Astronomers map a starburst galaxy

Monster galaxy COSMOS-AzTEC-1 observed with the ALMA telescope in Chile. ALMA revealed the distribution of molecular gas (left) and dust particles (right). In addition to the dense cloud in the center, the research team found 2 dense clouds several thousand light-years away from the center. These dense clouds are dynamically unstable and thought to be the sites of intense star formation. Image via ALMA (ESO/NAOJ/NRAO), Tadaki et al.

Starburst galaxies, sometimes called monster galaxies, typically form stars at a pace some 100 times faster than in our own Milky Way galaxy. But a newly mapped starburst galaxy labeled COSMOS-AzTEC-1 – located 12.4 billion light-years away, in the early universe – is now known to be forming stars 1,000 times faster than our Milky Way. It’s also been found to have star-forming regions not in its galactic center, but in vast clouds located off-center by several thousand light-years. This galaxy is, indeed, a dynamic and mysterious place, so much so that the astronomers who studied it called it an unstoppable monster.

It’s not truly unstoppable, of course. Stars are formed from gas and dust in a galaxy, and starburst galaxies use up their gas and dust faster than ordinary galaxies like our Milky Way. Once the gas and dust diminishes, star formation slows down.

Astronomer Min Yun at UMass Amherst was a member of the team that discovered this galaxy in 2007, using an instrument built at UMass called AzTEC. Note that this galaxy bears the name AzTEC-1. It’s likely the first galaxy, or a very important early galaxy, discovered by this instrument; that’s one way galaxies are named. Yun commented:

A real surprise is that this galaxy seen almost 13 billion years ago has a massive, ordered gas disk that is in regular rotation instead of what we had expected, which would have been some kind of a disordered train wreck that most theoretical studies had predicted.

He said the new observations – made at the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile – show that this gas disk is dynamically unstable now. That is, the entire gas disk that makes up this galaxy is fragmenting and undergoing a gigantic episode of starburst, at a rate more than 1,000 times that of our Milky Way.

The Atacama Large Millimeter/submillimeter Array (ALMA) at night. Image via Babak Tafreshi/ESO. Read more about this image.

Japanese astronomer Ken-ichi Tadaki is lead author of the new study – which is published in the peer-reviewed journal Nature. He said:

We found that there are two distinct large clouds several thousand light-years away from the center [of the galaxy COSMOS-AzTEC-1]. In most distant starburst galaxies, stars are actively formed in the center. So it is surprising to find off-center clouds.

Tadaki, Yun and team used the ALMA data to compile detailed maps of molecular clouds, which are the types of gas-and-dust clouds in which new stars are born. They found that COSMOS-AzTEC-1 is rich in the ingredients of stars, but it was still difficult to figure out the nature of the cosmic gas in the galaxy. They said they used ALMA’s high resolution and high sensitivity to observe the galaxy and obtain a detailed map of the distribution and the motion of the gas. They said it’s the highest resolution – that is, the sharpest and clearest – molecular-gas map of a distant monster galaxy ever made.

Yun explained part of the reason astronomers are so fascinated by these distant starburst galaxies:

How these galaxies have been able to amass such a large quantity of gas in the first place and then essentially turn the entire gas reserve into stars in the blink of an eye, cosmologically speaking, was a completely unknown question about which we could only speculate. We have the first answers now.

The team estimated that the gas in COSMOS-AzTEC-1 will be completely consumed in 100 million years, which is 10 times faster than in other star-forming galaxies.

Unstoppable? No. Awesome. Yes!

Read more via UMass and ALMA

Artist’s concept of the galaxy COSMOS-AzTEC-1, located 12.4 billion light-years away. New observations revealed 2 dense gas concentrations outside the galaxy’s center, with intense star formation in those concentrations. Image via National Astronomical Observatory of Japan/ALMA.

Bottom line: The monster or starburst galaxy COSMOS-AzTEC-1 is now known to have two gigantic star-forming lobes off-center in the galaxy. It’s known to be producing stars at a rate 1,000 times faster than our Milky Way.

Source: The gravitationally unstable gas disk of a starburst galaxy 12 billion years ago

from EarthSky https://ift.tt/2PQCFAb

Monster galaxy COSMOS-AzTEC-1 observed with the ALMA telescope in Chile. ALMA revealed the distribution of molecular gas (left) and dust particles (right). In addition to the dense cloud in the center, the research team found 2 dense clouds several thousand light-years away from the center. These dense clouds are dynamically unstable and thought to be the sites of intense star formation. Image via ALMA (ESO/NAOJ/NRAO), Tadaki et al.

Starburst galaxies, sometimes called monster galaxies, typically form stars at a pace some 100 times faster than in our own Milky Way galaxy. But a newly mapped starburst galaxy labeled COSMOS-AzTEC-1 – located 12.4 billion light-years away, in the early universe – is now known to be forming stars 1,000 times faster than our Milky Way. It’s also been found to have star-forming regions not in its galactic center, but in vast clouds located off-center by several thousand light-years. This galaxy is, indeed, a dynamic and mysterious place, so much so that the astronomers who studied it called it an unstoppable monster.

It’s not truly unstoppable, of course. Stars are formed from gas and dust in a galaxy, and starburst galaxies use up their gas and dust faster than ordinary galaxies like our Milky Way. Once the gas and dust diminishes, star formation slows down.

Astronomer Min Yun at UMass Amherst was a member of the team that discovered this galaxy in 2007, using an instrument built at UMass called AzTEC. Note that this galaxy bears the name AzTEC-1. It’s likely the first galaxy, or a very important early galaxy, discovered by this instrument; that’s one way galaxies are named. Yun commented:

A real surprise is that this galaxy seen almost 13 billion years ago has a massive, ordered gas disk that is in regular rotation instead of what we had expected, which would have been some kind of a disordered train wreck that most theoretical studies had predicted.

He said the new observations – made at the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile – show that this gas disk is dynamically unstable now. That is, the entire gas disk that makes up this galaxy is fragmenting and undergoing a gigantic episode of starburst, at a rate more than 1,000 times that of our Milky Way.

The Atacama Large Millimeter/submillimeter Array (ALMA) at night. Image via Babak Tafreshi/ESO. Read more about this image.

Japanese astronomer Ken-ichi Tadaki is lead author of the new study – which is published in the peer-reviewed journal Nature. He said:

We found that there are two distinct large clouds several thousand light-years away from the center [of the galaxy COSMOS-AzTEC-1]. In most distant starburst galaxies, stars are actively formed in the center. So it is surprising to find off-center clouds.

Tadaki, Yun and team used the ALMA data to compile detailed maps of molecular clouds, which are the types of gas-and-dust clouds in which new stars are born. They found that COSMOS-AzTEC-1 is rich in the ingredients of stars, but it was still difficult to figure out the nature of the cosmic gas in the galaxy. They said they used ALMA’s high resolution and high sensitivity to observe the galaxy and obtain a detailed map of the distribution and the motion of the gas. They said it’s the highest resolution – that is, the sharpest and clearest – molecular-gas map of a distant monster galaxy ever made.

Yun explained part of the reason astronomers are so fascinated by these distant starburst galaxies:

How these galaxies have been able to amass such a large quantity of gas in the first place and then essentially turn the entire gas reserve into stars in the blink of an eye, cosmologically speaking, was a completely unknown question about which we could only speculate. We have the first answers now.

The team estimated that the gas in COSMOS-AzTEC-1 will be completely consumed in 100 million years, which is 10 times faster than in other star-forming galaxies.

Unstoppable? No. Awesome. Yes!

Read more via UMass and ALMA

Artist’s concept of the galaxy COSMOS-AzTEC-1, located 12.4 billion light-years away. New observations revealed 2 dense gas concentrations outside the galaxy’s center, with intense star formation in those concentrations. Image via National Astronomical Observatory of Japan/ALMA.

Bottom line: The monster or starburst galaxy COSMOS-AzTEC-1 is now known to have two gigantic star-forming lobes off-center in the galaxy. It’s known to be producing stars at a rate 1,000 times faster than our Milky Way.

Source: The gravitationally unstable gas disk of a starburst galaxy 12 billion years ago

from EarthSky https://ift.tt/2PQCFAb

Sir Harpal Kumar: A spotlight on 15 years of progress against cancer

It’s the end of an era at Cancer Research UK: our Chief Executive, Sir Harpal Kumar, has stepped down after an illustrious career. Harpal joined us in late 2002 before being appointed Chief Executive in 2007.

As part of our 2017/18 Annual Review, which we published today, we spoke with Harpal about how things have changed in the world of cancer research during more than 15 years at the Charity. Here are his highlights.

Action against tobacco

“Making tobacco less attractive to kids has to be one of the biggest gifts we can give the next generation. Over the last decade or so, we’ve seen big changes in public attitudes: it’s now far less socially acceptable, and we hope this means fewer young people will fall into such a potentially lethal addiction. But the job is far from done – we still have more than eight million smokers in Britain, and tens of thousands of children taking up the deadly addiction every year.”

The importance of spotting cancer early

“Politically speaking, we really put the importance of early diagnosis on the map. Back in 2003, almost no-one was talking about it. Now it’s right at the top of the agenda – and that’s something the Charity can be very proud of.”

Renewed focus on hard-to-treat cancers

“When we made lung cancer a high priority in our 2009 research strategy, it got quite a strong reaction. People thought it was too tough a challenge, they didn’t want to risk their careers on it. That’s changed – just look at lung and brain cancers now – there’s so much high-quality research going on.”

Improving the UK’s cancer services

“We’ve pushed hard to make sure that governments across the UK have robust plans to keep cancer services focused on what’s important. Over the years, these strategies have done a great job in improving our cancer services. It was a privilege to be asked to chair the Independent Taskforce which wrote the most recent cancer plan for England, and aims to transform people’s experiences of cancer care, as well as their chances of beating the disease.”

The Crick

“Raising £100 million in just four years to help fund the Francis Crick Institute was an incredible achievement for the Charity. The Institute’s state-of-the-art facilities and world-class scientific minds are already accelerating and deepening our understanding of cancer, ultimately improving the lives of patients across the world.”

Radiotherapy

“Radiotherapy plays a vital role in curing cancer, but has often suffered from a lack of attention. Cancer Research UK has an incredible track record in radiotherapy research, but also – more recently – in pushing to modernise the UK’s radiotherapy infrastructure. The recent injection of cash from the Government to upgrade the nation’s radiotherapy equipment was fantastic news.”

Translating laboratory insights into patient benefit

“It’s hard to think of a single scientific advance that stands out, simply because there have been so many. What we know about cancer has advanced almost beyond recognition. And the thing that Cancer Research UK has been able to do is to make sure these advances are plugged into big national and international studies that make sure that they have the best possible chance of improving things for patients.”

The way people talk about cancer

“The language around cancer has completely changed. When I started here, it was something people barely mentioned. But now we discuss it much more openly. We celebrate people surviving it. I’m continually struck by this at Race for Life events. The notices on people’s backs used to be universally in memory of people who’d died. But when you go to a Race for Life today, they’re just as likely to be celebrating someone who’s survived.”

Immunotherapy

“The arrival in the early 2010s of a new generation of drugs that target a patient’s immune system – rather than their cancer – is one of the most important developments in my career. We’re now drawing together the UK’s immunology community to accelerate progress in this field, to develop drugs that work for more people, with even fewer side effects.”

Our growth in size and influence

“I’m leaving a charity that’s much larger, and funds so much more research. And along with that has come a big change in what we do. We’re as much a ‘convener’ as a funder now – we bring others together and we set the research agenda in a way that we just weren’t able to do when I started. When the Government decides to focus on something, we’re generally invited to sit at the table – and we’re listened to.”

Personal highlight

“When I try to think of a moment that sums up just how much progress we’ve made over the years, I keep coming back to April 2014, and being able to make the announcement that, for the first time in history, as many people now survived cancer long-term as died from it. That’s an incredible thing to be able to announce, a phenomenal achievement. Will I ever get to make a more profound announcement in my life? I doubt it.”

And a look to the future?

“I hope it will include something in the area of early detection. We’re getting towards a breakthrough that’ll allow us to detect cancers at an early stage – including some of the most aggressive, dangerous ones – and that’s going to have a huge impact on survival.”

Read more about the progress we’ve made in the last 12 months in our Annual Review 2017/18. We’ll also be publishing a selection of these stories over the next few weeks.

from Cancer Research UK – Science blog https://ift.tt/2BYTTs2

It’s the end of an era at Cancer Research UK: our Chief Executive, Sir Harpal Kumar, has stepped down after an illustrious career. Harpal joined us in late 2002 before being appointed Chief Executive in 2007.

As part of our 2017/18 Annual Review, which we published today, we spoke with Harpal about how things have changed in the world of cancer research during more than 15 years at the Charity. Here are his highlights.

Action against tobacco

“Making tobacco less attractive to kids has to be one of the biggest gifts we can give the next generation. Over the last decade or so, we’ve seen big changes in public attitudes: it’s now far less socially acceptable, and we hope this means fewer young people will fall into such a potentially lethal addiction. But the job is far from done – we still have more than eight million smokers in Britain, and tens of thousands of children taking up the deadly addiction every year.”

The importance of spotting cancer early

“Politically speaking, we really put the importance of early diagnosis on the map. Back in 2003, almost no-one was talking about it. Now it’s right at the top of the agenda – and that’s something the Charity can be very proud of.”

Renewed focus on hard-to-treat cancers

“When we made lung cancer a high priority in our 2009 research strategy, it got quite a strong reaction. People thought it was too tough a challenge, they didn’t want to risk their careers on it. That’s changed – just look at lung and brain cancers now – there’s so much high-quality research going on.”

Improving the UK’s cancer services

“We’ve pushed hard to make sure that governments across the UK have robust plans to keep cancer services focused on what’s important. Over the years, these strategies have done a great job in improving our cancer services. It was a privilege to be asked to chair the Independent Taskforce which wrote the most recent cancer plan for England, and aims to transform people’s experiences of cancer care, as well as their chances of beating the disease.”

The Crick

“Raising £100 million in just four years to help fund the Francis Crick Institute was an incredible achievement for the Charity. The Institute’s state-of-the-art facilities and world-class scientific minds are already accelerating and deepening our understanding of cancer, ultimately improving the lives of patients across the world.”

Radiotherapy

“Radiotherapy plays a vital role in curing cancer, but has often suffered from a lack of attention. Cancer Research UK has an incredible track record in radiotherapy research, but also – more recently – in pushing to modernise the UK’s radiotherapy infrastructure. The recent injection of cash from the Government to upgrade the nation’s radiotherapy equipment was fantastic news.”

Translating laboratory insights into patient benefit

“It’s hard to think of a single scientific advance that stands out, simply because there have been so many. What we know about cancer has advanced almost beyond recognition. And the thing that Cancer Research UK has been able to do is to make sure these advances are plugged into big national and international studies that make sure that they have the best possible chance of improving things for patients.”

The way people talk about cancer

“The language around cancer has completely changed. When I started here, it was something people barely mentioned. But now we discuss it much more openly. We celebrate people surviving it. I’m continually struck by this at Race for Life events. The notices on people’s backs used to be universally in memory of people who’d died. But when you go to a Race for Life today, they’re just as likely to be celebrating someone who’s survived.”

Immunotherapy

“The arrival in the early 2010s of a new generation of drugs that target a patient’s immune system – rather than their cancer – is one of the most important developments in my career. We’re now drawing together the UK’s immunology community to accelerate progress in this field, to develop drugs that work for more people, with even fewer side effects.”

Our growth in size and influence

“I’m leaving a charity that’s much larger, and funds so much more research. And along with that has come a big change in what we do. We’re as much a ‘convener’ as a funder now – we bring others together and we set the research agenda in a way that we just weren’t able to do when I started. When the Government decides to focus on something, we’re generally invited to sit at the table – and we’re listened to.”

Personal highlight

“When I try to think of a moment that sums up just how much progress we’ve made over the years, I keep coming back to April 2014, and being able to make the announcement that, for the first time in history, as many people now survived cancer long-term as died from it. That’s an incredible thing to be able to announce, a phenomenal achievement. Will I ever get to make a more profound announcement in my life? I doubt it.”

And a look to the future?

“I hope it will include something in the area of early detection. We’re getting towards a breakthrough that’ll allow us to detect cancers at an early stage – including some of the most aggressive, dangerous ones – and that’s going to have a huge impact on survival.”

Read more about the progress we’ve made in the last 12 months in our Annual Review 2017/18. We’ll also be publishing a selection of these stories over the next few weeks.

from Cancer Research UK – Science blog https://ift.tt/2BYTTs2

Watch for zodiacal light or false dawn

View larger. | Lubomir Lenko Photography wrote from Brehov, Slovakia, on August 18, 2018: “The rise of Orion is back with the fine shine of zodiacal light.” Orion is in the lower right. See its Belt, the 3 stars in a short, straight row? The zodiacal light nearly fills the frame in this photo. Can you see that the light is pyramid-shaped?

If you’re in the Northern Hemisphere, it’s time to start looking for the zodiacal light – or false dawn – an eerie light in the east before sunrise, visible in clear dark skies in the months around the autumn equinox. If you’re in the Southern Hemisphere in late August, September or October, look in the west after sunset instead, for the same phenomenon, now called the false dusk.

The light looks like a hazy pyramid. It’s comparable in brightness to the Milky Way, but even milkier in appearance.

Talay Daniel Erol caught this image of the zodical light last year (2017) in late August – with the bright planet Venus in its midst – from Adrasan Antalya, Turkey.

How can I see the zodiacal light? Maybe you’ve seen the zodiacal light in the sky already and not realized it. Maybe you glimpsed it while driving on a highway or country road. This strange light is a seasonal phenomenon. Springtime and autumn are best for seeing it, no matter where you live on Earth.

Suppose you’re driving toward the east – in the hour before dawn – in autumn. You catch sight of what you think is the light of a nearby town, just over the horizon. But it might not be a town. It might be the zodiacal light. The light extends up from the eastern horizon, shortly before morning twilight begins. The zodiacal light can be extremely bright and easy to see from latitudes like those in the southern U.S.

We also sometimes hear from skywatchers in the northern U.S. or Canada who’ve captured images of the zodiacal light.

You’ll need a dark sky location to see the zodiacal light, someplace where city lights aren’t obscuring the natural lights in the sky.

The zodiacal light is most visible before dawn in autumn because autumn is when the ecliptic – or path of the sun and moon – stands nearly straight up with respect to your eastern horizon before dawn. Likewise, the zodiacal light is easiest to see just after true night falls in your springtime months, because then the ecliptic is most perpendicular to your western horizon in the evening. That’s true no matter where you are on Earth.

In autumn, the zodiacal light can be seen in the hour before true dawn begins. Or, in spring, it can be seen for up to an hour after all traces of evening twilight leave the sky. Unlike true dawn or dusk, though, there’s no rosy color to the zodiacal light. The reddish skies at dawn and dusk are caused by Earth’s atmosphere, while the zodiacal light originates far outside our atmosphere, as explained below.

The darker your sky, the better your chances of seeing it. Your best bet is to pick a night when the moon is out of the sky, although it’s definitely possible, and very lovely, to see a slim crescent moon in the midst of this strange milky pyramid of light.

If you see it, let us know! If you catch a photo, submit it here.

Zodiacal Light over the Faulkes Telescope, Haleakala, Maui. Photo via Rob Ratkowski.

Springtime? Autumn? When should I look? Is there a Northern/ Southern Hemisphere difference between the best time of year to view the zodiacal light? Yes and no. For both hemispheres, springtime is the best time to see the zodiacal light in the evening. Autumn is the best time to see it before dawn.

No matter where you live on Earth, look for the zodiacal light in the east before dawn around the time of your autumn equinox. Look for it in the west after sunset around the time of your spring equinox.

Of course, spring and autumn fall in different months for Earth’s Northern and Southern Hemispheres.

So if you’re in the Northern Hemisphere look for the zodiacal light before dawn from about late August through early November.

In those same months, if you’re in the Southern Hemisphere, look for the light in the evening.

Likewise, if you’re in the Northern Hemisphere, look for the evening zodiacal light from late February through early May. During those months, from the Southern Hemisphere, look for the light in the morning.

Milky Way on left in this photo. Zodiacal light on right. This photo is from EarthSky Facebook friend Sean Parker Photography. He captured it at Kitt Peak National Observatory in Arizona.

What is zodiacal light? People used to think zodiacal light originated somehow from phenomena in Earth’s upper atmosphere, but today we understand it as sunlight reflecting off dust grains that circle the sun in the inner solar system. These grains are thought to be left over from the process that created our Earth and the other planets of our solar system 4.5 billion years ago.

These dust grains in space spread out from the sun in the same flat disc of space inhabited by Mercury, Venus, Earth, Mars and the other planets in our sun’s family. This flat space around the sun – the plane of our solar system – translates on our sky to a narrow pathway called the ecliptic. This is the same pathway traveled by the sun and moon as they journey across our sky.

The pathway of the sun and moon was called the zodiac or Pathway of Animals by our ancestors in honor of the constellations seen beyond it. The word zodiacal stems from the word zodiac.

In other words, the zodiacal light is a solar system phenomenon. The grains of dust that create it are like tiny worlds – ranging from meter-sized to micron-sized – densest around the immediate vicinity of the sun and extending outward beyond the orbit of Mars. Sunlight shines on these grains of dust to create the light we see. Since they lie in the flat sheet of space around the sun, we could, in theory, see them as a band of dust across our entire sky, marking the same path that the sun follows during the day. And indeed there are sky phenomena associated with this band of dust, such as the gegenschein.

But seeing such elusive sky phenomena as the gegenschein is difficult. Most of us see only the more obvious part of this dust band – the zodiacal light – in either spring or fall.

The zodiacal light is the diffuse cone-shaped light extending up from the horizon on the right side of this photo. Photo by Richard Hasbrouck in Truchas, New Mexico.

The zodiacal light is easier to see as you get closer to Earth’s equator. But it can be glimpsed from northerly latitudes, too. Here’s the zodiacal light seen by EarthSky Facebook friend Jim Peacock on the evening of February 5, 2013, over Lake Superior in northern Wisconsin. Thank you, Jim!

Here’s the zodiacal light as captured on film in Canada. This wonderful capture is from Robert Ede in Invermere, British Columbia.

Zodiacal light on the morning of August 31, 2017, with Venus in its midst, captured at Mono Lake in California. Eric Barnett wrote: “I woke from sleeping in the car thinking sunrise was coming. My photographer friend, Paul Rutigliano, said it was the zodiacal light. I jumped up, got my camera into position and captured about a dozen or so shots.”

Bottom line: The zodiacal light – or false dawn – is a hazy pyramid of light, really sunlight reflecting off dust grains that move in the plane of our solar system. No matter where you are on Earth, look east before dawn in autumn, or west after evening twilight ends in spring.

from EarthSky https://ift.tt/1l3mMSs

View larger. | Lubomir Lenko Photography wrote from Brehov, Slovakia, on August 18, 2018: “The rise of Orion is back with the fine shine of zodiacal light.” Orion is in the lower right. See its Belt, the 3 stars in a short, straight row? The zodiacal light nearly fills the frame in this photo. Can you see that the light is pyramid-shaped?

If you’re in the Northern Hemisphere, it’s time to start looking for the zodiacal light – or false dawn – an eerie light in the east before sunrise, visible in clear dark skies in the months around the autumn equinox. If you’re in the Southern Hemisphere in late August, September or October, look in the west after sunset instead, for the same phenomenon, now called the false dusk.

The light looks like a hazy pyramid. It’s comparable in brightness to the Milky Way, but even milkier in appearance.

Talay Daniel Erol caught this image of the zodical light last year (2017) in late August – with the bright planet Venus in its midst – from Adrasan Antalya, Turkey.

How can I see the zodiacal light? Maybe you’ve seen the zodiacal light in the sky already and not realized it. Maybe you glimpsed it while driving on a highway or country road. This strange light is a seasonal phenomenon. Springtime and autumn are best for seeing it, no matter where you live on Earth.

Suppose you’re driving toward the east – in the hour before dawn – in autumn. You catch sight of what you think is the light of a nearby town, just over the horizon. But it might not be a town. It might be the zodiacal light. The light extends up from the eastern horizon, shortly before morning twilight begins. The zodiacal light can be extremely bright and easy to see from latitudes like those in the southern U.S.

We also sometimes hear from skywatchers in the northern U.S. or Canada who’ve captured images of the zodiacal light.

You’ll need a dark sky location to see the zodiacal light, someplace where city lights aren’t obscuring the natural lights in the sky.

The zodiacal light is most visible before dawn in autumn because autumn is when the ecliptic – or path of the sun and moon – stands nearly straight up with respect to your eastern horizon before dawn. Likewise, the zodiacal light is easiest to see just after true night falls in your springtime months, because then the ecliptic is most perpendicular to your western horizon in the evening. That’s true no matter where you are on Earth.

In autumn, the zodiacal light can be seen in the hour before true dawn begins. Or, in spring, it can be seen for up to an hour after all traces of evening twilight leave the sky. Unlike true dawn or dusk, though, there’s no rosy color to the zodiacal light. The reddish skies at dawn and dusk are caused by Earth’s atmosphere, while the zodiacal light originates far outside our atmosphere, as explained below.

The darker your sky, the better your chances of seeing it. Your best bet is to pick a night when the moon is out of the sky, although it’s definitely possible, and very lovely, to see a slim crescent moon in the midst of this strange milky pyramid of light.

If you see it, let us know! If you catch a photo, submit it here.

Zodiacal Light over the Faulkes Telescope, Haleakala, Maui. Photo via Rob Ratkowski.

Springtime? Autumn? When should I look? Is there a Northern/ Southern Hemisphere difference between the best time of year to view the zodiacal light? Yes and no. For both hemispheres, springtime is the best time to see the zodiacal light in the evening. Autumn is the best time to see it before dawn.

No matter where you live on Earth, look for the zodiacal light in the east before dawn around the time of your autumn equinox. Look for it in the west after sunset around the time of your spring equinox.

Of course, spring and autumn fall in different months for Earth’s Northern and Southern Hemispheres.

So if you’re in the Northern Hemisphere look for the zodiacal light before dawn from about late August through early November.

In those same months, if you’re in the Southern Hemisphere, look for the light in the evening.

Likewise, if you’re in the Northern Hemisphere, look for the evening zodiacal light from late February through early May. During those months, from the Southern Hemisphere, look for the light in the morning.

Milky Way on left in this photo. Zodiacal light on right. This photo is from EarthSky Facebook friend Sean Parker Photography. He captured it at Kitt Peak National Observatory in Arizona.

What is zodiacal light? People used to think zodiacal light originated somehow from phenomena in Earth’s upper atmosphere, but today we understand it as sunlight reflecting off dust grains that circle the sun in the inner solar system. These grains are thought to be left over from the process that created our Earth and the other planets of our solar system 4.5 billion years ago.

These dust grains in space spread out from the sun in the same flat disc of space inhabited by Mercury, Venus, Earth, Mars and the other planets in our sun’s family. This flat space around the sun – the plane of our solar system – translates on our sky to a narrow pathway called the ecliptic. This is the same pathway traveled by the sun and moon as they journey across our sky.

The pathway of the sun and moon was called the zodiac or Pathway of Animals by our ancestors in honor of the constellations seen beyond it. The word zodiacal stems from the word zodiac.

In other words, the zodiacal light is a solar system phenomenon. The grains of dust that create it are like tiny worlds – ranging from meter-sized to micron-sized – densest around the immediate vicinity of the sun and extending outward beyond the orbit of Mars. Sunlight shines on these grains of dust to create the light we see. Since they lie in the flat sheet of space around the sun, we could, in theory, see them as a band of dust across our entire sky, marking the same path that the sun follows during the day. And indeed there are sky phenomena associated with this band of dust, such as the gegenschein.

But seeing such elusive sky phenomena as the gegenschein is difficult. Most of us see only the more obvious part of this dust band – the zodiacal light – in either spring or fall.

The zodiacal light is the diffuse cone-shaped light extending up from the horizon on the right side of this photo. Photo by Richard Hasbrouck in Truchas, New Mexico.

The zodiacal light is easier to see as you get closer to Earth’s equator. But it can be glimpsed from northerly latitudes, too. Here’s the zodiacal light seen by EarthSky Facebook friend Jim Peacock on the evening of February 5, 2013, over Lake Superior in northern Wisconsin. Thank you, Jim!

Here’s the zodiacal light as captured on film in Canada. This wonderful capture is from Robert Ede in Invermere, British Columbia.

Zodiacal light on the morning of August 31, 2017, with Venus in its midst, captured at Mono Lake in California. Eric Barnett wrote: “I woke from sleeping in the car thinking sunrise was coming. My photographer friend, Paul Rutigliano, said it was the zodiacal light. I jumped up, got my camera into position and captured about a dozen or so shots.”

Bottom line: The zodiacal light – or false dawn – is a hazy pyramid of light, really sunlight reflecting off dust grains that move in the plane of our solar system. No matter where you are on Earth, look east before dawn in autumn, or west after evening twilight ends in spring.

from EarthSky https://ift.tt/1l3mMSs

How a volcano helped defeat Napoleon at Waterloo

By Caroline Brogan/Imperial College London

Historians know that rainy and muddy conditions helped the Allied army defeat the French Emperor Napoleon Bonaparte at the Battle of Waterloo. The June 1815 event changed the course of European history.

Two months prior, a volcano named Mount Tambora erupted on the Indonesian island of Sumbawa, killing 100,000 people and plunging the Earth into a “year without a summer” in 1816.

Now, Matthew Genge, from Imperial College London, discovered that electrified volcanic ash from eruptions can “short-circuit” the electrical current of the ionosphere – the upper level of the atmosphere that is responsible for cloud formation.

The findings, published August 21, 2018, in the peer-reviewed journal Geology, could confirm the suggested link between the eruption and Napoleon’s defeat.

Image via Imperial College London.

Genge, from Imperial’s Department of Earth Science and Engineering, suggests that the Tambora eruption short-circuited the ionosphere, ultimately leading to a pulse of cloud formation. This, he said, brought heavy rain across Europe that contributed to Napoleon Bonaparte’s defeat.

The paper suggests that eruptions can hurl ash much higher than previously thought into the atmosphere – up to 62 miles (100 km) above ground.

Genge said:

Previously, geologists thought that volcanic ash gets trapped in the lower atmosphere, because volcanic plumes rise buoyantly. My research, however, shows that ash can be shot into the upper atmosphere by electrical forces.

Levitating volcanic ash

A series of experiments showed that that electrostatic forces could lift ash far higher than by buoyancy alone. Dr. Genge created a model to calculate how far charged volcanic ash could levitate, and found that particles smaller than 0.2 millionths of a meter in diameter could reach the ionosphere during large eruptions. He said:

Volcanic plumes and ash both can have negative electrical charges and thus the plume repels the ash, propelling it high in the atmosphere. The effect works very much like the way two magnets are pushed away from each other if their poles match.

The experimental results are consistent with historical records from other eruptions.

Weather records are sparse for 1815, so to test his theory, Genge examined weather records following the 1883 eruption of another Indonesian volcano, Krakatau.

The data showed lower average temperatures and reduced rainfall almost immediately after the eruption began, and global rainfall was lower during the eruption than either period before or after.

Ionosphere disturbances and rare clouds

He also found reports of ionosphere disturbance after the 1991 eruption of Mount Pinatubo, Philippines, which could have been caused by charged ash in the ionosphere from the volcano plume.

In addition, a special cloud type appeared more frequently than usual following the Krakatau eruption. Noctilucent clouds are rare and luminous, and form in the ionosphere. Genge suggests these clouds therefore provide evidence for the electrostatic levitation of ash from large volcanic eruptions.

Genge said:

Victor Hugo in the novel Les Miserables said of the Battle of Waterloo: ‘an unseasonably clouded sky sufficed to bring about the collapse of a World.’ Now we are a step closer to understanding Tambora’s part in the Battle from half a world away.

Bottom line: Electrically charged volcanic ash short-circuited Earth’s atmosphere in 1815, causing global poor weather and Napoleon’s defeat, says new research.

from EarthSky https://ift.tt/2C4Mx6a

By Caroline Brogan/Imperial College London

Historians know that rainy and muddy conditions helped the Allied army defeat the French Emperor Napoleon Bonaparte at the Battle of Waterloo. The June 1815 event changed the course of European history.

Two months prior, a volcano named Mount Tambora erupted on the Indonesian island of Sumbawa, killing 100,000 people and plunging the Earth into a “year without a summer” in 1816.

Now, Matthew Genge, from Imperial College London, discovered that electrified volcanic ash from eruptions can “short-circuit” the electrical current of the ionosphere – the upper level of the atmosphere that is responsible for cloud formation.

The findings, published August 21, 2018, in the peer-reviewed journal Geology, could confirm the suggested link between the eruption and Napoleon’s defeat.

Image via Imperial College London.

Genge, from Imperial’s Department of Earth Science and Engineering, suggests that the Tambora eruption short-circuited the ionosphere, ultimately leading to a pulse of cloud formation. This, he said, brought heavy rain across Europe that contributed to Napoleon Bonaparte’s defeat.

The paper suggests that eruptions can hurl ash much higher than previously thought into the atmosphere – up to 62 miles (100 km) above ground.

Genge said:

Previously, geologists thought that volcanic ash gets trapped in the lower atmosphere, because volcanic plumes rise buoyantly. My research, however, shows that ash can be shot into the upper atmosphere by electrical forces.

Levitating volcanic ash

A series of experiments showed that that electrostatic forces could lift ash far higher than by buoyancy alone. Dr. Genge created a model to calculate how far charged volcanic ash could levitate, and found that particles smaller than 0.2 millionths of a meter in diameter could reach the ionosphere during large eruptions. He said:

Volcanic plumes and ash both can have negative electrical charges and thus the plume repels the ash, propelling it high in the atmosphere. The effect works very much like the way two magnets are pushed away from each other if their poles match.

The experimental results are consistent with historical records from other eruptions.

Weather records are sparse for 1815, so to test his theory, Genge examined weather records following the 1883 eruption of another Indonesian volcano, Krakatau.

The data showed lower average temperatures and reduced rainfall almost immediately after the eruption began, and global rainfall was lower during the eruption than either period before or after.

Ionosphere disturbances and rare clouds

He also found reports of ionosphere disturbance after the 1991 eruption of Mount Pinatubo, Philippines, which could have been caused by charged ash in the ionosphere from the volcano plume.

In addition, a special cloud type appeared more frequently than usual following the Krakatau eruption. Noctilucent clouds are rare and luminous, and form in the ionosphere. Genge suggests these clouds therefore provide evidence for the electrostatic levitation of ash from large volcanic eruptions.

Genge said:

Victor Hugo in the novel Les Miserables said of the Battle of Waterloo: ‘an unseasonably clouded sky sufficed to bring about the collapse of a World.’ Now we are a step closer to understanding Tambora’s part in the Battle from half a world away.

Bottom line: Electrically charged volcanic ash short-circuited Earth’s atmosphere in 1815, causing global poor weather and Napoleon’s defeat, says new research.

from EarthSky https://ift.tt/2C4Mx6a

Hybrid super-snakes in South Florida?

A Burmese python coiled in the grass in South Florida. Image via Bryan Falk, USGS.

Pythons are an invasive species in South Florida, originally brought there by humans. Since 2000, when wildlife experts realized that pythons have a sizable population in Florida, scientists have been trying to study these creatures, trying to understand how to control them. Scientists at the U.S. Geological Survey (USGS) reported on August 21, 2018, on a new genetic study showing that many of Florida’s pythons are closely related to one another. In fact, most of them are genetically related as first or second cousins. The study also found that at least a few of the snakes in the invasive South Florida population are not 100 percent Burmese pythons. Instead, the genetic evidence shows at least 13 snakes out of about 400 studied are a cross between two separate species: Burmese pythons, which mostly inhabit wetlands, and Indian pythons, which prefer higher ground.

Does this mean that an entirely new species – a super-snake, as many media outlets suggest – has emerged or is emerging in South Florida?

Margaret Hunter is lead author of the new study, published August 19 in the peer-reviewed journal Ecology and Evolution In a statement, she said the South Florida pythons:

… spring from a tangled family tree, with consequences for the species’ future spread that are hard to predict …

Sometimes interbreeding between related species can lead to hybrid vigor, that is, the best traits of two species are passed onto their offspring. Hybrid vigor can potentially lead to a better ability to adapt to environmental stressors and changes.

In an invasive population like the Burmese pythons in South Florida, this could result in a broader or more rapid distribution.

So … super-snakes? Or no? Hunter told The Guardian that her study does not indicate a new species of super-snake has been unleashed on the Everglades. But her study’s results do suggest a possible greater range of habitats for the wild snakes today. This greater range could hamper already unsuccessful efforts to reduce or eliminate the almost 150,000 pythons that have decimated native species – including bobcats, foxes, rabbits and raccoons from the Florida Keys to north of Lake Okeechobee.

Pythons have been reported in Everglades National Park since the 1980s. According to an article in Popular Science, the first pythons were likely escaped pets, and a few pythons may have been released when a breeding facility was destroyed during Hurricane Andrew.

In 2000, scientists realized that there was an established python population in the Everglades. Since then, the snakes have swept across southern Florida.

This 18-foot (5.5-meter) Burmese python captured and killed in the Everglades in 2014 is one of the largest pythons discovered there. Image via Daily Mail.

Here’s more from The Guardian:

Wildlife officials admit they are fighting a losing battle. Failed initiatives have included training dogs to sniff out the snakes and releasing pythons with radio transmitters to lead hunters to females carrying up to 100 eggs at a time.

Probably the most audacious effort came last year when two renowned snake catchers from India’s mountain-dwelling Irula tribe chanted their way across the Everglades for two months. They bagged 33 pythons. But that figure, like the 1,000-plus snakes killed to date in civilian hunting programs, is a drop in the ocean.

Burmese python in Everglades National Park. Image via R. Cammauf, National Park Service.

According to USGS, in the wild, related species typically avoid interbreeding by using different habitats. In their native Asia, Burmese pythons prefer wet habitats, while Indian pythons tend to stick to drier ones.

In previous studies, scientists have observed South Florida’s Burmese pythons in both wet and dry habitat types.

Scientists are not unhopeful, however. Kristen Hart, a USGS research ecologist and a co-author on the study commented:

Our ability to detect Burmese pythons in the Greater Everglades has been limited by their effective camouflage and secretive behavior. By using genetic tools and techniques and continuing to monitor their movement patterns, we have been able to gain a better understanding of their habitat preferences and resource use.

The new information in this study will help scientists and wildlife managers better understand these invasive predators’ capacity to adapt to new environments.

Read more from USGS.

Bottom line: Researchers from USGS report on a new genetic analysis of invasive pythons in South Florida.

Source: Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus)

from EarthSky https://ift.tt/2Pe375q

A Burmese python coiled in the grass in South Florida. Image via Bryan Falk, USGS.

Pythons are an invasive species in South Florida, originally brought there by humans. Since 2000, when wildlife experts realized that pythons have a sizable population in Florida, scientists have been trying to study these creatures, trying to understand how to control them. Scientists at the U.S. Geological Survey (USGS) reported on August 21, 2018, on a new genetic study showing that many of Florida’s pythons are closely related to one another. In fact, most of them are genetically related as first or second cousins. The study also found that at least a few of the snakes in the invasive South Florida population are not 100 percent Burmese pythons. Instead, the genetic evidence shows at least 13 snakes out of about 400 studied are a cross between two separate species: Burmese pythons, which mostly inhabit wetlands, and Indian pythons, which prefer higher ground.

Does this mean that an entirely new species – a super-snake, as many media outlets suggest – has emerged or is emerging in South Florida?

Margaret Hunter is lead author of the new study, published August 19 in the peer-reviewed journal Ecology and Evolution In a statement, she said the South Florida pythons:

… spring from a tangled family tree, with consequences for the species’ future spread that are hard to predict …

Sometimes interbreeding between related species can lead to hybrid vigor, that is, the best traits of two species are passed onto their offspring. Hybrid vigor can potentially lead to a better ability to adapt to environmental stressors and changes.

In an invasive population like the Burmese pythons in South Florida, this could result in a broader or more rapid distribution.

So … super-snakes? Or no? Hunter told The Guardian that her study does not indicate a new species of super-snake has been unleashed on the Everglades. But her study’s results do suggest a possible greater range of habitats for the wild snakes today. This greater range could hamper already unsuccessful efforts to reduce or eliminate the almost 150,000 pythons that have decimated native species – including bobcats, foxes, rabbits and raccoons from the Florida Keys to north of Lake Okeechobee.

Pythons have been reported in Everglades National Park since the 1980s. According to an article in Popular Science, the first pythons were likely escaped pets, and a few pythons may have been released when a breeding facility was destroyed during Hurricane Andrew.

In 2000, scientists realized that there was an established python population in the Everglades. Since then, the snakes have swept across southern Florida.

This 18-foot (5.5-meter) Burmese python captured and killed in the Everglades in 2014 is one of the largest pythons discovered there. Image via Daily Mail.

Here’s more from The Guardian:

Wildlife officials admit they are fighting a losing battle. Failed initiatives have included training dogs to sniff out the snakes and releasing pythons with radio transmitters to lead hunters to females carrying up to 100 eggs at a time.

Probably the most audacious effort came last year when two renowned snake catchers from India’s mountain-dwelling Irula tribe chanted their way across the Everglades for two months. They bagged 33 pythons. But that figure, like the 1,000-plus snakes killed to date in civilian hunting programs, is a drop in the ocean.

Burmese python in Everglades National Park. Image via R. Cammauf, National Park Service.

According to USGS, in the wild, related species typically avoid interbreeding by using different habitats. In their native Asia, Burmese pythons prefer wet habitats, while Indian pythons tend to stick to drier ones.

In previous studies, scientists have observed South Florida’s Burmese pythons in both wet and dry habitat types.

Scientists are not unhopeful, however. Kristen Hart, a USGS research ecologist and a co-author on the study commented:

Our ability to detect Burmese pythons in the Greater Everglades has been limited by their effective camouflage and secretive behavior. By using genetic tools and techniques and continuing to monitor their movement patterns, we have been able to gain a better understanding of their habitat preferences and resource use.

The new information in this study will help scientists and wildlife managers better understand these invasive predators’ capacity to adapt to new environments.

Read more from USGS.

Bottom line: Researchers from USGS report on a new genetic analysis of invasive pythons in South Florida.

Source: Cytonuclear discordance in the Florida Everglades invasive Burmese python (Python bivittatus) population reveals possible hybridization with the Indian python (P. molurus)

from EarthSky https://ift.tt/2Pe375q

Orion and Sirius the Dog Star

In late August and early September, look for a hint of the changing season in the predawn sky: Orion the Hunter and Sirius the Dog Star. The very noticeable constellation Orion the Hunter rises before dawn at this time of year, recognizable for the short straight line of three stars that make up Orion’s Belt. And the sky’s brightest star Sirius – sometimes called the Dog Star because it’s part of the constellation Canis Major the Greater Dog – follows Orion into the sky as the predawn darkness gives way to dawn.

Have you noticed a very bright, madly twinkling star in early morning sky? Many do – around the world – at this time of year. That star is Sirius. It’s so bright that, when it’s low in the sky, it shines with glints of red and flashes of blue – very noticeable!

Orion and the nearby star Sirius will become visible in the evening by northern winter (or southern summer). But presently the Hunter and the Dog Star lord over the sky at dawn’s first light.

EarthSky astronomy kits are perfect for beginners. Order yours from the EarthSky store.

Matthew Chin in Hong Kong caught this photo of the stars and constellations we in the Northern Hemisphere associated with winter – in late July, 2014. In late August – a full month later – all of these stars will have shifted higher in the east before sunrise. by December, they’ll be ascending in the east in the evening!

Orion was low in the west after sunset around March and April. By June of each year, this constellation lies behind the sun as seen from Earth. Orion only returned to visibility in Earth’s sky about a month ago (see image above). When a constellation becomes visible again, after being behind the sun, it always appears in the east before sunrise.

Because – as Earth orbits the sun – all the stars rise two hours earlier with each passing month, Orion is now higher at dawn than a month ago.

As seen from the Northern Hemisphere, Orion precedes Sirius the Dog Star into the sky. After Orion first appears at morning dawn, you can count on Sirius to appear in the morning sky a few weeks later. You should be able to see Sirius at or before dawn right now – unless you live at far northern latitudes.

But, even from Earth’s far north, you won’t have much longer to wait to see Sirius!

Be sure too notice the colors of Rigel and Betelgeuse in Orion, and of Sirius itself. When seen low in the sky on a summer morning, you might notice bright Sirius flashing in many colors! In fact – although Rigel and Betelgeuse are intrinsically colorful, due to the types of stars they are – Sirius shines mostly white. The colors we seen in Sirius when it’s low in the sky are the result of looking at this very bright star through a greater-than-usual thickness of Earth’s atmosphere in the direction toward the horizons. Image via Amanda Cross. Read more about this image.

Bottom line: A sign of the changing season, Sirius – the sky’s brightest star – is visible before sunup. You’ll know it’s Sirius if the very noticeable three stars in Orion’s Belt point to it.

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Help support EarthSky! Check out the EarthSky store for fun astronomy gifts and tools for all ages!

from EarthSky https://ift.tt/1IbuVvw

In late August and early September, look for a hint of the changing season in the predawn sky: Orion the Hunter and Sirius the Dog Star. The very noticeable constellation Orion the Hunter rises before dawn at this time of year, recognizable for the short straight line of three stars that make up Orion’s Belt. And the sky’s brightest star Sirius – sometimes called the Dog Star because it’s part of the constellation Canis Major the Greater Dog – follows Orion into the sky as the predawn darkness gives way to dawn.

Have you noticed a very bright, madly twinkling star in early morning sky? Many do – around the world – at this time of year. That star is Sirius. It’s so bright that, when it’s low in the sky, it shines with glints of red and flashes of blue – very noticeable!

Orion and the nearby star Sirius will become visible in the evening by northern winter (or southern summer). But presently the Hunter and the Dog Star lord over the sky at dawn’s first light.

EarthSky astronomy kits are perfect for beginners. Order yours from the EarthSky store.

Matthew Chin in Hong Kong caught this photo of the stars and constellations we in the Northern Hemisphere associated with winter – in late July, 2014. In late August – a full month later – all of these stars will have shifted higher in the east before sunrise. by December, they’ll be ascending in the east in the evening!

Orion was low in the west after sunset around March and April. By June of each year, this constellation lies behind the sun as seen from Earth. Orion only returned to visibility in Earth’s sky about a month ago (see image above). When a constellation becomes visible again, after being behind the sun, it always appears in the east before sunrise.

Because – as Earth orbits the sun – all the stars rise two hours earlier with each passing month, Orion is now higher at dawn than a month ago.

As seen from the Northern Hemisphere, Orion precedes Sirius the Dog Star into the sky. After Orion first appears at morning dawn, you can count on Sirius to appear in the morning sky a few weeks later. You should be able to see Sirius at or before dawn right now – unless you live at far northern latitudes.

But, even from Earth’s far north, you won’t have much longer to wait to see Sirius!

Be sure too notice the colors of Rigel and Betelgeuse in Orion, and of Sirius itself. When seen low in the sky on a summer morning, you might notice bright Sirius flashing in many colors! In fact – although Rigel and Betelgeuse are intrinsically colorful, due to the types of stars they are – Sirius shines mostly white. The colors we seen in Sirius when it’s low in the sky are the result of looking at this very bright star through a greater-than-usual thickness of Earth’s atmosphere in the direction toward the horizons. Image via Amanda Cross. Read more about this image.

Bottom line: A sign of the changing season, Sirius – the sky’s brightest star – is visible before sunup. You’ll know it’s Sirius if the very noticeable three stars in Orion’s Belt point to it.

Enjoying EarthSky so far? Sign up for our free daily newsletter today!

Help support EarthSky! Check out the EarthSky store for fun astronomy gifts and tools for all ages!

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nano-Saturn

It never hurts to promote one’s science through clever names – think cubane, buckminsterfullerene, bullvalene, etc. Host-guest chemistry is not immune to this cliché too, and this post discusses the latest synthesis and computations of a nano-Saturn; nano-Saturns are a spherical guest molecule captured inside a ring host molecule. I discussed an example of this a number of years ago – the nano-Saturn comprised of C₆₀ fullerene surrounded by [10]cycloparaphenylene.

Yamamoto, Tsurumaki, Wakamatsu, and Toyota have prepared a nano-Saturn complex with the goal of making a flatter ring component.¹ The inner planet is modeled again by C₆₀ and the ring is the [24]circulene analogue 1. The x-ray crystal structure of this nano-Saturn complex is shown in Figure 1.

1: R = 2,4,6-tri-iso-propylphenyl
2: R = H

Figure 1. X-ray crystal structure of the nano-Saturn complex of 1 with C₆₀.

Variable temperature NMR experiments gave the binding values of ΔH = -18.1 ± 2.3 kJ mol^-1 and TΔS = 0.8 ± 2.2 kJ mol^-1 at 298 K. To gauge this binding energy, they computed the complex of C₆₀ with the parent compound 2 at B3LYP/6-1G(d)//M05-2X/6-31G(d), unfortunately without publishing the coordinates in the supporting materials. The computed binding enthalpy is ΔH = -50.6 kJ mol^-1, but this computation is for the gas phase. The computed structure shows close contacts of 0.29 nm between the fullerene and the C₉-proton of the anthracenyl groups, in excellent agreement with the x-ray structure. These weak C-H^…π interactions undoubtedly help stabilize the complex, especially given that the fullerene carries a very tiny Mulliken charge of +0.08 e.

References

1) Yuta, Y.; Eiji, T.; Kan, W.; Shinji, T., "Nano-Saturn: Experimental Evidence of Complex Formation of an Anthracene Cyclic Ring with C60." Angew. Chem. Int. Ed. 2018, 57, 8199-8202, DOI: 10.1002/anie.201804430.

InChIs

1: InChI=1S/C174H180/c1-91(2)121-78-150(97(13)14)164(151(79-121)98(15)16)163-90-128-71-139-70-127-59-109(37-38-120(127)77-162(139)163)110-39-49-140-129(60-110)72-130-61-111(40-50-141(130)165(140)170-152(99(17)18)80-122(92(3)4)81-153(170)100(19)20)112-41-51-142-131(62-112)73-132-63-113(42-52-143(132)166(142)171-154(101(21)22)82-123(93(5)6)83-155(171)102(23)24)114-43-53-144-133(64-114)74-134-65-115(44-54-145(134)167(144)172-156(103(25)26)84-124(94(7)8)85-157(172)104(27)28)116-45-55-146-135(66-116)75-136-67-117(46-56-147(136)168(146)173-158(105(29)30)86-125(95(9)10)87-159(173)106(31)32)118-47-57-148-137(68-118)76-138-69-119(128)48-58-149(138)169(148)174-160(107(33)34)88-126(96(11)12)89-161(174)108(35)36/h37-108H,1-36H3
InChIKey=AMDNULXMAMDTMX-UHFFFAOYSA-N

2: InChI=1S/C84H48/c1-13-61-25-62-15-3-51-33-75(62)43-73(61)31-49(1)50-2-14-63-26-64-16-4-52(34-76(64)44-74(63)32-50)54-6-18-66-28-68-20-8-56(38-80(68)46-78(66)36-54)58-10-22-70-30-72-24-12-60(42-84(72)48-82(70)40-58)59-11-23-71-29-69-21-9-57(39-81(69)47-83(71)41-59)55-7-19-67-27-65-17-5-53(51)35-77(65)45-79(67)37-55/h1-48H
InChIKey=ZYXXLAYETADMDM-UHFFFAOYSA-N

from Computational Organic Chemistry https://ift.tt/2LBo1Jz

It never hurts to promote one’s science through clever names – think cubane, buckminsterfullerene, bullvalene, etc. Host-guest chemistry is not immune to this cliché too, and this post discusses the latest synthesis and computations of a nano-Saturn; nano-Saturns are a spherical guest molecule captured inside a ring host molecule. I discussed an example of this a number of years ago – the nano-Saturn comprised of C₆₀ fullerene surrounded by [10]cycloparaphenylene.

Yamamoto, Tsurumaki, Wakamatsu, and Toyota have prepared a nano-Saturn complex with the goal of making a flatter ring component.¹ The inner planet is modeled again by C₆₀ and the ring is the [24]circulene analogue 1. The x-ray crystal structure of this nano-Saturn complex is shown in Figure 1.

1: R = 2,4,6-tri-iso-propylphenyl
2: R = H

Figure 1. X-ray crystal structure of the nano-Saturn complex of 1 with C₆₀.

Variable temperature NMR experiments gave the binding values of ΔH = -18.1 ± 2.3 kJ mol^-1 and TΔS = 0.8 ± 2.2 kJ mol^-1 at 298 K. To gauge this binding energy, they computed the complex of C₆₀ with the parent compound 2 at B3LYP/6-1G(d)//M05-2X/6-31G(d), unfortunately without publishing the coordinates in the supporting materials. The computed binding enthalpy is ΔH = -50.6 kJ mol^-1, but this computation is for the gas phase. The computed structure shows close contacts of 0.29 nm between the fullerene and the C₉-proton of the anthracenyl groups, in excellent agreement with the x-ray structure. These weak C-H^…π interactions undoubtedly help stabilize the complex, especially given that the fullerene carries a very tiny Mulliken charge of +0.08 e.

References

1) Yuta, Y.; Eiji, T.; Kan, W.; Shinji, T., "Nano-Saturn: Experimental Evidence of Complex Formation of an Anthracene Cyclic Ring with C60." Angew. Chem. Int. Ed. 2018, 57, 8199-8202, DOI: 10.1002/anie.201804430.

InChIs

1: InChI=1S/C174H180/c1-91(2)121-78-150(97(13)14)164(151(79-121)98(15)16)163-90-128-71-139-70-127-59-109(37-38-120(127)77-162(139)163)110-39-49-140-129(60-110)72-130-61-111(40-50-141(130)165(140)170-152(99(17)18)80-122(92(3)4)81-153(170)100(19)20)112-41-51-142-131(62-112)73-132-63-113(42-52-143(132)166(142)171-154(101(21)22)82-123(93(5)6)83-155(171)102(23)24)114-43-53-144-133(64-114)74-134-65-115(44-54-145(134)167(144)172-156(103(25)26)84-124(94(7)8)85-157(172)104(27)28)116-45-55-146-135(66-116)75-136-67-117(46-56-147(136)168(146)173-158(105(29)30)86-125(95(9)10)87-159(173)106(31)32)118-47-57-148-137(68-118)76-138-69-119(128)48-58-149(138)169(148)174-160(107(33)34)88-126(96(11)12)89-161(174)108(35)36/h37-108H,1-36H3
InChIKey=AMDNULXMAMDTMX-UHFFFAOYSA-N

2: InChI=1S/C84H48/c1-13-61-25-62-15-3-51-33-75(62)43-73(61)31-49(1)50-2-14-63-26-64-16-4-52(34-76(64)44-74(63)32-50)54-6-18-66-28-68-20-8-56(38-80(68)46-78(66)36-54)58-10-22-70-30-72-24-12-60(42-84(72)48-82(70)40-58)59-11-23-71-29-69-21-9-57(39-81(69)47-83(71)41-59)55-7-19-67-27-65-17-5-53(51)35-77(65)45-79(67)37-55/h1-48H
InChIKey=ZYXXLAYETADMDM-UHFFFAOYSA-N

from Computational Organic Chemistry https://ift.tt/2LBo1Jz