Black holes are like a hologram

Who could forget this image? It’s the first direct image of a black hole, in the galaxy M87, released in April 2019. This long-sought image provided the strongest evidence to date for the existence of supermassive black holes and opened a new window onto the study of black holes, their event horizons, and gravity. Image via the Event Horizon Telescope Collaboration.

Reprinted from the International School of Advanced Studies (SISSA) in Trieste, Italy.

We all remember that incredible image of a black hole that traveled around the world about a year ago. Yet, according to new research by scientists in Italy, black holes could be like a hologram, where all the information is amassed in a two-dimensional surface able to reproduce a three-dimensional image. In this way, these cosmic bodies, as affirmed by quantum theories, could be incredibly complex and concentrate an enormous amount of information inside themselves, as the largest hard disk that exists in nature, in two dimensions. This idea aligns with Einstein’s theory of relativity, which describes black holes as three dimensional, simple, spherical, and smooth, as they appear in that famous image. In short, black holes “appear” as three dimensional, just like holograms. The study which demonstrates it, and which unites two discordant theories, has recently been published in Physical Review X.

The study comes from the SISSA, and from the International Centre for Theoretical Physics (ICTP) and the National Institute for Nuclear Physics (INFN), all based in Italy.

The mystery of black holes

For scientists, black holes are a big question mark for many reasons. They are, for example, excellent representatives of the great difficulties of theoretical physics in putting together the principles of Einstein’s general theory of relativity with those of quantum physics when it comes to gravity. According to the first theory, they would be simple bodies without information. According to the other, as claimed by Jacob Bekenstein and Stephen Hawking, they would be “the most complex existing systems” because they would be characterized by an enormous “entropy,” which measures the complexity of a system, and consequently would have a lot of information inside them.

The holographic principle applied to black holes

To study black holes, the two authors of the research, Francesco Benini (SISSA Professor, ICTP scientific consultant and INFN researcher) and Paolo Milan (SISSA and INFN researcher), used an idea almost 30 years old, but still surprising, called the holographic principle.

The researchers said:

This revolutionary and somewhat counterintuitive principle proposes that the behavior of gravity in a given region of space can alternatively be described in terms of a different system, which lives only along the edge of that region and therefore in a one less dimension.

And, more importantly, in this alternative description (called holographic) gravity does not appear explicitly. In other words, the holographic principle allows us to describe gravity using a language that does not contain gravity, thus avoiding friction with quantum mechanics.

What Benini and Milan have done is:

… apply the theory of the holographic principle to black holes. In this way, their mysterious thermodynamic properties have become more understandable: focusing on predicting that these bodies have a great entropy and observing them in terms of quantum mechanics, you can describe them just like a hologram: they have two dimensions, in which gravity disappears, but they reproduce an object in three dimensions.

From theory to observation

The two scientists explained:

This study is only the first step towards a deeper understanding of these cosmic bodies and of the properties that characterize them when quantum mechanics crosses with general relativity.

Everything is more important now at a time when observations in astrophysics are experiencing an incredible development. Just think of the observation of gravitational waves from the fusion of black holes result of the collaboration between LIGO and Virgo or, indeed, that of the black hole made by the Event Horizon Telescope that produced this extraordinary image.

In the near future, we may be able to test our theoretical predictions regarding quantum gravity, such as those made in this study, by observation. And this, from a scientific point of view, would be something absolutely exceptional.

Artist’s concept of a black hole via SISSA.

Bottom line: The theory of relativity describes black holes as being spherical, smooth and simple. Quantum theory describes them as being extremely complex and full of information. Two scientists in Italy have applied the theory of the holographic principle to black holes in a way that appears to resolve this duality.

Source: Black Holes in 4D N = 4 Super-Yang-Mills Field Theory

Via SISSA

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

Who could forget this image? It’s the first direct image of a black hole, in the galaxy M87, released in April 2019. This long-sought image provided the strongest evidence to date for the existence of supermassive black holes and opened a new window onto the study of black holes, their event horizons, and gravity. Image via the Event Horizon Telescope Collaboration.

Reprinted from the International School of Advanced Studies (SISSA) in Trieste, Italy.

We all remember that incredible image of a black hole that traveled around the world about a year ago. Yet, according to new research by scientists in Italy, black holes could be like a hologram, where all the information is amassed in a two-dimensional surface able to reproduce a three-dimensional image. In this way, these cosmic bodies, as affirmed by quantum theories, could be incredibly complex and concentrate an enormous amount of information inside themselves, as the largest hard disk that exists in nature, in two dimensions. This idea aligns with Einstein’s theory of relativity, which describes black holes as three dimensional, simple, spherical, and smooth, as they appear in that famous image. In short, black holes “appear” as three dimensional, just like holograms. The study which demonstrates it, and which unites two discordant theories, has recently been published in Physical Review X.

The study comes from the SISSA, and from the International Centre for Theoretical Physics (ICTP) and the National Institute for Nuclear Physics (INFN), all based in Italy.

The mystery of black holes

For scientists, black holes are a big question mark for many reasons. They are, for example, excellent representatives of the great difficulties of theoretical physics in putting together the principles of Einstein’s general theory of relativity with those of quantum physics when it comes to gravity. According to the first theory, they would be simple bodies without information. According to the other, as claimed by Jacob Bekenstein and Stephen Hawking, they would be “the most complex existing systems” because they would be characterized by an enormous “entropy,” which measures the complexity of a system, and consequently would have a lot of information inside them.

The holographic principle applied to black holes

To study black holes, the two authors of the research, Francesco Benini (SISSA Professor, ICTP scientific consultant and INFN researcher) and Paolo Milan (SISSA and INFN researcher), used an idea almost 30 years old, but still surprising, called the holographic principle.

The researchers said:

This revolutionary and somewhat counterintuitive principle proposes that the behavior of gravity in a given region of space can alternatively be described in terms of a different system, which lives only along the edge of that region and therefore in a one less dimension.

And, more importantly, in this alternative description (called holographic) gravity does not appear explicitly. In other words, the holographic principle allows us to describe gravity using a language that does not contain gravity, thus avoiding friction with quantum mechanics.

What Benini and Milan have done is:

… apply the theory of the holographic principle to black holes. In this way, their mysterious thermodynamic properties have become more understandable: focusing on predicting that these bodies have a great entropy and observing them in terms of quantum mechanics, you can describe them just like a hologram: they have two dimensions, in which gravity disappears, but they reproduce an object in three dimensions.

From theory to observation

The two scientists explained:

This study is only the first step towards a deeper understanding of these cosmic bodies and of the properties that characterize them when quantum mechanics crosses with general relativity.

Everything is more important now at a time when observations in astrophysics are experiencing an incredible development. Just think of the observation of gravitational waves from the fusion of black holes result of the collaboration between LIGO and Virgo or, indeed, that of the black hole made by the Event Horizon Telescope that produced this extraordinary image.

In the near future, we may be able to test our theoretical predictions regarding quantum gravity, such as those made in this study, by observation. And this, from a scientific point of view, would be something absolutely exceptional.

Artist’s concept of a black hole via SISSA.

Bottom line: The theory of relativity describes black holes as being spherical, smooth and simple. Quantum theory describes them as being extremely complex and full of information. Two scientists in Italy have applied the theory of the holographic principle to black holes in a way that appears to resolve this duality.

Source: Black Holes in 4D N = 4 Super-Yang-Mills Field Theory

Via SISSA

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

Scientist identify cleanest air on Earth

The Southern Ocean. Image via Spartan & the green egg

Researchers have identified Earth’s cleanest air – free of particles caused by our human activity – in a region in the Southern Ocean off the coast of Antartica.

Weather and climate are complex processes that connect each part of the world to every other region. A team of climate scientists from Colorado State University were curious to see just how far particles produced by human industry and activity reach. To find out, they sailed from Tasmania into the Southern Ocean – which encircles Antartica below 40 degrees south latitude – and measured the bioaerosol composition – the particles in the atmosphere – at several points.

Location of the Southern Ocean. Image via Brittanica.

They took measurements from the boundary layer, a part of the lower atmosphere that comes in direct contact with the ocean’s surface and reaches as high as 1.2 miles (1.9 km) into the atmosphere.

The study, published June 1, 2020, in Proceedings of the National Academy of Sciences, found the boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine, free from particles, called aerosols, connected to human pollution or other activity or transported from distant lands.

Aerosol filter samplers probe the air over the Southern Ocean on the Australian Marine National Facility’s R/V Investigator. Image via Kathryn Moore/ Colorado State University.

The researchers said that it’s difficult to find any area or process on Earth untouched by people. The scientists suspected the air directly over the remote Southern Ocean that encircles Antarctica would be least affected by humans and dust from continents. They set out to discover what was in the air and where it came from. Colorado State University research scientist Thomas Hill is a study coauthor. Hill said in a statement:

We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer key properties of the lower atmosphere. For example, that the aerosols controlling the properties of Southern Ocean clouds are strongly linked to ocean biological processes, and that Antarctica appears to be isolated from southward dispersal of microorganisms and nutrient deposition from southern continents. Overall, it suggests that the Southern Ocean is one of very few places on Earth that has been minimally affected by anthropogenic activities.

These results counter other studies from oceans in the subtropics and northern hemisphere, which found that most microbes came from upwind continents.

Bottom line: A new study suggests the cleanest air on Earth – free from pollution from human activities – is in a region of the Southern Ocean which surrounds Antarctica.

Source: Airborne bacteria confirm the pristine nature of the Southern Ocean boundary layer

Via Colorado State University

from EarthSky https://ift.tt/3eU90Sg

The Southern Ocean. Image via Spartan & the green egg

Researchers have identified Earth’s cleanest air – free of particles caused by our human activity – in a region in the Southern Ocean off the coast of Antartica.

Weather and climate are complex processes that connect each part of the world to every other region. A team of climate scientists from Colorado State University were curious to see just how far particles produced by human industry and activity reach. To find out, they sailed from Tasmania into the Southern Ocean – which encircles Antartica below 40 degrees south latitude – and measured the bioaerosol composition – the particles in the atmosphere – at several points.

Location of the Southern Ocean. Image via Brittanica.

They took measurements from the boundary layer, a part of the lower atmosphere that comes in direct contact with the ocean’s surface and reaches as high as 1.2 miles (1.9 km) into the atmosphere.

The study, published June 1, 2020, in Proceedings of the National Academy of Sciences, found the boundary layer air that feeds the lower clouds over the Southern Ocean to be pristine, free from particles, called aerosols, connected to human pollution or other activity or transported from distant lands.

Aerosol filter samplers probe the air over the Southern Ocean on the Australian Marine National Facility’s R/V Investigator. Image via Kathryn Moore/ Colorado State University.

The researchers said that it’s difficult to find any area or process on Earth untouched by people. The scientists suspected the air directly over the remote Southern Ocean that encircles Antarctica would be least affected by humans and dust from continents. They set out to discover what was in the air and where it came from. Colorado State University research scientist Thomas Hill is a study coauthor. Hill said in a statement:

We were able to use the bacteria in the air over the Southern Ocean as a diagnostic tool to infer key properties of the lower atmosphere. For example, that the aerosols controlling the properties of Southern Ocean clouds are strongly linked to ocean biological processes, and that Antarctica appears to be isolated from southward dispersal of microorganisms and nutrient deposition from southern continents. Overall, it suggests that the Southern Ocean is one of very few places on Earth that has been minimally affected by anthropogenic activities.

These results counter other studies from oceans in the subtropics and northern hemisphere, which found that most microbes came from upwind continents.

Bottom line: A new study suggests the cleanest air on Earth – free from pollution from human activities – is in a region of the Southern Ocean which surrounds Antarctica.

Source: Airborne bacteria confirm the pristine nature of the Southern Ocean boundary layer

Via Colorado State University

from EarthSky https://ift.tt/3eU90Sg

Despite the full moon, comet Lemmon!

June 4, 2020, capture of comet C/2019 U6 (Lemmon) via Terry Lovejoy of Australia.

As always, there are multiple comets in the sky now, but one to watch is comet C/2019 U6 (Lemmon), which will make its closest approach to the sun on June 18, 2020, and which is currently visible in binoculars from Southern Hemisphere locations at an apparent magnitude of about 7. The comet is moving northward and will enter northern skies soon. By some reports, this comet might become nearly visible to the unaided eye this month. Seeing it will require finder charts and a very dark sky. Still, we’re hearing good reports about this comet. Veteran comet hunter Terry Lovejoy wrote on Twitter on June 4:

Even with a full moon, Comet Lemmon looking good. 10x20sec with C14 Hyperstar + QHY183c.

Terry is an experienced observer and astrophotographer, with comets bearing his name, and he captured this image with a 14-inch telescope and CCD imaging. The comet is not visible to the eye. Still, it’s a nice comet, isn’t it? Check out that tail!

Comet C/2019 U6 (Lemmon) is currently in the constellation Canis Major the Greater Dog, which means it’s currently a Southern Hemisphere object, but it’ll move into northern skies later this month (see finder charts). Here’s some information about comet Lemmon from TheSkyLive.com:

The current Right Ascension of Comet C/2019 U6 (Lemmon) is 07h 28m 47s and the Declination is -18° 11’ 15” … The current estimated magnitude of Comet C/2019 U6 (Lemmon) is 11.46 (JPL) while the latest observed magnitude is 7.0 (COBS).

Bright comets are the ones that get all the attention. And yet, although most of us aren’t aware of it, there are multiple faint comets visible via the telescopes of astronomers at any given time. You’ll find a list of comets in the sky now via In-The-Sky.org.

Follow Terry Lovejoy on Twitter.

Or read about him on Wikipedia.

Bottom line: A beautiful CCD image of comet C/2019 U6 (Lemmon), taken June 4, 2020, by Terry Lovejoy.

from EarthSky https://ift.tt/3cCBcHy

June 4, 2020, capture of comet C/2019 U6 (Lemmon) via Terry Lovejoy of Australia.

As always, there are multiple comets in the sky now, but one to watch is comet C/2019 U6 (Lemmon), which will make its closest approach to the sun on June 18, 2020, and which is currently visible in binoculars from Southern Hemisphere locations at an apparent magnitude of about 7. The comet is moving northward and will enter northern skies soon. By some reports, this comet might become nearly visible to the unaided eye this month. Seeing it will require finder charts and a very dark sky. Still, we’re hearing good reports about this comet. Veteran comet hunter Terry Lovejoy wrote on Twitter on June 4:

Even with a full moon, Comet Lemmon looking good. 10x20sec with C14 Hyperstar + QHY183c.

Terry is an experienced observer and astrophotographer, with comets bearing his name, and he captured this image with a 14-inch telescope and CCD imaging. The comet is not visible to the eye. Still, it’s a nice comet, isn’t it? Check out that tail!

Comet C/2019 U6 (Lemmon) is currently in the constellation Canis Major the Greater Dog, which means it’s currently a Southern Hemisphere object, but it’ll move into northern skies later this month (see finder charts). Here’s some information about comet Lemmon from TheSkyLive.com:

The current Right Ascension of Comet C/2019 U6 (Lemmon) is 07h 28m 47s and the Declination is -18° 11’ 15” … The current estimated magnitude of Comet C/2019 U6 (Lemmon) is 11.46 (JPL) while the latest observed magnitude is 7.0 (COBS).

Bright comets are the ones that get all the attention. And yet, although most of us aren’t aware of it, there are multiple faint comets visible via the telescopes of astronomers at any given time. You’ll find a list of comets in the sky now via In-The-Sky.org.

Follow Terry Lovejoy on Twitter.

Or read about him on Wikipedia.

Bottom line: A beautiful CCD image of comet C/2019 U6 (Lemmon), taken June 4, 2020, by Terry Lovejoy.

from EarthSky https://ift.tt/3cCBcHy

Coronavirus and cancer – June updates

• 31 May – Shielding advice updated in England, Wales and Northern Ireland
• 29 May – UK nations begin to ease lockdown restrictions
• 28 May – UK nations launch test and trace systems 
• 27 April – NHS campaign urges people to get help if they need it
• 21 April – Urgent cancer referrals fall across the UK
• 21 March – Shielding measures introduced to protect people at high risk of COVID-19
• See previous coronavirus and cancer updates from May or March and April.

We’re monitoring the latest government and NHS health updates from across the UK and updating this blog post regularly as new guidance emerges.

2 June – Risk of death confirmed to be higher for Black, Asian and Minority Ethnic Groups

Public Health England (PHE) has published a report showing that the impact of COVID-19 mirrors existing health inequalities and has increased them in some cases. Although not yet fully understood why, the effect of coronavirus is disproportionate for Black, Asian and Minority Ethnic groups, who are at a greater risk of dying from COVID-19.

Age was another risk factor confirmed by the review, with figures suggesting that people aged 80 or over with coronavirus were seventy times more likely to die than those under the age of 40. The report also references several studies that indicate an increased risk of adverse outcomes in people who are obese or morbidly obese.

Health secretary Matt Hancock said that that he felt a “deep responsibility because this pandemic has exposed huge disparities in the health of our nation”, BBC News reports. Hancock also said the Equalities Minister will now take forward a review on this, working closely with PHE.

1 June – Over 2 million people waiting for cancer screening, tests and treatments

New figures have revealed the disruption to cancer services during the COVID-19 pandemic. Over 2 million people in the UK are waiting for cancer screening, tests and treatments since lockdown began, according to calculations by Cancer Research UK.

Visit our previous blog posts for coronavirus and cancer updates from May or March and April.

Katie 

If you have questions about cancer, you can talk to our nurses Monday to Friday, 9-5pm, on freephone 0808 800 4040.

from Cancer Research UK – Science blog https://ift.tt/2zR0owY

• 31 May – Shielding advice updated in England, Wales and Northern Ireland
• 29 May – UK nations begin to ease lockdown restrictions
• 28 May – UK nations launch test and trace systems 
• 27 April – NHS campaign urges people to get help if they need it
• 21 April – Urgent cancer referrals fall across the UK
• 21 March – Shielding measures introduced to protect people at high risk of COVID-19
• See previous coronavirus and cancer updates from May or March and April.

We’re monitoring the latest government and NHS health updates from across the UK and updating this blog post regularly as new guidance emerges.

2 June – Risk of death confirmed to be higher for Black, Asian and Minority Ethnic Groups

Public Health England (PHE) has published a report showing that the impact of COVID-19 mirrors existing health inequalities and has increased them in some cases. Although not yet fully understood why, the effect of coronavirus is disproportionate for Black, Asian and Minority Ethnic groups, who are at a greater risk of dying from COVID-19.

Age was another risk factor confirmed by the review, with figures suggesting that people aged 80 or over with coronavirus were seventy times more likely to die than those under the age of 40. The report also references several studies that indicate an increased risk of adverse outcomes in people who are obese or morbidly obese.

Health secretary Matt Hancock said that that he felt a “deep responsibility because this pandemic has exposed huge disparities in the health of our nation”, BBC News reports. Hancock also said the Equalities Minister will now take forward a review on this, working closely with PHE.

1 June – Over 2 million people waiting for cancer screening, tests and treatments

New figures have revealed the disruption to cancer services during the COVID-19 pandemic. Over 2 million people in the UK are waiting for cancer screening, tests and treatments since lockdown began, according to calculations by Cancer Research UK.

Visit our previous blog posts for coronavirus and cancer updates from May or March and April.

Katie 

If you have questions about cancer, you can talk to our nurses Monday to Friday, 9-5pm, on freephone 0808 800 4040.

from Cancer Research UK – Science blog https://ift.tt/2zR0owY

Did galactic crash trigger solar system formation?

The Sagittarius dwarf galaxy has been orbiting the Milky Way for billions for years. As its orbit around the 10,000 times more massive Milky Way gradually tightened, it started colliding with our galaxy’s disk. The three known collisions between Sagittarius and the Milky Way have, according to a new study, triggered major star formation episodes, one of which may have given rise to the solar system. Image via ESA.

Via European Space Agency (ESA)

The formation of the sun, the solar system and the subsequent emergence of life on Earth may be a consequence of a collision between our galaxy, the Milky Way, and a smaller galaxy called Sagittarius, discovered in the 1990s to be orbiting our galactic home. That’s according to a new study published May 25, 2020, in the peer-reviewed journal Nature Astronomy.

Astronomers have known that Sagittarius repeatedly smashes through the Milky Way’s disk, as its orbit around the galaxy’s core tightens as a result of gravitational forces. Previous studies suggested that Sagittarius, a so-called dwarf galaxy, had had a profound effect on how stars move in the Milky Way. Some astronomers even claim that the 10,000 times more massive Milky Way’s trademark spiral structure might be a result of the at least three known crashes with Sagittarius over the past six billion years.

The new study, based on data gathered by ESA’s galaxy mapping Gaia spacecraft, revealed for the first time that the influence of Sagittarius on the Milky Way may be even more substantial. The ripples caused by the collisions seem to have triggered major star formation episodes, one of which roughly coincided with the time of the formation of the sun some 4.7 billion years ago.

Astrophysicist Tomás Ruiz-Lara of the Instituto de Astrofísica de Canarias in Tenerife, Spain, is lead author of the study. He said in a statement:

It is known from existing models that Sagittarius fell into the Milky Way three times – first about five or six billion years ago, then about two billion years ago, and finally one billion years ago.

When we looked into the Gaia data about the Milky Way, we found three periods of increased star formation that peaked 5.7 billion years ago, 1.9 billion years ago and 1 billion years ago, corresponding with the time when Sagittarius is believed to have passed through the disk of the Milky Way.

The Sagittarius dwarf galaxy has been orbiting the Milky Way for billions for years. As its orbit around the 10,000 times more massive Milky Way gradually tightened, it started colliding with our galaxy’s disk. The 3 known collisions between Sagittarius and the Milky Way have, according to a new study, triggered major star formation episodes, one of which may have given rise to the solar system. Image via ESA.

Ripples on the water

The researchers looked at luminosities, distances and colors of stars within a sphere of about 6,500 light-years around the sun and compared the data with existing stellar evolution models. According to Ruiz-Lara, the notion that the dwarf galaxy may have had such an effect makes a lot of sense. He said:

At the beginning you have a galaxy, the Milky Way, which is relatively quiet. After an initial violent epoch of star formation, partly triggered by an earlier merger as we described in a previous study, the Milky Way had reached a balanced state in which stars were forming steadily. Suddenly, you have Sagittarius fall in and disrupt the equilibrium, causing all the previously still gas and dust inside the larger galaxy to slosh around like ripples on the water.

In some areas of the Milky Way, these ripples would lead to higher concentrations of dust and gas, while emptying others. The high density of material in those areas would then trigger the formation of new stars. Carme Gallart, also of the Instituto de Astrofísica de Canarias, is a co-author of the paper. Gallart said:

It seems that not only did Sagittarius shape the structure and influence the dynamics of how stars are moving in the Milky Way, it has also led to a build-up of the Milky Way. It seems that an important part of the Milky Way’s stellar mass was formed due to the interactions with Sagittarius and wouldn’t exist otherwise.

The birth of the sun

In fact, it seems possible that even the sun and its planets would not have existed if the Sagittarius dwarf had not gotten trapped by the gravitational pull of the Milky Way and eventually smashed through its disk. Gallart said:

The sun formed at the time when stars were forming in the Milky Way because of the first passage of Sagittarius. We don’t know if the particular cloud of gas and dust that turned into the sun collapsed because of the effects of Sagittarius or not. But it is a possible scenario because the age of the sun is consistent with a star formed as a result of the Sagittarius effect.

Every collision stripped Sagittarius of some of its gas and dust, leaving the galaxy smaller after each passage. Existing data suggest that Sagittarius might have passed through the Milky Way’s disk again quite recently, in the last few hundred million years, and is currently very close to it. In fact, the new study found evidence of a recent burst of star formation, suggesting a possible new and ongoing wave of stellar birth.

Bottom line: A new study suggests that the formation of the sun and the solar system may be a consequence of a collision between our Milky Way galaxy and a smaller galaxy called Sagittarius.

Source: The recurrent impact of the Sagittarius dwarf on the Milky Way star formation history

Read more from ESA

from EarthSky https://ift.tt/30e6kdQ

The Sagittarius dwarf galaxy has been orbiting the Milky Way for billions for years. As its orbit around the 10,000 times more massive Milky Way gradually tightened, it started colliding with our galaxy’s disk. The three known collisions between Sagittarius and the Milky Way have, according to a new study, triggered major star formation episodes, one of which may have given rise to the solar system. Image via ESA.

Via European Space Agency (ESA)

The formation of the sun, the solar system and the subsequent emergence of life on Earth may be a consequence of a collision between our galaxy, the Milky Way, and a smaller galaxy called Sagittarius, discovered in the 1990s to be orbiting our galactic home. That’s according to a new study published May 25, 2020, in the peer-reviewed journal Nature Astronomy.

Astronomers have known that Sagittarius repeatedly smashes through the Milky Way’s disk, as its orbit around the galaxy’s core tightens as a result of gravitational forces. Previous studies suggested that Sagittarius, a so-called dwarf galaxy, had had a profound effect on how stars move in the Milky Way. Some astronomers even claim that the 10,000 times more massive Milky Way’s trademark spiral structure might be a result of the at least three known crashes with Sagittarius over the past six billion years.

The new study, based on data gathered by ESA’s galaxy mapping Gaia spacecraft, revealed for the first time that the influence of Sagittarius on the Milky Way may be even more substantial. The ripples caused by the collisions seem to have triggered major star formation episodes, one of which roughly coincided with the time of the formation of the sun some 4.7 billion years ago.

Astrophysicist Tomás Ruiz-Lara of the Instituto de Astrofísica de Canarias in Tenerife, Spain, is lead author of the study. He said in a statement:

It is known from existing models that Sagittarius fell into the Milky Way three times – first about five or six billion years ago, then about two billion years ago, and finally one billion years ago.

When we looked into the Gaia data about the Milky Way, we found three periods of increased star formation that peaked 5.7 billion years ago, 1.9 billion years ago and 1 billion years ago, corresponding with the time when Sagittarius is believed to have passed through the disk of the Milky Way.

The Sagittarius dwarf galaxy has been orbiting the Milky Way for billions for years. As its orbit around the 10,000 times more massive Milky Way gradually tightened, it started colliding with our galaxy’s disk. The 3 known collisions between Sagittarius and the Milky Way have, according to a new study, triggered major star formation episodes, one of which may have given rise to the solar system. Image via ESA.

Ripples on the water

The researchers looked at luminosities, distances and colors of stars within a sphere of about 6,500 light-years around the sun and compared the data with existing stellar evolution models. According to Ruiz-Lara, the notion that the dwarf galaxy may have had such an effect makes a lot of sense. He said:

At the beginning you have a galaxy, the Milky Way, which is relatively quiet. After an initial violent epoch of star formation, partly triggered by an earlier merger as we described in a previous study, the Milky Way had reached a balanced state in which stars were forming steadily. Suddenly, you have Sagittarius fall in and disrupt the equilibrium, causing all the previously still gas and dust inside the larger galaxy to slosh around like ripples on the water.

In some areas of the Milky Way, these ripples would lead to higher concentrations of dust and gas, while emptying others. The high density of material in those areas would then trigger the formation of new stars. Carme Gallart, also of the Instituto de Astrofísica de Canarias, is a co-author of the paper. Gallart said:

It seems that not only did Sagittarius shape the structure and influence the dynamics of how stars are moving in the Milky Way, it has also led to a build-up of the Milky Way. It seems that an important part of the Milky Way’s stellar mass was formed due to the interactions with Sagittarius and wouldn’t exist otherwise.

The birth of the sun

In fact, it seems possible that even the sun and its planets would not have existed if the Sagittarius dwarf had not gotten trapped by the gravitational pull of the Milky Way and eventually smashed through its disk. Gallart said:

The sun formed at the time when stars were forming in the Milky Way because of the first passage of Sagittarius. We don’t know if the particular cloud of gas and dust that turned into the sun collapsed because of the effects of Sagittarius or not. But it is a possible scenario because the age of the sun is consistent with a star formed as a result of the Sagittarius effect.

Every collision stripped Sagittarius of some of its gas and dust, leaving the galaxy smaller after each passage. Existing data suggest that Sagittarius might have passed through the Milky Way’s disk again quite recently, in the last few hundred million years, and is currently very close to it. In fact, the new study found evidence of a recent burst of star formation, suggesting a possible new and ongoing wave of stellar birth.

Bottom line: A new study suggests that the formation of the sun and the solar system may be a consequence of a collision between our Milky Way galaxy and a smaller galaxy called Sagittarius.

Source: The recurrent impact of the Sagittarius dwarf on the Milky Way star formation history

Read more from ESA

from EarthSky https://ift.tt/30e6kdQ

Moves and countermoves: How the immune system responds to lung cancer’s ‘tactics’

At its very core – cancer is a disease caused by DNA errors.

Within tumour cell DNA, there are a multitude of mutations that guide growth and make it difficult for the body to repair or destroy the tumour. But this doesn’t stop the body’s immune system from trying.

This contest between the immune system and cancer is complex, and one that Cancer Research UK researchers on the TRACERx project have been working to unpick. Previously, they’ve shown how tumour cells evolve to adapt to the immune system “micro-environment” surrounding them. But the team knew that it wasn’t simply a one-way process.

The main role of the immune system is quite simple: protect the body from threats. This involves multiple different types of cells, including a type of white blood cell known as T cells.

The mutations seen in cancer cells are extremely useful for T cells, as these are the markers they use to identify the cells as being cancerous. As little cancers develop within the body, T cells patrol and destroy them before they become too developed. But as tumours develop they find new ways to evade the immune system and begin to pose more of an issue.

“The question was ‘if mutations are the hook that makes a T-cell interested in the cancer – how are the mutations shaping up T-cells in the tumour?” says Professor Sergio Quezada, an expert in cancer immunology at University College London.

Quezada and other TRACERx researchers knew that the longer that the immune system is exposed to non-small cell lung cancer, the less able T cells are to do their job. What they didn’t know was just how the various mutations found in cancer changed the T cells and got them to the point where they’re no longer able to fight.

But to understand how T cells reach this point, the team needed to rewind and look at how they started out.

Training the squad

Lining up again any threats to the body – including cancer – is a squad of immune cells

The backbone of any team are the young players who have yet to face an opposition. These are known as immature (or naïve) T cells and like any inexperienced squad, they need to be trained before they can be effective.

As some of these cells come into contact with the cancer, they recognise the opponent and start to change, in a process known as differentiation. Like the early matches in any player’s career, they’re an opportunity to learn more about their opponents’ strengths, weaknesses, and unique playing styles.

Quezada and his team were keen to see how this contest unfolded. To learn more, they used surgical samples from 31 people with untreated non small cell lung cancer (NSCLC) at different points of their cancer progression (between stage 1 – 3). By analysing the genetic material inside the tumour, they were able to create a snapshot of the state of play inside the tumours.

This snapshot allowed them to understand the composition of the squad at different points in time and build a “road map” of differentiation – a guide to the different checkpoints T cells go through in order to be able to attack the cancer cells.

Building a map

What they found was that the mutations within the cancer cells played a huge role in shaping the squad of immune cells. By recognising and responding to cancer mutations, a huge diversity of players began to develop.

But as the young squad trained up into experienced players (mature T cells), able to effectively go up against the cancer cells, the cancer cells responded with new tactics.

Over time, the immune cells begin to tire.

“The cancer puts up resistant firewalls and it makes it harder for those T cells that are differentiated to really destroy every single cancer cell. So then the T cells go into a further process of differentiation where they get tired, and they stop functioning.”

After being exposed to cancer cells for too long, older, ultra-mature T cells slowly become exhausted and are unable to continue competing. And while new recruits can provide new energy and help keep the immune system going, there’s only a finite number.

The downfall of some of the greatest teams has been a lack of new talent to replace retiring players and it’s no different for the immune system. Once the immune system has run out of fresh, immature cells, it loses the ability to effectively fight cancer.

“What we learnt is that there is a fitness state within the tumour microenvironment that allows you to put up a fight. If you’re not able to fully eliminate the tumour, you’re going to start losing then pool of younger progenitor like cells, and then that ends up in in death.”

Looking to the future

Though powerful, there are limitations with this technique. Like photos taken during a player’s career, they can show the level of maturity at any one time but they’re only snapshots. They aren’t able to capture the continuous details of the day-to-day changes.

“We know that this this transition into different stages of tissue differentiation slightly correlates with stage. The higher the stage of the patient’s cancer correlates with the amount of time that the T cells have been engaged with the tumour and that correlates with this differentiation pattern. What we cannot say for certain is that from A to B takes 6 months – we don’t have that type of data.”

Looking forward, TRACERx researchers are looking into ways that they can use the genetic data to analyse the age of the tumour cells and use that to roughly map the time it takes for this differentiation to occur. But what it’s starting to confirm to scientists is that when it comes to immune-boosting treatments – the earlier the better.

“The therapeutic message out of that is that we believe that this tells us that we need to intervene as early as possible with immunotherapies when we have a younger immune system within the tumour.”

Alex

Read more on the TRACERx project and how lung cancers adapt and evolve.

Reference

Ghorani, E., Reading, J.L., Henry, J.Y. et al. The T cell differentiation landscape is shaped by tumour mutations in lung cancer. Nat Cancer 1, 546–561 (2020). https://doi.org/10.1038/s43018-020-0066-y

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

At its very core – cancer is a disease caused by DNA errors.

Within tumour cell DNA, there are a multitude of mutations that guide growth and make it difficult for the body to repair or destroy the tumour. But this doesn’t stop the body’s immune system from trying.

This contest between the immune system and cancer is complex, and one that Cancer Research UK researchers on the TRACERx project have been working to unpick. Previously, they’ve shown how tumour cells evolve to adapt to the immune system “micro-environment” surrounding them. But the team knew that it wasn’t simply a one-way process.

The main role of the immune system is quite simple: protect the body from threats. This involves multiple different types of cells, including a type of white blood cell known as T cells.

The mutations seen in cancer cells are extremely useful for T cells, as these are the markers they use to identify the cells as being cancerous. As little cancers develop within the body, T cells patrol and destroy them before they become too developed. But as tumours develop they find new ways to evade the immune system and begin to pose more of an issue.

“The question was ‘if mutations are the hook that makes a T-cell interested in the cancer – how are the mutations shaping up T-cells in the tumour?” says Professor Sergio Quezada, an expert in cancer immunology at University College London.

Quezada and other TRACERx researchers knew that the longer that the immune system is exposed to non-small cell lung cancer, the less able T cells are to do their job. What they didn’t know was just how the various mutations found in cancer changed the T cells and got them to the point where they’re no longer able to fight.

But to understand how T cells reach this point, the team needed to rewind and look at how they started out.

Training the squad

Lining up again any threats to the body – including cancer – is a squad of immune cells

The backbone of any team are the young players who have yet to face an opposition. These are known as immature (or naïve) T cells and like any inexperienced squad, they need to be trained before they can be effective.

As some of these cells come into contact with the cancer, they recognise the opponent and start to change, in a process known as differentiation. Like the early matches in any player’s career, they’re an opportunity to learn more about their opponents’ strengths, weaknesses, and unique playing styles.

Quezada and his team were keen to see how this contest unfolded. To learn more, they used surgical samples from 31 people with untreated non small cell lung cancer (NSCLC) at different points of their cancer progression (between stage 1 – 3). By analysing the genetic material inside the tumour, they were able to create a snapshot of the state of play inside the tumours.

This snapshot allowed them to understand the composition of the squad at different points in time and build a “road map” of differentiation – a guide to the different checkpoints T cells go through in order to be able to attack the cancer cells.

Building a map

What they found was that the mutations within the cancer cells played a huge role in shaping the squad of immune cells. By recognising and responding to cancer mutations, a huge diversity of players began to develop.

But as the young squad trained up into experienced players (mature T cells), able to effectively go up against the cancer cells, the cancer cells responded with new tactics.

Over time, the immune cells begin to tire.

“The cancer puts up resistant firewalls and it makes it harder for those T cells that are differentiated to really destroy every single cancer cell. So then the T cells go into a further process of differentiation where they get tired, and they stop functioning.”

After being exposed to cancer cells for too long, older, ultra-mature T cells slowly become exhausted and are unable to continue competing. And while new recruits can provide new energy and help keep the immune system going, there’s only a finite number.

The downfall of some of the greatest teams has been a lack of new talent to replace retiring players and it’s no different for the immune system. Once the immune system has run out of fresh, immature cells, it loses the ability to effectively fight cancer.

“What we learnt is that there is a fitness state within the tumour microenvironment that allows you to put up a fight. If you’re not able to fully eliminate the tumour, you’re going to start losing then pool of younger progenitor like cells, and then that ends up in in death.”

Looking to the future

Though powerful, there are limitations with this technique. Like photos taken during a player’s career, they can show the level of maturity at any one time but they’re only snapshots. They aren’t able to capture the continuous details of the day-to-day changes.

“We know that this this transition into different stages of tissue differentiation slightly correlates with stage. The higher the stage of the patient’s cancer correlates with the amount of time that the T cells have been engaged with the tumour and that correlates with this differentiation pattern. What we cannot say for certain is that from A to B takes 6 months – we don’t have that type of data.”

Looking forward, TRACERx researchers are looking into ways that they can use the genetic data to analyse the age of the tumour cells and use that to roughly map the time it takes for this differentiation to occur. But what it’s starting to confirm to scientists is that when it comes to immune-boosting treatments – the earlier the better.

“The therapeutic message out of that is that we believe that this tells us that we need to intervene as early as possible with immunotherapies when we have a younger immune system within the tumour.”

Alex

Read more on the TRACERx project and how lung cancers adapt and evolve.

Reference

Ghorani, E., Reading, J.L., Henry, J.Y. et al. The T cell differentiation landscape is shaped by tumour mutations in lung cancer. Nat Cancer 1, 546–561 (2020). https://doi.org/10.1038/s43018-020-0066-y

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

Strawberry Moon, penumbral lunar eclipse, on June 5

On both June 4 and 5, 2020, the moon will look full to the eye as it shines from dusk until dawn. On both nights, the moon will be close to the red supergiant star Antares, brightest star in the constellation Scorpius the Scorpion. The crest of the moon’s full phase – when the moon and sun are most opposite each other on our sky’s dome for this month – happens on June 5, 2020, at 19:12 UTC: translate UTC to your time. For us in North America, that means the moon turns precisely full during the daylight hours on June 5, when the moon will be below our horizon. Yet the other side of the world – those who can see the moon in the sky around the time it turns precisely full – will have access to a lunar eclipse. It’s the most subtle kind of lunar eclipse, one that most people won’t even notice: a penumbral eclipse of the moon.

The part of the world shaded in pink on this map will have access to an exceedingly subtle penumbral eclopse of the moon on June 5, 2020. For more details on the eclipse, and to see this map animated, visit TimeandDate.com.

For more details on the June 5 eclipse, visit TimeandDate.com.

If this full moon were truly opposite the sun, there’d be a total umbral eclipse of the moon for the world’s Eastern Hemisphere. However this June full moon sweeps to the north of the Earth’s dark shadow, and therefore no total or partial lunar eclipse in the Earth’s dark shadow can take place.

Instead, the southern side of the full moon just clips the northern part of the Earth’s penumbral shadow, to stage the faint partial penumbral eclipse of the moon on June 5.

This eclipse will be so faint that most people won’t be able to tell the moon is being eclipsed, even as they are looking at it.

The moon moves from west to east across the Earth’s penumbral shadow. The south side of the moon dips into the far northern reaches of the Earth’s faint penumbral shadow. Greatest eclipse on June 5, 2020, at 19:25 UTC.

For us in North America, no eclipse takes place. All the action (such as it is) will be happening while the moon is below our horizon. We’ll just enjoy the full-looking moon on the nights of June 4 and 5.

We’ll call this June full moon the Strawberry Moon or Rose Moon.

At temperate latitudes in the Southern Hemisphere, where the impending June winter solstice is bringing about short days and long nights, this June full moon could be called the Long Night Moon.

The full moon acts as a mirror, reflecting the sun’s position in the sky for six months hence. Because the sun is so far south in December, tonight’s moon will follow the low path of the winter sun in the Northern Hemisphere, yet the high path of the summer sun in the Southern Hemisphere.

A bit north of the Arctic Circle, where the sun shines 24 hours around the clock, the June full moon won’t be visible at all; yet, a bit south of the Antarctic Circle, where there is no sun, the June full moon will mimic the midnight sun of summer.

Day and night sides of Earth at the instant of full moon (2020 June 5 at 19:12 UTC). To view the moon at the instant it turns full, you have to be on the nighttime side of the world, where the full moon is above your horizon. See the worldwide map above, showing the day and night sides of the world at the instant of the full moon (June 5, 2020, at 19:12 UTC). Worldwide map via EarthView.

Next month, the northern part of the full moon will clip the southern part of the Earth’s penumbral shadow to give the Earth’s Western Hemisphere its chance to view a nearly imperceptible penumbral eclipse on July 4-5, 2020.

Read more: Middle of eclipse season June 20

Bottom line: All of us around the world (except those in the far-northern Arctic) can look for the moon and red supergiant star Antares on the nights of June 4 and 5, 2020. On June 5, a penumbral eclipse will take place for much of the world except North and South America. However, it’ll be such a faint eclipse that most people won’t be able to perceive it’s happening, even as they are looking at it.

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

On both June 4 and 5, 2020, the moon will look full to the eye as it shines from dusk until dawn. On both nights, the moon will be close to the red supergiant star Antares, brightest star in the constellation Scorpius the Scorpion. The crest of the moon’s full phase – when the moon and sun are most opposite each other on our sky’s dome for this month – happens on June 5, 2020, at 19:12 UTC: translate UTC to your time. For us in North America, that means the moon turns precisely full during the daylight hours on June 5, when the moon will be below our horizon. Yet the other side of the world – those who can see the moon in the sky around the time it turns precisely full – will have access to a lunar eclipse. It’s the most subtle kind of lunar eclipse, one that most people won’t even notice: a penumbral eclipse of the moon.

The part of the world shaded in pink on this map will have access to an exceedingly subtle penumbral eclopse of the moon on June 5, 2020. For more details on the eclipse, and to see this map animated, visit TimeandDate.com.

For more details on the June 5 eclipse, visit TimeandDate.com.

If this full moon were truly opposite the sun, there’d be a total umbral eclipse of the moon for the world’s Eastern Hemisphere. However this June full moon sweeps to the north of the Earth’s dark shadow, and therefore no total or partial lunar eclipse in the Earth’s dark shadow can take place.

Instead, the southern side of the full moon just clips the northern part of the Earth’s penumbral shadow, to stage the faint partial penumbral eclipse of the moon on June 5.

This eclipse will be so faint that most people won’t be able to tell the moon is being eclipsed, even as they are looking at it.

The moon moves from west to east across the Earth’s penumbral shadow. The south side of the moon dips into the far northern reaches of the Earth’s faint penumbral shadow. Greatest eclipse on June 5, 2020, at 19:25 UTC.

For us in North America, no eclipse takes place. All the action (such as it is) will be happening while the moon is below our horizon. We’ll just enjoy the full-looking moon on the nights of June 4 and 5.

We’ll call this June full moon the Strawberry Moon or Rose Moon.

At temperate latitudes in the Southern Hemisphere, where the impending June winter solstice is bringing about short days and long nights, this June full moon could be called the Long Night Moon.

The full moon acts as a mirror, reflecting the sun’s position in the sky for six months hence. Because the sun is so far south in December, tonight’s moon will follow the low path of the winter sun in the Northern Hemisphere, yet the high path of the summer sun in the Southern Hemisphere.

A bit north of the Arctic Circle, where the sun shines 24 hours around the clock, the June full moon won’t be visible at all; yet, a bit south of the Antarctic Circle, where there is no sun, the June full moon will mimic the midnight sun of summer.

Day and night sides of Earth at the instant of full moon (2020 June 5 at 19:12 UTC). To view the moon at the instant it turns full, you have to be on the nighttime side of the world, where the full moon is above your horizon. See the worldwide map above, showing the day and night sides of the world at the instant of the full moon (June 5, 2020, at 19:12 UTC). Worldwide map via EarthView.

Next month, the northern part of the full moon will clip the southern part of the Earth’s penumbral shadow to give the Earth’s Western Hemisphere its chance to view a nearly imperceptible penumbral eclipse on July 4-5, 2020.

Read more: Middle of eclipse season June 20

Bottom line: All of us around the world (except those in the far-northern Arctic) can look for the moon and red supergiant star Antares on the nights of June 4 and 5, 2020. On June 5, a penumbral eclipse will take place for much of the world except North and South America. However, it’ll be such a faint eclipse that most people won’t be able to perceive it’s happening, even as they are looking at it.

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