Archives For astronomy

Photo: Asteroid/dwarf planet Hygiea. Credit: ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS)

A new SPHERE/VLT image of Hygiea, which could be the Solar System’s smallest dwarf planet yet. As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighborhood around its orbit. The final requirement is that it have enough mass that its own gravity pulls it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea. Credit: ESO/P. Vernazza et al./MISTRAL algorithm (ONERA/CNRS)

Astronomers using ESO’s SPHERE instrument at the Very Large Telescope (VLT) have revealed that the asteroid Hygiea could be classified as a dwarf planet. The object is the fourth largest in the asteroid belt after Ceres, Vesta and Pallas. For the first time, astronomers have observed Hygiea in sufficiently high resolution to study its surface and determine its shape and size. They found that Hygiea is spherical, potentially taking the crown from Ceres as the smallest dwarf planet in the Solar System.

As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighborhood around its orbit. The final requirement is that it has enough mass for its own gravity to pull it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea.

“Thanks to the unique capability of the SPHERE instrument on the VLT, which is one of the most powerful imaging systems in the world, we could resolve Hygiea’s shape, which turns out to be nearly spherical,” says lead researcher Pierre Vernazza from the Laboratoire d’Astrophysique de Marseille in France. “Thanks to these images, Hygiea may be reclassified as a dwarf planet, so far the smallest in the Solar System.”

The team also used the SPHERE observations to constrain Hygiea’s size, putting its diameter at just over 430 km. Pluto, the most famous of dwarf planets, has a diameter close to 2,400 km, while Ceres is close to 950 km in size.

Surprisingly, the observations also revealed that Hygiea lacks the very large impact crater that scientists expected to see on its surface, the team report in the study published today in Nature Astronomy. Hygiea is the main member of one of the largest asteroid families, with close to 7,000 members that all originated from the same parent body. Astronomers expected the event that led to the formation of this numerous family to have left a large, deep mark on Hygiea.

“This result came as a real surprise as we were expecting the presence of a large impact basin, as is the case on Vesta,” says Vernazza. Although the astronomers observed Hygiea’s surface with a 95 percent coverage, they could only identify two unambiguous craters. “Neither of these two craters could have been caused by the impact that originated the Hygiea family of asteroids whose volume is comparable to that of a 100 km-sized object. They are too small,” explains study co-author Miroslav Brož of the Astronomical Institute of Charles University in Prague, Czech Republic.

The team decided to investigate further. Using numerical simulations, they deduced that Hygiea’s spherical shape and large family of asteroids are likely the result of a major head-on collision with a large projectile of diameter between 75 and 150 km. Their simulations show this violent impact, thought to have occurred about 2 billion years ago, completely shattered the parent body. Once the left-over pieces reassembled, they gave Hygiea its round shape and thousands of companion asteroids. “Such a collision between two large bodies in the asteroid belt is unique in the last 3–4 billion years,” says Pavel Ševeček, a PhD student at the Astronomical Institute of Charles University who also participated in the study.

Studying asteroids in detail has been possible thanks not only to advances in numerical computation, but also to more powerful telescopes. “Thanks to the VLT and the new generation adaptive-optics instrument SPHERE, we are now imaging main belt asteroids with unprecedented resolution, closing the gap between Earth-based and interplanetary mission observations,” Vernazza concludes.

Photo: First Quarter Moon, October 5, 2019.

Our First-Quarter Moon on International Observe the Moon Night, as seen through the Stephens telescope at 9:04 PM EDT. iPhone SE at eyepiece.

 

Our October 5 Open Night was the local event of the International Observe the Moon Night — an annual occurrence meant that encourages observation, appreciation, and understanding of our Moon and its connection to planetary science and exploration. Over the course of the night at Stephens Memorial Observatory some 34 enthusiastic and inquisitive visitors attended and were treated to beautiful and unusual views of Earth’s Moon and planet Saturn.

Unusual? The earliest visitors arrived just as the telescope was set to go … with the sky still bright with twilight. The Moon appeared light and against a power-blue sky background instead of the usual darkness of space. Saturn, invisible to the eye in the bright sky, was also viewed through the telescope in surprising detail.

 

Zooming in on the previous image: That dot in the center of dark-floored crater Alphonsus is its central peak. Over the course of two hours sun rose over that pinnacle making it brighter, and other features began to emerge as we watched. Alphonsus slightly overlaps the crater Ptolemaeus.

After darkness fell enthusiastic visitors took turns looking at a crater and watching a mountain peak become illuminated at sunrise on the Moon! It was a fine night appreciating a sight too often ignored: the wonder of Luna, our nearest neighbor in space.

Photo: August 21, 2017 total solar eclipse. Credits: NASA/Gopalswamy

The corona, a region of the Sun only seen from Earth when the Moon blocks out the Sun’s bright face during total solar eclipses. The corona holds the answers to many of scientists’ outstanding questions about the Sun’s activity and processes. This photo was taken during the total solar eclipse on Aug. 21, 2017. Credits: NASA/Gopalswamy

Be sure to be watching July 2 at 4:00 PM EDT as the total solar eclipse is presented live from Chile, via San Francisco’s Exploratorium. You will not be able to directly see the eclipse from the USA; the total solar eclipse will be visible from a narrow part of the South Pacific Ocean, Chile, and Argentina.

The Exploratorium will be bringing the total solar eclipse to you, no matter where you are. The have sent a team to Chile to broadcast from within the path of totality. Enjoy this full, unnarrated view of the eclipse from the telescopes at the National Science Foundation’s Cerro Tololo Observatory.

Live Telescope View – Not Narrated:
https://www.exploratorium.edu/video/total-solar-eclipse-live-july-2-2019

Live Coverage – Broadcast Style:
https://www.exploratorium.edu/video/total-solar-eclipse-2019-live-coverage

NASA has partnered with the Exploratorium to provide the coverage which it will livestream: three views via separate players on the agency’s website (all times EDT):

  • Live views from telescopes in Vicuna, Chile, without audio, from 3 to 6 PM
  • A one-hour program with live commentary in English, from 4 to 5 PM
  • A one-hour program with live commentary in Spanish, from 4 to 5 PM

NASA Television will also carry the English-language program on its public channel. Both programs will feature updates from NASA’s Parker Solar Probe and Magnetospheric Multiscale missions.

Jupiter and its Galilean Moons as they will appear the night of July 13, 2019. Labels for Ganymede and Io overlap. Simulation via "Gas Giants".

Jupiter and its Galilean Moons as they will appear the night of July 13, 2019. Labels for Ganymede and Io overlap. Simulation via “Gas Giants”.

 

WRAP-UP: We played peek-a-boo through clouds with Moon and Jupiter all evening. When they first became visible from behind neighboring trees, viewing of our Moon and the planet was fair to poor. As time passed and the atmosphere settled down, seeing became better and late visitors were treated to excellent views of Moon and fair to good views of Jupiter with his four Galilean Moons and even the Great Red Spot (GRS). In fact, just before we closed for the night, the GRS showed not just as a thickening in the Southern Equatorial Band but as a definite shape with red coloration! Saturday’s was not the best view we’ve had of Jupiter but in the end, it was pretty good. Thanks to the 34 visitors who came out on a muggy and buggy night to enjoy the sights!

Stephens Memorial Observatory of Hiram College will host a Public Night Saturday, July 13, from 9:30 to 11:00 PM. On the observing list are two Stephens favorites: Earth’s Moon, and planet Jupiter with its moons. Other objects of interest may also be viewed using the Observatory’s 1901 vintage telescope. Given good viewing conditions, organizers say, the telescope delivers outstanding detail of the Moon and impressive views of Jupiter including, when it’s in position as it will be July 13, the planet’s Great Red Spot feature.

Organizers hope for clear skies since recent weather conditions have made scheduled observing impossible. Cloudy skies at the scheduled starting time cancel the event in which case, the observatory will not open. No reservations are required and there is no admission fee for observatory public nights.

The Observatory is located on Wakefield Road (Rt. 82) less than a quarter of a mile west of Route 700 in Hiram. There is no parking at the Observatory. Visitors may park on permissible side streets near the Post Office, a short distance east of the observatory.

Updates on programming are available via the Observatory’s Twitter feed: @StephensObs or its website: StephensObservatory.org.

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.”

Image: ESO 577-24 Credit: ESO

The faint, ephemeral glow emanating from the planetary nebula ESO 577-24 persists for only a short time  — around 10,000 years, a blink of an eye in astronomical terms. ESO’s Very Large Telescope captured this shell of glowing ionized gas — the last breath of the dying star whose simmering remains are visible at the heart of this image. As the gaseous shell of this planetary nebula expands and grows dimmer, it will slowly disappear from sight. An object much closer to home is also visible in this image — an asteroid wandering across the field of view has left a faint track below and to the left of the central star. And in the far distance behind the nebula a glittering host of background galaxies can be seen. Credit: ESO

An evanescent shell of glowing gas spreading into space — the planetary nebula ESO 577-24 —  dominates this image. This planetary nebula is the remains of a dead giant star that has thrown off its outer layers, leaving behind a small, intensely hot dwarf star. This diminished remnant will gradually cool and fade, living out its days as the mere ghost of a once-vast red giant star.

Red giants are stars at the end of their lives that have exhausted the hydrogen fuel in their cores and begun to contract under the crushing grip of gravity. As a red giant shrinks, the immense pressure reignites the core of the star, causing it to throw its outer layers into the void as a powerful stellar wind. The dying star’s incandescent core emits ultraviolet radiation intense enough to ionize these ejected layers and cause them to shine. The result is what we see as a planetary nebula — a final, fleeting testament to an ancient star at the end of its life.

This dazzling planetary nebula was discovered as part of the National Geographic Society  — Palomar Observatory Sky Survey in the 1950s, and was recorded in the Abell Catalogue of Planetary Nebulae in 1966. At around 1400 light years from Earth, the ghostly glow of ESO 577-24 is only visible through a powerful telescope. As the dwarf star cools, the nebula will continue to expand into space, slowly fading from view.

This image of ESO 577-24 was created as part of the ESO Cosmic Gems Programme, an initiative that produces images of interesting, intriguing, or visually attractive objects using ESO telescopes for the purposes of education and public outreach. The program makes use of telescope time that cannot be used for scientific observations; nevertheless, the data collected are made available to astronomers through the ESO Science Archive.

Image: A bright fireball meteor streak captured by the NASA All Sky Fireball Network Camera located at Hiram College.

A bright fireball meteor streak captured by the NASA All Sky Fireball Network Camera located at Hiram College.


 
Did you see it? Our NASA All Sky Fireball Network camera picked up a pretty decent meteor streak in the wee hours (2:33 AM) this morning. It would have been a bit chilly to sit up all night watching ourselves, but the camera system operates all night, every clear night to record meteoric activity. Learn more here: https://fireballs.ndc.nasa.gov/