exoplanets (21)

"Boldly Going" Pretty Close...

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Artist's conception of the dwarf planet Sedna in the outer edges of the known solar system. (Image credit: NASA/JPL-Caltech/R. Hurt (SSC))

Topics: Astronomy, Astrophysics, Exoplanets, NASA, Space Exploration

Astronomers are racing to explain the peculiar orbits of faraway objects at the edge of our solar system.

Among the many mysteries that make the furthest reaches of our solar system, well, mysterious, is the exceptionally egg-shaped path of a dwarf planet called 90377 Sedna.

Its 11,400-year orbit, one of the longest of any resident of the solar system, ushers the dwarf planet to seven billion miles (11.3 billion km) from the sun, then escorts it out of the solar system and way past the Kuiper Belt to 87 billion miles (140 billion km), and finally takes it within a loose shell of icy objects known as the Oort cloud. Since Sedna's discovery in 2003, astronomers have struggled to explain how such a world could have formed in a seemingly empty region of space, where it is too far to be influenced by giant planets of the solar system and even the Milky Way galaxy itself.

Now, a new study suggests that a thus far undetected Earth-like planet hovering in that region could be deviating orbits of Sedna and a handful of similar trans-Neptunian objects (TNOs), which are the countless icy bodies orbiting the sun at gigantic distances. Many TNOs have oddly inclined and egg-shaped orbits, possibly due to being tugged at by a hidden planet, astronomers say.

Could an 'Earth-like' planet be hiding in our solar system's outer reaches? Sharmila Kuthunur, Space.com

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Planet Video...

 

Topics: Astronomy, Astrophysics, Exoplanets, Space Exploration

In 2008, HR8799 was the first extrasolar planetary system ever directly imaged. Now, the famed system stars in its very own video.

Using observations collected over the past 12 years, Northwestern University astrophysicist Jason Wang has assembled a stunning time-lapse video of the family of four planets — each more massive than Jupiter — orbiting their star. The video gives viewers an unprecedented glimpse into planetary motion.

“It’s usually difficult to see planets in orbit,” Wang said. “For example, it isn’t apparent that Jupiter or Mars orbit our sun because we live in the same system and don’t have a top-down view. Astronomical events happen too quickly or slowly to capture in a movie. But this video shows planets moving on a human time scale. I hope it enables people to enjoy something wondrous.”

An expert in exoplanet imaging, Wang is an assistant professor of physics and astronomy at Northwestern’s Weinberg College of Arts and Sciences and a member of the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).

Watch distant worlds dance around their sun, Amanda Morris, Northwestern University.

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WASP-39b and CO2...

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Researchers detected carbon dioxide in WASP-39b’s atmosphere when the exoplanet crossed in front of its star. The data plot shows a telltale blip where infrared wavelengths from the star’s light were absorbed by carbon dioxide on the exoplanet. Credit: NASA, ESA, CSA, Leah Hustak (STScI), Joseph Olmsted (STScI)

Topics: Astrophysics, Chemistry, ESA, Exoplanets, James Webb Space Telescope, NASA

The James Webb Space Telescope — already famous for its mesmerizing images of the cosmos — has done it again. The telescope has captured the first unambiguous evidence of carbon dioxide in the atmosphere of a planet outside the Solar System.

The finding not only provides tantalizing hints about how the exoplanet formed but is also a harbinger for what’s to come as Webb studies more and more alien worlds. It was reported in a manuscript posted on the preprint server arXiv1, ahead of peer review, and is expected to be published in Nature in the coming days. (Nature’s news team is independent of its journals team.)

The discovery is presented in a data plot with none of the luster of Webb’s previous images — which showed galaxies locked in a cosmic dance and radiant clouds in a stellar nursery. But Jessie Christiansen, an astronomer at the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena, describes the data as “gorgeous”.

The plot, or spectrum, reveals detailed information about the atmosphere of the exoplanet WASP-39b, called a hot Jupiter by scientists because it has a diameter similar to Jupiter’s but orbits its star much more closely than Mercury orbits the Sun, making it incredibly hot. The planet, which is more than 200 parsecs from Earth, was initially discovered during ground-based observations2 and later detected by NASA’s Spitzer Space Telescope, which operated between 2003 and 2020. Data from the latter suggested3 that WASP-39b’s atmosphere might contain carbon dioxide, but they were inconclusive.

Webb telescope spots CO2 on exoplanet for first time: what it means for finding alien life, Sharron Hall, Nature

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Proxima Oceans...

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An artist’s impression of the newly discovered planet orbiting Proxima Centauri.Credit: ESO/L. Calçada

Topics: Astronomy, Astrophysics, Exoplanets, Space Exploration, Spaceflight

Astronomers have discovered a third planet orbiting Proxima Centauri, the star closest to the Sun. Called Proxima Centauri d, the newly spotted world is probably smaller than Earth and could have oceans of liquid water.

“It’s showing that the nearest star probably has a very rich planetary system,” says Guillem Anglada-Escudé, an astronomer at the Institute of Space Sciences in Barcelona, Spain, who led the team that, in 2016, discovered the first planet to be seen orbiting Proxima Centauri.

Astronomer João Faria and his collaborators detected Proxima Centauri d by measuring tiny shifts in the spectrum of light from the star as the planet’s gravity pulled at it during orbit. The team used a state-of-the-art instrument called the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) at the Very Large Telescope, a system of four 8.2-meter telescopes at the European Southern Observatory in Cerro Paranal, Chile. The results were published on 10 February in Astronomy & Astrophysics.

Earth-like planet spotted orbiting Sun’s closest star, Davide Castelvecchi, Nature

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Exomoon Two...

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Artist’s impression of an exomoon (left) orbiting a giant planet around a distant star. Credit: Helena Valenzuela Widerström

Topics: Astronomy, Astrophysics, Exomoon, Exoplanets

And then there were two—maybe. Astronomers say they have found a second plausible candidate for a moon beyond our solar system, an exomoon, orbiting a world nearly 6,000 light-years from Earth. Called Kepler-1708 b-i, the moon appears to be a gas-dominated object, slightly smaller than Neptune, orbiting a Jupiter-sized planet around a sunlike star—an unusual but not wholly unprecedented planet-moon configuration. The findings appear in Nature Astronomy. Confirming or refuting the result may not be immediately possible, but given the expected abundance of moons in our galaxy and beyond, it could further herald the tentative beginnings of an exciting new era of extrasolar astronomy—one focused not on alien planets but on the natural satellites that orbit them and the possibilities of life therein.

There are more than 200 moons in our solar system, and they have an impressive array of variations. Saturn’s moon Titan possesses a thick atmosphere and frigid hydrocarbon seas on its surface, possibly an analog of early Earth. Icy moons such as Jupiter’s Europa are frozen balls that hide subsurface oceans, and they may be prime habitats for life to arise. Others still, such as our own moon, are apparently barren wastelands but could have water ice in their shadowed craters and maze-like networks of tunnels running underground. An important shared trait among these worlds, however, is their mere existence: six of the eight major planets of our solar system have moons. Logic would suggest the same should be true elsewhere. “Moons are common,” says Jessie Christiansen of the California Institute of Technology. “In our solar system, almost everything has a moon. I am very confident that moons are everywhere in the galaxy.”

Astronomers Have Found Another Possible ‘Exomoon’ beyond Our Solar System, Jonathan O'Callaghan, Scientific American

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Yonder Water Worlds...

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Hot and humid The surface of a Hycean planet as interpreted by an artist. (Courtesy: Amanda Smith, University of Cambridge).

Topics: Astronomy, Astrophysics, Astrobiology, Exoplanets, Space Exploration

Hot, ocean-covered exoplanets with hydrogen-rich atmospheres could harbor life and may be more common than planets that are Earth-like in size, temperature, and atmospheric composition. According to astronomers at the University of Cambridge, UK, this newly defined class of exoplanets could boost the search for life elsewhere in the universe by broadening the search criteria and redefining which biosignatures are important.

Astronomers define the habitable or “Goldilocks” zone as the region where an exoplanet is neither too close nor too far from its host star to have liquid water on its surface – water being the perfect solvent for many forms of life. Previous studies of planetary habitability have focused primarily on searching for Earth-like exoplanets and evidence that they could harbor the kind of chemistry found in life on Earth. However, it has so far proven difficult to detect atmospheric signatures from Earth-like planets orbiting Sun-like stars.

Potentially habitable mini-Neptunes

Larger exoplanets are easier to detect than smaller, Earth-sized ones, and exoplanets around 1.6‒4 times bigger than the Earth, with masses of up to 15 Earth masses and temperatures that in some cases exceed 2000 K, are relatively common. These planets are known as mini-Neptune's as they are similar to the ice giant planets in our solar system.

Previous studies suggested that the high pressures and temperatures beneath these planets’ hydrogen-rich atmospheres were incompatible with life. However, based on their analysis of an exoplanet called K2-18b, exoplanet scientist Nikku Madhusudhan and colleagues at Cambridge say that life could, in fact, exist on a subset of mini-Neptunes that meet specific criteria.

This subset, which the researchers dub “Hycean” (hydrogen + ocean) planets, consists of planets that have radii up to 2.6 times larger than Earth’s and are capable of harboring vast oceans under atmospheres dominated by molecular hydrogen and water vapor. Such oceans could cover the whole planet and reach depths greater than the Earth’s oceans, and the researchers say that the conditions within them could be compatible with some forms of Earth-based microbial life. Hycean planets tidally locked with their host star could also exhibit habitable conditions on their permanent night side.

Astronomers define new class of potentially habitable ocean worlds, Chaneil James, Physics World

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Nano, to Planck...

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Topics: Barrow Scale, Kardashev Scale, Exoplanets, SETI

The Kardashev Scale is a discussion, and ranking of civilizations based on energy output:

Type I: able to marshal energy resources for communications on a planet-wide scale, equivalent to the entire present power consumption of the human race, or about 1016 watts. Here, Carl Sagan begged to differ, due to power gradation, we're more like (on his measure) a 0.7 civilization, or 7 x 1015 watts. We have pockets of deployed resources, but definitely not "planet-wide," else there would be no economic distinctions: east/south side to west side; 1st and 3rd worlds. Perhaps we could edge up our score with renewable alternatives?
Type II: surpasses this by a factor of approximately ten billion, making available 1026 watts, by exploiting the total energy output of its central star, using a Dyson sphere.
Type III: evolved enough to tap the energy resources of an entire galaxy, ~ 1036 watts.
Type IV and V here.

Professor John D. Barrow is an astrophysicist and mathematician at Cambridge. His take is going not from the aspect of starships, instead of from ever-shrinking technology to make advanced control of energy, and technology possible.

DEEP FUTURE of BIG HISTORY: Cultural Evolution, Techno-culture, and Omega Civilization, Cadell Last

On the Barrow Scale, we're clearly in the Barrow Three minus or nanotechnology. Arthur C. Clarke said "any sufficiently advanced technology is indistinguishable from magic," and kind of gives a runway that is the impossible-to-design Trek technobabble.

Could we go further?

Well, that depends on whether the purveyors of this technological node haven't blown ourselves to smithereens, [climate] changed ourselves to death, or ignored another zoonotic virus and comforted ourselves with throwing caution to the winds, taking vitamins, and jogging to the self-made apocalypse. Sorry for being cynical.

Also, each technological node is driven by industry, and at the top of that are apex predators also known as CEOs/billionaires who have a propensity to not share the resources they plunder. Also after seeing the Netflix documentary: "The Social Dilemma," I wonder what an AI-enabled-Planck-technology Internet, or economy would LOOK like, and who would it ultimately favor? Billionaires don't occur naturally, and trillionaires, quadrillion, or quintillion-empowered varieties would likely be tyrannical, and obscene.

Though this tech through-line is ambitious, bold, imaginative, it has a Pollyannaish feel to it, dependent on the benevolence of our fellow human beings, and a shared vision of humanity's progress.

Then, there are those apex predators that won't pay taxes, give a damn, or build starships so they can first ride on for their three minutes of narcissistic pleasure. Star Trek and a United Federation of Planets post-scarcity is still a Gene Roddenberry dream.

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Adversary, Friendly, or Neutral...

 

An unidentified flying object as seen in a declassified Department of Defense video, DoD

Topics: Aerodynamics, Applied Physics, Biology, Exoplanets, General Relativity, SETI

May 17, 2019- No, little green men aren't likely after the conquest of humanity. Boyd's piece for Phys.org highlights the reason why the Pentagon wants to identify UFOs: they're unidentified. If a warfighter on the ground or in the sky can't ID an object, that creates an issue since they don't know if it's friendly, adversarial, or neutral.

U.S. Navy pilots and sailors won't be considered crazy for reporting unidentified flying objects, under new rules meant to encourage them to keep track of what they see writes Iain Boyd for Phys.org.

Why is the Pentagon interested in UFOs? Intelligent Aerospace

The Pentagon refers to them as "transmedium vehicles," meaning vehicles moving through air, water, and space. Carolina Coastline breathlessly uses the term "defying the laws of physics." So I looked at what the paper might have meant. The objects apparently exceed the speed of sound without a sonic boom (signature of breaking the barrier). Even though this is reported by Popular Mechanics, they're quoting John Ratcliffe, whose name somehow sounds like a pejorative. Consider the source.

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U.S. Navy F/A-18 flying faster than the speed of sound. The white cloud is formed by decreased air pressure and temperature around the tail of the aircraft.
ENSIGN JOHN GAY, U.S. NAVY

The speed of sound is 343 meters per second (761.21 miles per hour, 1,100 feet per second). Mach 1 is the speed of sound, Mach 2 is 1522.41 mph, Mach 3 is 2283.62 mph. NASA's X-43A scramjet sets the record at Mach 9.6 (7,000 mph), so, it's easy to see where Star Trek: The Next Generation got its Warp Speed analog from. The top speed of the F/A-18 is 1,190 mph. Pilots and astronauts under acceleration experience G Forces, and have suits to keep them from blacking out in a high-speed turn.

A Science Magazine article in 1967 reported the dimensions and speeds for the object were undeterminable. History.com reported an object exceeding 70 knots, or 80.5546 mph underwater (twice the speed of a nuclear submarine, so I can see the US Navy's concern). I found some of the descriptions on the site interesting:

5 UFO traits:

1. Anti-gravity lift (no visible means of propulsion), 2. Sudden and instantaneous acceleration (fast), 3. Hypersonic velocities without signatures (no sonic boom), 4. Low observability, or cloaking (not putting this on Romulans, or Klingons), 5. Trans-medium travel (air, water, space).

When I look at these factors, I don't get "little green men." First caveat: there are a lot of planets between us, and them with resources aplenty. Second caveat: any interest an alien intelligence might have in us is as caretakers of an experiment, or cattle. That's disturbing: ever see a rancher have conversations with a chicken, sow, or steer before slaughter?

My hypothesis (Occam's razor) - these are projections, but of a special kind:

For the first time, a team including scientists from the National Institute of Standards and Technology (NIST - 2016) have used neutron beams to create holograms of large solid objects, revealing details about their interiors in ways that ordinary laser light-based visual holograms cannot.

Holograms -- flat images that change depending on the viewer's perspective, giving the sense that they are three-dimensional objects -- owe their striking capability to what's called an interference pattern. All matter, such as neutrons and photons of light, has the ability to act like rippling waves with peaks and valleys. Like a water wave hitting a gap between the two rocks, a wave can split up and then re-combine to create information-rich interference patterns.

Move over, lasers: Scientists can now create holograms from neutrons, too, Science Daily

This of course doesn't explain the decades of observations, since holograms came into being in a 1948 paper by the Hungarian inventor Denis Gabor: “The purpose of this work is a new method for forming optical images in two stages. In the first stage, the object is lit using a coherent monochrome wave, and the diffraction pattern resulting from the interference of the secondary coherent wave coming from the object with the coherent background is recorded on the photographic plate. If the properly processed photographic plate is placed after its original position and only the coherent background is lit, an image of the object will appear behind it, in the original position.” Gabor won the Nobel Prize in 1971 for "his invention and development of the holographic method." Also: History of Holography

This is purely speculative. I have no intelligence other than what I've shared. It does in my mind, explain the physics-defying five traits described above. It does not explain the previous supposition of sightings since humans started recording history, or trying to hypothesize their sightings in antiquity. Solid objects flying at hypersonic speeds make sonic booms; projections - ball lightning, 3D laser, or solid neutron holograms - likely won't.

If these are projections (adversary, friendly, neutral), who is doing them, and why?

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Habitable Epoch...

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Artist's conception of GN-z11, the earliest known galaxy in the universe. Credit: Pablo Carlos Budassi Wikimedia (CC BY-SA 4.0)

Topics: Astrobiology, Evolution, Existentialism, Exoplanets

About 15 million years after the big bang, the entire universe had cooled to the point where the electromagnetic radiation left over from its hot beginning was at about room temperature. In a 2013 paper, I labeled this phase as the “habitable epoch of the early universe.” If we had lived at that time, we wouldn’t have needed the sun to keep us warm; that cosmic radiation background would have sufficed.

Did life start that early? Probably not. The hot, dense conditions in the first 20 minutes after the big bang produced only hydrogen and helium along with a tiny trace of lithium (one in 10 billion atoms) and a negligible abundance of heavier elements. But life as we know it requires water and organic compounds, whose existence had to wait until the first stars fused hydrogen and helium into oxygen and carbon in their interiors about 50 million years later. The initial bottleneck for life was not a suitable temperature, as it is today, but rather the production of the essential elements.

Given the limited initial supply of heavy elements, how early did life actually start? Most stars in the universe formed billions of years before the sun. Based on the cosmic star formation history, I showed in collaboration with Rafael Batista and David Sloan that life near sunlike stars most likely began over the most recent few billion years in cosmic history. In the future, however, it might continue to emerge on planets orbiting dwarf stars, like our nearest neighbor, Proxima Centauri, which will endure hundreds of times longer than the sun. Ultimately, it would be desirable for humanity to relocate to a habitable planet around a dwarf star like Proxima Centauri b, where it could keep itself warm near a natural nuclear furnace for up to 10 trillion years into the future (stars are merely fusion reactors confined by gravity, with the benefit of being more stable and durable than the magnetically confined versions that we produce in our laboratories).

When Did Life First Emerge in the Universe? Avi Loeb, Scientific American

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Ceres...

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Occator Crater and Ahuna Mons appear together in this view of the dwarf planet Ceres obtained by NASA's Dawn spacecraft on February 11, 2017. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/Handout via REUTERS.

Topics: Asteroids, Exoplanets, Space Exploration, Spaceflight

"Ceres was the Roman goddess of agriculture, grain, and the love a mother bears for her child. She was the daughter of Saturn and Ops, the sister of Jupiter, and the mother of Proserpine. Ceres was a kind and benevolent goddess to the Romans and they had a common expression, "fit for Ceres," which meant splendid." Source: Ceresva.org

WASHINGTON (Reuters) - Ceres, the largest object in the asteroid belt between Mars and Jupiter, is an “ocean world” with a big reservoir of salty water under its frigid surface, scientists said in findings that raise interest in this dwarf planet as a possible outpost for life.

Research published on Monday based on data obtained by NASA’s Dawn spacecraft, which flew as close as 22 miles (35 km) from the surface in 2018, provides a new understanding of Ceres, including evidence indicating it remains geologically active with cryovolcanism - volcanoes oozing icy material.

The findings confirm the presence of a subsurface reservoir of brine - salt-enriched water - remnants of a vast subsurface ocean that has been gradually freezing.

“This elevates Ceres to ‘ocean world’ status, noting that this category does not require the ocean to be global,” said planetary scientist and Dawn principal investigator Carol Raymond. “In the case of Ceres, we know the liquid reservoir is regional scale but we cannot tell for sure that it is global. However, what matters most is that there is liquid on a large scale.”

Dwarf planet Ceres is 'ocean world' with salty water deep underground, Will Dunham, Reuters Science

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Twins of a Young Sun...

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The first direct image of two exoplanets orbiting a Sun-like star, seen here, was captured by the SPHERE instrument on the ESO’s Very Large Telescope. The system is called TYC 8998-760-1 and is located some 300 light-years from Earth.

 

Topics: Astronomy, Astrophysics, Exoplanets

In another exoplanetary first, the European Southern Observatory's Very Large Telescope (VLT) in Chile's Atacama Desert has captured an image of two worlds orbiting a younger version of the Sun. The system, called TYC 8998-760-1, is located roughly 300 light-years away in the southern constellation Musca. And although it hides two gas giants orbiting a Sun-like star, we don’t have anything quite like these worlds in our own solar system.

The inner planet lies about 160 astronomical units from its host star (where one astronomical unit, or AU, is the average Earth-Sun distance) and is some 14 times the mass of Jupiter. With that amount of heft, the gas giant skirts the border between planet and brown dwarf, which is a type of almost-star. The more distant planet is located about 320 AU from its star and weighs in at about six Jupiter masses.

Two exoplanets seen dancing around Sun-like star for the first time, Mark Zastrow, Astronomy.com

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Our Galaxy's Water Worlds...

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This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. The composition of such water worlds has fascinated astronomers and astrophysicists for years. (Image by NASA/JPL-Caltech.)

 

Topics: Astronomy, Astrobiology, Astrophysics, Cosmology, Exoplanets

Out beyond our solar system, visible only as the smallest dot in space with even the most powerful telescopes, other worlds exist. Many of these worlds, astronomers have discovered, may be much larger than Earth and completely covered in water — basically ocean planets with no protruding land masses. What kind of life could develop on such a world? Could a habitat like this even support life?

A team of researchers led by Arizona State University (ASU) recently set out to investigate those questions. And since they couldn’t travel to distant exoplanets to take samples, they decided to recreate the conditions of those water worlds in the laboratory. In this case, that laboratory was the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science User Facility at the DOE’s Argonne National Laboratory.

What they found — recently published in Proceedings of the National Academy of Sciences — was a new transitional phase between silica and water, indicating that the boundary between water and rock on these exoplanets is not as solid as it is here on Earth. This pivotal discovery could change the way astronomers and astrophysicists have been modeling these exoplanets, and inform the way we think about life evolving on them.

Dan Shim, associate professor at ASU, led this new research. Shim leads ASU’s Lab for Earth and Planetary Materials and has long been fascinated by the geological and ecological makeup of these distant worlds. That composition, he said, is nothing like any planet in our solar system — these planets may have more than 50% water or ice atop their rock layers, and those rock layers would have to exist at very high temperatures and under crushing pressure.

Beneath the surface of our galaxy’s water worlds, Andre Salles, Argonne National Laboratory

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40 Eridani A...

 

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Vulcan from the link, also see Memory Alpha

 

Topics: Astronomy, Astrophysics, Exoplanets, Science Fiction, Star Trek

Note: 2018 article, but neat nonetheless.

One of the more interesting and rewarding aspects of astronomy and space exploration is seeing science fiction become science fact. While we are still many years away from colonizing the Solar System or reaching the nearest stars (if we ever do), there are still many rewarding discoveries being made that are fulfilling the fevered dreams of science fiction fans.

For instance, using the Dharma Planet Survey, an international team of scientists recently discovered a super-Earth orbiting a star just 16 light-years away. This super-Earth is not only the closest planet of its kind to the Solar System, it also happens to be located in the same star system as the fictional planet Vulcan from the Star Trek universe.

The study which details their findings, which recently appeared in the Monthly Notices of the Royal Astronomical Society, was led by Bo Ma and Jian Ge, a post-doctoral researcher and a professor of astronomy from the University of Florida, respectively. They were joined by researchers from Tennessee State University, the Instituto de Astrofisica de Canarias, the Universidad de La Laguna, Vanderbilt University, the University of Washington, and the University of Arizona’s Steward Observatory.

“The new planet is a ‘super-Earth’ orbiting the star HD 26965, which is only 16 light years from Earth, making it the closest super-Earth orbiting another Sun-like star. The planet is roughly twice the size of Earth and orbits its star with a 42-day period just inside the star’s optimal habitable zone.”

“Star Trek fans may know the star HD 26965 by its alternative moniker, 40 Eridani A,” he said. “Vulcan was connected to 40 Eridani A in the publications “Star Trek 2” by James Blish (Bantam, 1968) and “Star Trek Maps” by Jeff Maynard (Bantam, 1980).”

Astronomers find Planet Vulcan – 40 Eridani A – Right Where Star Trek Predicted it, Universe Today

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Improving View...

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View of the Alpha Centauri system. The bright binary star Alpha Centauri AB lies at the upper left. The much fainter red dwarf star Proxima Centauri is barely discernible towards the lower right of the picture. Credit: Digitized Sky Survey 2; Acknowledgement: Davide De Martin and Mahdi Zamani

 

Topics: Astronomy, Astrophysics, Exoplanets, Space Exploration


Little is more enticing than the prospect of seeing alien worlds around other stars—and perhaps one day even closely studying their atmosphere and mapping their surface. Such observations are exceedingly difficult, of course. Although more than 4,000 exoplanets are now known, the vast majority of them are too distant and dim for our best telescopes to discern against the glare of their host star. Exoplanets near our solar system provide easier imaging opportunities, however. And no worlds are nearer to us than those thought to orbit the cool, faint red dwarf Proxima Centauri—the closest star to our sun at 4.2 light-years away.

In 2016 astronomers discovered the first known planet in this system: the roughly Earth-sized Proxima b. But because of its star-hugging 11-day orbit around Proxima Centauri, Proxima b is a poor candidate for imaging. Proxima c, by contrast, offers much better chances. Announced in 2019, based on somewhat circumstantial evidence, the planet remains unconfirmed. If real, it is estimated to be several times more massive than Earth—a so-called super Earth or mini Neptune—and to orbit Proxima Centauri at about 1.5 times the span between Earth and the sun. Its size and distance from its star make the world a tempting target for current and near-future exoplanet-imaging projects. Now, in a new preprint paper accepted for publication in the journal Astronomy & Astrophysics, some astronomers say they might—just might— have managed to see Proxima c for the first time.

“This planet is extremely interesting because Proxima is a star very close to the sun,” says Raffaele Gratton of the Astronomical Observatory of Padova in Italy, who is the study’s lead author. “The idea was that since this planet is [far] from the star, it is possible that it can be observed in direct imaging. We found a reasonable candidate that looks like we have really detected the planet.”

 

Astronomers May Have Captured the First Ever Image of Nearby Exoplanet Proxima C
Jonathan O'Callaghan, Scientific American

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TNOs and Planet Nine...

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Over the past decade or so, astronomers have discovered a number of far-flung objects that all have very similar perihelia, meaning they make their closest approaches to the Sun at about the same location in space. One leading theory that attempts to explain the clustering is that a massive and unseen world known as Planet Nine hiding in the outer solar system.

Fauxtoez/WikiMedia Commons

 

Topics: Astronomy, Astrophysics, Exoplanets, Space Exploration


Note: Not an April 1st joke. With the COVID-19 crisis, I literally had to peruse some sites that DIDN'T talk about what we're all living through. It's been rough, thinking about how and when this all ends. I'll try to get my sea legs back to blogging about science. Bear with me. I'm human.

Astronomers have discovered 139 new minor planets orbiting the Sun beyond Neptune by searching through data from the Dark Energy Survey. The new method for spotting small worlds is expected to reveal many thousands of distant objects in coming years — meaning these first hundred or so are likely just the tip of the iceberg.

Taken together, the newfound distant objects, as well as those to come, could resolve one of the most fascinating questions of modern astronomy: Is there a massive and mysterious world called Planet Nine lurking in the outskirts of our solar system?

Neptune orbits the Sun at a distance of about 30 astronomical units (AU; where 1 AU is the Earth-Sun distance). Beyond Neptune lies the Kuiper Belt — a comet-rich band of frozen, rocky objects (including Pluto) that holds dozens to hundreds of times more mass than the asteroid belt. Both within the Kuiper Belt and past its outer edge at 50 AU orbit distant bodies called trans-Neptunian objects (TNOs). Currently, we know of nearly 3,000 TNOs in the solar system, but estimates put the total number closer to 100,000.

As more and more TNOs have been discovered over the years, some astronomers — including Konstantin Batygin and Mike Brown of Caltech — have noticed a small subset of these objects have peculiar orbits. They seem to bunch up in unexpected ways, as if an unseen object is herding these so-called extreme TNOs (eTNOs) into specific orbits. Batygin and Brown — in addition to other groups, like that led by Scott Sheppard of the Carnegie Institution for Science — think these bizarrely orbiting eTNOs point to the existence of a massive, distant world called Planet Nine.

Hypothesized to be five to 15 times the mass of Earth and to orbit some 400 AU (or farther) from the Sun, the proposed Planet Nine would have enough of a gravitational pull that it could orchestrate the orbits of the eTNOs, causing them to cluster together as they make their closest approaches to the Sun.

The problem is that the evidence for Planet Nine is so far indirect and sparse. There could be something else that explains the clumped orbits, or perhaps researchers stumbled on a few objects that just happen to have similar orbits. Discovering more TNOs, particularly beyond the Kuiper Belt, will allow astronomers to find more clues that could point to the location of the proposed Planet Nine — or deny its existence altogether. Of the 139 newly discovered minor planets found in this study, seven are eTNOs, which is a significant addition to a list that numbered around a dozen just a few months ago.

 

Astronomers find 139 new minor planets in the outer solar system
Erica Naone, Astronomy

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Astronomy's Top Ten 2019...

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Exoplanet K2-18 b orbits a red dwarf star and has an extended atmosphere containing at least some water vapor, as seen in this artist's concept. The system also contains another exoplanet sitting closer to the star, but it lies inside of the star's habitable zone

 

Topics: Astronomy, Astrophysics, Black Holes, Exoplanets, Hubble


Astronomers have finally uncovered water vapor in the atmosphere of a super-Earth exoplanet orbiting within the habitable zone of its star. The find means that liquid water could also exist on the rocky world's surface, potentially even forming a global ocean.

The discovery, made with NASA's Hubble Space Telescope, serves as the first detection of water vapor in the atmosphere of such a planet. And because the planet, dubbed K2-18 b, likely sports a temperature similar to Earth, the newfound water vapor makes the world one of the most promising candidates for follow-up studies with next-generation space telescopes.

"This is the only planet right now that we know outside the solar system that has the correct temperature to support water, it has an atmosphere, and it has water in it, making this planet the best candidate for habitability that we know right now," lead author Angelos Tsiaras, an astronomer at University College London, said in a press conference.
 
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Researchers created this enhanced view of Enceladus’ south polar region by combining Cassini images taken through infrared, green, and ultraviolet filters. The tiger stripe fractures, the source of the plumes venting gas and dust into space, are prominently visible at center.
NASA/JPL-Caltech/SSI/Lunar and Planetary Institute/Paul Schenk (LPI, Houston)

“In the old time Pallas [Athena] heaved on high Sicily, and on huge Enceladus dashed down the isle, which burns with the burning yet of that immortal giant, as he breathes fire underground.”

 


— Quintus Smyrnaeus, The Fall of Troy

 


Saturn’s sixth-largest moon, Enceladus has a diameter of only 310 miles (500 kilometers), and a mass less than 1/50,000 that of Earth. When it comes to places to look for life, however, Enceladus is at the top of the list, and it’s right in our cosmic backyard.

A bit ignored at first

 


English astronomer William Herschel discovered Enceladus in 1789, but it remained an enigma until the Cassini mission began orbiting Saturn in 2004. Prior to Cassini, Enceladus was a bit ignored. We didn’t know liquid water could exist that far out in the solar system, so why would anyone be that interested in another boring, dead ball of ice?

 


That all changed one year later, when Cassini’s magnetometer (think: fancy compass) detected something strange in Saturn’s magnetic field near Enceladus. This suggested the moon was active. Subsequent passes by Enceladus revealed four massive fissures — dubbed “tiger stripes” — in a hot spot centered on the south pole. And emanating from those cracks was a massive plume of water vapor and ice grains. Enceladus lost its label of being a dead relic of a bygone era and leaped to center stage as a dynamic world with a subsurface ocean.
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Mapping Titan...

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These infrared views of Titan peer through the gloom
NASA/JPL-Caltech/Stéphane Le Mouélic, University of Nantes, Virginia Pasek, University of Arizona

 

Topics: Astrophysics, Cassini, Exoplanets, Moon, Space Exploration


Slowly but surely, the surface of Saturn’s strange moon Titan is being revealed. Researchers have made the first map of the geology of Titan’s entire surface, and it will eventually help us figure out what the climate is like there.

Titan’s atmosphere is full of a thick, orange haze that blocks visible light from reaching the surface, making it difficult for spacecraft to take pictures. NASA’s Cassini spacecraft, which orbited Saturn from 2004 to 2017, took radar and infrared data of Titan’s surface, giving researchers a hint of the terrain below.

Rosaly Lopes at NASA’s Jet Propulsion Laboratory in California and her colleagues assembled those observations and placed each area, or unit, into one of six categories: lakes, craters, dunes, plains, hummocky terrain – meaning hills and mountains – and labyrinth, which looks like heavily eroded plateaus. They then made a map of where each of those terrains exists on Titan’s surface.
 

We have the first full map of the weird surface features of Titan
Leah Crane, New Scientist

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Galactic Armageddon...

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The planet, called WASP-12b, is so close to its sunlike star that it is superheated to nearly 2,800 degrees Fahrenheit and stretched into a football shape by enormous tidal forces. The atmosphere has ballooned to nearly three times Jupiter's radius and is spilling material onto the star. The planet is 40 percent more massive than Jupiter.

 

Topics: Astronomy, Astrophysics, Exoplanets, White Dwarfs


Some rocky exoplanets bear a striking resemblance to Earth, according to Alexandra Doyle, Edward Young and colleagues at the University of California at Los Angeles. The team used the properties of light coming from six white-dwarf stars to calculate how much oxygen, iron and other elements were present in planets that once orbited the stars. Their observations suggest that these planets – which were consumed by their stars long ago – have the same geophysical and geochemical properties as Earth. While astronomers are able to observe rocky exoplanets, working out what they are made of is difficult and this research provides important clues regarding the composition of these Earth-like objects.

White dwarfs are the ancient remnants of stars that had masses less than about 10 Suns. This means that most stars in the Milky Way will eventually become white dwarfs – including the Sun. Many white dwarfs would have had planets, which would have been consumed by the stars at some point in their stellar evolution. The atmosphere of a white dwarf is expected to comprise only the lightest elements – hydrogen and helium – so the presence of heavier substances in the stellar atmosphere such as magnesium, iron and oxygen means that the star has probably ingested rocky planets or asteroids.

 

Doomed exoplanets were much like Earth, Hamish Johnston, Physics World

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A Year of TESS...

 

Topics: Exoplanets, NASA, Planetary Science, Space Exploration, Star Trek


"Space: the final frontier. These are the voyages of the starship Enterprise. Her five-year mission: to explore strange new worlds. To seek out new life and new civilizations. To boldly go where no one has gone before." (Star Trek: The Captain's Oath)

“Kepler discovered the amazing result that, on average, every star system has a planet or planets around it. TESS takes the next step. If planets are everywhere, let’s find those orbiting bright, nearby stars because they’ll be the ones we can now follow up with existing ground and space-based telescopes, and the next generation of instruments for decades to come.” Padi Boyd, TESS project scientist, NASA GSFC

- HD 21749c, the first Earth-size planet the mission has found. The world orbits a K-class star with about 70 percent of the mass of the Sun, located 53 light years away in the constellation Reticulum, one of two planets identified in this system;

- A number of multi-planet systems, like that around L98-59, which includes a planet (L98-59b) between the size of Earth and Mars, the smallest yet found by TESS. Here the host star is an M-dwarf about a third the mass of the Sun, 35 light years away in the constellation Volans;

- Three exocomets identified in the Beta Pictoris system. A comet’s lightcurve differs significantly from that of a transiting planet because of the extended cometary tail. These discoveries demonstrate the ability of TESS to identify tiny objects around young, bright stars, and should lead to future exocomet detections that can supply information about planet formation;

- Six supernovae occurring in other galaxies, among them ASASSN-18rn, ASASSN-18tb and ATLAS18tne, found before ground-based surveys could identify them.

 

TESS: Concluding First Year of Observations, Paul Gilster, Centauri Dreams

#P4TC: TESS... August 2, 2018

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Brine Europa...

Salt-laden water welling up from below gives Europa’s fissures and cracks their distinctive color.
Credit: NASA, JPL-Caltech and SETI Institute

 

Topics: Astrobiology, Exoplanets, Planetary Exploration, SETI


The sea sloshing beneath the icy surface of Jupiter’s moon Europa just might be the best incubator for extraterrestrial life in our solar system. And yet it is concealed by the moon’s frozen outer shell—presenting a challenge for astrobiologists who would love nothing more than to peer inside. Luckily they can catch a partial glimpse by analyzing the flavor of the surface. And the results are salty.

A new study published this week in Science Advances suggests that sodium chloride—the stuff of table salt—exists on Europa’s surface. Because the exterior is essentially formed from frozen seawater, the finding suggests that Europa’s hidden sea is drenched in table salt—a crucial fact for constraining the possibilities for life on the alien world.

Not that scientists have tasted a slice of the distant moon. To analyze Europa’s composition, astronomers study the light emanating from its surface, splitting it into a rainbow-like spectrum to search for any telltale absorption or emission lines that reveal the world’s chemistry. There is just one problem: Ordinary table salt is white and thus gives off a featureless spectrum. But harsh radiation—which exists at Europa’s surface in abundance—just might add a dash of color. That much was realized in 2015 when two NASA planetary scientists Kevin Hand and Robert Carlson published a study suggesting the yellowish-brown gunk on Europa might be table salt baked by radiation. To reach that conclusion, Hand and Carlson re-created the conditions on Europa within vacuum chambers—or as Hand calls them, “stainless steel shiny objects that are humming and whizzing.” Next, they placed table salt into those chambers, lowered the pressures and temperatures to simulate Europa’s surface, and blasted the samples with an electron gun to simulate the intense radiation.

 

Water on Europa—with a Pinch of Salt, Shannon Hall, Scientific American

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