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Darja
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« Reply #2100 on: Sep 16, 2019, 03:21 AM »

The Maybe Comet From Another Star

Now zinging through Cancer: a glob of light from interstellar space?

By Dennis Overbye
Guardian
Sept. 16, 2019

The universe comes calling.

Astronomers around the world are sitting on the edges of their seats right now, waiting to see if yet another comet from another sun has invaded the solar system.

The first such interstellar invader ever detected, a cigar-shaped rock called Oumuamua, caused a sensation when it was seen streaking away from our sun in the fall of 2017. Some astronomers even considered the possibility that it was an alien artifact. But irregularities in its outward trajectory suggested that it was more likely a comet from another star system being jerked around by unseen jets of gas erupting from its surface. It has since passed out of sight.

That is not the case with the new object. Originally labeled gb00234, and now provisionally named C/2019 Q4 (Borisov), it is still on its way toward the heart of the solar system.


We’ll bring you stories that capture the wonders of the human body, nature and the cosmos.

The object was first detected by Gennady Borisov, a Crimean astronomer and veteran comet hunter at the Crimean Astrophysical Observatory (also known as Crimea-Nauchnij), near the city of Bakhchysarai. On Aug. 30, Dr. Borisov spotted a fuzzy blob of light, about 6 miles in diameter, moving in front of the stars in the constellation Cancer.

At the time, the object was 300 million miles from the sun and appeared to be moving too fast — some 20 miles per second — for the sun’s gravity to keep it bound in an orbit. That would suggest that it came from away and is destined to return into the night. But the intrinsic blurriness of the object, which on closer inspection seems to be shrouded in a cometary cloud of gas, makes accurate measurements of its position and velocity difficult. So far it has only been tracked for about two weeks.

Late on Wednesday the International Astronomical Union’s Minor Planet Center, in Cambridge, Mass., which tracks and certifies small objects in the solar system, published what it called a preliminary orbit suggesting that the object is indeed interstellar.

“The orbit looks strongly hyperbolic,” said Mathew Holman, a Harvard astronomer who is the center’s director. “Hyperbolic” is the technical term for an orbital path that does not close on itself.

On that basis, the center upgraded the name of Dr. Borisov’s discovery from BG00234 to C/2019 Q4 (Borisov).

Should more observations support an extrasolar origin, Dr. Holman said, the object would get a new name starting with “2I,” followed by some term redolent of the country or region that discovered it. (Oumuamua is now officially known as 1I/ Oumuamua, after the Hawaiian word for “scout.”)

More observations are sure to follow. “This object is going to be observable for some time,” Dr. Holman said.

“This is going to be a Christmas comet,” said Michele Bannister, an astronomer and expert on small bodies at Queen’s University Belfast, who said she was busy writing proposals to conduct observations.

Currently, the comet is only observable for about 20 minutes at twilight, as it appears in the sky relatively close to the sun. The first rule of astronomy, she noted, is “Don’t point a telescope at the sun.”

But by October the comet will appear far enough from the sun for space telescopes like Hubble to take a look.

According to the latest predictions, the comet should pass within 170 million miles of Earth around December 30. But experts still disagree on when it will pass closest to the sun: about Dec. 7, according to the Jet Propulsion Laboratory in Pasadena, or Dec. 10, according to the Minor Planet Center.

Either would grant astronomers plenty of time to carry out the kinds of observations they would have liked to do for Oumuamua, including listening for radio signals and exploring aspects of geophysics and interstellar astrophysics.

By the time Dr. Borisov’s comet arrives, it may be bright enough to be seen by amateur telescopes on our planet — if it behaves like ordinary comets.

That part remains to be seen.

“This is the first interstellar object that is really observably acting like a comet,” Dr. Bannister said. “It might behave the same as comets from our own sun, or it might not.”


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« Reply #2101 on: Sep 17, 2019, 03:57 AM »

Astronomers find clues of a volcanically active exomoon

Clues pointing towards a volcanically active exomoon hidden outside our solar system — a violent and dangerous world — have been discovered by astronomers.

Rob Lea byRob Lea
ZME
9/17/2019

A rocky extrasolar moon brimming with lava could orbit a planet 550 light-years from Earth, astronomers led by researchers from Bern University have discovered.

The volcanically active exomoon could be hidden in the exoplanet system WASP-49b, orbiting a hot giant planet in the inconspicuous constellation of Lepus, underneath the bright Orion constellation.

The researchers describe the exomoon as an ‘extreme’ version of Jupiter’s moon Io — the most volcanically active body in our own solar system. Thus, painting a picture of an exotic and dangerous world — an ‘exo-Io’.

Apurva Oza, a postdoctoral fellow at the Physics Insitute of the University of Bern and associate of the NCCR PlanetS, describes the exomoon, comparing it to a famous sci-fi setting: “It would be a dangerous volcanic world with a molten surface of lava — a lunar version of close-in Super-Earths like 55 Cancri-e.

“A place where Jedis go to die, perilously familiar to Anakin Skywalker.”

More than a grain of sodium. Uniting theory and circumstantial evidence.

Astronomers have yet to discover a moon beyond our solar system meaning that the researchers base their suspicions of the existence of this exo-Io on circumstantial evidence — namely sodium gas in WASP-49b at an unusually high-altitude.

Oza explains: “The neutral sodium gas is so far away from the planet that it is unlikely to be emitted solely by a planetary wind.

“The sodium is right where it should be.”

Comparing this feature to observations of the Jupiter and Io system using low-mass calculations demonstrated to the team that an exo-Io could, indeed, be a plausible mechanism for sodium at WASP-49b.

The theory that large amounts of sodium around an exoplanet could point to a hidden moon or a ring of material was advance by Bob Johnson and Patrick Huggins in 2006. Following this, researchers from the University of Virginia calculated that a three-body system comprised of a star, close giant planet and a moon could remain stable for billions of years.

Oza took these theoretical predictions to form the basis of he and his colleagues’ work — published in the Astrophysical Journal.

The astrophysicist explains: “The enormous tidal forces in such a system are the key to everything.

“The energy released by the tides to the planet and its moon keeps the moon’s orbit stable, simultaneously heating it up and making it volcanically active.”

The researchers also demonstrate in their study that a small rocky moon would eject more sodium and potassium into space via this extreme volcanism than a large gas planet. This would especially be the case at high altitudes.

These emissions can then be identified by astronomers using the technique of spectroscopy. These particular elements are particularly useful to astronomers.

Oza adds: “Sodium and potassium lines are quantum treasures to us astronomers because they are extremely bright.

“The vintage street lamps that light up our streets with yellow haze, is akin to the gas we are now detecting in the spectra of a dozen exoplanets.”

When comparing their calculations with actual observations of sodium and potassium, the team found five candidate systems where a hidden exomoon could survive thermal evaporation. In the case of WASP-49b, the best explanation for the observed data was the presence of an exo-Io.

This isn’t the only explanation, however. As mention above, the observations of sodium at high altitudes could instead indicate the exoplanet is surrounded by a ring of material — most likely ionised gas.

Oza admits that the team need to find more clues, and as such, are relying on future observations with both ground and space-based telescopes. Also, as a few of these exo-Ios could eventually be destroyed as a result of extreme mass-loss, the team also want to search for evidence of such destruction.

Oza concludes: “While the current wave of research is going towards habitability and biosignatures, our signature is a signature of destruction.

“The exciting part is that we can monitor these destructive processes in real-time, like fireworks.”

Original research: https://arxiv.org/pdf/1908.10732.pdf
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« Reply #2102 on: Sep 18, 2019, 03:50 AM »

Key variable used to study Mars’ ancient atmosphere varies during the day

This used to mess up our calculations, but now we understand why.

Alexandru Micu
ZME
9/19/2019

New research is helping to improve our understanding of how Mars lost its atmosphere — and how much of it the planet lost.
Image via Wikimedia.

A new study led by NASA shows that a key tracer used to estimate how much atmosphere the planet lost changes with the temperature and time of day on Mars. The work should help make sense of previous measurements of the tracer, which have found wildly conflicting results. Having an accurate measurement of this tracer — a particular isotope of the oxygen atom — will enable us to estimate whether Mars has ever been habitable and what it was like on its surface.

The air that was

    “We know Mars had more atmosphere. We know it had flowing water. We do not have a good estimate for the conditions apart from that — how Earthlike was the Mars environment? For how long?” said Timothy Livengood of the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who led the study.

Even today, Mars has features such as dry riverbeds and mineral compounds that form in liquid water which point to much milder days in its past. One element that’s critical for such a past is a thick atmosphere that could retain enough heat for water to stay liquid on the surface.
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However, Mars has lost all that atmosphere today, which transformed its climate from one that could (potentially) nurture life to the dry and freezing environment found by NASA missions such as MAVEN, Curiosity, and the Viking missions of 1976.

Naturally, researchers have a lot of questions regarding the Red Planet’s ancient atmosphere. One way to estimate its nature and properties is to look at oxygen isotopes — lighter isotopes escape into space faster than light ones, so the remaining atmosphere gets enriched in heavier ones.

In Mars’ case, the lighter (and more common) isotope of oxygen is 16O, while the heavier one is 18O. By analyzing the relative amount of each of these isotopes, researchers can get a good idea of how thick the atmosphere was on early Mars.

The glaring flaw in this approach is that the 18O/16O ratio has been measured several times, producing various readings. The new paper provides a way to resolve this discrepancy by showing that the ratio can change during the Martian day.

    “Previous measurements on Mars or from Earth have obtained a variety of different values for the isotope ratio,” said Livengood. “Ours are the first measurements to use a single method in a way that shows the ratio actually varying within a single day, rather than comparisons between independent devices.”

    “In our measurements, the isotope ratio varies from being about 9% depleted in heavy isotopes at noon on Mars to being about 8% enriched in heavy isotopes by about 1:30pm compared to the isotope ratios that are normal for Earth oxygen.”

This range of ratios, they explain, is consistent with previously reported measurements. This suggests that those measurements were corrent, but disagreed because the dynamics of the Martian atmosphere are more complex than we assumed.

These ratio changes throughout the day are likely a routine occurrence caused by changes in ground temperature, the team explains. Molecules with heavier isotopes likely stick to cold surface grains at night more than the lighter isotopes which are freed (thermally desorbed) as the surface warms up during the day.

As Mars’ atmosphere is mostly made up of carbon dioxide (CO2), the team studied oxygen isotopes bound up in CO2 molecules. For the observations, they used the Heterodyne Instrument for Planetary Winds and Composition developed at NASA Goddard, currently installed at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii.

    “While trying to understand the broad spread in estimated isotope ratios that we retrieved from the observations, we noticed that they were correlated with the surface temperature that we also obtained,” said Livengood. “That was the insight that set us on this path.”

The paper “Evidence for diurnally varying enrichment of heavy oxygen in Mars atmosphere” has been published in the journal Icarus.


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« Reply #2103 on: Sep 19, 2019, 05:28 AM »

HI All,

We are having trouble with our servers .. so will not be able to post as normal today: 9/19/2019

God Bless,Rad
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« Reply #2104 on: Sep 20, 2019, 03:39 AM »


Explosions may be responsible for the bizarre lakes on Saturn’s Titan

Mike Wehner
BGR
9/20/2019

Scientists have learned a lot about Saturn’s moon Titan thanks to NASA’s Cassini spacecraft, which orbited the planet for well over a decade before NASA, and the ESA had to pull the plug in 2017. The mission was a massive success, and it’s still yielding new discoveries today.

Titan, which is the only other world that we know of in our solar system that supports liquid on its surface, is well known for its colossal lakes that are filled with hydrocarbons, but it’s the towering structures on the shores of those lakes that are the subject of a new research effort published in Nature Geoscience.

In contrast to most lakes here on Earth, many of the lakes found on Titan’s surface are surrounded by steep ridges stretching hundreds of feet into the sky. Exactly how those structures formed is a question scientists are eager to answer, a new model suggests a possible explanation.

Using radar data from Cassini, scientists have built computer simulations that show how explosions of warming nitrogen within Titan’s crust could have formed such basins. It’s possible, the researchers say, that liquid nitrogen, enduring periods of cooling and heating thanks to the greenhouse effect from Titan’s atmosphere, could have heated rapidly enough that, when it vaporized, it caused an explosion in the crust and formed craters.

In this hypothetical scenario, the craters became the perfect places for raining hydrocarbons to pool, laying the groundwork for the lakes we see covering the moon today.

“This is a completely different explanation for the steep rims around those small lakes, which has been a tremendous puzzle,” Linda Spilker of NASA’s Jet Propulsion Laboratory explains. “As scientists continue to mine the treasure trove of Cassini data, we’ll keep putting more and more pieces of the puzzle together. Over the next decades, we will come to understand the Saturn system better and better.”


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« Reply #2105 on: Sep 21, 2019, 04:22 AM »


Scientists spotted a bizarre X-ray blast in a distant galaxy

Mike Wehner
BGR
9/21/2019

Thanks to ever-advancing observational technology, astronomers can now spot distant galaxies in greater detail than ever before. For scientists, being able to study these distant locations in space is exciting, but when they spot something unexpected, their incredible distance from Earth means coming up with an explanation is difficult.

That’s exactly what a team of researchers using NASA’s NuSTAR space observatory is dealing with after recent observations of the galaxy NGC 6946 revealed powerful flashes of X-ray energy where nobody was expecting them. In a new paper published in The Astrophysical Journal, the scientists venture a guess as to what exactly is going on.

The team spotted these unusual X-ray flashes while scanning the distant galaxy for something else entirely: supernova explosions. In searching for the telltale signals of supernova blasts within the galaxy’s long, curved arms, the team spotted a brilliant X-ray source that had appeared essentially out of nowhere.

The bright flash — seen in the above image as green, in contrast to the blue supernova signals near the top of the frame — wasn’t there just ten days prior, meaning that some incredibly powerful source created it. In follow-up observations using NASA’s Chandra X-ray Observatory, the brilliant flash was once again nowhere to be seen.

“Ten days is a really short amount of time for such a bright object to appear,” Hannah Earnshaw, lead author of the study, said in a statement. “Usually with NuSTAR, we observe more gradual changes over time, and we don’t often observe a source multiple times in quick succession. In this instance, we were fortunate to catch a source changing extremely quickly, which is very exciting.”

So what was it? Well, at a distance of over 22 million light-years from Earth, we may never know for certain. However, the most plausible explanation the researchers have come up with is that the bright beam was produced by a black hole swallowing a star, resulting in a brief but incredibly bright X-ray emission. In any case, it was a rare and exciting sighting.


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« Reply #2106 on: Sep 23, 2019, 03:37 AM »


Something is killing galaxies — and science is on the case

on September 23, 2019
By The Conversation

In the most extreme regions of the universe, galaxies are being killed. Their star formation is being shut down and astronomers want to know why.

The first ever Canadian-led large project on one of the world’s leading telescopes is hoping to do just that. The new program, called the Virgo Environment Traced in Carbon Monoxide survey (VERTICO), is investigating, in brilliant detail, how galaxies are killed by their environment.

As VERTICO’s principal investigator, I lead a team of 30 experts that are using the Atacama Large Millimeter Array (ALMA) to map the molecular hydrogen gas, the fuel from which new stars are made, at high resolution across 51 galaxies in our nearest galaxy cluster, called the Virgo Cluster.

Commissioned in 2013 at a cost of US$1.4 billion, ALMA is an array of connected radio dishes at an altitude of 5,000 metres in the Atacama Desert of northern Chile. It is an international partnership between Europe, the United States, Canada, Japan, South Korea, Taiwan and Chile. The largest ground-based astronomical project in existence, ALMA is the most advanced millimetre wavelength telescope ever built and ideal for studying the clouds of dense cold gas from which new stars form, which cannot be seen using visible light.

Large ALMA research programs such as VERTICO are designed to address strategic scientific issues that will lead to a major advance or breakthrough in the field.
Galaxy clusters

Where galaxies live in the universe and how they interact with their surroundings (the intergalactic medium that surrounds them) and each other are major influences on their ability to form stars. But precisely how this so-called environment dictates the life and death of galaxies remains a mystery.

Galaxy clusters are the most massive and most extreme environments in the universe, containing many hundreds or even thousands of galaxies. Where you have mass, you also have gravity and the huge gravitational forces present in clusters accelerates galaxies to great speeds, often thousands of kilometres-per-second, and superheats the plasma in between galaxies to temperatures so high that it glows with X-ray light.

In the dense, inhospitable interiors of these clusters, galaxies interact strongly with their surroundings and with each other. It is these interactions that can kill off — or quench — their star formation.

Understanding which quenching mechanisms shut off star formation and how they do it is main the focus of the VERTICO collaboration’s research.

The life cycle of galaxies

As galaxies fall through clusters, the intergalactic plasma can rapidly remove their gas in a violent process called ram pressure stripping. When you remove the fuel for star formation, you effectively kill the galaxy, turning it into a dead object in which no new stars are formed.

In addition, the high temperature of clusters can stop hot gas cooling and condensing onto galaxies. In this case, the gas in the galaxy isn’t actively removed by the environment but is consumed as it forms stars. This process leads to a slow, inexorable shut down in star formation known, somewhat morbidly, as starvation or strangulation.

While these processes vary considerably, each leaves a unique, identifiable imprint on the galaxy’s star-forming gas. Piecing these imprints together to form a picture of how clusters drive changes in galaxies is a major focus of the VERTICO collaboration. Building on decades of work to provide insight into how environment drives galaxy evolution, we aim to add a critical new piece of the puzzle.

An ideal case study

The Virgo Cluster is an ideal location for such a detailed study of environment. It is our nearest massive galaxy cluster and is in the process of forming, which means that we can get a snapshot of galaxies in different stages of their life cycles. This allows us to build up a detailed picture of how star formation is shut off in cluster galaxies.

Galaxies in the Virgo cluster have been observed at almost every wavelength in the electromagnetic spectrum (for example, radio, optical and ultra-violet light), but observations of star-forming gas (made at at millimetre wavelengths) with the required sensitivity and resolution do not exist yet. As one of the largest galaxy surveys on ALMA to date, VERTICO will provide high resolution maps of molecular hydrogen gas — the raw fuel for star formation — for 51 galaxies.

With ALMA data for this large sample of galaxies, it will be possible to reveal exactly which quenching mechanisms, ram pressure stripping or starvation, are killing galaxies in extreme environments and how.

By mapping the star-forming gas in galaxies that are the smoking gun examples of environment-driven quenching, VERTICO will advance our current understanding of how galaxies evolve in the densest regions of the Universe.

Toby Brown, Post Doctorate Fellow in Astrophysics, McMaster University

This article is republished from The Conversation under a Creative Commons license. Read the original article.


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« Reply #2107 on: Sep 24, 2019, 03:48 AM »


NASA just released a high-res 3D model of the Moon that’ll blow you away

Mike Wehner
BGR
9/24/2019

NASA has provided us with some truly fantastic images of the Moon over the years. We’ve gotten to see Earth’s friendly little neighbor from just about every angle, and anyone who wants to scour images of its surface for interesting sights should have no problem doing so.

But photos are two-dimensional and as cool as high-resolution photos can be, they’re not quite as cool as a fully-realized 3D model. Now, using a wealth of information gathered by NASA’s own Lunar Reconnaissance Orbiter, the space agency has produced a pair of maps that can be used to create the most detailed and accurate model of Earth’s moon ever, and anyone can download it.

The maps, which NASA is calling the CGI Moon Kit, include a visible color map of the Moon’s surface weighing in at nearly half a gigabyte on its own. That image, combined with a displacement map that provides elevation data for a 3D model, can easily be applied to a simple sphere in a variety of model programs to generate a stunningly accurate digital version of the Moon.

Virtual 3D models are often made of several layers, including color, depth, and texture. In this case, the displacement map gives the resulting 3D model the peaks and valleys we see on the Moon, many of which were produced by impacts. This simple animation offers an easy way to grasp how such a model might be made using the available images:

The displacement map allows for the model to react realistically to light, giving the ridges around craters the ability to cast shadows over the surface. The result is a photo-accurate model of the Moon that can be used for any number of purposes.

If you’d like to download the kit for yourself, it’s freely available on NASA’s Scientific Visualization Studio site: https://svs.gsfc.nasa.gov/4720


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« Reply #2108 on: Sep 25, 2019, 03:56 AM »


Mars’ North Pole looks so bizarre in new photo by ExoMars orbiter

Mike Wehner
BGR
9/25/2019

The Mars we often seen in photos from rovers and orbiters is dry, dusty, and barren, but there are parts of the planet that, when viewed separately, could trick you into thinking you’re looking at a totally foreign alien land. The latest snapshot captured by the ExoMars Trace Gas Orbiter fits perfectly into that latter category.

The image was captured using the CaSSIS camera, one of the orbiter’s many instruments, and it shows the frosty dunes that cover the northern region of Mars that is rarely seen up-close. It also definitely looks at least a little bit like cookie-flavored ice cream.

As the European Space Agency explains in a post highlighting the photo, the dark areas are cracks and gaps in the ice that are formed when gas trapped below is released. When the gas breaks free, it carries dust and sand with it, covering the edges of the cracks with the darker material.

Similar to dunes seen on Earth, the flowing shapes that form on the surface of Mars are carved by winds. As ESA explains, the shapes we see in this particular image can tell scientists a lot about the processes happening on the surface:

    The image also captures ‘barchan’ dunes – the crescent or U-shaped dunes seen in the right of the image – as they join and merge into barchanoid ridges. The curved tips of the barchan dunes point downwind. The transition from barchan to barchanoid dunes tells us that secondary winds also play a role in shaping the dune field.

Despite the fact that humans are seemingly destined to explore the Red Planet in person sooner rather than later, locations like this probably won’t be first on the list for those early travelers. For now, we’ll just have to enjoy the view from above.


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« Reply #2109 on: Sep 26, 2019, 03:41 AM »


A colossal volcano on Jupiter’s Moon Io is about to blow its top

Mike Wehner
BGR
9/26/219

Volcanic eruptions happen regularly here on Earth, and for the most part, we’ve learned to deal with them. But volcanism isn’t something that’s unique to Earth, and scientists know that volcanos on other planets in our solar system may be equally active. Now, researchers say that one such volcano — the massive 125-mile-wide Loki Patera on Jupiter’s moon Io — is on the edge of eruption.

The volcano, which scientists believe erupts with startling regularity, blows its top roughly once every 475 days or so, which is even more frequent than previous rates observed in the 1990s. Based on that schedule, the volcano is due for an eruption this month, and it’ll likely be visible from telescopes on Earth.

Loki’s size dwarfs any active volcano here on Earth, and Io is considered to be the most volcanically active body in our entire solar system. When it erupts, it’s a big deal, and as the Planetary Science Institute explains, the volcano has a serious temper.

“Loki is the largest and most powerful volcano on Io, so bright in the infrared that we can detect it using telescopes on the Earth,” Julie Rathbun of the Planetary Science Institute said in a statement. “We think that Loki could be predictable because it is so large. Because of its size, basic physics are likely to dominate when it erupts, so the small complications that affect smaller volcanoes are likely to not affect Loki as much.”

Without actually visiting Io, researchers have to forecast eruptions based solely on the pattern they’ve observed in the past. Loki has been relatively punctual with its eruptions, but it’s also thrown scientists for a loop in the past, with long periods of silence before picking back up where it left off. If the volcano is keeping to its usual schedule, it won’t be long before we see another round of fireworks.


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« Reply #2110 on: Sep 27, 2019, 03:47 AM »

How scientists detected water on an alien planet for the first time

K2-18 b is probably the most Earth-like planet we've discovered so far.

BGR
9/27/2019

With more than 4,000 exoplanets – planets orbiting stars other than our sun – discovered so far, it may seem like we are on the cusp of finding out whether we are alone in the universe. Sadly though, we don’t know much about these planets – in most cases just their mass and their radius.

Understanding whether a planet could host life requires a lot more information. At the moment, one extremely important piece of information that is missing is the presence, composition and structure of their atmospheres. Signs of atmospheric water, oxygen and methane would all be signs that a planet may support life.

Now we have for the first time managed to detect water vapour in the atmosphere of an exoplanet that is potentially habitable. Our results have been published in Nature Astronomy.

A planet’s atmosphere plays a vital role in shaping the conditions inside it – or on its surface, if it has one. Its composition, stability and structure all provide important clues about what it is like to be there. Through atmospheric studies, we can therefore learn about the history of the planet, investigate its habitability and, ultimately, discover signs of life.

The primary method that we use when examining exoplanets is transit spectroscopy. This involves looking at starlight as a planet passes in front of its host star. As it transits, stellar light is filtered through the planet’s atmosphere – with light being absorbed or deflected based on what compounds the atmosphere consists of.

The atmosphere therefore leaves a characteristic footprint in the stellar light that we try to observe. Further analysis can then help us match this footprint to known elements and molecules, such as water or methane.

At the moment, the study of exoplanets atmospheres is limited, as this kind of measurement requires very high precision, which current instruments were not built to deliver. But molecular signatures from water have been found in the atmospheres of gaseous planets, similar to Jupiter or Neptune. It has never before been seen in smaller planets – until now.

K2-18 b

K2-18 b was discovered in 2015 and is one of hundreds of “super-Earths” – planets with a mass between Earth and Neptune – found by NASA’s Kepler spacecraft. It is a planet with eight times the mass of the Earth that orbits a so called “red dwarf” star, which is much cooler than the sun.

However, K2-18b is located in the “habitable zone” of its star which means it has the right temperature to support liquid water. Given its mass and radius, K2-18 b is not a gaseous planet, but has a high probability of having a rocky surface.

We developed algorithms to analyse the starlight filtered by this planet using transit spectroscopy, with data provided by the Hubble Space Telescope.

This enabled us to make the first successful detection of an atmosphere with water vapour around a non-gaseous planet, which is also located within the habitable zone of its star.

In order for an exoplanet to be defined as habitable, there is a long list of requirements that need to be satisfied. One is that the planet needs to be in the habitable zone where water can exist in liquid form. It is also necessary that the planet has an atmosphere to protect the planet from any harmful radiation coming from its host star.

Another important element is the presence of water, vital for life as we know it. Although there are many other criteria for habitability, such as the presence of oxygen in the atmosphere, our research has made K2-18b the best candidate to date. It is the only exoplanet to fulfil three requirements for habitability: the right temperatures, an atmosphere and the presence of water.

However, we cannot say, with current data, exactly how likely the planet is to support life. Our data are limited to an area of the spectrum – this shows how light is broken down by wavelength – where water dominates, so other molecules can unfortunately not be confirmed.

First of many?

With the next generation of telescopes, such as the James Webb Space Telescope and the ARIEL space mission, we will be able to find more information on the chemical composition, cloud coverage and structure of the atmosphere of K2-18 b. This will help us understand just how habitable it is.

These missions could also make it easier to make similar detections for other rocky bodies in the habitable zones of their parent stars.

That would certainly be exciting. With K2-18 b being 110 light years away, it is not really a planet we could visit – even with tiny robotic probes – in the foreseeable future.

Excitingly, it is probably just a matter of time before we find similar planets that are closer. So we may be well on our way to answering the age-old question of whether we are alone in the universe after all.

Angelos Tsiaras, Research Associate of Physics and Astronomy, UCL


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« Reply #2111 on: Sep 28, 2019, 04:29 AM »


‘A protocluster is a rare and special system’: Scientists discover oldest galaxy cluster

on September 28, 2019
By Agence France-Presse

Astronomers have discovered a 13-billion-year-old galaxy cluster that is the earliest ever observed, according to a paper released Friday, a finding that may hold clues about how the universe developed.

Such an early-stage cluster — called a protocluster — is “not easy to find”, Yuichi Harikane, a researcher at the National Astronomical Observatory of Japan who led the international team, said in a press release.

“A protocluster is a rare and special system with an extremely high density,” Harikane said, adding that the researchers used the wide viewing field of the Subaru telescope in Hawaii to “map a large area of the sky” in their search.

The discovery of the protocluster, a collection of 12 galaxies, suggests that large cosmic structures were present in the very early stages of the universe, which scientists believe was born 13.8 billion years ago.

One of the 12 galaxies is known as Himiko, a giant gas cloud found in 2009 by using the same telescope.

“It is reasonable to find a protocluster near a massive object, such as Himiko. However, we’re surprised to see that Himiko was located… on the edge 500 million light-years away from the center,” the paper’s co-author Masami Ouchi said.

“It is still not understood why Himiko is not located in the center,” he said.

“These results will be key for understanding the relationship between clusters and massive galaxies.”

The team included scientists from Imperial College London and the study is published in Friday’s Astrophysical Journal.

© 2019 AFP


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« Reply #2112 on: Sep 30, 2019, 03:55 AM »

Newfound comet could be an interstellar object, experts argue

It's only the second time that astronomers have detected an interstellar visitor.

Fermin Koop
ZME
9/30/2019

A newly discovered comet heading towards the orbit of Mars has scientists working to confirm whether it came from outside the solar system, a likely prospect that would make it the second time astronomers see an interstellar visitor on its way past the sun.

The comet, firstdetected by Crimean astronomer Gennady Borisov, follows a highly curved pathbarreling in the sun’s direction at unusually high speeds, evidence that itoriginated beyond the solar system.

    “We’ve been scrambling here at the University of Hawaii to get observations to make position measurements,” said Karen Meech, an astronomer at the university whose team concluded that the object classifies as a comet. “Every time a new comet is discovered, everybody starts to try and get data so that you can get the orbit.”

An apparent amalgam of ice and dust, the comet is expected to make its closest approach to the sun on December 8, putting it 190 million miles (300 million km) from Earth, on a route believed unique to such objects of interstellar origin.

The cometis now heading toward the inner solar system and will enter it on Oct. 26 fromabove at roughly a 40-degree angle relative to the ecliptic plane. That’s theplane in which the Earth and planets orbit the Sun.

It wasestablished as being cometary due to its fuzzy appearance, which indicates thatthe object has a central icy body that is producing a surrounding cloud of dustand particles as it approaches the Sun and heats up.

Onceconfirmed interstellar, the comet – dubbed C/2019 Q4 by astronomers – wouldbecome only the second such body ever observed by scientists. The first was acigar-shaped comet dubbed ‘Oumuamua – a name of Hawaiian origin meaning amessenger from afar arriving first – that sailed into our planetaryneighborhood in 2017.

    “It’s going to be a nice Christmas comet,” says astronomer Michele Bannister of Queen’s University Belfast in Northern Ireland. “We’ll be able to observe it for probably a year, which is really different from ‘Oumuamua.”

Unlike‘Oumuamua, which visited the solar system for only a week, the newfound cometwill linger near Mars’ orbit for almost a year, giving scientists ample time tocharacterize its chemical signatures and seek further clues about its origin.


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« Reply #2113 on: Oct 01, 2019, 03:37 AM »

The supermassive black hole at the heart of the Milky Way just got very hungry

This big boy just got the munchies.

Tibi Puiu
ZME
10/1/2019

Like virtually all other galaxies, the Milky Way houses a supermassive black hole at its center with a mass millions of times greater than the sun. It constantly gobbles up enormous amounts of gas and dust from its surroundings but scientists have noticed that even for its gargantuan appetite, this black hole is now unusually hungry.

    “We have never seen anything like this in the 24 years we have studied the supermassive black hole,” said Andrea Ghez, UCLA professor of physics and astronomy and a co-senior author of the research. “It’s usually a pretty quiet, wimpy black hole on a diet. We don’t know what is driving this big feast.”

The astronomers employed more than 13,000 observations of the black hole, called Sagittarius A*, performed by the W.M. Keck Observatory in Hawaii and the European Southern Observatory’s Very Large Telescope in Chile since 2003.

Although black holes cannot be imaged directly since their massive gravity allows nothing to escape their grasp, not even light, astronomers can see brightness at the edge of the black hole’s point of no return — the event horizon.

The brightness is generated by radiation from gas and dust that are accelerated to huge speeds as they circle the event horizon. Moving at close to the speed of light, the matter generates powerful jets of plasma containing electrons and positrons that ricochet off the event horizon and get hurled outward along the black hole’s axis of rotation. It is these enormous jets of energetic subatomic particles that emit light, which our telescopes can see. Last year, researchers were able to produce the first image of a black hole’s event horizon.

Observations of Sagittarius A* performed on May 13 showed that its brightness had enhanced considerably.

    “The first image I saw that night, the black hole was so bright I initially mistook it for the star S0-2, because I had never seen Sagittarius A* that bright,” said UCLA research scientist Tuan Do, the study’s lead author. “But it quickly became clear the source had to be the black hole, which was really exciting.”

Astronomers aren’t sure what’s gone into Sagittarius A* but it’s possible that the extreme brightness swings may have been triggered after a nearby star called S0-2 made a close approach to the black hole during 2018. In the process, it should have discharged a large quantity of gas.

Another hypothesis is that G2, a binary star system was stripped off its outer layer during a close approach to the black hole in 2014. This may explain the black hole’s sudden variations in brightness just outside of it.

Alternatively, very large asteroids that ventured too close to the black hole may have contributed to the jump in brightness, the astronomers noted in a recent paper published in The Astrophysical Journal.

Whatever may be the case, the anomaly is no threat to life on Earth. The black hole is located about 26,000 light-years away from Earth and its radiation would have to be 10 billion times brighter to affect us in a significant way.

What’s perhaps more fascinating than this anomaly, however, is the way the astronomers were able to track the black hole’s feeding patterns all of these years.

In 2004, Ghez and colleagues helped pioneer a crucial piece of technology, called adaptive optics, which corrects the distorting effects of Earth’s atmosphere in real-time. This allowed them to observe more than 3,000 stars in the vicinity of Sagittarius A*.

However, astronomers have been observing Sagittarius A* since long before adaptive optics were invented. In order to make good use of observations made prior to 2004, Ghez developed a new technique called speckle holography that can use faint information from 24 years of data recorded on the black hole and fill in the blanks. The technique was recently described in The Astrophysical Journal Letters and allowed the researchers to determine that the black hole’s brightness is at an all-time high since we’ve been observing it.

Remarkably, the technique also allowed the astronomers to test Einstein’s theory of general relativity near the black hole. The researchers observed the black hole’s effects on S0-2 at it completed an orbit; effects which mirrored Einstein’s predictions.

    “It was like doing LASIK surgery on our early images,” Ghez said. “We collected the data to answer one question and serendipitously unveiled other exciting scientific discoveries that we didn’t anticipate.”


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« Reply #2114 on: Oct 02, 2019, 03:35 AM »


NASA couldn’t find India’s crashed Moon lander, and hope is fading fast

Mike Wehne
BGR
10/2/2019

It’s now been nearly two full weeks since India’s lunar lander, Chandrayaan-2, went quiet moments before what was supposed to be a soft landing on the Moon. Rather than gracefully gliding to a halt, the spacecraft crashed, and its handlers back on Earth haven’t been able to establish contact since.

Last week, NASA said it would do its best to help by targeting the suspected crash site with its Lunar Reconnaissance Orbiter. It was thought that if the LRO could capture a clear image of the downed spacecraft it might provide some additional information and help the India Space Research Organization decide how to proceed. Unfortunately, the LRO’s powerful camera just couldn’t spot the lander, and hope of salvaging the mission is fading rapidly.

The Chandrayaan-2 mission included a lunar orbiter, a lander, and a small rover. The orbiter, which is still traveling around the Moon, apparently spotted the crash site itself, according to ISRO. However, the agency has not made any of those images public, and it’s unlikely the camera on the orbiter would have been able to determine the condition of the crashed lander anyway.

NASA’s LRO had a better shot at gathering some useful information, but it couldn’t locate the lander or any evidence of a crash. This isn’t entirely surprising, since the angle of the Sun cast huge shadows over much of the area while the LRO was attempting its search. As Aviation Week explains, it’s likely that this obscured the crash site.

So, where does ISRO go from here? Nobody really knows. The lander hasn’t said a thing since it went quiet moments before it crashed, and repeated attempts to wake it back up have been met with only silence.

At this point, it seems clear the lander is severely damaged, even if ISRO says its initial glimpse of the crash site suggested it was still in one piece. It’s a huge bummer for the Indian space program, and right now there’s little the Chandrayaan-2 team can do but hold on to the last shreds of hope that the lander might wake back up.


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