astronomy (18)

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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Starspots and Red Giants...

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Red-giant spotter: artist’s impression of the Kepler space telescope in Earth orbit. (Courtesy: NASA)

 

Topics: Astronomy, Astrophysics, Solar Physics

Some red-giant stars are rotating much faster than previously thought, according to a study led by Patrick Gaulme at Germany’s Max Planck Institute for Solar System Research. Using NASA’s Kepler space telescope, the astronomers found that about 8% of the red giants they observed are rotating fast enough to display starspots. The team reckons that the elderly stars acquire their rapid rotation by following one of three distinct routes in their evolution.

In main sequence stars like the Sun, the complex interplay that occurs between stellar rotation and the motions of plasma creates incredibly lively magnetic fields. When this magnetic activity is particularly strong, upwelling plumes of plasma in a star’s convective outer layers can be blocked, producing dark patches on its surface. To an observer on Earth, these starspots cause a periodic variation in the star’s brightness as it rotates, bringing the spots in and out of our field of view.

Until recently, starspots were not thought to be present on red giant surfaces. Since these older stars expand rapidly as they move out of the main sequence, while maintaining their angular momentum, previous theories had predicted that they must rotate more slowly than main sequence stars. Slower rotation should reduce magnetic activity, preventing starspots from forming.

Starspot study sheds light on why some red giants spin faster than others, Sam Jarman, Physics World

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Comet NEOWISE...

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Comet NEOWISE over Mount Hood on July 11, 2020. Credit: Kevin Morefield Getty Images

 

Topics: Astronomy, Astrophysics, Comets

Comet NEOWISE has been entertaining space enthusiasts across the Northern Hemisphere. Although its official name is C/2020 F3, the comet has been dubbed NEOWISE after the Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) space telescope that first noticed it earlier this year. This “icy snowball” with a gassy tail made its closest approach to the sun on July 3 and is now heading back from whence it came: the far reaches of the outer solar system. Its long, looping orbit around our star ensures that after passing closest to Earth on July 22, Comet NEOWISE will not return for some 6,800 years.

Even though the comet is now bright enough to observe with unaided eyes, inexperienced stargazers might have trouble knowing when and where to look. Scientific American spoke to Jackie Faherty, an astronomer at the American Museum of Natural History in New York City, for observing tips and a better appreciation of why comets are so special.

How does one prepare to watch Comet NEOWISE with the naked eye?

Find the darkest possible swath of sky and make sure your eyes are adjusted so that you give yourself the best possible opportunity to see faint objects. It means: don’t just walk outside after staring at lights or screens and expect to see [the comet] really well. You need 15 minutes or so to adjust your eyes, so that your pupils are adjusted, and they’re used to seeing fainter things. It’s the same as walking into a dark room, and everybody knows that [you] can’t see [things] first—and then, all of a sudden, you start seeing things. You need to do the same thing when you walk outside. And use the Comet NEOWISE app developed by astrophysicist Hanno Rein of University of Toronto Scarborough to see exactly where it is, so that you know what direction you need to look. And then the key would be to find yourself a place that is the darkest possible, that [has] no lights.

The Best Way to Watch Comet NEOWISE, Wherever You Are, Karen Kwon, Scientific American

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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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Pioneer...

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Burbidge, pictured with her husband and research partner, Geoffrey, was appointed to numerous leadership positions previously held only by men. | W.W. Girdner/Caltech Archives

 

Topics: Astronomy, Astrophysics, Diversity, Diversity in Science, Women in Science


Margaret Burbidge, a past president of the American Association for the Advancement of Science who overcame gender discrimination on the way to becoming one of the most influential astrophysicists of her time, died on April 5 at her home in San Francisco. She was 100.

In 1957, Burbidge was the lead author of a study detailing the chemical processes by which elements heavier than lithium, including the carbon and oxygen that drive life on Earth, are created inside stars. The origins of such elements were previously unknown, and the research paper is the foundation of current understanding of what astronomers now call stellar nucleosynthesis.

Later in her career, Burbidge was appointed to numerous leadership positions previously held only by men and helped develop the Faint Object Spectrograph, one of the original scientific instruments aboard NASA’s Hubble Space Telescope. The FOS team provided the first strong, observational evidence for the existence of a supermassive black hole in the core of another galaxy.

Eleanor Margaret Peachey was born in Davenport, England, on August 12, 1919. Her father was a chemistry lecturer in nearby Manchester, and her mother had been one of his students.

When Peachey was two, the family moved to London, where cloudy skies often prevented starlight from reaching the city.

“The first time I consciously remember really noticing the stars was the summer that I was four, and we were going on a night crossing to France for summer vacation,” Burbidge said in a 1978 interview with the American Institute of Physics. “These twinkling lights became another fascination to me.”

Aware of her interest in the stars, Peachey’s grandfather gave her books by English astronomer James Jeans for her 12th and 13th birthdays. By the age of 19, she had graduated with honors from University College London, where she studied astronomy, physics and mathematics. In 1943, she earned her Ph.D. from UCL.

After receiving her doctorate in the midst of World War II, Peachey continued to use the telescope at the UCL Observatory, sometimes with bombs exploding in the city around her. Hoping to work with better equipment and clearer skies, she applied for a fellowship that would have placed her at the Mount Wilson Observatory outside of Los Angeles.

“The turn-down letter simply pointed out that Carnegie Fellowships were available only for men,” Burbidge wrote in a 1994 memoir. “A guiding operational principle in my life was activated: If frustrated in one’s endeavor by a stone wall or any kind of blockage, one must find a way around — another route towards one’s goal. This is advice I have given to many women facing similar situations.”

In 1948, Peachey married Geoffrey Burbidge, a UCL graduate student in physics who soon switched fields to collaborate with his wife on her astronomy research. When Geoff applied for the same Carnegie Fellowship, he was accepted, and Margaret took a position at the California Institute of Technology in Pasadena. When they needed to use the Mount Wilson telescope, the couple would arrive with Margaret posing as her husband’s assistant.

 

In Memoriam:
Margaret Burbidge, Pioneering Astronomer and Advocate for Women in Science
Adam D. Cohen, American Association for the Advancement of Science

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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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Primordial Black Holes...

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Snapshot from the central region of a numerical simulation of two merging neutron stars. It shows the stars stretched out by tidal forces just before their collision. Credit: CoRe/Jena FSU

 

Topics: Astronomy, Astrophysics, Black Holes, Einstein, General Relativity


In the nearly five years since their first direct detection, gravitational waves have become one of the hottest topics in astronomy. With facilities such as the Laser Interferometer Gravitational-Wave Observatory (LIGO), researchers have mostly used these ripples in spacetime to study the inner workings of merging black holes, but LIGO has also detected gravitational waves from other sorts of celestial crashes, such as the collisions of ultradense stellar remnants called neutron stars. Sometimes, however, LIGO serves up gravitational waves that leave astronomers scratching their heads—as was the case for GW190425, an event detected last April that was recently attributed to a neutron star merger.

The trouble is that LIGO’s data suggest this neutron star pair was substantially overweight—collectively, some 3.4 times the mass of the sun, which is half a solar mass heavier than the most massive neutron star binaries ever seen. “It is the heaviest known by a pretty wide margin,” says Chad Hanna, an astrophysicist at Pennsylvania State University who hunts gravitational waves.

The trouble is that LIGO’s data suggest this neutron star pair was substantially overweight—collectively, some 3.4 times the mass of the sun, which is half a solar mass heavier than the most massive neutron star binaries ever seen. “It is the heaviest known by a pretty wide margin,” says Chad Hanna, an astrophysicist at Pennsylvania State University who hunts gravitational waves.

 

Did Astronomers Just Discover Black Holes from the Big Bang? Nola Taylor Redd, Scientific American

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Through the Looking-Glass...

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An animation shows the random appearance of fast radio bursts (FRBs) across the sky.
(Image: © NRAO Outreach/T. Jarrett (IPAC/Caltech); B. Saxton, NRAO/AUI/NSF)

 

Topics: Astronomy, Astrophysics, Radio Astronomy, Research, Space Exploration


“Curiouser and curiouser!” Cried Alice (she was so much surprised, that for the moment she quite forgot how to speak good English).”

― Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass


HONOLULU — Mysterious ultra-fast pinpricks of radio energy keep lighting up the night sky and nobody knows why. A newly discovered example of this transient phenomenon has been traced to its place of origin — a nearby spiral galaxy — but it's only made things murkier for astronomers.

The problem concerns a class of blink-and-you'll-miss-them heavenly events known as fast radio bursts (FRBs). In a few thousandths of a second, these explosions produce as much energy as the sun does in nearly a century. Researchers have only known about FRBs since 2007, and they still don't have a compelling explanation regarding their sources.

"The big question is what can produce an FRB," Kenzie Nimmo, a doctoral student at the University of Amsterdam in the Netherlands, said during a news briefing on Monday (Jan. 6) here at the 235th meeting of the American Astronomical Society in Honolulu, Hawaii.
 

FRB 180916.J0158+65, as the object is known, is a repeating FRB discovered by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) observatory, a radio telescope near Okanagan Falls in British Columbia that Nimmo called "the world's best FRB-finding machine."

Follow-up observations by a network of telescopes in Europe allowed the research team to produce a high-resolution image of the FRB's location. This location turned out to be a medium-sized spiral galaxy like our Milky Way that is surprisingly nearby, only 500 million light-years away, making it the closest-known FRB to date. The results were published yesterday (Jan. 6) in the journal Nature.

Origin of Deep-Space Radio Flash Discovered, and It's Unlike Anything Astronomers Have Ever Seen
Adam Mann, Live Science

#P4TC links:

FRBs...December 7, 2015
Fast Radio Bursts and Missing Matter...February 25, 2016
ET, FRBs and Light Sails...March 13, 2017

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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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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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The Whims of Tyche...

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Fossil of trilobite that evolved following the mid-Ordovician ice age. | Birger Schmitz

 

Topics: Asteroids, Astronomy, Biology, Planetary Science


Tyche: Modern Greek: [ˈti.çi] "luck"; Roman equivalent: Fortuna) was the presiding tutelary deity who governed the fortune and prosperity of a city, its destiny. In Classical Greek mythology, she is the daughter of Aphrodite and Zeus or Hermes. Source: Wikipedia

Dust from the breakup of a 150-kilometer- (93 mile) diameter asteroid may have caused — or at least intensified — an ice age half a billion years ago, providing the impetus for a sweeping array of aquatic animal adaptations that shaped today's spectacularly diverse ocean ecosystems, according to a new study published in the September 20 issue of Science Advances.

The authors uncovered extraterrestrial material in sediments that correlate the timing of asteroid breakup with a major dip in sea level frequently attributed to the onset of the Mid-Ordovician ice age. Their findings suggest that asteroid dust may have settled in Earth's atmosphere, shading the planet from the sun's radiation and cooling global temperatures.

While extraterrestrial dust only accounts for about one percent of the modern atmosphere and does not impact the climate, large quantities of dust lingering for several hundred thousand years or more would be expected to cause global cooling.

"This is the first time anyone has shown that asteroid breakups and asteroid dust can lead to ice ages," said Birger Schmitz, a professor of geology at Lund University in Sweden and the first author of the study. "This is also the first time since the discovery of the asteroid impact that killed the dinosaurs that an important event in the history of life has been tied to an astronomical event."

 

Asteroid Dust May Have Triggered Ice Age and Sea Life Explosion
Shannon Kelleher, American Association for the Advancement of Science

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Yggdrasil...

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The rings of Saturn take center stage in this portrait by the Hubble Space Telescope taken on June 20, 2019. Credit: NASA, ESA, A. Simon (GSFC), M.H. Wong (University of California, Berkeley) and the OPAL Team

 

Topics: Astronomy, Planetary Science, Space Exploration


There was a strong temptation to use the Norse legend of Bifrost - the rainbow bridge made popular in Thor, but rings of trees tell their age, so...

Yggdrasil is the tree of life, and it is an eternal green Ash tree; the branches stretch out over all of the nine worlds in Norse mythology, and extend up and above the heavens. Norse mythology: Yggdrasil.

Against earlier studies estimating an age of just 100 million years, new research suggests the planet’s rings could be as old as the solar system itself.

The great Saturn ring debate is far from settled, a new study suggests.

For years, scientists have argued about the age of Saturn’s famous rings: Are they ancient, dating to the birth of the planet itself? Or did the ring system form more recently, in just the past hundred million years or so?

This latter hypothesis has been gaining steam in the last few years, with multiple papers reporting that the rings could be even younger than the dinosaurs. Such studies cite the rings’ composition—more than 95% pure water ice—and total mass, which NASA’s Cassini mission pegged at about 15.4 million billion metric tons shortly after the probe’s epic “grand finale” at Saturn in 2017. (For perspective, 15.4 million billion metric tons is about 40% the mass of the Saturn moon Mimas, which is 250 miles, or 400 kilometers, wide.)

 

Saturn’s Rings May Be Ancient After All, Mike Wall, Space.com and Scientific American

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Aleph Null or Not...

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No, it's not real. Credit: Getty Images

 

Topics: Astronomy, Drake Equation, Existentialism, SETI


For many people, "UFO" is synonymous with aliens, but it's worth reminding ourselves that it literally stands for "unidentified flying object." An unidentified object could be just about anything, because … well, it's unidentified. One of our mottoes in science is that "extraordinary claims require extraordinary evidence." This doesn't mean that crazy-sounding things are never true; it means that we should practice due diligence when thinking about overturning well-understood or well-tested ideas. This motto also suggests we keep an eye on Occam's razor—the idea that the simplest explanation is the most likely to be true.

As enthusiastic as I had been regarding alien visitations (there was a cottage industry in the 1970s that still thrives in Internet circles), one has to ask the question: what would aliens want with Earth? Between here and there whatever their governments are in need of, they can either engineer it or find other options way before engaging warp speed.

Colonization: If history serves as guide, the First Nation/Native Americans encountered colonists that barely survived their first winter. They were repaid like the natives who met Columbus with slaughter.

Africans did trade captured rival tribesmen and women in the budding international slave trade that "made America great." They conferred with Europeans typically with superior weaponry for trade of valuables to compensate their treachery.

Any aliens that can travel parsecs from their home world to Earth doesn't have anything benevolent in mind once arriving, E.T. or Star Trek not withstanding.

Ignoring us: When is the last time you had a conversation with a moth? On the evolutionary scale, you have way more sophistication than something flitting from tree to flower. Aliens if existing and surviving millions of years older than us probably if anything might have the same relationship to us as we have to Lepidoptera.

The sobering possibility: climate change, conventional conflicts, mass shootings pollution and nuclear conflagration - humans are far smarter than the lowly moth, but moths nor butterflies are destroying their own habitat.

We may not see aliens because they may have caused their own extinction before they built starships.

 

No E.T. Life Yet? That might be a warning, Kelsey Johnson, Scientific American

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Remnants...

An artist's impression of the planetesimal orbiting on a 2-hour period within the gaseous disc around SDSS J1228+1040 (by Mark Garlick).

 

Topics: Astronomy, Astrophysics, Exoplanets, Spectrograph, White Dwarfs


When the hydrogen fuel that keeps a star like our sun burning brightly is exhausted, the star expands into a red giant before collapsing into a hot, dense white dwarf. Although the stellar swelling engulfs nearby planets, theoretical models suggest that some planets and planetary cores up to hundreds of kilometers in diameter can survive the star’s death and fall into closer orbit. But identifying solid bodies around a dim stellar core is difficult. Now Christopher Manser (University of Warwick) and colleagues have used a new spectroscopic method to identify a planetesimal orbiting a white dwarf 400 light-years from our solar system.

Astronomers have discovered most exoplanets—including an asteroid-like body orbiting a white dwarf—via the transit method, identifying periodic dimming as an object passes in front of its host star. But the method requires a lucky geometry of the planetary system’s orbital plane relative to Earth. Manser and his team instead turned to short-cadence optical spectroscopy using data from the 10.4 m Gran Telescopio Canarias in Spain. They focused on one of just a few white dwarfs that, based on metal emission lines in the stellar and disk spectra, are suspected to be surrounded by disks of gas and dust. Minute-by-minute observations over several nights in 2017 and 2018 let the researchers deconstruct the light emanating from the disk and determine how much variation had occurred over a year.

 

A glimpse of a planetary system’s final stages, Rachel Berkowitz, Physics Today

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Lumpy Neutron Stars...

An artist’s rendition of a neutron star. Credit: Kevin Gill Flickr (CC by 2.0)

 

Topics: Astronomy, Astrophysics, Einstein, Gravitational Waves, Neutron Stars


Gravitational waves—the ghostly ripples in spacetime first predicted by Einstein and finally detected a century later by advanced observatories—have sparked a revolution in astrophysics, revealing the otherwise-hidden details of merging black holes and neutron stars. Now, scientists have used these waves to open another new window on the universe, providing new constraints on neutron stars' exact shapes. The result will aid researchers in their ongoing quest to understand the inner workings of these exotic objects.

So far, 11 gravitational-wave events have been detected by the LIGO (Laser Interferometer Gravitational-Wave Observatory) interferometers in Washington and Louisiana and the Virgo gravitational-wave observatory in Italy. Of these events, 10 came from mergers of binary black holes, and one from the merger of two neutron stars. In all cases, the form of the waves matched the predictions of Einstein's theory of general relativity.

For the binary black hole events, the passing waves lasted less than a second; for the merging neutron stars, the emissions occurred for about 100 seconds. But such rapid pulses aren't the only types of gravitational waves that could be streaming through the universe. In particular, solitary neutron stars might be emitting detectable gravitational waves as they spin—signals that could reveal important new details of the stars' topography and internal composition.

 

Gravitational Observatories Hunt for Lumpy Neutron Stars
David Appell, Scientific American

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Sagittarius A...

Getty Images


Topics: Astronomy, Astrophysics, Black Holes, Cosmology, Einstein


They've captured our imaginations for decades, but we've never actually photographed a black hole before – until now.

Next Wednesday, at several press briefings around the world, scientists will apparently unveil humanity's first-ever photo of a black hole, the European Space Agency said in a statement. Specifically, the photo will be of "Sagittarius A," the supermassive black hole that's at the center of our Milky Way galaxy.

But aren't black holes, well, black, and thus invisible, so none of our telescopes can "see" them? Yes – therefore the image we're likely to see will be of the "event horizon," the edge of the black hole where light can't escape. [1]

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Next week, a collection of countries around the world are going to make a big announcement, and no one is sure exactly what it’s going to be. However, there are some possibilities, and the most exciting one is that they are about to reveal the first-ever photograph of the event horizon of a black hole.

Taking a photo of a black hole is not an easy task. Not only are black holes famous for not letting any light escape, even the nearest known black holes are very far away. The specific black hole astronomers wanted to photograph, Sagittarius A*, lies at the center of our galaxy 25,000 light-years away.

The international Event Horizon Telescope project announced its plan to photograph Sagittarius A* back in 2017, and they enlisted some of the world’s biggest telescopes to help out. The researchers used half a dozen radio telescopes, including the ALMA telescope in Chile and the James Clerk Maxwell telescope in Hawaii, to stare at Sagittarius A* over the past two years.

And while a picture of the black hole itself is impossible, the EHT astronomers were really aiming at the next best thing: the event horizon, the border of the black hole beyond which not even light can escape. At the event horizon, gravity is so strong that light will orbit the black hole like planets orbit stars, and our telescopes should be able to pick that up. [2]
 

1. 'Something no human has seen before': The first-ever photograph of a black hole will likely be unveiled next week, Doyle Rice, USA Today
2. We Might Be About to See the First Ever Photo of a Black Hole, Avery Thomson, Popular Mechanics

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