Imaged: The first direct visual evidence of a supermassive black hole and its shadow

Photo: Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of galaxy M87, outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon. Credit: Event Horizon Telescope collaboration et al.

Using the Event Horizon Telescope, scientists obtained an image of the black hole at the center of galaxy M87, outlined by emission from hot gas swirling around it under the influence of strong gravity near its event horizon. Credit: Event Horizon Telescope collaboration et al.

April 10, 2019 — Today, in coordinated press conferences across the globe, Event Horizon Telescope researchers reveal that they have succeeded in unveiling the first direct visual evidence of a supermassive black hole and its shadow. The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole.

This breakthrough was announced in a series of six papers published in a special issue of The Astrophysical Journal Letters. The image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5-billion times that of the Sun.

“This is a huge day in astrophysics,” said NSF Director France Córdova. “We’re seeing the unseeable. Black holes have sparked imaginations for decades. They have exotic properties and are mysterious to us. Yet with more observations like this one they are yielding their secrets. This is why NSF exists. We enable scientists and engineers to illuminate the unknown, to reveal the subtle and complex majesty of our universe.”

The EHT links telescopes around the globe to form an Earth-sized virtual telescope with unprecedented sensitivity and resolution. The EHT is the result of years of international collaboration and offers scientists a new way to study the most extreme objects in the Universe predicted by Einstein’s general relativity during the centennial year of the historic experiment that first confirmed the theory.

“We have taken the first picture of a black hole,” said EHT project director Sheperd S. Doeleman of the Center for Astrophysics | Harvard & Smithsonian. “This is an extraordinary scientific feat accomplished by a team of more than 200 researchers.”

The National Science Foundation (NSF) played a pivotal role in this discovery by funding individual investigators, interdisciplinary scientific teams and radio astronomy research facilities since the inception of EHT. Over the last two decades, NSF has directly funded more than $28 million in EHT research, the largest commitment of resources for the project.

Black holes are extraordinary cosmic objects with enormous masses but extremely compact sizes. The presence of these objects affects their environment in extreme ways, warping spacetime and super-heating any surrounding material.

“If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow — something predicted by Einstein’s general relativity that we’ve never seen before,” explained chair of the EHT Science Council Heino Falcke of Radboud University, the Netherlands. “This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87’s black hole.”

Streaming out from the center of M87 like a cosmic searchlight is one of nature’s most amazing phenomena: a black-hole-powered jet of subatomic particles traveling at nearly the speed of light. In this Hubble image, the blue jet contrasts with the yellow glow from the combined light of billions of unresolved stars and the point-like clusters of stars that make up this galaxy. Credits: NASA and the Hubble Heritage Team (STScI/AURA)

Streaming out from the center of M87 like a cosmic searchlight is one of nature’s most amazing phenomena: a black-hole-powered jet of subatomic particles traveling at nearly the speed of light. In this Hubble image, the blue jet contrasts with the yellow glow from the combined light of billions of unresolved stars and the point-like clusters of stars that make up this galaxy.
Credits: NASA and the Hubble Heritage Team (STScI/AURA)

Multiple calibration and imaging methods have revealed a ring-like structure with a dark central region — the black hole’s shadow — that persisted over multiple independent EHT observations.

“Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter and strong magnetic fields. Many of the features of the observed image match our theoretical understanding surprisingly well,” remarks Paul T.P. Ho, EHT Board member and Director of the East Asian Observatory. “This makes us confident about the interpretation of our observations, including our estimation of the black hole’s mass.”

Creating the EHT was a formidable challenge that required upgrading and connecting a worldwide network of eight preexisting telescopes deployed at a variety of challenging high-altitude sites. These locations included volcanoes in Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, the Chilean Atacama Desert, and Antarctica.

The EHT observations use a technique called very-long-baseline interferometry (VLBI). which synchronizes telescope facilities around the world and exploits the rotation of our planet to form one huge, Earth-size telescope observing at a wavelength of 1.3mm. VLBI allows the EHT to achieve an angular resolution of 20 micro-arcseconds — enough to read a newspaper in New York from a sidewalk café in Paris.

The telescopes contributing to this result were ALMA, APEX, the IRAM 30-meter telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope. Petabytes of raw data from the telescopes were combined by highly specialized supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory.

The construction of the EHT and the observations announced today represent the culmination of decades of observational, technical, and theoretical work. This example of global teamwork required close collaboration by researchers from around the world. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the US National Science Foundation, the EU’s European Research Council (ERC), and funding agencies in East Asia.

“We have achieved something presumed to be impossible just a generation ago,” concluded Doeleman. “Breakthroughs in technology, connections between the world’s best radio observatories, and innovative algorithms all came together to open an entirely new window on black holes and the event horizon.”

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April 8 Membership Meeting: The Great Melbourne Telescope rises again

Photo: Author Trudy E. Bell, M.A.

Trudy E. Bell, M.A.

The April 2019 Membership Meeting of the Cuyahoga Astronomical Association will take place on Monday, April 8 beginning at 7:30 PM. The evening’s program, “Rising From the Ashes: Restoration of the Great Melbourne Telescope,” will be presented by Trudy E. Bell, M.A. Ms. Bell is a Sky & Telescope Contributing Editor, 2006 recipient of the American Astronomical Society’s David N. Schramm Award, and board member of the Antique Telescope Society.

When completed in 1869, the Great Melbourne Telescope was the world’s largest equatorial reflector. Today, 150 years later — after a bushfire that devastated the Mount Stromlo Observatory — Australian opticians and machinists are restoring the GMT to become one of the world’s largest telescopes for public outreach! Ms. Bell’s latest article about the restoration appears in the October 2018 issue of Sky and Telescope magazine.

Photo: Photo: The Great Melbourne Telescope was built by Thomas Grubb of Dublin in 1868 and erected at Melbourne Observatory in 1869. It was a reflector telescope with a speculum (metal) mirror of 48 inches. Image Courtesy:  Museums Victoria

Photo: The Great Melbourne Telescope was built by Thomas Grubb of Dublin in 1868 and erected at Melbourne Observatory in 1869. It was a reflector telescope with a speculum (metal) mirror of 48 inches. Image Courtesy: Museums Victoria

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks. Meeting programs are open to the public. Following the presentation and a brief social break, the club will conduct its membership business meeting.

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ESO announces first direct observation of an exoplanet using optical interferometry

Image: Aerial view of the observing platform on the top of Paranal mountain (from late 1999), with the four enclosures for the 8.2-m Unit Telescopes (UTs) and various installations for the VLT Interferometer (VLTI). Three 1.8-m VLTI Auxiliary Telescopes (ATs) and paths of the light beams have been superimposed on the photo. Also seen are some of the 30 "stations" where the ATs will be positioned for observations and from where the light beams from the telescopes can enter the Interferometric Tunnel below. The straight structures are supports for the rails on which the telescopes can move from one station to another. The Interferometric Laboratory (partly subterranean) is at the center of the platform. Credit: ESO

Aerial view of the observing platform on the top of Paranal mountain (from late 1999), with the four enclosures for the 8.2-m Unit Telescopes (UTs) and various installations for the VLT Interferometer (VLTI). Three 1.8-m VLTI Auxiliary Telescopes (ATs) and paths of the light beams have been superimposed on the photo. The Interferometric Laboratory (partly subterranean) is at the center of the platform. Credit: ESO

March 27 — The GRAVITY instrument on ESO’s Very Large Telescope Interferometer (VLTI) has made the first direct observation of an exoplanet using optical interferometry. This method revealed a complex exoplanetary atmosphere with clouds of iron and silicates swirling in a planet-wide storm. The technique presents unique possibilities for characterizing many of the exoplanets known today.

The observation was announced today in a letter in the journal Astronomy and Astrophysics by the GRAVITY Collaboration, in which they present observations of the exoplanet HR8799e using optical interferometry. The exoplanet was discovered in 2010 orbiting the young main-sequence star HR8799, which lies around 129 light-years from Earth in the constellation of Pegasus.

Image: This chart shows the constellation of Pegasus, which depicts a winged horse from Greek mythology. The chart shows the location of HR8799 and marks most of the stars visible to the unaided eye on a clear dark night. The constellation is familiar to stargazers as it contains three of the four stars that make up the bright asterism known as the Square of Pegasus, used to locate various objects in the sky. The constellation also contains multiple deep-sky objects of interest to astronomers, including the gravitationally lensed quasar known as Einstein’s Cross.

This chart shows the constellation of Pegasus, which depicts a winged horse from Greek mythology. The chart shows the location of HR8799 and marks most of the stars visible to the unaided eye on a clear dark night. The constellation is familiar to stargazers as it contains three of the four stars that make up the bright asterism known as the Square of Pegasus, used to locate various objects in the sky. The constellation also contains multiple deep-sky objects of interest to astronomers, including the gravitationally-lensed quasar known as Einstein’s Cross. Credit: ESO, IAU and Sky & Telescope

Today’s result, which reveals new characteristics of HR8799e, required an instrument with very high resolution and sensitivity. GRAVITY can use ESO’s VLT’s four unit telescopes to work together to mimic a single larger telescope using a technique known as interferometry. This creates a super-telescope — the VLTI  — that collects and precisely disentangles the light from HR8799e’s atmosphere and the light from its parent star.
HR8799e is a ‘super-Jupiter’, a world unlike any found in our Solar System, that is both more massive and much younger than any planet orbiting the Sun. At only 30 million years old, this baby exoplanet is young enough to give scientists a window onto the formation of planets and planetary systems. The exoplanet is thoroughly inhospitable — leftover energy from its formation and a powerful greenhouse effect heat HR8799e to a hostile temperature of roughly 1000°C.

This is the first time that optical interferometry has been used to reveal details of an exoplanet, and the new technique furnished an exquisitely detailed spectrum of unprecedented quality — ten times more detailed than earlier observations. The team’s measurements were able to reveal the composition of HR8799e’s atmosphere  — which contained some surprises.

“Our analysis showed that HR8799e has an atmosphere containing far more carbon monoxide than methane — something not expected from equilibrium chemistry,” explains team leader Sylvestre Lacour researcher CNRS at the Observatoire de Paris – PSL and the Max Planck Institute for Extraterrestrial Physics. “We can best explain this surprising result with high vertical winds within the atmosphere preventing the carbon monoxide from reacting with hydrogen to form methane.”

The team found that the atmosphere also contains clouds of iron and silicate dust. When combined with the excess of carbon monoxide, this suggests that HR8799e’s atmosphere is engaged in an enormous and violent storm.

Image: This artist’s impression shows the observed exoplanet, which goes by the name HR8799e. Credit: ESO/L. Calçada

This artist’s impression shows the observed exoplanet, which goes by the name HR8799e. Credit: ESO/L. Calçada

“Our observations suggest a ball of gas illuminated from the interior, with rays of warm light swirling through stormy patches of dark clouds,” elaborates Lacour. “Convection moves around the clouds of silicate and iron particles, which disaggregate and rain down into the interior. This paints a picture of a dynamic atmosphere of a giant exoplanet at birth, undergoing complex physical and chemical processes.”

This result builds on GRAVITY’s string of impressive discoveries, which have included breakthroughs such as last year’s observation of gas swirling at 30% of the speed of light just outside the event horizon of the massive Black Hole in the Galactic Center. It also adds a new way of observing exoplanets to the already extensive arsenal of methods available to ESO’s telescopes and instruments — paving the way to many more impressive discoveries

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Get Out! Pulsar imaged speeding away from supernova birthplace

Image: Pulsar ejected from expanding "bubble" of supernova remnant.

Observations using the Very Large Array (orange) reveal the needle-like trail of pulsar J0002+6216 outside the shell of its supernova remnant, shown in image from the Canadian Galactic Plane Survey. The pulsar escaped the remnant some 5,000 years after the supernova explosion.
Credit: Composite by Jayanne English, University of Manitoba; F. Schinzel et al.; NRAO/AUI/NSF; DRAO/Canadian Galactic Plane Survey; and NASA/IRAS.

Astronomers using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have found a pulsar speeding away from its presumed birthplace at nearly 700 miles per second, with its trail pointing directly back at the center of a shell of debris from the supernova explosion that created it. The discovery is providing important insights into how pulsars — superdense neutron stars left over after a massive star explodes — can get a “kick” of speed from the explosion.

“This pulsar has completely escaped the remnant of debris from the supernova explosion,” said Frank Schinzel, of the National Radio Astronomy Observatory (NRAO). “It’s very rare for a pulsar to get enough of a kick for us to see this,” he added.

The pulsar, dubbed PSR J0002+6216, about 6,500 light-years from Earth, was discovered in 2017 by a citizen-science project called Einstein@Home. That project uses computer time donated by volunteers to analyze data from NASA’s Fermi Gamma-ray Space Telescope. So far, using more than 10,000 years of computing time, the project has discovered a total of 23 pulsars.

Radio observations with the VLA clearly show the pulsar outside the supernova remnant, with a tail of shocked particles and magnetic energy some 13 light-years long behind it. The tail points back toward the center of the supernova remnant.

“Measuring the pulsar’s motion and tracing it backwards shows that it was born at the center of the remnant, where the supernova explosion occurred,” said Matthew Kerr, of the Naval Research Laboratory. The pulsar now is 53 light-years from the remnant’s center.

“The explosion debris in the supernova remnant originally expanded faster than the pulsar’s motion,” said Dale Frail, of NRAO. “However, the debris was slowed by its encounter with the tenuous material in interstellar space, so the pulsar was able to catch up and overtake it,” he added.

The astronomers said that the pulsar apparently caught up with the shell about 5,000 years after the explosion. The system now is seen about 10,000 years after the explosion.

The pulsar’s speed of nearly 700 miles per second is unusual, the scientists said, with the average pulsar speed only about 150 miles per second. “This pulsar is moving fast enough that it eventually will escape our Milky Way Galaxy,” Frail said.

Astronomers have long known that pulsars get a kick when born in supernova explosions, but still are unsure how that happens.

“Numerous mechanisms for producing the kick have been proposed. What we see in PSR J0002+6216 supports the idea that hydrodynamic instabilities in the supernova explosion are responsible for the high velocity of this pulsar,” Frail said.

“We have more work to do to fully understand what’s going on with this pulsar, and it’s providing an excellent opportunity to improve our knowledge of supernova explosions and pulsars,” Schinzel said.

Schinzel, Kerr, and Frail worked with Urvashi Rau and Sanjay Bhatnagar, both of NRAO. The scientists are reporting their results at the High Energy Astrophysics Division meeting of the American Astronomical Society in Monterey, California, and have submitted a paper to the Astrophysical Journal Letters.

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Visualization of colliding black holes

Robert Owen’s presentation at the CAA’s March 11 meeting featured a fascinating and beautiful animated simulation of what colliding black holes might look like if somehow viewed through a telescope. Watch the video here:

This computer simulation shows the collision of two black holes, a tremendously powerful event detected for the first time ever by the Laser Interferometer Gravitational-Wave Observatory, or LIGO. LIGO detected gravitational waves, or ripples in space and time generated as the black holes spiraled in toward each other, collided, and merged. This simulation shows how the merger would appear to our eyes if we could somehow travel in a spaceship for a closer look. It was created by solving equations from Albert Einstein’s general theory of relativity using the LIGO data.

The two merging black holes are each roughly 30 times the mass of the sun, with one slightly larger than the other. Time has been slowed down by a factor of about 100. The event took place 1.3 billion years ago.

The stars appear warped due to the incredibly strong gravity of the black holes. The black holes warp space and time, and this causes light from the stars to curve around the black holes in a process called gravitational lensing. The ring around the black holes, known as an Einstein ring, arises from the light of all the stars in a small region behind the holes, where gravitational lensing has smeared their images into a ring.

The gravitational waves themselves would not be seen by a human near the black holes and so do not show in this video, with one important exception. The gravitational waves that are traveling outward toward the small region behind the black holes disturb that region’s stellar images in the Einstein ring, causing them to slosh around, even long after the collision. The gravitational waves traveling in other directions cause weaker, and shorter-lived sloshing, everywhere outside the ring.

This simulation was created by the multi-university SXS (Simulating eXtreme Spacetimes) project. For more information, visit http://www.black-holes.org.

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March Membership Meeting

Robert Owen, Ph.D. - Oberlin College Photo

Robert Owen, Ph.D. – Oberlin College Photo

The March 2019 Membership Meeting of the Cuyahoga Astronomical Association will take place on Monday, March 11 beginning at 7:30 PM. The evening’s program, “Gravitational Waves from Colliding Black Holes,” will be presented by Rob Owen, Associate Professor of Physics and Astronomy, at Oberlin College.

Dr. Owen is a member of the Simulating Extreme Spacetimes collaboration (www.black-holes.org), which carries out supercomputer simulations of colliding black holes and neutron stars. Such simulations are essential for relating gravitational wave signals (such as those measured by the revolutionary LIGO observatory) to the astrophysical sources that produce them. In this talk he will describe the work and the often misunderstood physics of black holes and how they relate to the structure of space and time!

The CAA’s monthly meetings are held on the second Monday of every month (except December) at 7:30 PM at the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks. Meeting programs are open to the public. Following the presentation and a brief social break, the club will conduct its membership business meeting.

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Mission’s end for “Oppy”

Opportunity's Tracks on Mars - Image credit: NASA/JPL-Caltech

Opportunity’s Tracks on Mars – Image credit: NASA/JPL-Caltech

February 12, 2019 — One of the most successful and enduring feats of interplanetary exploration, NASA’s Opportunity rover mission is at an end after almost 15 years exploring the surface of Mars and helping lay the groundwork for NASA’s return to the Red Planet.

The Opportunity rover stopped communicating with Earth when a severe Mars-wide dust storm blanketed its location in June 2018. After more than a thousand commands to restore contact, engineers in the Space Flight Operations Facility at NASA’s Jet Propulsion Laboratory (JPL) made their last attempt to revive Opportunity Tuesday, to no avail. The solar-powered rover’s final communication was received June 10.

“It is because of trailblazing missions such as Opportunity that there will come a day when our brave astronauts walk on the surface of Mars,” said NASA Administrator Jim Bridenstine. “And when that day arrives, some portion of that first footprint will be owned by the men and women of Opportunity, and a little rover that defied the odds and did so much in the name of exploration.”

Artist's Concept: Spirit & Opportunity Mars Rovers. Image Credit: NASA

Artist’s Concept: Spirit & Opportunity Mars Rovers. Image Credit: NASA

Designed to last just 90 Martian days and travel 1,100 yards (1,000 meters), Opportunity vastly surpassed all expectations in its endurance, scientific value and longevity. In addition to exceeding its life expectancy by 60 times, the rover traveled more than 28 miles (45 kilometers) by the time it reached its most appropriate final resting spot on Mars – “Perseverance Valley.”

“For more than a decade, Opportunity has been an icon in the field of planetary exploration, teaching us about Mars’ ancient past as a wet, potentially habitable planet, and revealing uncharted Martian landscapes,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate. “Whatever loss we feel now must be tempered with the knowledge that the legacy of Opportunity continues – both on the surface of Mars with the Curiosity rover and InSight lander – and in the clean rooms of JPL, where the upcoming Mars 2020 rover is taking shape.”

Click here for more on NASA’s Mars rovers!

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