been created nearly 10 seconds after the Big Bang. No evidence for such objects has yet been discovered, but it’s still an open possibility.
Detecting dark matter
Many ideas for the detection of each plausible candidate have been developed.
Through cosmology, the main evidence comes from the Cosmic Microwave Background (CMB). Yes, the same radiation Dr. Darcy Lewis detected (for real) in the TV miniseries WandaVision. It is the remnant electromagnetic radiation from when the universe was a 380,000-year-old baby.
The best CMB observations we have currently are from the Planck satellite 2018 survey. Different amounts of matter have distinct signals in the CMB observations, forming the temperature power spectrum.
If the theory is correct, the shape of the power spectrum is different for different amounts of matter. There’s such a thing known as the critical density of the universe, which describes the density of the universe if it was coasting, expanding but not accelerating, and if it stopped its expansion. When you divide the density of the observable matter by the critical density, you get its density parameter (Ω).
The temperature power spectrum is modeled according to the different amounts of ingredients in the universe, more matter or less matter changes its shape. Planck’s observations have shown that the matter density parameter is Ω h² ~0.14, so if the shape of the graph corresponds to that value we have evidence of the amount of dark matter in the universe.
There are also ways to detect dark matter directly, not through cosmology but through particle physics. The Large Hadron Collider (LHC) is the most powerful particle accelerator, can collide protons at extremely high (relativistic) speeds, generating a bunch of scattered particles that are then measured by the detectors.
Physicists hope to find dark matter by comparing the energy before and after the collision. Since the dark matter particles are elusive, the missing energy could explain their presence. However, no experiment has observed dark matter so far — though researchers are still looking.
Another underground experiment uses high purity sodium iodide crystals as detectors. The detectors at DAMA/LIBRA (Large sodium Iodide Bulk for RAre processes), for example, try to observe an annual variation of regular matter colliding with WIMPs due to the planet’s motion around the Sun which means we’re changing our velocity relative to the galactic dark matter halo. The problem is that DAMA’s 20 years’ worth of data didn’t have enough statistical significance. However, in an identical experiment meant to directly detect dark matter, called ANAIS (Annual modulation with NaI Scintillators), in 3 years scientists gathered more reliable data indicating this method is not conducive to finding dark matter anytime soon.
To get a better picture of the challenge in having a conclusive result, take a look at the image below. All those lines and colorful contours represent the results of different experiments, none of them seem to agree. That’s the problem with dark matter, we still don’t have the evidence to match any theory we came up with — and we can’t really rule out any possibilities either.
The questions of what dark matter is and how it works still have no satisfying answer. There are many detection experiments being planned and conducted in order to explain and verify different hypotheses, but nothing conclusive thus far. Let’s hope we don’t have to wait another 20 years to figure out if one experiment is right or wrong. Unfortunately, groundbreaking discoveries can take a lot of time, especially in astrophysics. While we wait, dark matter will continue to entertain our imagination.
The article was primarily based on the 2020 Review of Particle Physics from Particle Data Group’s Dark Matter category.
Researchers from the University of Bern have discovered that the Earth would be approximately 5% larger if it were hot and molten rather than rocky and solid. Pinpointing the difference between rocky exoplanets and their hot, molten counterparts is vital for the search for Earth-like exoplanets orbiting stars outside the solar system.
The fact that rocky exoplanets that are approximately Earth-sized are small in comparison to other planets, makes them notoriously difficult for astronomers to spot and characterise. Identification of a rocky exoplanet around a bright, Sun-like star will likely not be plausible until the launch of the PLATO mission in 2026. Thankfully, spotting Earth-size planets around cooler and smaller stars such as the red dwarfs Trappist-1 or Proxima b is currently possible.
But, searching for molten exoplanets could help astronomers probe the darkness of space — and identify Earth-sized rocky-exoplanets around stars like our own.
“A rocky planet that is hot, molten, and possibly harbouring a large, outgassed atmosphere ticks all the boxes,” says Dan Bower, an astrophysicist at the Center for Space and Habitability (CSH) of the University of Bern. “Such a planet could be more easily seen by telescopes due to strong outgoing radiation than its solid counterpart.”
Learning more about these hot, molten worlds could also teach astronomers and astrophysicists more about how planets such as our’s form. This is because rocky planets such as the Earth are built from ‘leftovers of leftovers’ — material not utilised in either the formation of stars or giant planets.
“Everything that doesn’t make its way into the central star or a giant planet has the potential to end up forming a much smaller terrestrial planet,” says Bower: “We have reason to believe that processes occurring during the baby years of a planet’s life are fundamental in determining its life path.”
This drove Bower and a team of colleagues mostly from within the Planet S network to attempt to discover the observable characteristics of such a planet. The resulting study — published in the journal Astronomy and Astrophysics — shows that a molten Earth would have a radius 5% or so larger than the actual solid counterpart. They believe this disparity in size is a result of the differences in behaviour between solid and molten materials under the extreme conditions generated beneath the planet’s surface.
As Bower explains: “In essence, a molten silicate occupies more volume than its equivalent solid, and this increases the size of the planet.”
This 5% difference in radii is something that can currently be measured, and future advances such as the space telescope CHEOPS — launching later this year — should make this even easier.
In fact, the most recent collection of exoplanet data suggests that low-mass molten planets, sustained by intense starlight, may already be present in the exoplanet catalogue. Some of these planets may well then be similar to Earth in regards to the material from which they are formed — with the variation in size no more than the result of the different ratios of solid and molten rock.
Bower explains: They do not necessarily need to be made of exotic light materials to explain the data.”
Even a completely molten planet would fail to explain the observation of the most extreme low-density planets, however. The research team suggest that these planets form as a result of molten planets releasing — or outgassing — large atmospheres of gas originally trapped within interior magma. This would result in a decrease in the observed density of the exoplanet.
Spotting such outgassed atmospheres of this nature should be a piece of cake for the James Webb Telescope if it is around a planet that orbits a cool red dwarf — especially should it be mostly comprised of water or carbon dioxide.
The research and its future continuation have a broader and important context, points out Bower. Probing the history of our own planet, how it formed and how it evolved.
“Clearly, we can never observe our own Earth in its history when it was also hot and molten. But interestingly, exoplanetary science is opening the door for observations of early Earth and early Venus analogues that could greatly impact our understanding of Earth and the Solar System planets,” the astrophysicist says. “Thinking about Earth in the context of exoplanets, and vice-versa offers new opportunities for understanding planets both within and beyond the Solar System.”
Original research: Dan J. Bower et al: Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations, Astronomy & Astrophysics. DOI: https://doi.org/10.1051/0004-6361/201935710
Some of the oldest galaxies in the universe are right in front of our doorstep — cosmically speaking.
The blue circles surround brighter galactic satellites, the white circles ultrafaint satellites (so faint that they are not readily visible in the image). Ultrafaint satellites are amongst the most ancient galaxies in the Universe, beginning to form when the Universe was only about 100 million years old (compared to its current age of 13.8 billion years). The image has been generated from simulations from the Auriga project. Image credits: Institute for Computational Cosmology, Durham University, UK / Heidelberg Institute for Theoretical Studies, Germany / Max Planck Institute for Astrophysics, Germany.
The universe dark ages
Some 13.8 billion years ago (give or take), something pretty weird happened: the Universe started existing. According to the Big Bang theory, the universe formed out of a point of infinite density and temperature. In the immediate second after the Big Bang, a whole bunch of weird processes started taking place. The four fundamental forces started taking hold but the temperature of the universe was still too high to allow the formation of particles.
Then, after around 377,000 years, the universe had cooled to a point where free electrons could combine with the hydrogen and helium nuclei to form neutral atoms. This is where it gets tricky: although the universe had cooled down and was essentially transparent, nothing that could produce light had yet formed. There were no stars, no galaxies, maybe some primordial black holes and other structures — but no light. The universe was dark and essentially unobservable.
This is the so-called Dark Age of the universe.
[panel style=”panel-info” title=”Looking back in time” footer=””] Observing a faraway cosmic object is like looking back in time. For instance, when something is 1 million light years away, we’re perceiving it as it was 1 million years ago — because that’s how long it took light from it to get to us.
But because in its opaque form there were no light-producing structures, we can’t look back to that period of time. It simply remains hidden to us — at least as far as visible light is concerned. [/panel]
Eventually, stars and galaxies started forming — and some of these early galaxies were recently discovered by British astronomers.
Our old neighbors
Image of a galaxy generated from simulations from the Auriga project. Credit: Institute for Computational Cosmology, Durham University, UK / Heidelberg Institute for Theoretical Studies, Germany / Max Planck Institute for Astrophysics, Germany.
The research team has found evidence that the faintest satellite galaxies orbiting our own Milky Way galaxy are amongst the very first galaxies to form in our Universe. The galaxies they identified were likely formed more than 13 billion years ago — right after the Dark Ages settled in.
“Finding some of the very first galaxies that formed in our Universe orbiting in the Milky Way’s own backyard is the astronomical equivalent of finding the remains of the first humans that inhabited the Earth. It is hugely exciting.”
If their findings are confirmed, that would mean that the galaxies emerged just 380,000 years after the Big Bang, which means they formed by some of the first atoms in the universe.
Remarkably, the data fitted perfectly with a model of galaxy formation that the team had previously developed — the model essentially allowed them to infer the formation times of the satellite galaxies, and now, observation has confirmed the model.
“Our finding supports the current model for the evolution of our Universe, the ‘Lambda-cold-dark-matter model’ in which the elementary particles that make up the dark matter drive cosmic evolution,” Frenk adds.
It’s always exciting when theoretical and real data blend in so well together and, as Dr. Sownak Bose points out, we simply wouldn’t have had the technological capacity to carry out this study a decade or two ago. Bose, who was a Ph.D. student at the ICC when this work began and is now a research fellow at the Harvard-Smithsonian Center for Astrophysics, concluded:
“A decade ago, the faintest galaxies in the vicinity of the Milky Way would have gone under the radar. With the increasing sensitivity of present and future galaxy censuses, a whole new trove of the tiniest galaxies has come into the light, allowing us to test theoretical models in new regimes.”
The work was carried out as part of the Auriga project — a large suite of high-resolution simulations of Milky Way-sized galaxies, simulated in a fully cosmological environment by means of the ‘zoom-in’ technique. Read more about Auriga here.
Journal Reference: Sownak Bose, Alis J. Deason, and Carlos S. Frenk. “The Imprint of Cosmic Reionization on the Luminosity Function of Galaxies,” The Astronomical Journal.
It almost sounds too cheesy to be true: NASA wants to send a shuttle to an asteroid, pluck a piece of it, then make it return to the Moon and orbit it. Then, brave astronauts will go and retrieve the sample, bringing it back to Earth for study. But that’s exactly what astronomers and engineers at the space agency want to do.
A piece of an asteroid
NASA is making plans to retrieve a chunk of an asteroid and make it orbit the Moon. Image via NASA.
This is actually “Option B” – because Option A was even more crazier: they wanted to deflect an asteroid to make it orbit close to home so we can then pick it up. But administrator Ross Lightfoot says that grabbing a piece of the asteroid as opposed to bringing an entire asteroid closer gives them more options.
“I’m going to have multiple targets when I get there”, Lightfoot said. “That’s what it boils down to.”
Option A was also a bit more expensive, but that wasn’t decisive, Lightfood said. A key aspect was that Option B also demonstrates capabilities critical for a mission to Mars.
There are currently three asteroid candidates: Itokawa, Bennu, and 2008 EV5. NASA will decide on which asteroid to focus based on size, rotation speed, shape and orbit. The mission is expected to take several years whichever asteroid they do decide on. It will take the shuttle two years to reach its target; it will then spend up to 400 days on the asteroid, looking for a good boulder to bring back (something around 13 feet in diameter – 4 meters). It will then return and start orbiting the Moon, if everything goes according to plan. In 2025, astronauts will fly NASA’s still-to-be-built Orion to dock with the asteroid-carrying spacecraft and retrieve the sample for study.
Science and technology
The mission will be a so-called test bed for a number of technologies, including an almost sci-fi Solar Electric Propulsion (SEP) ion drive. SEP is slower than a conventional blast rocket, it needs a lot less propellant to get the job done.
Ion engine test firing. Image via Wikipedia.
Another interesting technology which will be tested is “planetary defense technique”, which includes using the small gravity of a nearby spacecraft to disturb an asteroid’s orbit enough that something on a potential Earth-impact path would pass us by.
In a way, these are not the most scientific methods that can be used for this mission – but NASA chose them anyway, because of the potential benefits they might provide in the future. The entire effort also has a “human exploration emphasis”, as Lightfoot explains.
“The technologies used to grab onto the asteroid … are the kinds of things we know we’re going to need when we go to another planetary body,” Lightfoot said.
Despite the fact that NASA has committed to this asteroid mission for several years already, the mission doesn’t seem to be extremely popular – with the general public, and with Republican members of the US Senate, who insist that we should focus on a mission to Mars. Unfortunately, science and exploration is not always as spectacular as members of the Senate would like it, but hopefully, we’ll leave the science to the scientists.
A team led by astronomers at The Australian National University has discovered what they believe to be the oldest star in the known Universe – forming shortly after the Big Bang, some 13.7 billion years ago.
This is the first time astrophysicists get the chance to study the chemistry of the oldest stars, giving scientists a clearer idea of what the Universe was like in its infancy.
“This is the first time that we’ve been able to unambiguously say that we’ve found the chemical fingerprint of a first star,” said lead researcher, Dr Stefan Keller of the ANU Research School of Astronomy and Astrophysics. “This is one of the first steps in understanding what those first stars were like. What this star has enabled us to do is record the fingerprint of those first stars.”
The discovery was possible thanks to the ANU SkyMapper – a fully automated 1.35m wide-angle optical telescope at Siding Spring Observatory in northern New South Wales, Australia; the telescope was designed to look at the southern sky in search for ancient stars, as part of a five year project. So far, results are very encouraging.
The ancient star (SMSS J031300.36-670839.3) is 6.000 light years away from us – which is a huge distance in and of itself, but pretty close in astronomical terms. It is one of the 60 million stars photographed by SkyMapper in its first year, so it was quite the fortuitous find. SMSS J031300.36-670839.3 also has a much higher carbon supply compared to iron, more than a thousand times greater. Apart from hydrogen, which appeared in the Big Bang the star also contains carbon, magnesium, and calcium which could have been formed in a low energy supernova.
“The stars we are finding number one in a million,” says team member Professor Mike Bessell, who worked with Keller on the research. “Finding such needles in a haystack is possible thanks to the ANU SkyMapper telescope that is unique in its ability to find stars with low iron from their colour.”
The chemistry of primordial stars
The spectrum of SMSS J031300.36-670839.3 hardly contains any absorption lines in its spectrum: the strong lines are from hydrogen, and carbon – at 4300A, and from the Earth atmosphere – at 5800 and 6300A; not from the star itself. Image credit: Anna Frebel.
Its chemical composition shows it formed in the wake of a primordial star, which had a mass 60 times that of our Sun – so it is basically a second-generation star. In case you’re wondering how astronomers study the chemistry of distant stars (since obviously they can’t go there and take samples), they do it through a technique called astronomical spectroscopy. In astronomical spectroscopy, the object of study is the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other hot celestial objects; judging by the wavelength emitted by the star, a number of properties can be derived, including chemical composition, temperature, density, mass, distance, luminosity, and relative motion using Doppler shift measurements.
“To make a star like our Sun, you take the basic ingredients of hydrogen and helium from the Big Bang and add an enormous amount of iron – the equivalent of about 1,000 times the Earth’s mass,” Dr Keller says. “To make this ancient star, you need no more than an Australia-sized asteroid of iron and lots of carbon. It’s a very different recipe that tells us a lot about the nature of the first stars and how they died.”
It was previously believed that primordial stars didn’t survive the early period of the universe – disappearing in extremely violent explosions which polluted huge volumes of space with iron. But the ancient star shows signs of pollution with lighter elements such as carbon and magnesium, and no sign of pollution with iron.
“This indicates the primordial star’s supernova explosion was of surprisingly low energy. Although sufficient to disintegrate the primordial star, almost all of the heavy elements such as iron, were consumed by a black hole that formed at the heart of the explosion,” he says.
The world, known as HD189733b, has a deep azure hue, probably the result of molten silicate glass rain in the atmosphere, which scatters blue light.
The giant planet is one of the closest and most studied in the exoplanets recently discovered; it is a sauna, a hazy hothouse swept by blow-torch winds powered by the molten silicates. It is most likely what astrophysicists call a “hot Jupiter” – a planet which originally was very similar to Jupiter, both in terms of composition and distance to its star, but then migrated much closer to its star.
Astronomers used the Hubble’s imaging spectrograph and measured both the light emitted by the star which it orbits, and the light reflected by the planet. To isolate the planet’s light, they substracted one from the other, though the process is not nearly as simple as it sounds.
“We inferred the color,” said astrophysicist Tom Evans at the U.K.’s University of Oxford, who led the study. By knowing the wavelength, “we can imagine the color the planet would have if we could look at it with our own eyes.”
It’s estimated that the temperature on the surface of the planet is a whopping 1000 C (1832 F) with winds howling at 7000 km/h (4349 miles/h). It’s atmosphere is extremely volatile, changeable and exotic, with hazes and violent bursts of evaporation. Not the habitable paradise Earth is.
So our planet appears blue from outer space due to the oceans, which absorb red and green wavelengths more strongly than blue ones. To accentuate the effect, scattered molecules of oxygen and nitrogen in the atmosphere also selectively absorb wavelengths. Mars appears red due to its rusty surface, very rich in oxide, absorbing the blue and green wavelengths and reflecting the red ones. But the color of HD 189733b comes solely from the interplay of light in its super-heated atmosphere.
The fact that astronomers were able to measure this is a stunning achievement in itself.
“We are really pushing the limits of what we can measure,” said Mr. Evans.
This year’s Nobel Prize winning finding that the ‘Universe is accelerating’ is being subjected to another validation test in the USA to confirm whether the expansion is “even or uneven”.
“We are testing the acceleration theory through another experiment to find whether the expansion is even or multi-directional. We are confident it would be ‘even’,” says eminent cosmologist Prof.Robert Kirshner who guided two of the three-member team of researchers that bagged the Nobel Prize in Physics – 2011 for the revolutionary finding recently.
With the experimental study now on, this time using the MMT telescope in Arizona and the Magellan Telescope in Northern Chile, he said, the researchers would, within two years, be in a position to collect enough data to determine whether the expansion of the Universe is even or in all directions, Kirshner said.
Kirshner of the Centre for Astrophysics, Harvard University (USA) was interacting with this Indian Science Writers Association(ISWA) representative in South Goa on the sidelines of the just concluded week-long VII International Conference on “Gravitation and Cosmology” organised by the International Centre for Theoretical Sciences(ICTS) under the prestigious Tata Institute of Fundamental Research, Mumbai.
As many as 300 astrophysicists from across the world had participated in the conference and shared their findings and experiences on black holes,gravitation wave experiments and need for international collaborations to promote research in astrophysics of the 21st century.
His researchers – Adam Riess and Brian Schmidt – along with Perl mutter, had recently received the Nobel Prize in Physics for their stellar discovery in 1998, used the Panstars Telescope with big array of detectors with a gigapixel resolution to capture the image of many galaxies at the same time for the study.
“I am also confident that such high resolution and higher sensitive telescopes enable us trace the history of their shifts by recognizing what is known as their “Red Shifts” as the galaxies move away from us,” he said.
The on-going studies may also throw light on the ‘fossils of light” emitted when stars exploded during what is known as the “Big Bang” 14 billion years ago that led to the creation of the Universe.
“We expect data we gather could unlock the secrets of the origin of the Universe including the history of the first galaxies, stars and the supernovae and their death,” he said.
Scientists believe that the Universe contain galaxies, each composed of about 100 billion stars observable enough and 100 billion unobservable galaxies.
Earlier in his plenary talk in the conference on “Exploding Stars and the Accelerating Universe,” Kirshner said observations of exploding stars halfway across the universe show that the expansion of the universe is speeding up.
“We attribute this to a pervasive ‘dark energy’ whose properties we would like to understand. This work was recently honoured by the 2011 Nobel Prize in Physics to Perl Mutter, Schmidt and Riess.”
He had also presented the most recent evidence from supernovae, Cosmic Microwave Background (CMB) fluctuations, and galaxy clustering. The present state of knowledge on dark energy is completely consistent with a modern version of the cosmological constant, but with a ridiculously low value.
He also discussed ways to use infrared observations to make the supernova measurements with better accuracy and higher precision.
Kirshner also explained how improved supernova measurements and the matrix of evidence from other observations can help us understand whether modifications to general relativity or a time-varying component of dark energy can be ruled out.//EOM//
One of the most outstanding dreams astronomers and other scientists hope to accomplish is to someday encounter proof that extraterestrial life exists. Intelligent life might be extremely far off, however microbiological life should without a doubt be present elsewhere other than our planet or solar system. For life to blossom, however, the right conditions have to be met, and one of the major prerequisites for life supporting conditions is liquid water. Along the years, scientists have come up with what’s called the habitable zone, an area around a star’s orbit where favorable conditions for harboring life may exist. Now, after hundreds of potential Earth-life planets have been found, scientists have enough data at their disposal to elaborate a statistical hypothesis – there are billions of planets similar to Earth that might potentially support life in our galaxy alone!
The great blue marble. Does is it have a sister planet? A question astronomers seek to answer.
Astronomers using the European Southern Observatory’s HARPS, a high precision instrument fitted to the 3.6m telescope at the Silla Observatory in Chile, studied 102 red dwarf stars neighbouring the sun over a period of six years. Red dwarfs are smaller and cooler than the sun, however it’s been found that 40% of red dwarf stars may have Earth-sized planets orbiting them that have the right conditions for life.
“Our new observations with Harps mean that about 40% of all red dwarf stars have a super-Earth orbiting in the habitable zone where liquid water can exist on the surface of the planet,” said team leader Xavier Bonfils from the Observatoire des Sciences de l’Univers de Grenoble, France.
“Because red dwarfs are so common – there are about 160 billion of them in the Milky Way – this leads us to the astonishing result that there are tens of billions of these planets in our galaxy alone.”
During their survey, the group of astronomers found a total of nine super-Earths, planets with a rocky structure that have a mass up to ten times that of Earth, while two such planets are orbiting inside their stars’ habitable zones. Extrapolating with data gathered from non-dwarf stars were super-Earths have also been found, the scientists were able to produce an estimate for how common different sorts of planets are around red dwarf.
Huge planets, the size of Jupiter for instance, have been found to orbit in less than 12% of red dwarfs, suggesting their much rarer than small rocky words, like the Earth. Alright, but why should we care if there’s another potential Earth out there if its thousands of light years away? Well, the scientists found that there could be at least 100 super-Earths’ orbiting in the habitable zones of their stars, located in a radius 30 light years away from our own sun. That’s not that far at all, in the astronomical scale.
Astronomers at UC Santa Cruz have set a new benchmark for cosmological research for decades to come maybe, after successfully simulating the forming of distant galaxies, like our very own Milky Way, under the mysterious forces of dark matter and dark energy.
Named Bolshoi – for the Russian word meaning “grand” or “great” – the simulation’s results are on par with what astrophysicists have theorized for years, confirming the current models which try to explain how the “Big Bang” sparked the origin of the subatomic particles and galaxies that populate our expanding Universe. This extraordinary feat was reached after more than four years of hard work and with the help of the invaluable Pleiades supercomputer at NASA‘s Ames Research Center in Mountain View – one of the most powerful computing unit in the world.
“In one sense, you might think the initial results are a little boring, because they basically show that our standard cosmological model works,” physics Professor Joel Primack said in a university release Thursday. “What’s exciting is that we now have this highly accurate simulation that will provide the basis for lots of important new studies in the months and years to come.”
Anatoly Klypin, an astronomer at New Mexico State University, wrote the computer code that produced it, Primack said. He went on to say, the simulation will provide astronomers around the world with new guides for observing and describing the most distant galaxies that telescopes can see.
The simulation is based on a “map” of the early universe that was created nearly 10 years ago by a satellite called the Wilkinson Microwave Anisotropy Probe, or Wmap. The afformentioned probe captured a faint microwave echoed by the long forgoten Big Bang, now calculated to have occurred 13.7 billion years ago, and has since then provided invaluable data for various models, simulations or Universe maps.
The simulation traces the evolution of large-scale structures in the universe, and reveals how “halos” of dark matter, still covered in mystery to scientists, surround all the known galaxies to provide them with the gravity that holds them together.
“We know that the dark matter exists, but we still don’t know exactly what it is, yet it’s essential to explain the evolution and structure of all the stars and all the galaxies,” Primack said in an interview.
Dark matter – everywhere
Astronomers have calculated that dark matter accounts for something between 75 and 82 percent of all the matter in the Universe. The rest is the ordinary matter that makes up everything else in the Universe, protons and neutrons for the atoms that form our surroundings, from star dust to burgers.
The initial release of data from the Bolshoi simulation began in early September.
“We’ve released a lot of the data so that other astrophysicists can start to use it,” he said. “So far it’s less than one percent of the actual output, because the total output is so huge, but there will be additional releases in the future.”
I'll admit, it doesn't look like much here, but wait till you hit play on the embedded video.
Incredibly enough, using a a simple, standard issued astrophotography set-up, amateur astronomer Scott Ferguson was able to film in incredible detail the ISS docked together with Atlantis as they both orbited above him – all in clear sky, broad daylight.
How did he do this? Well, as equipment goes Scott, like I said, used a simple 20 cm (8 inch) telescope and a video camera optimized for astrophotography, but what really helped him with his en-devour was a piece of software that predicted the position and path of the two orbiting spacecraft. Seeing how the ISS is so hard to spot during daylight, this software was critical for the catch on film.
Phil Plait, who writes at Bad Astronomy, claims that during its overhead pass, when the ISS is only 350 km above the Earth’s surface, a simple pair of binoculars is enough to see it, albeit only a distinguishable dot in the skyline. With a telescope, as you’ve probably amazed yourself already in the above video, that’s something different, and for the short time Atlantis – the last shuttle mission in fact – is still docked above, maybe you can catch the same glimpse for yourself as well. You can start from heavensabove.com so you can begin timing preparations.
Since 1995, over 500 planets that don’t orbit our Sun have been discovered, with the numbers increasing more and more in the past years. But only recently did astrophysicists observe that in some of these cases, the star seems to be spinning in one direction, and the planet orbits it in the totally opposite direction – totally counterintuitive and against what we generally believe about planetary formation.
“That’s really weird, and it’s even weirder because the planet is so close to the star,” said Frederic A. Rasio, a theoretical astrophysicist at Northwestern University. “How can one be spinning one way and the other orbiting exactly the other way? It’s crazy. It so obviously violates our most basic picture of planet and star formation.”
The size and proximity to the star is what led to the ‘hot Jupiter’ name, but aside from this information, researchers didn’t really know that much about them; so they set out to study what can cause such a flipped rotation, and why these hot Jupiters have such close orbits.
“Once you get more than one planet, the planets perturb each other gravitationally,” Rasio said. “This becomes interesting because that means whatever orbit they were formed on isn’t necessarily the orbit they will stay on forever. These mutual perturbations can change the orbits, as we see in these extrasolar systems.”
The thing is, typically enough, astrophysicists have considered our solar system to be typical for the Universe, but observations don’t seem to confirm this belief.
“We had thought our solar system was typical in the universe, but from day one everything has looked weird in the extrasolar planetary systems,” Rasio said. “That makes us the odd ball really. Learning about these other systems provides a context for how special our system is. We certainly seem to live in a special place.”
The physics they used to solve this issue is basically orbital mechanics, but the approach they needed, and the amount of detail and successful approximation is absolutely stunning.
“It was a beautiful problem,” said Naoz, “because the answer was there for us for so long. It’s the same physics, but no one noticed it could explain hot Jupiters and flipped orbits.”
“Doing the calculations was not obvious or easy,” Rasio said, “Some of the approximations used by others in the past were really not quite right. We were doing it right for the first time in 50 years, thanks in large part to the persistence of Smadar.”
Of course, a computer model was necessary, but the steps that have to be taken until that computer model are the most important. It takes a sharp mind, and a correct approach to take everything from paper and put it on a hard disk.
“It takes a smart, young person who first can do the calculations on paper and develop a full mathematical model and then turn it into a computer program that solves the equations,” Rasio added. “This is the only way we can produce real numbers to compare to the actual measurements taken by astronomers.”
In their model, they created a simple solar system with a star similar to the Sun and two planets; one of them is a Jupiter-like planet that forms far from the star, where this kind of planets are thought to form. The other planet is even farther away from the sun than the inner planet, and it interacts gravitationally with it, shaking the whole system.
The effects of this model are the exact ones they were trying to get: the inner gas giant moves closer and closer towards the Sun and starts orbiting in the opposite direction of the star’s spin. These changes occur because (according to the model) the two orbits are exchanging angular momentum, and the inner one loses energy via strong tides. The gravitational couple forces the inner planet to adopt an eccentric, needle-like orbit; in order for this to happen, it has to lose a lot lot of angular momentum, giving it away to the outer planet, and thus its orbit gradually shrinks because of all the dissipated energy, pulling it closer and closer to the star, and sometimes flipping its orbit in the process.
An intriguing hypothesis was brought up by Professor Bernard Carr from Queen Mary University in London and Professor Alan Coley from Canada’s Dalhousie University, who claims that some of the black holes we see today may actually be remnants of a past universe that collapsed into itself after a Big Crunch.
I don’t know about you, but I’m having some really big problems wrapping my mind around this; the controversial theory that states the black holes might have collapsed (somehow), and then were reborn at the Big Bang of our universe. Called primordial black holes, they were formed again in the hyper dense conditions existing in the moments after the, which would make them even more exotic and harder to understand than the supermassive black holes at the center of most galaxies.
Professor Carr and Professor Coley say if the universe expands and contracts in cycles of big bangs and big crunches, some primordial black holes may survive.
So far, these primordial black holes exist only in theory, but even if one was found, it’s extremely unlikely that anybody would be able to figure out if it was born before our universe. Again, this seems extremely interesting, but highly speculative. Dr Tamara Davis, an astrophysicist and theoretical cosmologist with the University of Queensland claims the same thing.
“We know our theories break down when you get to the densities and pressures existing near the big bang,” she said. “We don’t know the physics of what would happen in this bounce, or even if the bounce occurs at all. It’s just one of the possible theories of how our universe began, and it’s a very speculative one.”
She also makes a pretty convincing statement, explaining that the laws of physics change as the universe changes.
“We know our theories break down when you get to the densities and pressures existing near the big bang,” she said.
“The strength of gravity, the speed of light, or the strength of the electric charge could be different in different universes,” she said. So it becomes even more speculative to say black holes from one universe could exist in another. But this kind of research is also very important because it’s only by pushing the boundaries of our current theories that we can find out where the weaknesses are and make progress in figuring out how to solve those weaknesses.”
In case you have no idea who Carl Sagan is… well, you should, basically. Carl Sagan is one of those men who brought science to the people, making numerous fields such as astronomy, astrophysics, exobiology, and many, many more accessible for the masses. He published more than six hundred research papers and popular science works, and reached the minds and hearts of millions. He also wrote the novel ‘Contact’, after which a movie was made (despite the fact that it doesn’t quite follow the book).
He also made a wonderful series of documentaries, which I highly recommend for absolutely everybody. Entitled ‘Cosmos: a personal voyage‘, the series lucidly and clearly explains topics such as Einstein’s theory of relativity, Darwin’s evolutionary theory, pollution, how galaxies are formed, etc. The 13 hours of documentaries should make their way onto television all the time if you ask me, but until then, you can grab them from here. Sadly, not all of them can be embedded here, so I will only put the link for these ones.
Carl Sagans Cosmos – Episode 1 – The Shores Of The Cosmic Ocean:
Carl Sagans Cosmos – Episode 2 – One Voice In The Cosmic Fugue
Carl Sagans Cosmos – Episode 3 – The Harmony Of The Worlds
Carl Sagans Cosmos – Episode 4 – Heaven & Hell
Carl Sagans Cosmos – Episode 5 – Blues for a Red Planet
In 2004, NASA researchers identified the Apophis asteroid and after some quick calculations they states there is a chance the asteroid will hit our homey planet in 2029. A few observations and some other calculations later, they explained that that chance is extremely small for 2029, as well as other years to come. However, reports from Russia claim that the chance of Apophis hitting Earth is quite significant, and in this case, the asteroid, despite not being larger than two football fields, would do a whole lot of damage.
Still, NASA explains there is no need to panic.
“Technically, they’re correct, there is a chance in 2036 [that Apophis will hit Earth],” said Donald Yeomans, head of NASA’s Near-Earth Object Program Office. However, that chance is just 1-in-250,000, Yeomans said.
I’m not really sure, but I think those odds are way better than the odds of a car accident by 2036, so there is no major need to get agitated here. Russian researchers based their research on the fact that in 2029, Apophis will pass through what is called a gravitational keyhole, a precise region in space, only slightly larger than the asteroid itself, in which the effect of Earth’s gravity is such that it could tweak Apophis’ path.
“The situation is that in 2029, April 13, [Apophis] flies very close to the Earth, within five Earth radii, so that will be quite an event, but we’ve already ruled out the possibility of it hitting at that time,” Yeomans explains “On the other hand, if it goes through what we call a keyhole during that close Earth approach … then it will indeed be perturbed just right so that it will come back and smack Earth on April 13, 2036. The chances of the asteroid going through the keyhole, which is tiny compared to the asteroid, are “minuscule,” he added.
However, it will pass quite close to Earth in 2012, which will allow researchers to study it in far more detail, and we will still have time to devise a successful plan, even with today’s technology. All in all, no reason whatsoever to panic over this one.
The discovery of 9 new planets raises some serious questions on the matter of how planets are formed. Two astronomers from the University of California, Santa Barbara reported the discovery, and of them, two are spinning in the opposite direction the planets in our solar system are spinning. This, along with other recent studies of exoplanets (planets outside the solar system) seems to put the final nail in the primary theory regarding planetary formation.
Artistic illustration of a Hot Jupiter
This was the highlight at the UK National Astronomy Meeting in Glasgow, Scotland that took place this week, and now researchers from this field will have a whole lot of work to do, basically starting from scratch (almost).
“Planet evolution theorists now have to explain how so many planets came to be orbiting like this,” said Tim Lister, a project scientist at LCOGT. Lister leads a major part of the observational campaigns along with Rachel Street of LCOGT, Andrew Cameron of the University of St. Andrews in Scotland, and Didier Queloz, of the Geneva Observatory in Switzerland.
The 9 planets are pretty interesting by themselves too; they are so-called “Hot Jupiters”. As you could guess by the name, they are giant gas planets that orbit quite close to their star (which is of course why they’re hot). Since this type of planet was discovered no more than 15 years ago, their origin has remained a mystery. However, they are quite easy to detect due to the gravitational effect they have on their star.
The general belief is that at their cores, these planets have a mix of rock and ice particles found only in the cold outer reaches of planetary systems. The logical conclusion is that Hot Jupiters have to form quite far away from their star and then migrate closer as millions of years pass. Numerous astronomers believed this happens due to the interactions the planets have with the dust cloud from which they are formed. However, this idea does not explain why they orbit in a direction contrary to that of the disk.
Another theory suggests that it was not interaction with the disk at all, but rather a slower evolution that was affected by gravitational relationships with more distant planetary or stellar companions over hundreds of millions of years. It would probably be imposed an elongated orbit and would suffer have a “tidal” movement, until it was parked in a more circular orbit close to the star.
“In this scenario, smaller planets in orbits similar to Earth’s are unlikely to survive,” said Rachel Street.
The most recent flyby showed a significant number of geysers just waiting to pop out from under the surface – even more than previously believed. The pictures taken show them in great detail, and by taking photographs across a period of time, researchers can understand their activity and overall planetary influence.
“This last flyby confirms what we suspected,” said Carolyn Porco, Cassini’s imaging team lead at the Space Science Institute in Boulder, Colo. “The vigor of individual jets can vary with time, and many jets, large and small, erupt all along the tiger stripes.”
“The fractures are chilly by Earth standards, but they’re a cozy oasis compared to the numbing 50 Kelvin (minus 370 Fahrenheit) of their surroundings,” said John Spencer, a composite infrared spectrometer team member based at Southwest Research Institute also in Boulder. “The huge amount of heat pouring out of the tiger stripe fractures may be enough to melt the ice underground.”
With the Cassini mission prolonged until 2017, we’ll definitely be hearing from the frozen giant quite soon.
Researchers have long been interested in finding other planets that have approximately the same size as our mother earth, because it’s estimated that they have the biggest odds of hosting life in a significant diversity. However, out of the over 400 planets that have been discovered so far, the vast majority resembles Jupiter rather than Earth.
Scientists using the Keck telescope in Hawaii discovered a new planet they’ve called HD156668b. Located in the Hercules constellation 80 light years away from us, this “Super Earth” has all the odds of being inhabited.
“This is quite a remarkable discovery,” said astronomer Andrew Howard of the University of California at Berkeley. “It shows that we can push down and find smaller and smaller planets.”
Super Earths are planets with a mass relatively close to that of Terra; they are rather bigger than smaller (from 2 to 10 times bigger, actually). They have to be bigger, because if they are smaller (like Mars, for example) the interior would just not be hot enough to drive tectonics (tectonic plates slide on a layer of molten rock called a mantle, and convection currents make it move around).
But of course, even such a (relatively) small difference can cause significant modification in the planetary dynamics. With these bigger planets, the interior would of course be hotter, bigger, and the planetary crust would be thinner and would suffer more stress. The tectonic movement would be much active and as a result, earthquakes, volcanic eruptions and other such processes would take place way more often.
The US-Japan Sukazu observatory reported the finding of some never-before seen embers from the high temperature fireballs that immediately follower the supernovae explosions. Even after thousands of years in which they haven’t been exposed to any heat source, gas within these stellar wrecks is 10.000 hotter than the Sun’s surface.
Supernovae usually cool off quickly, due to the massive expansion that follows the explosion; after that it basically sweeps stellar gas and during the following thousands of years, starts to heat up again. In this studied supernova from the Jellyfish Nebula they also found some structures that raise questions.
“These structures indicate the presence of a large amount of silicon and sulfur atoms from which all electrons have been stripped away,” Yamaguchi said. These “naked” nuclei produce X-rays as they recapture their lost electrons.