A Japanese telescope has produced our most detailed radio wave image yet of the Milky Way galaxy. Over a 3-year time period, the Nobeyama 45 meter telescope observed the Milky Way for 1100 hours to produce the map. The image is part of a project called FUGIN (FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope.) The multi-institutional research group behind FUGIN explained the project in the Publications of the Astronomical Society of Japan and at arXiv.
The Nobeyama 45 meter telescope is located at the Nobeyama Radio Observatory, near Minamimaki, Japan. The telescope has been in operation there since 1982, and has made many contributions to millimeter-wave radio astronomy in its life. This map was made using the new FOREST receiver installed on the telescope.
When we look up at the Milky Way, an abundance of stars and gas and dust is visible. But there are also dark spots, which look like voids. But they’re not voids; they’re cold clouds of molecular gas that don’t emit visible light. To see what’s happening in these dark clouds requires radio telescopes like the Nobeyama.
The Nobeyama was the largest millimeter-wave radio telescope in the world when it began operation, and it has always had great resolution. But the new FOREST receiver has improved the telescope’s spatial resolution ten-fold. The increased power of the new receiver allowed astronomers to create this new map.
The new map covers an area of the night sky as wide as 520 full Moons. The detail of this new map will allow astronomers to study both large-scale and small-scale structures in new detail. FUGIN will provide new data on large structures like the spiral arms—and even the entire Milky Way itself—down to smaller structures like individual molecular cloud cores.
FUGIN is one of the legacy projects for the Nobeyama. These projects are designed to collect fundamental data for next-generation studies. To collect this data, FUGIN observed an area covering 130 square degrees, which is over 80% of the area between galactic latitudes -1 and +1 degrees and galactic longitudes from 10 to 50 degrees and from 198 to 236 degrees. Basically, the map tried to cover the 1st and 3rd quadrants of the galaxy, to capture the spiral arms, bar structure, and the molecular gas ring.
The aim of FUGIN is to investigate physical properties of diffuse and dense molecular gas in the galaxy. It does this by simultaneously gathering data on three carbon dioxide isotopes: 2CO, 13CO, and 18CO. Researchers were able to study the distribution and the motion of the gas, and also the physical characteristics like temperature and density. And the studying has already paid off.
FUGIN has already revealed things previously hidden. They include entangled filaments that weren’t obvious in previous surveys, as well as both wide-field and detailed structures of molecular clouds. Large scale kinematics of molecular gas such as spiral arms were also observed.
But the main purpose is to provide a rich data-set for future work by other telescopes. These include other radio telescopes like ALMA, but also telescopes operating in the infrared and other wavelengths. This will begin once the FUGIN data is released in June, 2018.
Millimeter wave radio astronomy is powerful because it can “see” things in space that other telescopes can’t. It’s especially useful for studying the large, cold gas clouds where stars form. These clouds are as cold as -262C (-440F.) At temperatures that low, optical scopes can’t see them, unless a bright star is shining behind them.
Even at these extremely low temperatures, there are chemical reactions occurring. This produces molecules like carbon monoxide, which was a focus of the FUGIN project, but also others like formaldehyde, ethyl alcohol, and methyl alcohol. These molecules emit radio waves in the millimeter range, which radio telescopes like the Nobeyama can detect.
The top-level purpose of the FUGIN project, according to the team behind the project, is to “provide crucial information about the transition from atomic gas to molecular gas, formation of molecular clouds and dense gas, interaction between star-forming regions and interstellar gas, and so on. We will also investigate the variation of physical properties and internal structures of molecular clouds in various environments, such as arm/interarm and bar, and evolutionary stage, for example, measured by star-forming activity.”
This new map from the Nobeyama holds a lot of promise. A rich data-set like this will be an important piece of the galactic puzzle for years to come. The details revealed in the map will help astronomers tease out more detail on the structures of gas clouds, how they interact with other structures, and how stars form from these clouds.
When is a Brown Dwarf star not a star at all, but only a mere Gas Giant? And when is a Gas Giant not a planet, but a celestial object more akin to a Brown Dwarf? These questions have bugged astronomers for years, and they go to the heart of a new definition for the large celestial bodies that populate solar systems.
An astronomer at Johns Hopkins University thinks he has a better way of classifying these objects, and it’s not based only on mass, but on the company the objects keep, and how the objects formed. In a paper published in the Astrophysical Journal, Kevin Schlaufman made his case for a new system of classification that could helps us all get past some of the arguments about which object is a gas giant planet or a brown dwarf. Mass is the easy-to-understand part of this new definition, but it’s not the only factor. How the object formed is also key.
Schlaufman is an assistant professor in the Johns Hopkins Department of Physics and Astronomy. He has set a limit for what we should call a planet, and that limit is between 4 and 10 times the mass of our Solar System’s biggest planet, Jupiter. Above that, you’ve got yourself a Brown Dwarf star. (Brown Dwarfs are also called sub-stellar objects, or failed stars, because they never grew massive enough to become stars.)
“An upper boundary on the masses of planets is one of the most prominent details that was missing.” – Kevin Schlaufman, Johns Hopkins University, Dept. of Physics and Astronomy.
Improvements in observing other solar systems have led to this new definition. Where previously we only had our own Solar System as reference, we now can observe other solar systems with increasing effectiveness. Schlaufman observed 146 solar systems, and that allowed him to fill in some of the blanks in our understanding of brown dwarf and planet formation.
“While we think we know how planets form in a big picture sense, there’s still a lot of detail we need to fill in,” Schlaufman said. “An upper boundary on the masses of planets is one of the most prominent details that was missing.”
Let’s back up a bit and look at how Brown Dwarfs and Gas Giants are related.
Solar systems are formed from clouds of gas and dust. In the early days of a solar system, one or more stars are formed out of this cloud by gravitational collapse. They ignite with fusion and become the stars we see everywhere in the Universe. The leftover gas and dust forms into planets, or brown dwarfs. This is a simplified version of solar system formation, but it serves our purposes.
In our own Solar System, only a single star formed: the Sun. The gas giants Jupiter and Saturn gobbled up most of the rest of the material. Jupiter gobbled up the lion’s share, making it the largest planet. But what if conditions had been different and Jupiter had kept growing? According to Schlaufman, if it had kept growing to over 10 times the size it is now, it would have become a brown dwarf. But that’s not where the new definition ends.
Metallicity and Chemical Makeup
Mass is only part of it. What’s really behind his new classification is the way in which the object formed. This involves the concept of metallicity in stars.
Stars have a metallicity content. In astrophysics, this means the fraction of a star’s mass that is not hydrogen or helium. So any element from lithium on down is considered a metal. These metals are what rocky planets form from. The early Universe had only hydrogen and helium, and almost insignificant amounts of the next two elements, lithium and beryllium. So the first stars had no metallicity, or almost none.
But now, 13.5 billion years after the Big Bang, younger stars like our Sun have more metal in them. That’s because generations of stars have lived and died, and created the metals taken up in subsequent star formation. Our own Sun was formed about 5 billion years ago, and it has the metallicity we expect from a star with its birthdate. It’s still overwhelmingly made of hydrogen and helium, but about 2% of its mass is made of other elements, mostly oxygen, carbon, neon, and iron.
This is where Schlaufman’s study comes in. According to him, we can distinguish between gas giants like Jupiter, and brown dwarfs, by the nature of the star they orbit. The types of planets that form around stars mirror the metallicity of the star itself. Gas giants like Jupiter are usually found orbiting stars with metallicity equal to or greater than our Sun. But brown dwarfs aren’t picky; they form around almost any star. Why?
Brown Dwarfs and Planets Form Differently
Planets like Jupiter are formed by accretion. A rocky core forms, then gas collects around it. Once the process is done, you have a gas giant. For this to happen, you need metals. If metals are present for these rocky cores to form, their presence will be reflected in the metallicity of the host star.
But brown dwarfs aren’t formed by accretion like planets are. They’re formed the same way stars are; by gravitational collapse. They don’t form from an initial rocky core, so metallicity isn’t a factor.
This brings us back to Kevin Schlaufman’s study. He wanted to find out the mass at which point an object doesn’t care about the metallicity of the star they orbit. He concluded that objects above 10 times the mass of Jupiter don’t care if the star has rocky elements, because they don’t form from rocky cores. Hence, they’re not planets akin to Jupiter; they’re brown dwarfs that formed by gravitational collapse.
What Does It Matter What We Call Them?
Let’s look at the Pluto controversy to understand why names are important.
The struggle to accurately classify all the objects we see out there in space is ongoing. Who can forget the plight of poor Pluto? In 2006, the International Astronomical Union (IAU) demoted Pluto, and stripped it of its long-standing status as a planet. Why?
Because the new definition of what a planet is relied on these three criteria:
a planet is in orbit around a star.
a planet must have sufficient mass to assume a hydrostatic equilibrium (a nearly round shape.)
a planet has cleared the neighbourhood around its orbit
The more we looked at Pluto with better telescopes, the more we realized that it did not meet the third criteria, so it was demoted to Dwarf Planet. Sorry Pluto.
Our naming conventions for astronomical objects are important, because they help people understand how everything fits together. But sometimes the debate over names can get tiresome. (The Pluto debate is starting to wear out its welcome, which is why some suggest we just call them all “worlds.”)
Though the Pluto debate is getting tiresome, it’s still important. We need some way of understanding what makes objects different, and names that reflect that difference. And the names have to reflect something fundamental about the objects in question. Should Pluto really be considered the same type of object as Jupiter? Are both really planets in the same sense? The IAU says no.
The same principle holds true with brown dwarfs and gas giants. Giving them names based solely on their mass doesn’t really tell us much. Schlaufman aims to change that.
His new definition makes sense because it relies on how and where these objects form, not simply their size. But not everyone will agree, of course.
There’s nothing an astronomer – whether professional or amateur – loves more than a clear dark night sky away from the city lights. Outside the glare and glow and cloud cover that most of us experience every day, the night sky comes alive with a life of its own.
Thousands upon countless thousands of glittering jewels – each individual star a pinprick of light set against the velvet-smooth blackness of the deeper void. The arching band of the Milky Way, itself host to billions more stars so far away that we can only see their combined light from our vantage point. The familiar constellations, proudly showing their true character, drawing the eye and the mind to the ancient tales spun about them.
There are few places left in the world to see the sky as our ancestors did; to gaze in wonder at the celestial dome and feel the weight of billions of years of cosmic history hanging above us. Thankfully the International Dark Sky Association is working to preserve what’s left of the true night sky, and they’ve rightfully marked northern Chile to preserve for posterity.
About 130 million years ago, in a galaxy far away, two neutron stars collided. The cataclysmic crash produced gravitational waves, ripples in the fabric of space and time. This event is now the 5th observation of gravitational waves by the Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo collaboration, and the first detected that was not caused by the collision of two black holes.
But this event — called a kilonova — produced something else too: light, across multiple wavelengths.
The most powerful space telescope ever built will have to wait on the ground for a few more months into 2019 before launching to the High Frontier and looking back nearly to the beginning of time and unraveling untold astronomical secrets on how the early Universe evolved – Engineers need a bit more time to complete the Webb telescopes incredibly complex assembly and testing here on Earth.
“NASA’s James Webb Space Telescope now is planning to launch between March and June 2019 from French Guiana, following a schedule assessment of the remaining integration and test activities,” the agency announced.
Until now the Webb telescope was scheduled to launch on a European Space Agency (ESA) Ariane V booster from the Guiana Space Center in Kourou, French Guiana in October 2018.
“The change in launch timing is not indicative of hardware or technical performance concerns,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at Headquarters in Washington, in a statement.
“Rather, the integration of the various spacecraft elements is taking longer than expected.”
NASA’s says the currently approved budget will not bust the budget or reduce the science output. It “accommodates the change in launch date, and the change will not affect planned science observations.”
NASA’s $8.8 Billion James Webb Space Telescope is the most powerful space telescope ever built and is the scientific successor to the phenomenally successful Hubble Space Telescope (HST).
The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).
Since Webb is not designed to be serviced by astronauts, the extremely thorny telescope deployment process is designed to occur on its own over a period of several months and must be fully successful. Webb will be positioned at the L2 Lagrange point- a gravitationally stable spot approximately 930,000 miles (1.5 million km) away from Earth.
So its better to be safe than sorry and take the extra time needed to insure success of the hugely expensive project.
Various completed components of the Webb telescope are undergoing final testing around the country to confirm their suitability for launch.
Critical cryogenic cooling testing of Webb’s mirrors and science instrument bus is proceeding well inside a giant chamber at NASA’s Johnson Space Center in Texas.
However integration and testing of the complex multilayered sunshield at Northrup Grumman’s Redondo Beach, Ca. facility is taking longer than expected and “has experienced delays.”
The tennis court sized sunshield will protect the delicate optics and state of the art infrared science instruments on NASA’s Webb Telescope.
Webb’s four research instruments cannot function without the essential cooling provided by the sunshield deployment to maintain them at an operating temperature of minus 388 degrees F (minus 233 degrees C).
The Webb telescopes groundbreaking sunshield subsystem consists of five layers of kapton that will keep the optics and instruments incredibly cool, by reducing the incoming sunside facing temperature more than 570 degrees Fahrenheit. Each layer is as thin as a human hair.
“Webb’s spacecraft and sunshield are larger and more complex than most spacecraft. The combination of some integration activities taking longer than initially planned, such as the installation of more than 100 sunshield membrane release devices, factoring in lessons learned from earlier testing, like longer time spans for vibration testing, has meant the integration and testing process is just taking longer,” said Eric Smith, program director for the James Webb Space Telescope at NASA Headquarters in Washington, in a statement.
“Considering the investment NASA has made, and the good performance to date, we want to proceed very systematically through these tests to be ready for a Spring 2019 launch.”
Northrop Grumman designed the Webb telescope’s optics and spacecraft bus for NASA’s Goddard Space Flight Center in Greenbelt, Maryland, which manages Webb.
Watch for Ken’s onsite space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Learn more about the upcoming ULA Atlas NRO NROL-52 spysat launch on Oct 5 and SpaceX Falcon 9 SES-11 launch on Oct 7, JWST, OSIRIS-REx, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
Oct 3-6, 8: “ULA Atlas NRO NROL-52 spysat launch, SpaceX SES-11, CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
SANTEE, SOUTH CAROLINA – Witnessing ‘Totality’ during Monday’s ‘Great American Solar Eclipse’ was a truly mesmerizing experience far beyond anything I imagined and something I will never forget -That’s a sentiment shared by millions upon millions of fellow gushing spectators.
I was stationed in Santee, South Carolina, near Lake Marion and close to the centerline of Totality, along with space journalist friend and colleague Jeff Seibert. And we could not have asked for clearer skies to enjoy this awesome natural event made possible by a uniquely rare confluence of miraculous celestial mechanics.
Check out our expanding gallery of personal photos and videos as well as many more gathered from friends and colleagues herein.
Totality was mesmerizing! Although I fully hoped to see a science spectacle (weather permitting) – I wasn’t really prepared for the majesty of the ‘coronal fire’ of Totality on display in the sky that started with what seemed like a startling electric flash – – The sun was alive far beyond anything I imagined beforehand. An out of body experience truly beyond my wildest dreams.
And we really lucked out with the weather – – as the odds of good weather are apparently better near Lake Marion, local residents told me. Just 15 miles south in Saint George, SC where I held a well attended eclipse outreach event at my hotel the night before, it was sadly socked in.
Despite a less than promising weather forecast, the threatening Carolina storm clouds obscuring our sun as we awoke and got our camera gear together Monday morning, fortunately scooted away.
Just in the nick of time the rainy gray breakfast clouds miraculously parted as eclipse time approached and almost completely disappeared by lunchtime – fully an hour prior to the eclipses beginning from our viewing location in Santee; near beautiful Lake Marion, South Carolina, which intersects the heavily traveled I-95 North/South Interstate highway corridor.
Like tens of millions of others, I’ve seen several partial solar eclipses, but this was my first total solar eclipse and it did not disappoint!
And there is just no comparison between seeing a partial and a total solar eclipse – sort of like a family before and after having a baby.
A few hundred excited people from across the East Coast including some families with kids had coincidentally gathered at our Santee location by the Water Park.
At Santee, SC, we enjoyed unobstructed totality for all 2 minutes, 34 seconds – very close to the longest possible duration of 2 min 43 seconds experienced by folks congregated in Carbondale, Illinois.
Overall our eclipse experience began at 1:14:55 p.m. EDT and concluded at 4:08:01 EDT – nearly three hours.
Totality started at 2:43:42 p.m. EDT and concluded at 2:46:16 p.m. EDT.
At lunchtime it was a boiling hot, skin stinging 95+ degrees F. But barely half an hour into the eclipse and with the sun perhaps only a third covered the area noticeably cooled and darkened and the sunburn was gone.
As the eclipse deepened, the sky really darkened to the point we almost needed a flashlight and it was downright comfortable temperature wise.
I’m over the Moon so to speak and still replaying the totality event in my mind from start to finish.
You can follow along by watching this thrilling solar eclipse video produced by Jeff Seibert, and listen to the cheering crowd to get a sense of our Carolina Totality adventure:
Video Caption: Total Solar eclipse from Santee, SC on August 21, 2017. We were 4.8 miles South of the Umbra center line, and had clear weather until just before last contact. Credit: Jeff Seibert
At Santee we were 87% into the umbra with a 70 mile wide (115 km) lunar shadow path width, at 136 feet elevation above sea level.
There is just nothing like ‘Totality’ in my experience as a research scientist and journalist – working with and seeing cool science and space hardware up close.
Totality is a natural wonder of the Universe and it was an electrifying event.
At the moment that totality commenced, day turned almost instantly to night as though someone threw a light switch.
I distinctly heard crackling sounds burst through the air, akin to a thunderbolt clap at that very moment – heralding our sudden jolt to totality.
Cheers broke out. Everyone and myself were so totally in awe of totality. And the sun’s brilliant while corona suddenly became visible, alive and in motion as the solar surface was completely blocked, hidden behind our moon. So I just stared at the stunning beauty, barely able to function as a photographer.
The planet Venus quickly and suddenly and incredibly popped out brilliantly from the darkness of the daytime sky. Some stars were also visible.
You absolutely must experience this incomparable wonder of nature with you own eyeballs.
Focus on the fleeting moment.
Because in a flash of just 2.5 minutes #Eclipse2017 was gone & done!
The all natural light switch had been turned back on by mother nature herself.
If only a replay or restart were possible – someone in the crowd yelled in glee. And we all thought the same way.
Totality, like rockets and science can be addictive in a very positive way.
Furthermore, we also saw the famed partial solar crescents reflecting through trees onto the ground during the partial eclipse phases.
We very luckily enjoyed virtually perfect weather and clear blue skies for the entirely of the eclipse – from first contact, through totality and the last limb of contact of Earth’s moon covering the sun.
Only a few scattered cloud patches dotted overhead at the start and rapidly exited.
And very happily we were not alone.
The Aug. 21 ‘Total Solar ‘Eclipse Across America’ was enjoyed by tens of millions more lucky spectators, including many friends lining the solar eclipses narrow path of Totality from coast to coast.
The 70-mile-wide (115 km) swath of the Moons shadow raced across America from Oregon to South Carolina in a thrilling event that became sort of a communal experience with all the explanatory news coverage foreshadowing what was to come.
Everyone in North America was able to witness at least a partial solar eclipse, weather permitting- and many did either on there own or at special solar eclipse events organized at towns and cities at museums, parks and open spaces across the country.
12 million people live directly in the path of 2017 solar eclipse totality as it passed through 14 states.
It was the first total solar eclipse visible from the United States since Feb. 26, 1979. And it was the first such coast to coast eclipse crossing the entire continental United States in 99 years since June 8, 1918 during World War 1.
The umbra (or dark inner shadow) of the Moon moved west to east at 3000 MPH in Oregon and 1500 MPH by the time it reached our location in South Carolina.
The 2017 solar eclipse began on the west coast with the lunar shadow entering the US near Lincoln City, Oregon at 9:05 PDT, with totality beginning at 10:15 PDT, according to a NASA description.
Totality ended along the US East Coast in the coastal city of Charleston, South Carolina at 2:48 p.m. EDT. The last remnants of lunar shadow departed at 4:09 p.m. EDT. Charleston is about an hour or so east of my viewing location in Santee and folks there enjoyed stunning views too.
For as long as I live the 2017 Solar Eclipse Totality will be burned into my mind!
“I’m pretty sure it was not nearly as epic as the total eclipse. It was fun to watch with teenagers though. I think what was unique to me was that I was capturing the equivalent of a crescent sun. Did it get dark here, of course not, but there were a few minutes where the Space Coast went a bit dim. The most fun was looking for the shadows,” writes Julia Bergeron from Port Canaveral, FL.
Watch for Ken’s continuing onsite Minotaur IV ORS-5, TDRS-M, CRS-12 and NASA and space mission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.
Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.
Learn more about the 2017 Total Solar Eclipse, upcoming Minotaur IV ORS-5 military launch on Aug. 25, recent ULA Atlas TDRS-M NASA comsat on Aug. 18, 2017 , SpaceX Dragon CRS-12 resupply launch to ISS on Aug. 14, NASA missions and more at Ken’s upcoming outreach events at Kennedy Space Center Quality Inn, Titusville, FL:
Aug 24-26: “2017 Total Solar Eclipse Minotaur IV ORS-5, TDRS-M NASA comsat, SpaceX CRS-12 resupply launches to the ISS, Intelsat35e, BulgariaSat 1 and NRO Spysat, SLS, Orion, Commercial crew capsules from Boeing and SpaceX , Heroes and Legends at KSCVC, ULA Atlas/John Glenn Cygnus launch to ISS, SBIRS GEO 3 launch, GOES-R weather satellite launch, OSIRIS-Rex, Juno at Jupiter, InSight Mars lander, SpaceX and Orbital ATK cargo missions to the ISS, ULA Delta 4 Heavy spy satellite, Curiosity and Opportunity explore Mars, Pluto and more,” Kennedy Space Center Quality Inn, Titusville, FL, evenings
“Astonished at the vivacity and brightness of the corona, and the contrast with the infinitely dark moon. Through binos it almost had me in tears,” writes John Gould from Red Bank, SC.
A third gravitational wave has been detected by the Laser Interferometer Gravitational-wave Observatory (LIGO). An international team announced the detection today, while the event itself was detected on January 4th, 2017. Gravitational waves are ripples in space-time predicted by Albert Einstein over a century ago.
LIGO consists of two facilities: one in Hanford, Washington and one in Livingston, Louisiana. When LIGO announced its first gravitational wave back in February 2016 (detected in September 2015), it opened up a new window into astronomy. With this gravitational wave, the third one detected, that new window is getting larger. So far, all three waves detected have been created by the merging of black holes.
When the first gravitational wave was finally detected, over a hundred years after Einstein predicted it, it helped confirm Einstein’s description of space-time as an integrated continuum. It’s often said that it’s not a good idea to bet against Einstein, and this third detection just strengthens Einstein’s theory.
Like the previous two detections, this one was created by the merging of two black holes. These two were different sizes from each other; one was about 31.2 solar masses, and the other was about 19.4 solar masses. The combined 50 solar mass event caused the third wave, which is named GW170104. The black holes were about 3 billion light years away.
LIGO is showing us that their is a population of binary black holes out there. “Our handful of detections so far is revealing an intriguing black hole population we did not know existed until now,” said Northwestern’s Vicky Kalogera, a senior astrophysicist with the LIGO Scientific Collaboration (LSC), which conducts research related to the twin LIGO detectors, located in the U.S.
“Now we have three pairs of black holes, each pair ending their death spiral dance over millions or billions of years in some of the most powerful explosions in the universe. In astronomy, we say with three objects of the same type you have a class. We have a population, and we can do analysis.”
When we say that gravitational waves have opened up a new window on astronomy, that window opens onto black holes themselves. Beyond confirming Einstein’s predictions, and establishing a population of binary black holes, LIGO can characterize and measure those black holes. We can learn the holes’ masses and their spin characteristics.
“Once again, the black holes are heavy,“ said Shane Larson, of Northwestern University and Adler Planetarium in Chicago. “The first black holes LIGO detected were twice as heavy as we ever would have expected. Now we’ve all been churning our cranks trying to figure out all the interesting myriad ways we can imagine the universe making big and heavy black holes. And Northwestern is strong in this research area, so we are excited.”
This third finding strengthens the case for the existence of a new class of black holes: binary black holes that are locked in relationship with each other. It also shows that these objects can be larger than thought before LIGO detected them.
“It is remarkable that humans can put together a story and test it, for such strange and extreme events that took place billions of years ago and billions of light-years distant from us.” – David Shoemaker, MIT
“We have further confirmation of the existence of black holes that are heavier than 20 solar masses, objects we didn’t know existed before LIGO detected them,” said David Shoemaker of MIT, spokesperson for the LIGO Scientific Collaboration . “It is remarkable that humans can put together a story and test it, for such strange and extreme events that took place billions of years ago and billions of light-years distant from us.”
“With the third confirmed detection of gravitational waves from the collision of two black holes, LIGO is establishing itself as a powerful observatory for revealing the dark side of the universe,” said David Reitze of Caltech, executive director of the LIGO Laboratory and a Northwestern alumnus. “While LIGO is uniquely suited to observing these types of events, we hope to see other types of astrophysical events soon, such as the violent collision of two neutron stars.”
A tell-tale chirping sound confirms the detection of a gravitational wave, and you can hear it described and explained here, on a Northwestern University podcast.
At the center of our Milky Way galaxy dwells a behemoth. An object so massive that nothing can escape its gravitational pull, not even light. In fact, we think most galaxies have one of them. They are, of course, supermassive black holes.
Supermassive black holes are stars that have collapsed into a singularity. Einstein’s General Theory of Relativity predicted their existence. And these black holes are surrounded by what’s known as an event horizon, which is kind of like the point of no return for anything getting too close to the black hole. But nobody has actually proven the existence of the event horizon yet.
Some theorists think that something else might lie at the center of galaxies, a supermassive object event stranger than a supermassive black hole. Theorists think these objects have somehow avoided a black hole’s fate, and have not collapsed into a singularity. They would have no event horizon, and would have a solid surface instead.
“Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not,” – Pawan Kumar Professor of Astrophysics, University of Texas at Austin.
A team of researchers at the University of Texas at Austin and Harvard University have tackled the problem. Wenbin Lu, Pawan Kumar, and Ramesh Narayan wanted to shed some light onto the event horizon problem. They wondered about the solid surface object, and what would happen when an object like a star collided with it. They published their results in the Monthly Notices of the Royal Astronomical Society.
“Our whole point here is to turn this idea of an event horizon into an experimental science, and find out if event horizons really do exist or not,” said Pawan Kumar, Professor of Astrophysics at The University of Texas at Austin, in a press release.
Since a black hole is a star collapsed into a singularity, it has no surface area, and instead has an event horizon. But if the other theory turns out to be true, and the object has a solid surface instead of an event horizon, then any object colliding with it would be destroyed. If a star was to collide with this hard surface and be destroyed, the team surmised, then the gas from the star would enshroud the object and shine brightly for months, or even years.
If that were the case, then the team knew what to look for. They also worked out how often this would happen.
“We estimated the rate of stars falling onto supermassive black holes,” Lu said in the same press release. “Nearly every galaxy has one. We only considered the most massive ones, which weigh about 100 million solar masses or more. There are about a million of them within a few billion light-years of Earth.”
Now they needed a way to search the sky for these objects, and they found it in the archives of the Pan-STARRS telescope. Pan-STARRS is a 1.8 meter telescope in Hawaii. That telescope recently completed a survey of half of the northern hemisphere of the sky. In that survey, Pan-STAARS spent 3.5 years looking for transient objects in the sky, objects that brighten and then fade. They searched the Pan-STARR archives for transient objects that had the signature they predicted from stars colliding with these supermassive, hard-surfaced objects.
The trio predicted that in the 3.5 year time-frame captured by the Pan-STAARS survey, 10 of these collisions would occur and should be represented in the data.
“It turns out it should have detected more than 10 of them, if the hard-surface theory is true.” – Wenbin Lu, Dept. of Astronomy, University of Texas at Austin.
“Given the rate of stars falling onto black holes and the number density of black holes in the nearby universe, we calculated how many such transients Pan-STARRS should have detected over a period of operation of 3.5 years. It turns out it should have detected more than 10 of them, if the hard-surface theory is true,” Lu said.
The team found none of the flare-ups they expected to see if the hard-surface theory is true.
“Our work implies that some, and perhaps all, black holes have event horizons…” – Ramesh Narayan, Harvard-Smithsonian Center for Astrophysics.
What might seem like a failure, isn’t one of course. Not for Einstein, anyway. This represents yet another successful test of Einstein’s Theory of General Relativity, showing that the event horizon predicted in his theory does seem to exist.
As for the team, they haven’t abandoned the idea yet. In fact, according to Pawan Kumar, Professor of Astrophysics, University of Texas at Austin, “Our motive is not so much to establish that there is a hard surface, but to push the boundary of knowledge and find concrete evidence that really, there is an event horizon around black holes.”
“General Relativity has passed another critical test.” – Ramesh Narayan, Harvard-Smithsonian Center for Astrophysics.
“Our work implies that some, and perhaps all, black holes have event horizons and that material really does disappear from the observable universe when pulled into these exotic objects, as we’ve expected for decades,” Narayan said. “General Relativity has passed another critical test.”
The team plans to continue to look for the flare-ups associated with the hard-surface theory. Their look into the Pan-STARRS data was just their first crack at it.
They’re hoping to improve their test with the upcoming Large Synoptic Survey Telescope (LSST) being built in Chile. The LSST is a wide field telescope that will capture images of the night sky every 20 seconds over a ten-year span. Every few nights, the LSST will give us an image of the entire available night sky. This will make the study of transient objects much easier and effective.
There are a lot of ways that life on Earth could come to an end: an asteroid strike, global climate catastrophe, or nuclear war are among them. But perhaps the most haunting would be death by supernova, because there’s absolutely nothing we could do about it. We’d be sitting ducks.
New research suggest that a supernova’s kill zone is bigger than we thought; about 25 light years bigger, to be exact.
Iron in the Ocean
In 2016, researchers confirmed that Earth has been hit with the effects from multiple supernovae. The presence of iron 60 in the seabed confirms it. Iron 60 is an isotope of iron produced in supernova explosions, and it was found in fossilized bacteria in sediments on the ocean floor. Those iron 60 remnants suggest that two supernovae exploded near our solar system, one between 6.5 to 8.7 million years ago, and another as recently as 2 million years ago.
Iron 60 is extremely rare here on Earth because it has a short half life of 2.6 million years. Any of the iron 60 created at the time of Earth’s formation would have decayed into something else by now. So when researchers found the iron 60 on the ocean floor, they reasoned that it must have another source, and that logical source is a supernova.
This evidence was the smoking gun for the idea that Earth has been struck by supernovae. But the questions it begs are, what effect did that supernova have on life on Earth? And how far away do we have to be from a supernova to be safe?
“…we can look for events in the history of the Earth that might be connected to them (supernova events).” – Dr. Adrian Melott, Astrophysicist, University of Kansas.
In a press release from the University of Kansas, astrophysicist Adrian Melott talked about recent research into supernovae and the effects they can have on Earth. “This research essentially proves that certain events happened in the not-too-distant past,” said Melott, a KU professor of physics and astronomy. “They make it clear approximately when they happened and how far away they were. Knowing that, we can consider what the effect may have been with definite numbers. Then we can look for events in the history of the Earth that might be connected to them.”
Earlier work suggested that a supernova kill zone is about 25-30 light years. If a supernova exploded that close to Earth, it would trigger a mass extinction. Bye-bye humanity. But new work suggests that 25 light years is an under-estimation, and that a supernova 50 light years away would be powerful enough to cause a mass extinction.
Supernovae: A Force Driving Evolution?
But extinction is just one effect a supernova could have on Earth. Supernovae can have other effects, and they might not all be negative. It’s possible that a supernovae about 2.6 million years ago even drove human evolution.
“Our local research group is working on figuring out what the effects were likely to have been,” Melott said. “We really don’t know. The events weren’t close enough to cause a big mass extinction or severe effects, but not so far away that we can ignore them either. We’re trying to decide if we should expect to have seen any effects on the ground on the Earth.”
Melott and his colleagues have written a new paper that focuses on the effects a supernova might have on Earth. In a new paper titled “A SUPERNOVA AT 50 PC: EFFECTS ON THE EARTH’S ATMOSPHERE AND BIOTA”, Melott and a team of researchers tried to shed light on Earth-supernova interactions.
The Local Bubble
There are a number of variables that come into play when trying to determine the effects of a supernova, and one of them is the idea of the Local Bubble. The Local Bubble itself is the result of one or more supernova explosion that occurred as long as 20 million years ago. The Local Bubble is a 300 light year diameter bubble of expanding gas in our arm of the Milky Way galaxy, where our Solar System currently resides. We’ve been travelling through it for the last five to ten million years. Inside this bubble, the magnetic field is weak and disordered.
Melott’s paper focused on the effects that a supernova about 2.6 million years ago would have on Earth in two instances: while both were within the Local Bubble, and while both were outside the Local Bubble.
The disrupted magnetic field inside the Local Bubble can in essence magnify the effects a supernova can have on Earth. It can increase the cosmic rays that reach Earth by a factor of a few hundred. This can increase the ionization in the Earth’s troposphere, which mean that life on Earth would be hit with more radiation.
Outside the Local Bubble, the magnetic field is more ordered, so the effect depends on the orientation of the magnetic field. The ordered magnetic field can either aim more radiation at Earth, or it could in a sense deflect it, much like our magnetosphere does now.
Focusing on the Pleistocene
Melott’s paper looks into the connection between the supernova and the global cooling that took place during the Pleistocene epoch about 2.6 million years ago. There was no mass extinction at that time, but there was an elevated extinction rate.
According to the paper, it’s possible that increased radiation from a supernova could have changed cloud formation, which would help explain a number of things that happened at the beginning of the Pleistocene. There was increased glaciation, increased species extinction, and Africa grew cooler and changed from predominantly forests to semi-arid grasslands.
Cancer and Mutation
As the paper concludes, it is difficult to know exactly what happened to Earth 2.6 million years ago when a supernova exploded in our vicinity. And it’s difficult to pinpoint an exact distance at which life on Earth would be in trouble.
But high levels of radiation from a supernova could increase the cancer rate, which could contribute to extinction. It could also increase the mutation rate, another contributor to extinction. At the highest levels modeled in this study, the radiation could even reach one kilometer deep into the ocean.
There is no real record of increased cancer in the fossil record, so this study is hampered in that sense. But overall, it’s a fascinating look at the possible interplay between cosmic events and how we and the rest of life on Earth evolved.
One night 400 years ago, Galileo pointed his 2 inch telescope at Jupiter and spotted 3 of its moons. On subsequent nights, he spotted another, and saw one of the moons disappear behind Jupiter. With those simple observations, he propelled human understanding onto a path it still travels.
Galileo’s observations set off a revolution in astronomy. Prior to his observations of Jupiter’s moons, the prevailing belief was that the entire Universe rotated around the Earth, which lay at the center of everything. That’s a delightfully childish viewpoint, in retrospect, but it was dogma at the time.
Until Galileo’s telescope, this Earth-centric viewpoint, called Aristotelian cosmology, made sense. To all appearances, we were at the center of the action. Which just goes to show you how wrong we can be.
But once it became clear that Jupiter had other bodies orbiting it, our cherished position at the center of the Universe was doomed.
Galileo’s observations were an enormous challenge to our understanding of ourselves at the time, and to the authorities at the time. He was forced to recant what he had seen, and he was put under house arrest. But he never really backed down from the observations he made with his 2 inch telescope. How could he?
Now, of course, there isn’t so much hostility towards people with telescopes. As time went on, larger and more powerful telescopes were built, and we’ve gotten used to our understanding going through tumultuous changes. We expect it, even anticipate it.
In our current times, Super Telescopes rule the day, and their sizes are measured in meters, not inches. And when new observations challenge our understanding of things, we cluster around out of curiosity, and try to work our way through it. We don’t condemn the results and order scientists to keep quiet.
The first of the Super Telescopes, as far as most of us are concerned, is the Hubble Space Telescope. From its perch in Low Earth Orbit (LEO), the Hubble has changed our understanding of the Universe on numerous fronts. With its cameras, and the steady stream of mesmerizing images those cameras deliver, a whole generation of people have been exposed to the beauty and mystery of the cosmos.
Hubble has gazed at everything, from our close companion the Moon, all the way to galaxies billions of light years away. It’s spotted a comet breaking apart and crashing into Jupiter, dust storms on Mars, and regions of energetic star-birth in other galaxies. But Hubble’s time may be coming to an end soon, and other Super Telescopes are on the way.
Nowadays, Super Telescopes are expensive megaprojects, often involving several nations. They’re built to pursue specific lines of inquiry, such as:
What is the nature of Dark Matter and Dark Energy? How are they distributed in the Universe and what role do they play?
Are there other planets like Earth, and solar systems like ours? Are there other habitable worlds?
Are we alone or is there other life somewhere?
How do planets, solar systems, and galaxies form and evolve?
Some of the Super Telescopes will be on Earth, some will be in space. Some have enormous mirrors made up of individual, computer-controlled segments. The Thirty Meter Telescope has almost 500 of these segments, while the European Extremely Large Telescope has almost 800 of them. Following a different design, the Giant Magellan Telescope has only seven segments, but each one is over 8 meters in diameter, and each one weighs in at a whopping 20 tons of glass each.
Some of the Super Telescopes see in UV or Infrared, while others can see in visible light. Some see in several spectrums. The most futuristic of them all, the Large Ultra-Violet, Optical, and Infrared Surveyor (LUVOIR), will be a massive space telescope situated a million-and-a-half kilometers away, with a 16 meter segmented mirror that dwarfs that of the Hubble, at a mere 2.4 meters.
Some of the Super Telescopes will discern the finest distant details, while another, the Large Synoptic Survey Telescope, will complete a ten-year survey of the entire available sky, repeatedly imaging the same area of sky over and over. The result will be a living, dynamic map of the sky showing change over time. That living map will be available to anyone with a computer and an internet connection.
We’re in for exciting times when it comes to our understanding of the cosmos. We’ll be able to watch planets forming around young stars, glimpse the earliest ages of the Universe, and peer into the atmospheres of distant exoplanets looking for signs of life. We may even finally crack the code of Dark Matter and Dark Energy, and understand their role in the Universe.
Along the way there will be surprises, of course. There always are, and it’s the unanticipated discoveries and observations that fuel our sense of intellectual adventure.
The Super Telescopes are technological masterpieces. They couldn’t be built without the level of technology we have now, and in fact, the development of Super Telescopes help drives our technology forward.
But they all have their roots in Galileo and his simple act of observing with a 2-inch telescope. That, and the curiosity about nature that inspired him.