How does a whole world of star and planets come into being? What happens during a star’s life, and what fate will its planets meet when it dies? Learn more from NASA, here.
How does a whole world of star and planets come into being? What happens during a star’s life, and what fate will its planets meet when it dies? Learn more from NASA, here.
Comet C/2018 Y1 (Iwamoto) is seen at the bottom of this beautiful image by Rolando Ligustri. Used with permission.
A new celestial visitor has been discovered by Japanese astronomer Masayuki Iwamoto. As of December 26, 2018, reports of observations of the comet were coming in from observatories around the world. It’s a fast-moving comet that will be closest to Earth by early February 2019. The celestial visitor will safely pass by Earth at some 15.5 million miles (25 million km), or about 64.8 lunar distances. The comet has been designated C/2018 Y1 (Iwamoto).
Closest pass by the sun will occur on January 25, 2019, and closest approach to Earth is expected to be on February 4-5. Preliminary estimates suggest the newly found comet might reach a brightness or magnitude between 6.7 and 7.5 , which means it should be easily seen with small telescopes and binoculars in a few weeks.
A closer look at the celestial visitor orbit. Image via NASA/JPL.
During closest approach to Earth, comet Iwamoto will be located in front of the constellation Leo the Lion, which is visible late at night at this time of year.
This comet is moving fast. As of Christmas Eve (December 24, 2018), comet Iwamoto was approaching Earth at 115,426 miles per hour (185,760 km/h) or 51.6 km per second.
Path of comet C/2018 Y1 (Iwamoto) late on the nights of February 1 to 6. This chart faces east around midnight. The comet should be visible in binoculars at this time. Observers using small telescopes in early February 2019 should be able to detect this fast-moving comet’s motion in front of the stars, within a timeframe of perhaps 10 minutes. Illustration by Eddie Irizarry using Stellarium.
A good late night for trying to spot comet Iwamoto with binoculars or a small telescope should be Saturday, February 2, 2019. This chart faces east around midnight, as seen from Central U.S. Observers at other locations should also look east around midnight. The comet will be at this same approximate location. Illustration by Eddie Irizarry using Stellarium.
The comet was detected in images taken on December 18, 2018.
We will keep you updated …
The orbit of comet C/2018 Y1 (Iwamoto) is very elliptical (elongated). Its orbit suggests this comet came from the Oort cloud of comets surrounding our solar system.
Bottom line: A new comet soon to be within reach of binoculars and small telescopes is heading toward a late January/early February 2019 encounter with the sun and Earth. It’ll pass Earth safely at an estimated 64.8 lunar distances on February 4-5.
from EarthSky http://bit.ly/2Sn8mSb
Comet C/2018 Y1 (Iwamoto) is seen at the bottom of this beautiful image by Rolando Ligustri. Used with permission.
A new celestial visitor has been discovered by Japanese astronomer Masayuki Iwamoto. As of December 26, 2018, reports of observations of the comet were coming in from observatories around the world. It’s a fast-moving comet that will be closest to Earth by early February 2019. The celestial visitor will safely pass by Earth at some 15.5 million miles (25 million km), or about 64.8 lunar distances. The comet has been designated C/2018 Y1 (Iwamoto).
Closest pass by the sun will occur on January 25, 2019, and closest approach to Earth is expected to be on February 4-5. Preliminary estimates suggest the newly found comet might reach a brightness or magnitude between 6.7 and 7.5 , which means it should be easily seen with small telescopes and binoculars in a few weeks.
A closer look at the celestial visitor orbit. Image via NASA/JPL.
During closest approach to Earth, comet Iwamoto will be located in front of the constellation Leo the Lion, which is visible late at night at this time of year.
This comet is moving fast. As of Christmas Eve (December 24, 2018), comet Iwamoto was approaching Earth at 115,426 miles per hour (185,760 km/h) or 51.6 km per second.
Path of comet C/2018 Y1 (Iwamoto) late on the nights of February 1 to 6. This chart faces east around midnight. The comet should be visible in binoculars at this time. Observers using small telescopes in early February 2019 should be able to detect this fast-moving comet’s motion in front of the stars, within a timeframe of perhaps 10 minutes. Illustration by Eddie Irizarry using Stellarium.
A good late night for trying to spot comet Iwamoto with binoculars or a small telescope should be Saturday, February 2, 2019. This chart faces east around midnight, as seen from Central U.S. Observers at other locations should also look east around midnight. The comet will be at this same approximate location. Illustration by Eddie Irizarry using Stellarium.
The comet was detected in images taken on December 18, 2018.
We will keep you updated …
The orbit of comet C/2018 Y1 (Iwamoto) is very elliptical (elongated). Its orbit suggests this comet came from the Oort cloud of comets surrounding our solar system.
Bottom line: A new comet soon to be within reach of binoculars and small telescopes is heading toward a late January/early February 2019 encounter with the sun and Earth. It’ll pass Earth safely at an estimated 64.8 lunar distances on February 4-5.
The Doctor used this time machine, called the TARDIS, to travel through space and time on the BBC television show Doctor Who. Image via Babbel1996/Wikimedia Commons.
The concept of time travel has always captured the imagination of physicists and laypersons alike. But is it really possible? Of course it is. We’re doing it right now, aren’t we? We are all traveling into the future one second at a time.
But that was not what you were thinking. Can we travel much further into the future? Absolutely. If we could travel close to the speed of light, or in the proximity of a black hole, time would slow down enabling us to travel arbitrarily far into the future. The really interesting question is whether we can travel back into the past.
I am a physics professor at the University of Massachusetts Dartmouth, and first heard about the notion of time travel when I was 7, from a 1980 episode of Carl Sagan’s classic TV series, Cosmos. I decided right then that someday, I was going to pursue a deep study of the theory that underlies such creative and remarkable ideas: Einstein’s relativity. Twenty years later, I emerged with a Ph.D. in the field and have been an active researcher in the theory ever since.
Now, one of my doctoral students has just published a paper in the journal Classical and Quantum Gravity that describes how to build a time machine using a very simple construction.
Closed time-like curves
Einstein’s general theory of relativity allows for the possibility of warping time to such a high degree that it actually folds upon itself, resulting in a time loop. Imagine you’re traveling along this loop; that means that at some point, you’d end up at a moment in the past and begin experiencing the same moments since, all over again – a bit like deja vu, except you wouldn’t realize it. Such constructs are often referred to as “closed time-like curves” or CTCs in the research literature, and popularly referred to as “time machines.” Time machines are a byproduct of effective faster-than-light travel schemes and understanding them can improve our understanding of how the universe works.
Here’s what scientists call a time loop. Green shows the short way through a wormhole. Red shows the long way through normal space. Since the travel time on the green path could be very small compared to the red, a wormhole can allow for the possibility of time travel. Image via Panzi/Wikimedia Commons.
Over the past few decades well-known physicists like Kip Thorne and Stephen Hawking produced seminal work on models related to time machines.
The general conclusion that has emerged from previous research, including Thorne’s and Hawking’s, is that nature forbids time loops. This is perhaps best explained in Hawking’s “Chronology Protection Conjecture,” which essentially says that nature doesn’t allow for changes to its past history, thus sparing us from the paradoxes that can emerge if time travel were possible.
Perhaps the most well-known amongst these paradoxes that emerge due to time travel into the past is the so-called “grandfather paradox” in which a traveler goes back into the past and murders his own grandfather. This alters the course of history in a way that a contradiction emerges: The traveler was never born and therefore cannot exist. There have been many movie and novel plots based on the paradoxes that result from time travel – perhaps some of the most popular ones being the Back to the Future movies and Groundhog Day.
Exotic matter
Depending on the details, different physical phenomena may intervene to prevent closed time-like curves from developing in physical systems. The most common is the requirement for a particular type of “exotic” matter that must be present in order for a time loop to exist. Loosely speaking, exotic matter is matter that has negative mass. The problem is negative mass is not known to exist in nature.
Caroline Mallary, a doctoral student at the University of Massachusetts Dartmouth has published a new model for a time machine in the journal Classical & Quantum Gravity. This new model does not require any negative mass exotic material and offers a very simple design.
Mallary’s model consists of two super long cars – built of material that is not exotic, and have positive mass – parked in parallel. One car moves forward rapidly, leaving the other parked. Mallary was able to show that in such a setup, a time loop can be found in the space between the cars.
An animation shows how Mallary’s time loop works. As the spacecraft enters the time loop, its future self appears as well, and one can trace back the positions of both at every moment afterwards. This animation is from the perspective of an external observer, who is watching the spacecraft enter and emerge from the time loop.
So can you build this in your backyard?
If you suspect there is a catch, you are correct. Mallary’s model requires that the center of each car has infinite density. That means they contain objects – called singularities – with an infinite density, temperature and pressure. Moreover, unlike singularities that are present in the interior of black holes, which makes them totally inaccessible from the outside, the singularities in Mallary’s model are completely bare and observable, and therefore have true physical effects.
Physicists don’t expect such peculiar objects to exist in nature either. So, unfortunately a time machine is not going to be available anytime soon. However, this work shows that physicists may have to refine their ideas about why closed time-like curves are forbidden.
Bottom line: A physicist explains why and how time travel is possible.
from EarthSky http://bit.ly/2EKQpJu
The Doctor used this time machine, called the TARDIS, to travel through space and time on the BBC television show Doctor Who. Image via Babbel1996/Wikimedia Commons.
The concept of time travel has always captured the imagination of physicists and laypersons alike. But is it really possible? Of course it is. We’re doing it right now, aren’t we? We are all traveling into the future one second at a time.
But that was not what you were thinking. Can we travel much further into the future? Absolutely. If we could travel close to the speed of light, or in the proximity of a black hole, time would slow down enabling us to travel arbitrarily far into the future. The really interesting question is whether we can travel back into the past.
I am a physics professor at the University of Massachusetts Dartmouth, and first heard about the notion of time travel when I was 7, from a 1980 episode of Carl Sagan’s classic TV series, Cosmos. I decided right then that someday, I was going to pursue a deep study of the theory that underlies such creative and remarkable ideas: Einstein’s relativity. Twenty years later, I emerged with a Ph.D. in the field and have been an active researcher in the theory ever since.
Now, one of my doctoral students has just published a paper in the journal Classical and Quantum Gravity that describes how to build a time machine using a very simple construction.
Closed time-like curves
Einstein’s general theory of relativity allows for the possibility of warping time to such a high degree that it actually folds upon itself, resulting in a time loop. Imagine you’re traveling along this loop; that means that at some point, you’d end up at a moment in the past and begin experiencing the same moments since, all over again – a bit like deja vu, except you wouldn’t realize it. Such constructs are often referred to as “closed time-like curves” or CTCs in the research literature, and popularly referred to as “time machines.” Time machines are a byproduct of effective faster-than-light travel schemes and understanding them can improve our understanding of how the universe works.
Here’s what scientists call a time loop. Green shows the short way through a wormhole. Red shows the long way through normal space. Since the travel time on the green path could be very small compared to the red, a wormhole can allow for the possibility of time travel. Image via Panzi/Wikimedia Commons.
Over the past few decades well-known physicists like Kip Thorne and Stephen Hawking produced seminal work on models related to time machines.
The general conclusion that has emerged from previous research, including Thorne’s and Hawking’s, is that nature forbids time loops. This is perhaps best explained in Hawking’s “Chronology Protection Conjecture,” which essentially says that nature doesn’t allow for changes to its past history, thus sparing us from the paradoxes that can emerge if time travel were possible.
Perhaps the most well-known amongst these paradoxes that emerge due to time travel into the past is the so-called “grandfather paradox” in which a traveler goes back into the past and murders his own grandfather. This alters the course of history in a way that a contradiction emerges: The traveler was never born and therefore cannot exist. There have been many movie and novel plots based on the paradoxes that result from time travel – perhaps some of the most popular ones being the Back to the Future movies and Groundhog Day.
Exotic matter
Depending on the details, different physical phenomena may intervene to prevent closed time-like curves from developing in physical systems. The most common is the requirement for a particular type of “exotic” matter that must be present in order for a time loop to exist. Loosely speaking, exotic matter is matter that has negative mass. The problem is negative mass is not known to exist in nature.
Caroline Mallary, a doctoral student at the University of Massachusetts Dartmouth has published a new model for a time machine in the journal Classical & Quantum Gravity. This new model does not require any negative mass exotic material and offers a very simple design.
Mallary’s model consists of two super long cars – built of material that is not exotic, and have positive mass – parked in parallel. One car moves forward rapidly, leaving the other parked. Mallary was able to show that in such a setup, a time loop can be found in the space between the cars.
An animation shows how Mallary’s time loop works. As the spacecraft enters the time loop, its future self appears as well, and one can trace back the positions of both at every moment afterwards. This animation is from the perspective of an external observer, who is watching the spacecraft enter and emerge from the time loop.
So can you build this in your backyard?
If you suspect there is a catch, you are correct. Mallary’s model requires that the center of each car has infinite density. That means they contain objects – called singularities – with an infinite density, temperature and pressure. Moreover, unlike singularities that are present in the interior of black holes, which makes them totally inaccessible from the outside, the singularities in Mallary’s model are completely bare and observable, and therefore have true physical effects.
Physicists don’t expect such peculiar objects to exist in nature either. So, unfortunately a time machine is not going to be available anytime soon. However, this work shows that physicists may have to refine their ideas about why closed time-like curves are forbidden.
The answer is now – late December and early January – but you’ll have to look for it at just the right place and time of night. Each year at this time, Hawaiians – or those at the latitude of Hawaii – can see the Southern Cross in the southern sky briefly before dawn. The Southern Cross, aka the constellation Crux, stands close to upright, but quite low in the sky for the latitude of Honolulu. Be sure to find an unobstructed southern horizon. Follow the links below to learn more about the Southern Cross.
From the latitude of Hawaii (see arrow), or farther south, you can see the Southern Cross before sunrise in late December and early January. Map via WorldAtlas.com.
How far south do I have to be to see the Southern Cross? Hawaii is at 21 degrees N. latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.
All of you at this latitude will be able to see the Southern Cross before dawn for at least another month.
Are you south of Hawaii’s latitude? Then you can see the Southern Cross, Rigel Kentaurus and Hadar all the higher in the sky before dawn now. From Australia or New Zealand – or South America or South Africa – Crux is circumpolar. That is, it circles around the sky’s southern pole and appears for most, if not all, of the night.
Rigel Kentaurus (aka Alpha Centauri), Hadar and the Southern Cross
Are there guide stars to the Southern Cross? Look at the photo at the top of this post, by Jv Noriega in the Philippines. Also look at the chart above. Notice the two stars, Rigel Kentaurus and Hadar, in the constellation Centaurus. Rigel Kentaurus is also known as Alpha Centauri, the star system nearest to Earth, at a little more than four light-years away.
Rigel Kentaurus (Alpha Centauri) and Hadar point to the Southern Cross.
This U.S. Naval Observatory page tells you the rise and set times for the Crux star Mimosa, and the stars Hadar and Rigel Kentaurus.
If you can see the constellation Cassiopeia in your northern sky, then the Southern Cross is below your horizon. Cassiopeia is shaped like the letter M or W.
How else can I know if the Southern Cross is visible in my sky? If you know a bit about the sky, then there is one surefire way to know if the Southern Cross is visible in your sky. When the easy-to-find constellation Cassiopeia the Queen is visible in your sky, the Southern Cross is below your horizon. So, for example, Cassiopeia lights up Hawaiian skies on winter evenings, but it sets beneath Hawaii’s northern horizon several hours before sunrise. As Cassiopeia sets, the Southern Cross rises.
Meanwhile, for latitudes north of Hawaii (for example, most of continental U.S. – except for southern Florida and Texas), Cassiopeia is circumpolar. It circles endlessly around the sky’s north pole and never sets. Therefore, the Southern Cross never rises as seen from northerly latitudes.
The Southern Cross marks the southern terminus of the glowing band of stars that we call the Milky Way – really the edgewise view into our own Milky Way galaxy. Meanwhile, Cassiopeia lodges at the Milky Way’s northern terminus in our sky.
Matthew Chin in Hong Kong caught Crux – aka the Southern Cross – on December 21, 2017.
Bottom line: Late December and early January are a good time for those at northerly latitudes – latitude of Hawaii or comparable latitudes – to look before dawn for the Southern Cross. It is visible briefly before dawn. Hawaii is at 21 degrees N. latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.
The answer is now – late December and early January – but you’ll have to look for it at just the right place and time of night. Each year at this time, Hawaiians – or those at the latitude of Hawaii – can see the Southern Cross in the southern sky briefly before dawn. The Southern Cross, aka the constellation Crux, stands close to upright, but quite low in the sky for the latitude of Honolulu. Be sure to find an unobstructed southern horizon. Follow the links below to learn more about the Southern Cross.
From the latitude of Hawaii (see arrow), or farther south, you can see the Southern Cross before sunrise in late December and early January. Map via WorldAtlas.com.
How far south do I have to be to see the Southern Cross? Hawaii is at 21 degrees N. latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.
All of you at this latitude will be able to see the Southern Cross before dawn for at least another month.
Are you south of Hawaii’s latitude? Then you can see the Southern Cross, Rigel Kentaurus and Hadar all the higher in the sky before dawn now. From Australia or New Zealand – or South America or South Africa – Crux is circumpolar. That is, it circles around the sky’s southern pole and appears for most, if not all, of the night.
Rigel Kentaurus (aka Alpha Centauri), Hadar and the Southern Cross
Are there guide stars to the Southern Cross? Look at the photo at the top of this post, by Jv Noriega in the Philippines. Also look at the chart above. Notice the two stars, Rigel Kentaurus and Hadar, in the constellation Centaurus. Rigel Kentaurus is also known as Alpha Centauri, the star system nearest to Earth, at a little more than four light-years away.
Rigel Kentaurus (Alpha Centauri) and Hadar point to the Southern Cross.
This U.S. Naval Observatory page tells you the rise and set times for the Crux star Mimosa, and the stars Hadar and Rigel Kentaurus.
If you can see the constellation Cassiopeia in your northern sky, then the Southern Cross is below your horizon. Cassiopeia is shaped like the letter M or W.
How else can I know if the Southern Cross is visible in my sky? If you know a bit about the sky, then there is one surefire way to know if the Southern Cross is visible in your sky. When the easy-to-find constellation Cassiopeia the Queen is visible in your sky, the Southern Cross is below your horizon. So, for example, Cassiopeia lights up Hawaiian skies on winter evenings, but it sets beneath Hawaii’s northern horizon several hours before sunrise. As Cassiopeia sets, the Southern Cross rises.
Meanwhile, for latitudes north of Hawaii (for example, most of continental U.S. – except for southern Florida and Texas), Cassiopeia is circumpolar. It circles endlessly around the sky’s north pole and never sets. Therefore, the Southern Cross never rises as seen from northerly latitudes.
The Southern Cross marks the southern terminus of the glowing band of stars that we call the Milky Way – really the edgewise view into our own Milky Way galaxy. Meanwhile, Cassiopeia lodges at the Milky Way’s northern terminus in our sky.
Matthew Chin in Hong Kong caught Crux – aka the Southern Cross – on December 21, 2017.
Bottom line: Late December and early January are a good time for those at northerly latitudes – latitude of Hawaii or comparable latitudes – to look before dawn for the Southern Cross. It is visible briefly before dawn. Hawaii is at 21 degrees N. latitude. Other cities at about this same latitude include Mecca in Saudi Arabia, Leon and Guanajuato in Mexico, and Hanoi in Vietnam.
These next two nights – December 25 and 26, 2018 – you might see the moon and Regulus, the Royal Star, coming up above your eastern horizon before your bedtime. If not, you can always get up before daybreak to view the waning gibbous moon and Regulus much higher up in the sky.
Want to know when the moon and Regulus rise into your sky? Then Click here for the moon’s rising time (remember to check the Moonrise and moonset box). An app such as Stellarium can help you find out the rising time for Regulus.
Regulus, the brightest star in the constellation Leo the Lion, is the only 1st-magnitude star to sit almost squarely on the ecliptic – the sun’s apparent annual path in front of the constellations of the zodiac. Of course, the sun’s apparent motion in front of the background stars is really a reflection of the Earth revolving around the sun.
Chart of the constellation Leo via the IAU. The ecliptic depicts the annual pathway of the sun in front of the constellations of the zodiac. The sun passes in front of the constellation Leo each year from around August 10 to September 17, and has its yearly conjunction with the star Regulus on or near August 23.
Regulus is considered to be the most important of the four Royal Stars of ancient Persia. Possibly, Regulus’ proximity with the ecliptic elevated this star’s status.
Four to five thousand years ago, the Royal Stars defined the approximate positions of equinoxes and solstices in the sky. Regulus reigned as the summer solstice star, Antares as the autumn equinox star, Fomalhaut as the winter solstice star, and Aldebaran as the spring equinox star. Regulus is often portrayed as the most significant Royal Star, possibly because it symbolized the height and glory of the summer solstice sun. Although the Royal Stars as seasonal signposts change over the long course of time, they still mark the four quadrants of the heavens.
An imaginary line drawn between the pointer stars in the Big Dipper – the 2 outer stars in the Dipper’s bowl – points in one direction toward Polaris, the North Star, and in the opposite direction toward Leo.
Regulus coincided with the summer solstice point some 4,300 years ago. In our time, the sun has its annual conjunction with Regulus on or near August 23, or about two months after the summer solstice – or alternatively, one month before the autumn equinox. Regulus will mark the autumn equinox point some 2,100 years in the future.
The constellation Leo, with the star Regulus at its heart, as depicted on a set of constellation cards published in London in about 1825. Image via Wikimedia Commons.
Bottom line: These next few nights, use the waning gibbous moon to locate Regulus, the Royal Star!
from EarthSky http://bit.ly/2QM7km9
These next two nights – December 25 and 26, 2018 – you might see the moon and Regulus, the Royal Star, coming up above your eastern horizon before your bedtime. If not, you can always get up before daybreak to view the waning gibbous moon and Regulus much higher up in the sky.
Want to know when the moon and Regulus rise into your sky? Then Click here for the moon’s rising time (remember to check the Moonrise and moonset box). An app such as Stellarium can help you find out the rising time for Regulus.
Regulus, the brightest star in the constellation Leo the Lion, is the only 1st-magnitude star to sit almost squarely on the ecliptic – the sun’s apparent annual path in front of the constellations of the zodiac. Of course, the sun’s apparent motion in front of the background stars is really a reflection of the Earth revolving around the sun.
Chart of the constellation Leo via the IAU. The ecliptic depicts the annual pathway of the sun in front of the constellations of the zodiac. The sun passes in front of the constellation Leo each year from around August 10 to September 17, and has its yearly conjunction with the star Regulus on or near August 23.
Regulus is considered to be the most important of the four Royal Stars of ancient Persia. Possibly, Regulus’ proximity with the ecliptic elevated this star’s status.
Four to five thousand years ago, the Royal Stars defined the approximate positions of equinoxes and solstices in the sky. Regulus reigned as the summer solstice star, Antares as the autumn equinox star, Fomalhaut as the winter solstice star, and Aldebaran as the spring equinox star. Regulus is often portrayed as the most significant Royal Star, possibly because it symbolized the height and glory of the summer solstice sun. Although the Royal Stars as seasonal signposts change over the long course of time, they still mark the four quadrants of the heavens.
An imaginary line drawn between the pointer stars in the Big Dipper – the 2 outer stars in the Dipper’s bowl – points in one direction toward Polaris, the North Star, and in the opposite direction toward Leo.
Regulus coincided with the summer solstice point some 4,300 years ago. In our time, the sun has its annual conjunction with Regulus on or near August 23, or about two months after the summer solstice – or alternatively, one month before the autumn equinox. Regulus will mark the autumn equinox point some 2,100 years in the future.
The constellation Leo, with the star Regulus at its heart, as depicted on a set of constellation cards published in London in about 1825. Image via Wikimedia Commons.
Bottom line: These next few nights, use the waning gibbous moon to locate Regulus, the Royal Star!
Simulation of galaxies and gas in the universe. Within the gas in the (blue) filaments connecting the (orange) galaxies lurk rare pockets of pristine gas – vestiges of the Big Bang that have somehow been orphaned from the explosive, polluting deaths of stars, seen here as circular shock waves around some orange points. Image via TNG COLLABORATION.
Astronomers using the powerful twin optical telescopes at the W. M. Keck Observatory on Maunakea, Hawaii, have used the light of a quasar to discover a relic cloud of gas in the distant universe. They’re calling it a “fossil” from our universe’s earliest time. How do they know it’s a young cloud? The cloud is made mainly of the elements born in the Big Bang, hydrogen and helium. It lacks the heavier elements that are born inside stars and released to the universe via supernova explosions. Astronomers Fred Robert and Michael Murphy at Swinburne University of Technology made the discovery. Robert commented in a statement:
Everywhere we look, the gas in the universe is polluted by waste heavy elements from exploding stars. But this particular cloud seems pristine, unpolluted by stars even 1.5 billion years after the Big Bang.
If it has any heavy elements at all, it must be less than 1/10,000th of the proportion we see in our sun. This is extremely low; the most compelling explanation is that it’s a true relic of the Big Bang.
Robert and Murphy’s results have been accepted for publication in the peer-reviewed journal Monthly Notices of the Royal Astronomical Society (preprint available here).
These astronomers used two of Keck Observatory’s instruments – the Echellette Spectrograph and Imager (ESI) and the High-Resolution Echelle Spectrometer (HIRES) – to observe the spectrum of a quasar behind the gas cloud. The quasar – labeled PSS1723+2243 – emits a bright glow from material falling into a supermassive black hole, providing a light source against which, these astronomers said:
… the spectral shadows of the hydrogen in the gas cloud can be seen.
Robert added:
We targeted quasars where previous researchers had only seen shadows from hydrogen and not from heavy elements in lower-quality spectra. This allowed us to discover such a rare fossil quickly with the precious time on Keck Observatory’s twin telescopes.
Only two other Big Bang fossils are known. These two clouds were discovered in 2011 by Michele Fumagalli of Durham University, John O’Meara, recently named the new Chief Scientist at Keck Observatory, and J. Xavier Prochaska of the University of California, Santa Cruz. Both Fumagalli and O’Meara are co-authors on the new research. O’Meara said:
The first two were serendipitous discoveries, and we thought they were the tip of the iceberg. But no one has discovered anything similar – they are clearly very rare and difficult to see. It’s fantastic to finally discover one systematically.
Murphy added:
It’s now possible to survey for these fossil relics of the Big Bang. That will tell us exactly how rare they are and help us understand how some gas formed stars and galaxies in the early universe, and why some didn’t.
Bottom line: Astronomers used the light of a distant quasar to discover a cloud made mainly of elements released in the Big Bang, lacking the heavier elements made inside stars. They’re calling this cloud a “fossil” of the Big Bang.
Simulation of galaxies and gas in the universe. Within the gas in the (blue) filaments connecting the (orange) galaxies lurk rare pockets of pristine gas – vestiges of the Big Bang that have somehow been orphaned from the explosive, polluting deaths of stars, seen here as circular shock waves around some orange points. Image via TNG COLLABORATION.
Astronomers using the powerful twin optical telescopes at the W. M. Keck Observatory on Maunakea, Hawaii, have used the light of a quasar to discover a relic cloud of gas in the distant universe. They’re calling it a “fossil” from our universe’s earliest time. How do they know it’s a young cloud? The cloud is made mainly of the elements born in the Big Bang, hydrogen and helium. It lacks the heavier elements that are born inside stars and released to the universe via supernova explosions. Astronomers Fred Robert and Michael Murphy at Swinburne University of Technology made the discovery. Robert commented in a statement:
Everywhere we look, the gas in the universe is polluted by waste heavy elements from exploding stars. But this particular cloud seems pristine, unpolluted by stars even 1.5 billion years after the Big Bang.
If it has any heavy elements at all, it must be less than 1/10,000th of the proportion we see in our sun. This is extremely low; the most compelling explanation is that it’s a true relic of the Big Bang.
Robert and Murphy’s results have been accepted for publication in the peer-reviewed journal Monthly Notices of the Royal Astronomical Society (preprint available here).
These astronomers used two of Keck Observatory’s instruments – the Echellette Spectrograph and Imager (ESI) and the High-Resolution Echelle Spectrometer (HIRES) – to observe the spectrum of a quasar behind the gas cloud. The quasar – labeled PSS1723+2243 – emits a bright glow from material falling into a supermassive black hole, providing a light source against which, these astronomers said:
… the spectral shadows of the hydrogen in the gas cloud can be seen.
Robert added:
We targeted quasars where previous researchers had only seen shadows from hydrogen and not from heavy elements in lower-quality spectra. This allowed us to discover such a rare fossil quickly with the precious time on Keck Observatory’s twin telescopes.
Only two other Big Bang fossils are known. These two clouds were discovered in 2011 by Michele Fumagalli of Durham University, John O’Meara, recently named the new Chief Scientist at Keck Observatory, and J. Xavier Prochaska of the University of California, Santa Cruz. Both Fumagalli and O’Meara are co-authors on the new research. O’Meara said:
The first two were serendipitous discoveries, and we thought they were the tip of the iceberg. But no one has discovered anything similar – they are clearly very rare and difficult to see. It’s fantastic to finally discover one systematically.
Murphy added:
It’s now possible to survey for these fossil relics of the Big Bang. That will tell us exactly how rare they are and help us understand how some gas formed stars and galaxies in the early universe, and why some didn’t.
Bottom line: Astronomers used the light of a distant quasar to discover a cloud made mainly of elements released in the Big Bang, lacking the heavier elements made inside stars. They’re calling this cloud a “fossil” of the Big Bang.
Artist’s concept of exoplanet GJ 3470b, located some 96 light-years away, orbiting a red dwarf star in the direction of our constellation Cancer the Crab. This world is gradually losing its atmosphere to space. It’s essentially “evaporating.” Image via NASA/ESA/D. Player (STScI).
How long can planets live? At least in part, the answer may depend on how far away a planet is from its star. In recent years, astronomers have begun finding a type of planet – which they call warm Neptunes – observed to be “evaporating” into space. The planet may be losing its atmosphere. Or the mass of the planet itself may be being lost. Basically, these planets are gradually shrinking and vanishing from existence. Two such worlds have been discovered so far.
According to David Sing, a Bloomberg Distinguished Professor at Johns Hopkins and an author on the new study:
This is the smoking gun that planets can lose a significant fraction of their entire mass. GJ 3470b is losing more of its mass than any other planet we seen so far; in only a few billion years from now, half of the planet may be gone.
The discovery was made as part of the Panchromatic Comparative Exoplanet Treasury (PanCET) program. The purpose of PanCET is to measure the atmospheres of 20 different exoplanets in ultraviolet, optical and infrared light, using the Hubble Space Telescope.
Other planets have also been observed losing their upper atmospheres, such as “hot Jupiters” and “super-Earths” that orbit very close to their stars. Since they are much hotter than planets farther away, their atmospheres can be blown off into space. They are also more common, at least among observed exoplanets, than Neptune-sized worlds.
Hubble found that GJ 3470b had lost significantly more mass and had a noticeably smaller exosphere than the first Neptune-sized exoplanet studied, GJ 436b. This is thought to be due to its lower density and the stronger radiation blast it receives from its host star. It is estimated that GJ 3470b may have already lost 35 percent of its original mass. A few billion years from now, all that may remain is a small rocky core. As Sing explained:
We’re starting to better understand how planets are shaped and what properties influence their overall makeup. Our goal with this study and the overarching PanCET program is to take a broad look at these planets’ atmospheres to determine how each planet is affected by its own environment. By comparing different planets, we can start piecing together the larger picture in how they evolve.
Also, the parent star of GJ 3470b is only 2 billion years old, compared to the 4-billion to 8-billion-year-old star that planet GJ 436b orbits. The younger star is more energetic, so it blasts the planet with more intense radiation than GJ 436b receives. Both are red dwarf stars, which are smaller and longer-lived than our own sun, and red dwarfs are known for being very active, with frequent bursts of solar flares.
Graphic depicting exoplanets based on their sizes and distances from their stars. There are relatively few Neptune-sized exoplanets that orbit close to their stars. GJ 3470b is near the border of that “hot Neptune desert.” Image via NASA/ESA/A. Feild (STScI).
It is a significant discovery, according to lead researcher Vincent Bourrier of the University of Geneva in Sauverny, Switzerland:
I think this is the first case where this is so dramatic in terms of planetary evolution. It’s one of the most extreme examples of a planet undergoing a major mass-loss over its lifetime. This sizable mass loss has major consequences for its evolution, and it impacts our understanding of the origin and fate of the population of exoplanets close to their stars.
These findings suggest that warm Neptunes may have started off as “hot Neptunes” – a transitory kind of planets which tend to shrink down over time to become mini-Neptunes. Those worlds are larger than Earth but smaller than Neptune, and have heavy, hydrogen-dominated atmospheres. They may then continue to shrink to become super-Earths – rocky like Earth but more massive. According to Bourrier:
The question has been, where have the hot Neptunes gone? If we plot planetary size and distance from the star, there’s a desert, a hole, in that distribution. That’s been a puzzle. We don’t really know how much the evaporation of the atmospheres played in forming this desert. But our Hubble observations, which show a large amount of mass loss from a warm Neptune at the edge of the desert, is a direct confirmation that atmospheric escape plays a major role in forming this desert.
While it is primarily hydrogen that is being lost to space, other trace gases may be as well, and researchers plan to use Hubble to search for those too, according to Bourrier:
We think that the hydrogen gas could be dragging heavy elements such as carbon, which reside deeper in the atmosphere, upward and out into space.
Artist’s concept of a super-Earth exoplanet. The new study supports the idea that hot Neptunes can gradually shrink to become mini-Neptunes and then super-Earths. Image via NASA/Ames/JPL-Caltech.
Astronomers want to observe other similar warm Neptunes, but unfortunately GJ 3470b and GJ 436b may be the only ones close enough. With current technology, hydrogen can’t be detected in warm Neptunes farther than 150 light-years away. Helium, however, can be detected at those distances – by both Hubble and the upcoming James Webb Space Telescope (JWST) – as noted by Bourrier:
Looking for helium could expand our survey range. Webb will have incredible sensitivity, so we would be able to detect helium escaping from smaller planets, such as mini-Neptunes.
As reported recently on EarthSky, astronomers did just discover that another exoplanet – HAT-P-11b – is losing its helium atmosphere to space in a similar manner and is “inflated like a helium balloon.” HAT-P-11b is just a little larger than Neptune, 124 light-years away.
Bottom line: Warm Neptunes may not be all that common, but the fact that two of them have now been found to be “evaporating” as their hydrogen atmospheres leak away into space provides valuable clues as to how they may evolve eventually into mini-Neptunes and super-Earths over billions of years.
Artist’s concept of exoplanet GJ 3470b, located some 96 light-years away, orbiting a red dwarf star in the direction of our constellation Cancer the Crab. This world is gradually losing its atmosphere to space. It’s essentially “evaporating.” Image via NASA/ESA/D. Player (STScI).
How long can planets live? At least in part, the answer may depend on how far away a planet is from its star. In recent years, astronomers have begun finding a type of planet – which they call warm Neptunes – observed to be “evaporating” into space. The planet may be losing its atmosphere. Or the mass of the planet itself may be being lost. Basically, these planets are gradually shrinking and vanishing from existence. Two such worlds have been discovered so far.
According to David Sing, a Bloomberg Distinguished Professor at Johns Hopkins and an author on the new study:
This is the smoking gun that planets can lose a significant fraction of their entire mass. GJ 3470b is losing more of its mass than any other planet we seen so far; in only a few billion years from now, half of the planet may be gone.
The discovery was made as part of the Panchromatic Comparative Exoplanet Treasury (PanCET) program. The purpose of PanCET is to measure the atmospheres of 20 different exoplanets in ultraviolet, optical and infrared light, using the Hubble Space Telescope.
Other planets have also been observed losing their upper atmospheres, such as “hot Jupiters” and “super-Earths” that orbit very close to their stars. Since they are much hotter than planets farther away, their atmospheres can be blown off into space. They are also more common, at least among observed exoplanets, than Neptune-sized worlds.
Hubble found that GJ 3470b had lost significantly more mass and had a noticeably smaller exosphere than the first Neptune-sized exoplanet studied, GJ 436b. This is thought to be due to its lower density and the stronger radiation blast it receives from its host star. It is estimated that GJ 3470b may have already lost 35 percent of its original mass. A few billion years from now, all that may remain is a small rocky core. As Sing explained:
We’re starting to better understand how planets are shaped and what properties influence their overall makeup. Our goal with this study and the overarching PanCET program is to take a broad look at these planets’ atmospheres to determine how each planet is affected by its own environment. By comparing different planets, we can start piecing together the larger picture in how they evolve.
Also, the parent star of GJ 3470b is only 2 billion years old, compared to the 4-billion to 8-billion-year-old star that planet GJ 436b orbits. The younger star is more energetic, so it blasts the planet with more intense radiation than GJ 436b receives. Both are red dwarf stars, which are smaller and longer-lived than our own sun, and red dwarfs are known for being very active, with frequent bursts of solar flares.
Graphic depicting exoplanets based on their sizes and distances from their stars. There are relatively few Neptune-sized exoplanets that orbit close to their stars. GJ 3470b is near the border of that “hot Neptune desert.” Image via NASA/ESA/A. Feild (STScI).
It is a significant discovery, according to lead researcher Vincent Bourrier of the University of Geneva in Sauverny, Switzerland:
I think this is the first case where this is so dramatic in terms of planetary evolution. It’s one of the most extreme examples of a planet undergoing a major mass-loss over its lifetime. This sizable mass loss has major consequences for its evolution, and it impacts our understanding of the origin and fate of the population of exoplanets close to their stars.
These findings suggest that warm Neptunes may have started off as “hot Neptunes” – a transitory kind of planets which tend to shrink down over time to become mini-Neptunes. Those worlds are larger than Earth but smaller than Neptune, and have heavy, hydrogen-dominated atmospheres. They may then continue to shrink to become super-Earths – rocky like Earth but more massive. According to Bourrier:
The question has been, where have the hot Neptunes gone? If we plot planetary size and distance from the star, there’s a desert, a hole, in that distribution. That’s been a puzzle. We don’t really know how much the evaporation of the atmospheres played in forming this desert. But our Hubble observations, which show a large amount of mass loss from a warm Neptune at the edge of the desert, is a direct confirmation that atmospheric escape plays a major role in forming this desert.
While it is primarily hydrogen that is being lost to space, other trace gases may be as well, and researchers plan to use Hubble to search for those too, according to Bourrier:
We think that the hydrogen gas could be dragging heavy elements such as carbon, which reside deeper in the atmosphere, upward and out into space.
Artist’s concept of a super-Earth exoplanet. The new study supports the idea that hot Neptunes can gradually shrink to become mini-Neptunes and then super-Earths. Image via NASA/Ames/JPL-Caltech.
Astronomers want to observe other similar warm Neptunes, but unfortunately GJ 3470b and GJ 436b may be the only ones close enough. With current technology, hydrogen can’t be detected in warm Neptunes farther than 150 light-years away. Helium, however, can be detected at those distances – by both Hubble and the upcoming James Webb Space Telescope (JWST) – as noted by Bourrier:
Looking for helium could expand our survey range. Webb will have incredible sensitivity, so we would be able to detect helium escaping from smaller planets, such as mini-Neptunes.
As reported recently on EarthSky, astronomers did just discover that another exoplanet – HAT-P-11b – is losing its helium atmosphere to space in a similar manner and is “inflated like a helium balloon.” HAT-P-11b is just a little larger than Neptune, 124 light-years away.
Bottom line: Warm Neptunes may not be all that common, but the fact that two of them have now been found to be “evaporating” as their hydrogen atmospheres leak away into space provides valuable clues as to how they may evolve eventually into mini-Neptunes and super-Earths over billions of years.
