Space: The Final Frontier

[Stan]

Impressive! 

 

[CaaC (John)+]

Betelgeuse, the curiously dimming star, maybe covered in giant starspots

(CNN) - Betelgeuse, the red supergiant star that acts as the shoulder of Orion in his constellation, intrigued astronomers when the normally bright star showed signs of unprecedented dimming in December. Many have suggested potential causes for this dimming, including dust or the fact that the star is likely to explode in a supernova between now and 100,000 years from now.

New research has suggested that large starspots, like sunspots on our sun, are on the surface of Betelgeuse and causing the dimming. The researchers said their result rules out the dust scenario, which suggested that Betelgeuse ejected dust and it was obscuring the star.

The study published Monday in The Astrophysical Journal Letters.

Betelgeuse is estimated to be a few million years old and is about 700 light-years away. And the "supergiant" name is no joke: According to NASA, the star is thought to be somewhere between the diameter of Mars and Jupiter's orbits in size. It's estimated to be between 11 to 12 times the mass of our sun.

Astronomers expected it to begin dimming in December because the star experiences periods of dimming and subsequent brightening every 425 days

However, Betelgeuse dropped to 40% of its normal luminosity between October 2019 and April 2020, which surprised astronomers.

Thavisha Dharmawardena, a postdoctoral researcher at the Max Planck Institute for Astronomy in Germany, led a team of international astronomers as they studied Betelgeuse amid this unusual dimming episode. The team's data showed that temperature variations in the surface of the star caused the drop in brightness. And the most probable cause of this would be gigantic starspots covering 50% to 70% of Betelgeuse's surface.

"Towards the end of their lives, stars become red giants," Dharmawardena said in a statement. "As their fuel supply runs out, the processes change by which the stars release energy. As a result, they bloat, become unstable and pulsate with periods of hundreds or even thousands of days, which we see as a fluctuation in brightness."

The star is so massive that the gravitational pull on the surface is less than that of a smaller star, so any pulsating by the star can actually eject layers of it easily. When this gas released by the star cools, it essentially forms a dust.

Dharmawardena and her collaborators analyzed new and archival data taken from the Atacama Pathfinder Experiment in Chile and the James Clerk Maxwell Telescope in Hawaii to search for this dust. Both telescopes can measure radiation in submillimeter waves, which have wavelengths a thousand times greater than that of visible light. This allows them to study interstellar dust, which is otherwise invisible — but can emit a glow in these particular waves.

"What surprised us was that Betelgeuse turned 20% darker even in the submillimetre wave range," said Steve Mairs, study co-author and researcher at the East Asian Observatory in Hawaii, in a statement.

• New photos show Betelgeuse star's unprecedented dimming

• Betelgeuse star will explode

• Why the world is waiting for Betelgeuse to go supernova

Star spots on a grand scale

This darkening of Betelgeuse didn't match up with their dust hypothesis. But the data reflected that the star was causing its own change in brightness and a dip in surface temperature.

"Corresponding high-resolution images of Betelgeuse from December 2019 show areas of varying brightness," said Peter Scicluna, study co-author and researcher at the European Southern Observatory, in a statement. "Together with our result, this is a clear indication of huge starspots covering between 50 and 70% of the visible surface and having a lower temperature than the brighter photosphere [or luminous surface of the star]."

While starspots are common in giant stars, it's not usually on this scale, the researchers said. And they aren't certain about how long these spots can last. But taking into account calculations based on theoretical models, the starspots match up with the drop in Betelgeuse's brightness.

Our own sun experiences sunspots that fluctuate over an 11-year cycle, increasing and decreasing over that time period. The same could be true of more massive stars.

"Observations in the coming years will tell us whether the sharp decrease in Betelgeuse's brightness is related to a spot cycle. In any case, Betelgeuse will remain an exciting object for future studies," Dharmawardena said.

Betelgeuse will eventually explode, whether it happens in the next few years or 100,000 years from now. Why the uncertainty? Because there are multiple factors we just don't know about Betelgeuse; the star is so bright it makes it harder to observe and study using telescopes.

The star swelled to its current size because it burned through the hydrogen in its core and switched to fusing helium instead. When the helium runs out, and the star has exhausted its supply of carbon and silicon, it will run out of energy.

When that happens, the star's remaining iron collapses and causes a supernova. The star will implode, releasing shock waves and neutrinos, or ghostly particles, and blow apart. Astronomers have estimated it will likely become a condensed neutron star, but it could also turn into a black hole.

CNN

 

 

Edited June 29, 2020 by CaaC (John)
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[CaaC (John)+]

On 26/06/2020 at 09:09, Stan said:

Impressive! 

 

Watching that reminds me of the opening scene of 2001: A Space Odyssey, and the haunting music that can mesmerise you, well, it does to me.  

 

[CaaC (John)+]

Mystery over monster star's vanishing act

Astronomers have been baffled by the disappearance of a massive star they had been observing.

They now wonder whether the distant object collapsed to form a black hole without exploding in a supernova.

If correct, it would be the first example of such a huge stellar object coming to the end of its life in this manner.

But there is another possibility, the study in Monthly Notices of the Royal Astronomical Society reports.

The object's brightness might have dipped because it is partially obscured by dust.

It is located some 75 million light-years away in the Kinman Dwarf galaxy, in the constellation of Aquarius.

The giant star belongs - or belonged - to a type known as a luminous blue variable; it is some 2.5 million times brighter than the Sun.

Stars of this kind are unstable, showing occasional dramatic shifts in their spectra - the amount of light emitted at different wavelengths - and brightness.

Between 2001 and 2011, various teams of astronomers studied the massive star, concluding that it was in a late stage of evolution. The Kinman Dwarf galaxy is too far away for astronomers to see its individual stars, but they can detect the signatures of some of them.

In 2019, a team led by PhD student Andrew Allan of Trinity College Dublin, Ireland, targeted the galaxy, with the aim of finding out more about how very massive stars end their lives.

But when they pointed the European Southern Observatory's (Eso) Very Large Telescope (VLT) at it, they could no longer find the tell-tale signatures of the star.

Mr Allan commented: "We were surprised to find out that the star had disappeared!"

He added: "It would be highly unusual for such a massive star to disappear without producing a bright supernova explosion."

The older observations seem to indicate that the star was experiencing giant eruptions, in which material is lost from the star. These are thought to have stopped sometime after 2011.

Luminous blue variable stars such as this one are prone to such outbursts over the course of their life. They cause the star to lose mass and lead to a dramatic peak in brightness.

Based on their observations and models, the astronomers suggest two explanations for the star's disappearance and lack of a supernova.

The outbursts may have resulted in the luminous blue variable being transformed into a less luminous star, which could also be partly hidden by dust.

Alternatively, the team says the star may have collapsed into a black hole, without producing a supernova explosion.

This would be a rare event: our current understanding of how massive stars die suggests most of them meet their end in a violent nova.

If the black hole explanation is correct, says Mr Allan, "this would be the first direct detection of such a monster star ending its life in this manner".

Co-author Jose Groh, also of Trinity College Dublin, commented: "We may have detected one of the most massive stars of the local Universe going gently into the night."

Future studies are needed to confirm what happened to the star.

Eso's Extremely Large Telescope (ELT) - expected to begin operations in 2025 - will be capable of resolving stars in distant galaxies such as the Kinman Dwarf, helping to shed more light on cosmic mysteries such as this one.

https://www.bbc.co.uk/news/science-environment-53235909

[CaaC (John)+]

Faster-than-light travel: Is warp drive really possible?

A NASA scientist recently released a report analysing the feasibility of warp drive as a means of faster-than-light travel. Could this Star Trek technology really be possible?

________________________________________________________________________________________________________________________________________________________

In the Universe of Star Trek, humanity ventures out into the Galaxy on 5 April 2063 with the first-ever journey on a ship capable of faster-than-light travel. The newly-invented ‘warp drive’ not only lets humans explore the cosmos, but attracts the attention of Vulcans and brings about our first contact with an alien species.

It’s been 54 years since we were first introduced to the Enterprise, and many of Star Trek’s futuristic technologies have since been invented, from handheld communicators to universal translators. Warp drive is the next obvious choice: Voyager 1, which has travelled furthest from Earth of any spacecraft, took nearly 35 years to leave the Solar System. Not exactly handy for interstellar travel.

Luckily for humanity, theoretical physicists have been working on it. In May 2020, NASA scientist Harold “Sonny” White released an internal feasibility report discussing the technology from the point of view of ‘early mission planning’.

The first scientific theory of warp drive came about in 1994 when theoretical physicist Miguel Alcubierre used Einstein’s theory of General Relativity to develop a framework that would allow faster-than-light travel within the confines of the laws of physics. The key that makes it possible is that, technically, the ship itself doesn’t travel faster than light.

“What warp drive is doing is basically saying that there is no law of physics that says space-time itself can’t go faster than the speed of light,” says Dr Erin Macdonald, astrophysicist and science consultant for Star Trek.

“And so the concept of warp drive is to say, all right, let’s take our ship, let’s build a bubble of space-time around it, and then we’ll have that propel us faster than the speed of light,” she says. It’s similar to the idea of a racecar driving onboard a train: someone standing by the tracks would see the car travelling much faster than its top speed.

According to General Relativity, the Universe is a flat sheet of space-time which is warped by any object with mass. “We think of the bowling ball on the trampoline and that bowling ball dips the trampoline down,” says Macdonald, “and that’s what mass does to space-time.” This distortion of space-time is what we experience as gravity.

The Alcubierre drive uses the same concept. The ‘bubble’ surrounding the ship is an area of space-time that is compressed in front of the ship and expanded behind it. As with gravity, you could create this distortion using a large amount of mass. Alternatively, thanks to Einstein’s E = mc2 (energy is equal to mass, times the speed of light squared), you could equally use a huge amount of energy.

Inside the bubble, space-time is completely flat, meaning the space travellers wouldn’t notice any strange, relativistic effects. The result is that the bubble of space-time is hurled across the Universe, with the travellers sitting comfortably inside their ship, speedometer still reading the same number.

Unfortunately, actually creating a warp drive is even harder than it sounds. “You have to have a very, very large amount of energy,” says José Natário, Associate Professor in mathematics at the Instituto Superior Técnico in the University of Lisbon.

“To have the deformation that you need for this kind of thing to work, you’d need much, much more energy than the Sun or the Galaxy,” he says. “But also, it’s negative energy.”

Negative energy is not something that we can currently create – certainly not in the quantities needed to power a warp drive. How could energy be negative at all?

One way to think about it is to consider a particle with negative mass. These particles would react to gravity in the exact opposite way to particles of positive mass. Instead of being pulled towards a planet or star, they would be thrown away.

“If we had some sort of component like that where we had a negative mass, whatever is keeping that mass together would be that negative energy,” says Macdonald.

This isn’t a problem that will go away with refining the idea, either: Natário proved mathematically that any form of warp drive will require negative energy.

Joseph Agnew is a graduate student at the University of Alabama in Huntsville whose undergraduate work on warp drive was published in the AIAA journal. He thinks that more research into the fundamentals of physics is the way forward for warp drive.

“Further experimental study of naturally occurring gravitational waves and perhaps a study on trying to generate artificial gravitational waves would really advance the understanding of gravity, and therefore spacetime and all the connected science,” Agnew says.

Star Trek‘s USS Enterprise, the iconic warp-capable ship © Alamy

Natário believes there’s an even greater problem with the concept of the Alcubierre drive. Imagine a supersonic aircraft travelling faster than the speed of sound. You don’t hear the aircraft until it has already gone past, because the sound waves can’t keep up. The warp drive experiences the same effect with light waves, meaning there is no way to send a message ahead of you.

“I call it the ‘you need one to make one’ problem,” says Natário. How do you create the warped space-time geometry around your ship? First, you would need to send a signal ahead of you to ‘tell’ space-time to warp, Natário says. “To make it go faster than light, you need something that would be going faster than light, to begin with, so that you’d be able to communicate outside the horizon.”

These two problems – combined with the slight issue that the travellers would be bombarded with incredibly high-energy radiation – are the downfall of warp drive, Nátario believes. “The bottom line is, in my opinion, it’s completely impossible,” he says.

Agnew is more optimistic. “Many of these theoretical space transportation concepts rely extensively on a thorough understanding of gravity and spacetime, which just isn’t the case currently,” he says.

“I don’t yet see any way we can say, with absolute certainty, that it will ‘never happen in a million years’. When in doubt, history dictates it’s better to err on the side of cautious, scientific optimism.”

Macdonald, too, is hopeful. “I’m an eternal optimist with this because I want to join Starfleet,” she says. “The way I think about it is it’s like we never know what’s going to come down the pipe with sort of these weird, exotic, fun thought experiments.

“I agree at this stage, right now, it’s a fun thought experiment. But that’s not to preclude some massive discovery that may happen that we can’t predict.”

Science Focus

 

[nudge+]

18 minutes ago, CaaC (John) said:

Faster-than-light travel: Is warp drive really possible?

A NASA scientist recently released a report analysing the feasibility of warp drive as a means of faster-than-light travel. Could this Star Trek technology really be possible?

________________________________________________________________________________________________________________________________________________________

In the Universe of Star Trek, humanity ventures out into the Galaxy on 5 April 2063 with the first-ever journey on a ship capable of faster-than-light travel. The newly-invented ‘warp drive’ not only lets humans explore the cosmos, but attracts the attention of Vulcans and brings about our first contact with an alien species.

It’s been 54 years since we were first introduced to the Enterprise, and many of Star Trek’s futuristic technologies have since been invented, from handheld communicators to universal translators. Warp drive is the next obvious choice: Voyager 1, which has travelled furthest from Earth of any spacecraft, took nearly 35 years to leave the Solar System. Not exactly handy for interstellar travel.

Luckily for humanity, theoretical physicists have been working on it. In May 2020, NASA scientist Harold “Sonny” White released an internal feasibility report discussing the technology from the point of view of ‘early mission planning’.

The first scientific theory of warp drive came about in 1994 when theoretical physicist Miguel Alcubierre used Einstein’s theory of General Relativity to develop a framework that would allow faster-than-light travel within the confines of the laws of physics. The key that makes it possible is that, technically, the ship itself doesn’t travel faster than light.

“What warp drive is doing is basically saying that there is no law of physics that says space-time itself can’t go faster than the speed of light,” says Dr Erin Macdonald, astrophysicist and science consultant for Star Trek.

“And so the concept of warp drive is to say, all right, let’s take our ship, let’s build a bubble of space-time around it, and then we’ll have that propel us faster than the speed of light,” she says. It’s similar to the idea of a racecar driving onboard a train: someone standing by the tracks would see the car travelling much faster than its top speed.

According to General Relativity, the Universe is a flat sheet of space-time which is warped by any object with mass. “We think of the bowling ball on the trampoline and that bowling ball dips the trampoline down,” says Macdonald, “and that’s what mass does to space-time.” This distortion of space-time is what we experience as gravity.

The Alcubierre drive uses the same concept. The ‘bubble’ surrounding the ship is an area of space-time that is compressed in front of the ship and expanded behind it. As with gravity, you could create this distortion using a large amount of mass. Alternatively, thanks to Einstein’s E = mc2 (energy is equal to mass, times the speed of light squared), you could equally use a huge amount of energy.

Inside the bubble, space-time is completely flat, meaning the space travellers wouldn’t notice any strange, relativistic effects. The result is that the bubble of space-time is hurled across the Universe, with the travellers sitting comfortably inside their ship, speedometer still reading the same number.

Unfortunately, actually creating a warp drive is even harder than it sounds. “You have to have a very, very large amount of energy,” says José Natário, Associate Professor in mathematics at the Instituto Superior Técnico in the University of Lisbon.

“To have the deformation that you need for this kind of thing to work, you’d need much, much more energy than the Sun or the Galaxy,” he says. “But also, it’s negative energy.”

Negative energy is not something that we can currently create – certainly not in the quantities needed to power a warp drive. How could energy be negative at all?

One way to think about it is to consider a particle with negative mass. These particles would react to gravity in the exact opposite way to particles of positive mass. Instead of being pulled towards a planet or star, they would be thrown away.

“If we had some sort of component like that where we had a negative mass, whatever is keeping that mass together would be that negative energy,” says Macdonald.

This isn’t a problem that will go away with refining the idea, either: Natário proved mathematically that any form of warp drive will require negative energy.

Joseph Agnew is a graduate student at the University of Alabama in Huntsville whose undergraduate work on warp drive was published in the AIAA journal. He thinks that more research into the fundamentals of physics is the way forward for warp drive.

“Further experimental study of naturally occurring gravitational waves and perhaps a study on trying to generate artificial gravitational waves would really advance the understanding of gravity, and therefore spacetime and all the connected science,” Agnew says.

Star Trek‘s USS Enterprise, the iconic warp-capable ship © Alamy

Natário believes there’s an even greater problem with the concept of the Alcubierre drive. Imagine a supersonic aircraft travelling faster than the speed of sound. You don’t hear the aircraft until it has already gone past, because the sound waves can’t keep up. The warp drive experiences the same effect with light waves, meaning there is no way to send a message ahead of you.

“I call it the ‘you need one to make one’ problem,” says Natário. How do you create the warped space-time geometry around your ship? First, you would need to send a signal ahead of you to ‘tell’ space-time to warp, Natário says. “To make it go faster than light, you need something that would be going faster than light, to begin with, so that you’d be able to communicate outside the horizon.”

These two problems – combined with the slight issue that the travellers would be bombarded with incredibly high-energy radiation – are the downfall of warp drive, Nátario believes. “The bottom line is, in my opinion, it’s completely impossible,” he says.

Agnew is more optimistic. “Many of these theoretical space transportation concepts rely extensively on a thorough understanding of gravity and spacetime, which just isn’t the case currently,” he says.

“I don’t yet see any way we can say, with absolute certainty, that it will ‘never happen in a million years’. When in doubt, history dictates it’s better to err on the side of cautious, scientific optimism.”

Macdonald, too, is hopeful. “I’m an eternal optimist with this because I want to join Starfleet,” she says. “The way I think about it is it’s like we never know what’s going to come down the pipe with sort of these weird, exotic, fun thought experiments.

“I agree at this stage, right now, it’s a fun thought experiment. But that’s not to preclude some massive discovery that may happen that we can’t predict.”

Science Focus

 

Interesting line of research, but unlikely to ever be feasible, especially given that all original designs require not only unimaginably high amounts of energy, but also the existence of hypothetical exotic matter (negative mass/negative energy), which seems to be a component of all proposed crazy stuff (including time travel), and which almost definitely doesn't exist, haha.

[CaaC (John)+]

We can dream though "Beam me up @nudge"...sigh 

 

 

[nudge+]

11 minutes ago, CaaC (John) said:

We can dream though "Beam me up @nudge"...sigh 

There are others, by far more feasible concepts to dream about  

[CaaC (John)+]

The core of a gas planet seen for the first time

Astronomers have found a previously unseen type of object circling a distant star.

It could be the core of a gas world like Jupiter, offering an unprecedented glimpse inside one of these giant planets.

Giant planets like Jupiter and Saturn have a solid planetary core beneath a thick envelope of hydrogen and helium gas.

But no-one has previously been able to see what these solid cores are like.

Now, a team of astronomers has discovered what they think are the rocky innards of a giant planet that's missing its thick atmosphere. Their findings have been published in the journal Nature.

Lead author David Armstrong, from Warwick University, and colleagues had been running a programme to detect exposed planetary cores in data from the Tess space telescope.

"This was one of the candidates we picked out as something to try to observe," he told BBC News.

"We followed it up with an instrument called the Harps spectrograph in Chile, which we used to measure the masses of these candidates. This one came out as being exceptionally massive - much more than we expected really. That's when we started to look into what could have caused that."

When the researchers first looked at the object, they thought it might be a binary star.

"We kept taking data and it turned out to still be a planet - just an exceptionally massive one for its size," Dr Armstrong explained.

Its radius is about three-and-a-half times larger than Earth's but the planet is around 39 times more massive.

The object, called TOI 849 b, was found circling a star much like the Sun that's located 730 light-years away.

The core orbits so close to its parent star that a year is a mere 18 hours and its surface temperature is around 1,527C.

Researchers aren't sure whether the core lost its atmosphere in a collision or just never developed one.

If it was once similar to Jupiter, there are several ways it could have lost its gaseous envelope. These could include tidal disruption, where the planet is ripped apart from orbiting too close to its star, or even a collision with another planet late in its formation.

If it's a "failed" gas giant, this could have occurred if there was a gap in the disc of gas and dust that it emerged from, or if it formed late, after the disc ran out of material.

"I think one of the biggest clues is that we found the planet inside the 'Hot Neptunian desert', which in this region of parameter space where we don't typically find planets," Dr Armstrong told BBC News.

"That hints that it has gone through quite an unusual evolution. To me, that hints that it is more likely that it did lose its atmosphere... but we'll need some more observations to be sure."

These further observations could help test ideas about how giant gas planets evolve.

"It's a first, telling us that planets like this exist and can be found. We have the opportunity to look at the core of a planet in a way that we can't do in our own Solar System.

"There are still big open questions about the nature of Jupiter's core, for example, so strange and unusual exoplanets like this give us a window into planet formation that we have no other way to explore."

https://www.bbc.co.uk/news/science-environment-53250819

 

Edited July 2, 2020 by CaaC (John)

[CaaC (John)+]

Fireworks cancelled this year? Watch the lunar eclipse 'Buck Moon' instead

VIDEO

(CNN) - If your family's Fourth of July fireworks plans are up in smoke because of the pandemic, watch the sky for a lunar eclipse instead.

On July 4, just after 11 p.m. ET, the moon will begin its temporary new look. For exactly two hours and 45 minutes, the moon will pass through the feathered outer shadow cast from Earth, creating a partial penumbral lunar eclipse.

Here are the best places based on the forecasted cloud cover to watch the penumbral lunar eclipse.

A penumbral lunar eclipse occurs when the moon passes through the faint penumbra shadow cast by Earth. The moon misses the Earth's umbral shadow, which is best known for creating total and partial lunar eclipses.

This event might not be as illustrious as a partial or total lunar eclipse where parts of the moon seem to disappear.

Still, a noticeable darkening of the moon's surface will be visible without a telescope. The eclipse will begin at 11:07 p.m. ET and last through 1:52 a.m. ET, with peak darkening occurring just after midnight.

It's also the Buck Moon

During this time, it will also peak as the full moon -- nicknamed the Buck Moon -- just after midnight on Sunday morning. It will appear opposite the Sun (in Earth-based longitude) at 12:44 a.m. ET, according to NASA.

"The Maine Farmer's Almanac first published 'Indian' names for the Full Moons in the 1930s," according to NASA. "According to this almanack, as the full Moon in July and the first full moon of summer, the Algonquin tribes of what is now the northeastern United States called this full Moon the Buck Moon."

The July full moon also has been called Thunder Moon, Hay Moon, Mead Moon, Rose Moon, Guru Moon and Dharma Day.

This event is just the beginning of an astronomical month.

If the clouds get in the way of your lunar eclipse viewing, mark your calendar for these other July astronomical events.

Saturn and Jupiter make their closest approach to Earth

A great meeting of planets, known by astronomers as a conjunction, will occur every night this summer. In mid-July, Jupiter and Saturn will make their closest approach to Earth in 20 years.

Expect a brighter than usual illumination of the planets as they take centre stage across the horizon. Jupiter takes the cake, though, as it's expected to outshine Saturn by 15 times.

The largest planets of our solar system will follow each other westward across the night sky.

They will be bundled brightly together overhead, creating their most dazzling display of the year.

July will end with duelling meteor showers

The capstone of the July astronomy calendar will be marked by two meteor showers peaking on the same night.

At their peak, the Alpha Capricornids and the southern Delta Aquariids will provide roughly 20 to 25 visible meteors per hour.

North American stargazers should look to the low, southern horizon for the best Delta Aquariid meteor viewing.

The event will happen on the evening of July 28, lasting into July 29.

The waning crescent moon and ideal summer temperatures will make for perfect viewing conditions for the dual July meteor showers.

Now we just need the clouds to participate, too, in hopes of clear skies to watch streaking meteors.

CNN

[CaaC (John)+]

A new comet is now visible with the naked eye

(CNN) - A newly-discovered comet dubbed NEOWISE will be visible this week to the naked eye. It's the first visible comet of 2020.

The comet, officially known as C/2020 F3, was spotted by NASA's NEOWISE satellite in March, as it made its initial approach to the sun. It survived its loop around the sun and will be reaching the point in its orbit where it is closest to Earth in the next week. NEOWISE is expected to remain visible to the naked eye through July.

Those in the northern hemisphere can catch this comet in the north sky for most of the month at early dawn and dusk. Comets often appear faint in the sky, so it is easiest to catch a glimpse in the early morning and evening when there is just enough sunlight to see them against the night sky, but not so much they are washed out.

"For the northern hemisphere, it's very low to the horizon in the early morning," says Karl Battams, an astrophysicist with the Naval Research Laboratory. "People need to get up early, but it's easily visible with binoculars."

Look for NEOWISE to climb higher into the sky before disappearing into its orbit in August.

The comet got a special shout-out over the weekend from Bob Behnken, a NASA astronaut currently aboard the International Space Station after participating in the first launch of SpaceX Dragon Crew in May.

ISS astronaut Ivan Vagner also tweeted about the comet, noting its large, visible tail. The tail on NEOWISE could indicate that it is strong enough to remain intact in orbit.

People on Earth have also started seeing the comet on the horizon, says NASA. With its Astronomy Picture of the Day program, NASA invites anyone -- amateur to professional astronomers -- to submit their own photos of cosmic events here.

In case you wondered, the comet does not pose any danger to the planet and will pass by harmlessly.

Part of the NEOWISE satellite operations is to help researchers distinguish between near-earth objects with dangerous orbits (potentially hazardous asteroids, or PHAs), and those that are not a threat, according to NASA. Its infrared lens allows it to see comets particularly well, as they are commonly darker objects in the night sky, says Battams.

NASA's NEOWISE satellite launched first in 2009 as WISE. It's relaunch in 2013 as NEOWISE brought with it a new mission: "to assist NASA's efforts to identify and characterize the population of near-Earth objects," says NASA.

"NEOWISE is a really crucial satellite for nearer or potentially hazardous asteroids," says Battams. "It's a really important satellite to have."

During its tenure, NEOWISE has discovered hundreds of thousands of near-Earth objects or NEOs. Data collected by NEOWISE is critical in mapping solar bodies and analyzing the trajectory of space objects, including this new comet.

CNN

[CaaC (John)+]

Astronomers detect a series of unexpected mysterious circular objects in space

Astronomers have sighted a series of unidentified circles in space, visible only in radio light, using one of the world's most sensitive observatories.

The mysterious rings have been dubbed Odd Radio Circles, or ORCs, as they "do not seem to correspond to any known type of object", according to a recent study published by a team led by Western Sydney University astrophysicist Ray Norris.

All four ORCs are only visible in radio wavelengths. They are completely invisible in X-ray, optical, or infrared wavelengths.

“We have discovered, to the best of our knowledge, a new class of radio-astronomical object, consisting of a circular disc, which in some cases is limb-brightened, and sometimes contains a galaxy at its centre,” the researchers' study said.

The team's study has been posted on the preprint server arXiv. It has not yet been peer-reviewed.

Commenting further on the sightings of the ORCs, the scientists added: "None of the known types of radio object seems able to explain it."

Three of the four ORCs described by the team were detected by the Australian Square Kilometre Array Pathfinder (ASKAP) telescope — a network of radio antennae located in western Australia.

The telescope has been scanning the sky in the radio spectrum as part of efforts to create an Evolutionary Map of the Universe and help scientists better comprehend the development of stars and galaxies.

Norris and his team noticed three ORCs in ASKAP’s 2019 observations, with each of the circle's measures about one arcminute in diameter, which is roughly equivalent to 3 per cent the size of the Moon in the night sky.

It remains unclear how far away from Earth they are, which makes it challenging to estimate the actual size of the objects.

The unusual appearance of the glowing circles prompted the researchers to consider whether they might be an instrumental glitch, especially since radio imagery often contains errors that look like rounded apparitions, according to the study.

But later analysis of archival datasets revealed a fourth ORC was imaged in 2013 by India’s Giant Metrewave Radio Telescope.

The fact that the circles show up across multiple telescope datasets makes instrumental error “a very improbable explanation,” the team said in their study.

The team went on to identify several possible identities for the objects, saying they could be the fallout of exploded stars, or "Einstein rings,” which are signatures of warped spacetime created by the gravity of massive objects.

The researchers also mooted the possibility the ORCs could be the ghosts of highly energetic events that occurred millions of years ago - such as gamma-ray bursts or plasma jets spewed out by active galactic cores.

“We also acknowledge the possibility that the ORCs may represent more than one phenomenon,” the team noted, adding that they may have been “discovered simultaneously because they match the spatial frequency characteristics of the ASKAP observations, which occupy a part of the observational parameter space which has hitherto been poorly studied.”

Now, the team plan to continue examining the ORCs to see if they can unveil their secrets and sharpen further our view of space.

https://www.msn.com/en-gb/news/newslondon/astronomers-detect-series-of-unexpected-mysterious-circular-objects-in-space/ar-BB16Gk6I?li=BBoPWjQ

[CaaC (John)+]

Desert telescope takes aim at ageing our Universe

Another telescope has entered the debate about the age and expansion rate of the Universe.

This topic has recently become the subject of an energetic too and fro among scientists using different astronomical facilities and techniques.

The new entrant is the Atacama Cosmology Telescope in Chile.

It's been studying the "oldest light" on the sky and has concluded the Big Bang occurred 13.77 billion years ago, give or take 40 million years.

• 'Black neutron star' discovery changes astronomy
• A breathtaking new map of the X-ray Universe

That's almost exactly the same number we got from Europe's flagship Planck space observatory mission, which mapped the ancient light in the early 2010s.

But therein lies the problem because other telescopes using different methods have come out with ages that are a few hundred million years younger.

What they've all been trying to do is measure what's known as the Hubble Constant - the value used by astronomers to describe cosmic expansion.

The further away you look, the faster galaxies are receding from us. Ever since the American astronomer Edwin Hubble first detailed this relationship in 1929, researchers have meticulously tried to put a number on it.

There are two leading approaches. One is to map the distance to a local variable (cepheids) and exploding (supernovas) stars and try to gauge the recession rate from their movement. The other is to look at the state of the cosmos shortly after the Big Bang and to use what we know about the physics at work at this early time to predict what the constant should be.

Planck, and now the ACT, pursued this latter concept. To do it, they've both surveyed the Cosmic Microwave Background.

The CMB was the first light to sweep out across space once the Universe had cooled sufficiently to permit the formation of neutral hydrogen atoms - about 380,000 years into the life of the cosmos.

The light still bathes the Earth in a near-uniform glow at microwave frequencies and has a temperature profile that is just 2.7 degrees above absolute zero.

But it's possible to detect minute deviations in this signal - and in the way, the light has become twisted, or polarised, as it's come towards us - to pull out a welter of information. One of these nuggets of information is that value for the Hubble Constant.

The international team behind the ACT published its figure on Wednesday in a paper on the arXiv pre-print server (not full peer review).

This number is 67.6 kilometres per second per megaparsec - a megaparsec being 3.26 million light-years.

To put it another way - the expansion of the Universe increases by 67.6km per second for every 3.26 million light-years we look further out into space. Planck's version of this number was 67.4.

• Gaia clocks speedy cosmic expansion
• Gravitational waves clue to cosmic expansion

Should we be surprised? Shouldn't similar approaches yield very similar results?

ACT collaborator Prof Erminia Calabrese, from Cardiff University, UK, says that's true on one level but argues the experiments were sufficiently different to throw up any contradictions.

"If you understand how to build experiments, and if you understand what you're modelling in terms of physics - yes, you're right, it's perhaps no big surprise that you find the same thing. But these experiments were different," she told BBC News.

"Planck went to space, we stayed on the ground; and when you stay on the ground and have higher precision, you observe smaller angular scales, and these don't necessarily need to behave in the same way. There could have been a process or a mechanism that gives you different physics on different scales. That could have been an outcome."

For comparison, telescopes that have used the alternative approach produce a Hubble Constant that is around 74km per second per megaparsec.

This other camp includes the mighty Hubble Space Telescope itself and the Gaia space observatory, which is mapping the positions of nearby stars with a precision that's unprecedented in the history of astronomy.

Both groups have now hammered down the uncertainties in their respective measurements that the gap between them has become unbridgeable. One or both is wrong somewhere, or perhaps there is some new physics out there that neither side has grasped.

"It's possible that there are still some small biases in either the CMB or supernova datasets (or both) that are not being accounted for completely. But as the observations improve, it's becoming more difficult to see what that could be," commented Prof Isobel Hook from Lancaster University, UK.

"The alternative is that there's something fundamental about the Universe that we're not understanding.

"There are several theories that try to explain the discrepancy - one idea is that some extra early expansion in the Universe makes the CMB 'yardstick' a different physical size than what's assumed. But there are problems with these theories, too. I honestly don't know which side I'm on, but it's a fascinating debate!" she told BBC News.

https://www.bbc.co.uk/news/science-environment-53420433

[CaaC (John)+]

A Nuclear blast sends star hurtling across the galaxy

A star has been sent hurtling across the galaxy after undergoing a partial supernova, astronomers say.

A supernova is a powerful explosion that occurs when some stars reach the ends of their lives; in this case, the blast was not sufficient to destroy it.

Instead, it sent the star hurtling through space at 900,000 km/hr.

Astronomers think the object, known as a white dwarf, was originally circling another star, which would have been sent flying in the opposite direction.

When two stars orbit each other like this, they are described as a "binary". Only one of the stars has been detected by astronomers, however.

The object, known as SDSS J1240+6710, was previously found to have an unusual atmospheric composition.

Discovered in 2015, it seemed to contain neither hydrogen nor helium (which are usually found), appearing to be composed instead of an unusual mix of oxygen, neon, magnesium and silicon.

• Mystery over monster star's vanishing act
• Nearby 'supernova' star's dimming explained

Now, using the Hubble Space Telescope, an international team has also identified carbon, sodium, and aluminium in the star's atmosphere, all of which are produced in the first thermonuclear reactions of a supernova.

But there is also a clear absence of what is known as the "iron group" of elements, iron, nickel, chromium and manganese.

These heavier elements are normally cooked up from the lighter ones, and make up the defining features of thermonuclear supernovas.

The lack of iron group elements in SDSSJ1240+6710 suggests that the star only underwent a partial supernova before the nuclear burning died out.

Lead author Professor Boris Gänsicke, from the department of physics at the University of Warwick, UK, said: "This star is unique because it has all the key features of a white dwarf but it has this very high velocity and unusual abundances that make no sense when combined with its low mass.

"It has a chemical composition which is the fingerprint of nuclear burning, a low mass and a very high velocity; all of these facts imply that it must have come from some kind of close binary system and it must have undergone thermonuclear ignition. It would have been a type of supernova, but of a kind that we haven't seen before."

The high velocity could be accounted for if both stars in the binary were carried off in opposite directions at their orbital velocities in a kind of slingshot manoeuvre after the explosion.

The scientists were also able to measure the star's mass, which is particularly low for a white dwarf - only 40% the mass of our Sun - which would be consistent with a partial supernova that did not quite destroy the star.

The nature of the nuclear burning that occurs in a supernova is different from the reactions that release energy in nuclear power plants or most nuclear weapons. Most uses of nuclear energy on Earth rely on fission - which breaks down heavier elements into lighter ones - rather than the fusion that occurs in a star.

"The process developing during a thermonuclear supernova is very similar to what we try to achieve on Earth in our future power plants: nuclear fusion of lighter elements into heavier ones, which releases vast amounts of energy," Prof Gänsicke told BBC News.

"In a fusion reactor, we use the lightest element, hydrogen (more specifically, different flavours, or isotopes of it). In a thermonuclear supernova, the density and temperature in the star becomes so high that fusion of heavier elements ignites, starting with carbon and oxygen as 'fuel', and fusing heavier and heavier elements."

The best-studied thermonuclear supernovas are classified as Type Ia. These helped lead to the discovery of dark energy, and are now routinely used to map the structure of the Universe. But there is growing evidence that thermonuclear supernovas can happen under very different conditions.

SDSSJ1240+6710 may be the survivor of a type of supernova that hasn't yet been observed as it's happening.

Without the radioactive nickel that powers the long-lasting afterglow of the Type Ia supernovas, the explosion that sent the white dwarf careering across our Galaxy would have been a brief flash of light that would have been difficult to discover.

The research has been published in the Monthly Notices of the Royal Astronomical Society.

https://www.bbc.co.uk/news/science-environment-53415294

[CaaC (John)+]

Solar Orbiter sees ‘campfires’ on the Sun

The first images from ESA’s Solar Orbiter, captured around the spacecraft’s first close pass of the Sun, some 77 million kilometres from its surface, are already exceeding expectations revealing interesting new phenomena on our parent star. This animation shows a series of close-up views captured by the Extreme Ultraviolet Imager (EUI) at wavelengths of 17 nanometers, showing the upper atmosphere of the Sun, or corona, with a temperature of around 1 million degrees. These images reveal a multitude of small flaring loops, erupting bright spots and dark, moving fibrils. A ubiquitous feature of the solar surface, uncovered for the first time by these images, have been called ‘campfires’. They are omnipresent miniature eruptions that could be contributing to the high temperatures of the solar corona and the origin of the solar wind. Captured on 30 May 2020, when Solar Orbiter was roughly halfway between the Earth and the Sun, these are the closest views of the Sun ever taken, allowing EUI to see features in the solar corona of only 400 km across. As the mission continues, Solar Orbiter will go closer to the Sun and this will increase the instrument’s resolving power by a factor of two at closest approach. The colour on this image has been artificially added because the original wavelength detected by the instrument is invisible to the human eye. Solar Orbiter is a space mission of international collaboration between ESA and NASA.

 

Edited July 24, 2020 by CaaC (John)

[CaaC (John)+]

Planet Nine could be a grapefruit-sized black hole, say astrophysicists

We can prove it by looking for the black hole's 'accretion flares', the astrophysicists say.

Astrophysicists have suggested that the hypothetical Planet Nine could be a tiny black hole, and they’ve proposed a way to find out.

Planet Nine has never been seen directly. But the existence of a ninth planet orbiting our Sun could explain certain features of the outer Solar System, such as the clustering together of icy rocks called ‘trans-Neptunian objects’ with similarly tilted orbits.

Last year, scientists in the UK and US suggested that Planet Nine, which is also known as Nibiru, could instead be a primordial black hole. These as-yet-unseen black holes are thought to have formed a fraction of a second after the Big Bang. If Planet Nine was such an entity, it would be about the size of a grapefruit, with a mass of five to ten times that of Earth.

An artist’s illustration of a tiny black hole in the outer Solar System ripping apart a comet from the Oort cloud © M Weiss

Read more about black holes:

• A mysterious object may be smallest black hole ever found
• Researchers verify ‘extremely odd’ black hole physics

“LSST has a wide field of view, covering the entire sky again and again, and searching for transient flares,” said study co-author Prof Avi Loeb. “Other telescopes are good at pointing at a known target, but we do not know exactly where to look for Planet Nine. We only know the broad region in which it may reside.”

“The outskirts of the Solar System is our backyard,” adds Loeb. “Finding Planet Nine [would be] like discovering a cousin living in the shed behind your home [who] you never knew about.”

 

ScienceFocus

 

 

Edited July 18, 2020 by CaaC (John)

[CaaC (John)+]

 

[CaaC (John)+]

How to find comet Neowise, lying low in the northern sky

© Provided by The Guardian Photograph: Mark Kerton/REX/Shutterstock

There’s only one thing to see this week: comet C/2020 F3 Neowise. Discovered on 27 March on images taken by the Nasa NEOWISE space telescope, by the beginning of this month the comet had grown in brightness to become visible to the naked eye. It passed its closest approach to the sun on 3 July and this week, on 23 July, it will make its closest approach to Earth.
To see the comet from the UK, look north in the early hours of the morning. Find the Plough, which is conveniently located between the bright yellow star of Capella to the east, and the orange star of Arcturus to the west. The comet will appear as a misty spot, close to the horizon. Its tail will be pointing straight up, although you are unlikely to see this with the naked eye. The best you can hope for is a slight elongation of the central patch of light. However, if you take binoculars with you, this will increase the amount of detail you can see. Unfortunately, the comet is too far north to be visible from the southern hemisphere. It is one of the brightest comets since comet Hale-Bopp in 1997.

https://www.msn.com/en-gb/news/world/how-to-find-comet-neowise-lying-low-in-the-northern-sky/ar-BB16W81A?li=BBoPWjQ

[CaaC (John)+]

Edit: Deleted - Posted in the wrong Forum 

 

Re-posted in the Mission to Mars thread  

 

Edited July 25, 2020 by CaaC (John)

[CaaC (John)+]

 

[CaaC (John)+]

Venus has at least 37 recently-active volcanoes

It was previously thought that the planet had cooled down too much to show volcanic activity.

Venus is home to at least 37 recently-active volcanic structures, a study by researchers at the University of Maryland and the Institute of Geophysics at ETH Zurich has found. It is the first evidence that the interior of the planet is still geologically active.

Previous studies have found evidence of a warm interior and ring-like structures known as coronae, which form when plumes of hot material deep inside the planet rise through the mantle layer and crust in a manner similar to the way mantle plumes formed the volcanic Hawaiian Islands.

However, it was thought that they were signs of the ancient activity and that the planet had cooled enough to slow down geological activity in the planet’s interior and harden the crust so much that any warm material from deep inside would not be able to puncture through.

In the new study, the researchers created models of the thermal activity beneath the surface of Venus to create high-resolution, 3D simulations of coronae formation. They then used these to identify features that are present only in recently-active coronae and looked for similar structures on the surface of Venus.

A 3D render showing two coronae observed on the surface of Venus © University of Maryland

“This is the first time we are able to point to specific structures and say ‘Look, this is not an ancient volcano but one that is active today, dormant perhaps, but not dead,’” said Laurent Montési, a professor of geology at the University of Maryland.

“This study significantly changes the view of Venus from a mostly inactive planet to one whose interior is still churning and can feed many active volcanoes.”

A global map of Venus showing active coronae (red) and inactive coronae (white) © Anna Gülcher

The active coronae on Venus are clustered together in a handful of locations, which suggests areas where the planet is most active. This may help identify target areas where geologic instruments should be placed on future missions to Venus, such as Europe’s EnVision that is scheduled to launch in 2032.

Science Focus

[CaaC (John)+]

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Is the Betelgeuse star about to explode?

The supergiant star has been behaving strangely in recent months. Could it be about to go supernova?

In the constellation of Orion, something strange is afoot. In October 2019, the red star Betelgeuse – which marks Orion’s right shoulder (or left as we look at it) – began to get unusually dim. During January and February 2020, it reached a record low – around 40 per cent of its usual brightness.

We know that Betelgeuse is a mature star and that it will one day explode in a supernova. But this dimming has led to speculation that a supernova could be imminent. Might this be a moment of calm before the star expires in a cosmic death-blast?

The dimming of Betelgeuse (the name of the star has its origins in Arabic, and there’s no consensus on how to pronounce the Westernised version, but ‘Beet-el-joos’ is one of the more common variants – as popularised in the 1988 film Beetlejuice) is not completely unexpected.

It’s what’s known as a ‘variable’ star, whose brightness fluctuates. In Betelgeuse’s case, this fluctuation follows a roughly 420-day cycle, and – in line with this cycle – there are now signs that the star is slowly brightening again.

“But even if Betelgeuse perks up, it still leaves us with questions,” says Dr Emily Levesque, an astronomer who studies the physics of massive stars at the University of Washington. “It’s got so much dimmer than normal – way more than we would expect.”

Betelgeuse is a red supergiant – the largest class of stars in the Universe in terms of volume. It has a radius of around 600 million kilometres: if you plonked Betelgeuse in the middle of the Solar System – where the Sun is – it would reach almost to Jupiter, engulfing Mercury, Venus, Earth and Mars.

Red supergiants form when a massive star runs out of hydrogen in its core and can no longer convert hydrogen into helium via nuclear fusion. At this point, the core begins to contract, which raises the star’s internal temperature and ignites a shell of hydrogen fusion around the core, causing the star’s outer layers to expand and cool.

The temperature inside Betelgeuse’s core is so hot that the helium there has begun to fuse into carbon. Once the helium is exhausted, the core will rapidly work its way through heavier elements, all the way to iron. At this point, the star can generate no more energy, so the core will collapse. The outer layers will follow, bouncing off the core and exploding in a supernova.

Why is Betelgeuse dimming?

So could the dimming be a sign of an imminent supernova? Levesque admits that we still know very little about what a star will do in the final days and weeks before it explodes. But she says that the best guess for when Betelgeuse will die, according to where scientists think it is in its life cycle, is in 100,000 years.

“A supernova tomorrow is not flat out impossible,” she says, “But it’s unlikely.”

So what’s responsible for the recent dimming? Betelgeuse’s usual 420-day pulsation cycle – which is caused by variations in the star’s size – cannot alone account for the dimming, says Levesque, so there’s probably at least one other mechanism going on.

One possibility is that the star is being obscured, making it appear dimmer.

“We know that stars like Betelgeuse periodically shed mass from their surface, which condenses into dust around the star,” she says. “This would effectively block our view.”

“We also know that red supergiants have big convective zones on their surfaces,” says adds. Hot gas from deep inside the star rises to the surface, where it cools and sinks again. Changes in this circulation could be altering the star’s surface temperature, and hence its brightness – another possible explanation for what’s going on.

Whatever Betelgeuse is currently doing, there’s no question that it’ll explode at some point.

“It’ll be absolutely unmissable,” says Levesque. “The star is only a few hundred light-years away, so the light from the supernova will be incredibly bright – comparable to Venus or the Moon.”

We’ll see it in the sky as a pinprick of light – even during daytime – and our telescopes will be able to see the nebulous ‘supernova remnant’ in all its glory. But don’t worry: although Betelgeuse is relatively close to us, it’s still far enough away that there’ll be no danger from the supernova’s high-energy radiation. As for Betelgeuse, it’ll most likely become an ultra-dense neutron star.

In the meantime, astronomers are getting all the data they can.

“As we study more of these red supergiants, we should get better at pinpointing what stage of their evolution they’re in, and when they’re likely to die,” says Levesque.

“We know that stars like this make most of the elements in the Universe – both when they’re alive and when they die as supernovae. Understanding how this works will tell us more about how the make-up of the Universe evolved. These stars seeded the chemistry that made life possible.”

Science Focus

[CaaC (John)+]

 

[nudge+]

Deorbit burn was successful, now about 20 minutes until entry, 27 minutes until splashdown.

[nudge+]

Splashdown successful! A smooth ride, and Dragon is back to planet Earth