Category Archives: Astronomy

ESO: Black hole found in triple star system just 1000 light years away

The latest report from ESO (European Southern Observatory):

ESO Instrument Finds Closest Black Hole to Earth
Invisible object has two companion stars visible to the naked eye

This artist’s impression shows the orbits of the objects in the HR 6819 triple system. This system is made up of an inner binary with one star (orbit in blue) and a newly discovered black hole (orbit in red), as well as a third star in a wider orbit (also in blue). The team originally believed there were only two objects, the two stars, in the system. However, as they analysed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole, the closest ever found to Earth. The black hole is invisible, but it makes its presence known by its gravitational pull, which forces the luminous inner star into an orbit. The objects in this inner pair have roughly the same mass and circular orbits. The observations, with the FEROS spectrograph on the 2.2-metre telescope at ESO’s La Silla, showed that the inner visible star orbits the black hole every 40 days, while the second star is at a large distance from this inner pair.

A team of astronomers from the European Southern Observatory (ESO) and other institutes has discovered a black hole lying just 1000 light-years from Earth. The black hole is closer to our Solar System than any other found to date and forms part of a triple system that can be seen with the naked eye. The team found evidence for the invisible object by tracking its two companion stars using the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. They say this system could just be the tip of the iceberg, as many more similar black holes could be found in the future.

“We were totally surprised when we realised that this is the first stellar system with a black hole that can be seen with the unaided eye,”

says Petr Hadrava, Emeritus Scientist at the Academy of Sciences of the Czech Republic in Prague and co-author of the research. Located in the constellation of Telescopium, the system is so close to us that its stars can be viewed from the southern hemisphere on a dark, clear night without binoculars or a telescope.

“This system contains the nearest black hole to Earth that we know of,”

says ESO scientist Thomas Rivinius, who led the study published today in Astronomy & Astrophysics.

The team originally observed the system, called HR 6819, as part of a study of double-star systems. However, as they analysed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole. The observations with the FEROS spectrograph on the MPG/ESO 2.2-metre telescope at La Silla showed that one of the two visible stars orbits an unseen object every 40 days, while the second star is at a large distance from this inner pair.

Dietrich Baade, Emeritus Astronomer at ESO in Garching and co-author of the study, says:

“The observations needed to determine the period of 40 days had to be spread over several months. This was only possible thanks to ESO’s pioneering service-observing scheme under which observations are made by ESO staff on behalf of the scientists needing them.”

This animation shows the orbits and movements of the objects in the HR 6819 triple system. This system includes an inner binary with one star (orbit indicated in blue) and a newly discovered black hole (orbit indicated in red). As we move away from this inner pair, we see the outer object in the system, another star in a much wider orbit (in blue). 

The team originally believed there were only two objects, the two stars, in the system. However, as they analysed their observations, they were stunned when they revealed a third, previously undiscovered body in HR 6819: a black hole, the closest ever found to Earth. The black hole is invisible, but it makes its presence known by its gravitational pull, which forces the luminous inner star into an orbit. The objects in this inner pair have roughly the same mass and circular orbits.

The observations, with the FEROS spectrograph on the 2.2-metre telescope at La Silla, showed that the inner visible star orbits the black hole every 40 days, while the second star is at a large distance from this inner pair. 

The hidden black hole in HR 6819 is one of the very first stellar-mass black holes found that do not interact violently with their environment and, therefore, appear truly black. But the team could spot its presence and calculate its mass by studying the orbit of the star in the inner pair.

“An invisible object with a mass at least 4 times that of the Sun can only be a black hole,”

concludes Rivinius, who is based in Chile.

Astronomers have spotted only a couple of dozen black holes in our galaxy to date, nearly all of which strongly interact with their environment and make their presence known by releasing powerful X-rays in this interaction. But scientists estimate that, over the Milky Way’s lifetime, many more stars collapsed into black holes as they ended their lives. The discovery of a silent, invisible black hole in HR 6819 provides clues about where the many hidden black holes in the Milky Way might be.

“There must be hundreds of millions of black holes out there, but we know about only very few. Knowing what to look for should put us in a better position to find them,” says Rivinius. Baade adds that finding a black hole in a triple system so close by indicates that we are seeing just “the tip of an exciting iceberg.”

Already, astronomers believe their discovery could shine some light on a second system.

“We realised that another system, called LB-1, may also be such a triple, though we’d need more observations to say for sure,” says Marianne Heida, a postdoctoral fellow at ESO and co-author of the paper. “LB-1 is a bit further away from Earth but still pretty close in astronomical terms, so that means that probably many more of these systems exist. By finding and studying them we can learn a lot about the formation and evolution of those rare stars that begin their lives with more than about 8 times the mass of the Sun and end them in a supernova explosion that leaves behind a black hole.”

The discoveries of these triple systems with an inner pair and a distant star could also provide clues about the violent cosmic mergers that release gravitational waves powerful enough to be detected on Earth. Some astronomers believe that the mergers can happen in systems with a similar configuration to HR 6819 or LB-1, but where the inner pair is made up of two black holes or of a black hole and a neutron star. The distant outer object can gravitationally impact the inner pair in such a way that it triggers a merger and the release of gravitational waves. Although HR 6819 and LB-1 have only one black hole and no neutron stars, these systems could help scientists understand how stellar collisions can happen in triple star systems.

This wide-field view shows the region of the sky, in the constellation of Telescopium, where HR 6819 can be found, a triple system consisting of two stars and the closest black hole to Earth ever found. This view was created from images forming part of the Digitized Sky Survey 2. While the black hole is invisible, the two stars in HR 6819 can be viewed from the southern hemisphere on a dark, clear night without binoculars or a telescope.

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Videos: Night sky highlights for May 2020

[ Update 2: What’s Up: May 2020 – Skywatching Tips from NASA JPL

What astronomy highlights can you see in the sky in May 2020? Venus, Sirius and the Milky Way. With so many of us staying home these days, here’s a look into the sky at dusk and dawn with an eye toward the vast stretches of wide open space right above our heads. Additional information about topics covered in this episode of What’s Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/whats-up… Credit: NASA/JPL-Caltech

UpdateSkywatch: What’s happening in the heavens in May – The Washington Post.

]

** Tonight’s Sky: Space Telescope Science Institute – YouTube

In May, we are looking away from the crowded, dusty plane of our own galaxy toward a region where the sky is brimming with distant galaxies. Locate Virgo to find a concentration of roughly 2,000 galaxies and search for Coma Berenices to identify many more. Keep watching for space-based views of galaxies like the Sombrero Galaxy, M87, and M64.

** What’s in the Night Sky May 2020Alyn Wallace – YouTube

** What to see in the night sky: May 2020BBC Sky at Night Magazine – YouTube

Pete Lawrence and Paul Abel guide us through May’s stargazing highlights.

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NIAC project aims to image exoplanets with solar gravity lens system enabled by advanced solar sail

Xplore sent me this press release:

NASA $2M Grant Advances Study to Directly Image Exoplanets Light Years Away
Xplore’s Advanced Solar Sail Design will be the Fastest Spacecraft Ever Made,
Expanding Xplore’s Reach Beyond the Inner Solar System

Xplore Inc., a commercial space exploration company providing Space as a Service™ today announced they and their teammates won a NASA Innovative Advanced Concepts (NIAC) Phase III award for a two-year, $2M NASA grant to further mature the Solar Gravity Lens Focus (SGLF) architecture to image planets in orbit around distant stars starting with a Technology Demonstration Mission (TDM). Dr. Slava G. Turyshev, a NIAC Fellow and Senior Research Scientist at NASA’s Jet Propulsion Laboratory (JPL) is the Principal Investigator leading the SGLF mission which includes Xplore, JPL and The Aerospace Corporation. The SGLF mission study is only the third Phase III award granted in the NIAC program ever.

Xplore’s Advanced Solar Sail for NASA’s Solar Gravity Lens Focus Mission, visualization by Bryan Versteeg, SpaceHabs.com

Reaching the focus region where the Sun’s gravity acts like a magnifying lens to the background sky is an immense technological challenge. This region, the SGLF, is over 500 times the distance between Earth and the Sun (547 AU). One Astonomical Unit (AU) is the distance from Earth to the Sun, about 93 million miles (149.5 million km). Even by using our fastest deep space probe, Voyager 1, moving at 11 miles/s (17 km/s) it will take over 150 years to reach just the edge of the SGLF region.

During the previous two NIAC phases nearly every credible propulsion technology was assessed to not only accurately navigate across this vast distance, but also to communicate and operate once at the SGLF — all within a goal of 25 years from launch. To reach the SGLF on a timescale of 25 years requires a propulsion system capable of accelerating a spacecraft to a speed seven times faster than Voyager 1 (> 20 AU/yr or 100 km/s). The resulting propulsion technology was found to meet both the high speed requirement and the proposed architecture of sending many vehicles to the SGLF. This propulsion does not exploit chemical or nuclear reactions, but simply harnesses sunlight reflecting from a solar sail.

As a key enabler for the SGLF mission, Xplore will design the spacecraft for the SGLF’s Technology Demonstration Mission (TDM). The TDM vehicle as pictured is an advanced solar sail design based upon L’Garde’s SunVane concept. The SunVane concept addresses the control, packaging and scalability challenges of traditional large planar solar sails by breaking up the required overall sail area into smaller rotatable vanes distributed across a lightweight truss. Xplore will transition this concept to a prototype design as a first step toward demonstrating the key technologies necessary to achieve the SGLF mission. The goal for the Xplore TDM vehicle using current technologies is to reach speeds in excess of two to three times that of Voyager 1 (5-8 AU/year). At these unprecedented speeds it would allow the TDM vehicle to reach Jupiter in less than a year and Saturn in two years.

Xplore Founder Lisa Rich said,

“Xplore is laying the groundwork to revolutionize the transit speed to destinations in our solar system, and beyond. Once Xplore completes the design, build and first flight of the TDM vehicle, the company would accelerate these missions — perhaps sending one per year, to rapidly advance solar system exploration while providing fast reaction options for flybys of newly-discovered interstellar objects like Oumuamua and high energy intercepts for planetary defense.”

The TDM will enable rapid transit to dramatically transform and ease the exploration of the outer solar system and Kuiper belt objects. At 5-8 AU per year, the TDM vehicle’s extraordinary speed will allow it to reach Voyager in 20 years. To put these distances into perspective, New Horizons launched in 2006 and thirteen years later performed the first flyby of Ultima Thule, a distant Kuiper Belt object that lies 1 billion miles (1.6 billion km) beyond Pluto.

Alan Stern, planetary scientist, Associate Vice President of the Southwest Research Institute and the Principal Investigator on New Horizons mission to Pluto said,

“This is an incredible mission with incredible technology. I am incredibly excited to see it selected for study by NIAC. SGLF offers to revolutionize both exoplanet science and propulsion technology if implemented.”

The design of the TDM spacecraft is led by Xplore Founder and Chief Technology Officer, Dr. Darren Garber, who helped develop L’Garde’s SunVane concept and provided operational support to LightSail. Dr. Garber will coordinate with JPL and Aerospace team members to ensure that the TDM vehicle’s design and future flight will represent the next step toward traversing 500 AU in 25 years or less.

Dr. Louis D. Friedman, Xplore Advisor and Co-Founder of The Planetary Society, worked on numerous flagship missions including Mariner, Voyager, Magellan and the Mars Program. A well-known champion of the Halley’s Comet Rendezvous-Solar Sail project back in the 70s with Dr. Carl Sagan, Dr. Friedman said,

“I’m proud that Xplore, led by our colleague Dr. Slava Turyshev, will advance the vision for space exploration Carl Sagan and I put in motion many years ago. The ability to harness the power of the Sun to rapidly transit to distant corners of our universe is a groundbreaking effort that will impact the science community for generations.”

Xplore’s team is comprised entirely of experienced U.S. space professionals who have supported all aspects of the design, development and operations of advanced technology missions for commercial, civil and national security space customers.

For the TDM, Dr. Garber and Xplore’s advanced engineering team will leverage key components, software and system engineering processes employed for its Xcraft™, a high-performance, ESPA-class, multi-mission spacecraft uniquely designed for missions in the inner solar system with a planned lunar radar mapping mission in early 2022. Their expertise will further define the SGLF Phase III study mission and architecture analysis such as using clusters of follow-on TDM vehicles to collectively mitigate risk and lower total system cost. Multiple mass-produced TDM spacecraft offer resiliency and scalability for a future decades-long mission, and the concept could allow other partners to contribute their own set of clustered spacecraft to cooperatively operate during the journey to the solar gravitational lens region in deep space.

Solar Gravity Lens Concept Receives $2M NASA Grant for Technology Maturation.
Aerospace Corp.

Lisa Rich said,

“Designing the fastest object ever made in the history of humanity is a challenge worthy of the legacy of Carl Sagan, and we look forward to advancing solar sail technologies with our Advisor, Dr. Lou Friedman. SGLF aligns with Xplore’s long-term vision for frequent, low-cost commercial missions to deep space. The ability to rapidly travel anywhere in the solar system expands our human footprint and will open up new avenues for scientific exploration.”

About Xplore Inc.: Xplore is a Seattle-based company offering Space as a Service™. Xplore provides hosted payloads, communication relay services and exclusive datasets to its customers via the Xcraft™, the company’s multi-mission spacecraft. Xplore’s mission is to expand robotic exploration via commercial missions at and beyond Earth, to the Moon, Mars, Venus, Lagrange points and near-Earth asteroids for national space agencies, national security agencies, sovereign space agencies and universities.

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ESO: Star orbiting supermassive black hole follows path predicted by Einstein

The latest ESO (European Southern Observatory) report:

ESO Telescope Sees Star Dance Around Supermassive Black Hole,
Proves Einstein Right

Observations made with ESO’s Very Large Telescope (VLT) have revealed for the first time that a star orbiting the supermassive black hole at the centre of the Milky Way moves just as predicted by Einstein’s theory of general relativity. Its orbit is shaped like a rosette and not like an ellipse as predicted by Newton’s theory of gravity. This effect, known as Schwarzschild precession, had never before been measured for a star around a supermassive black hole. This artist’s impression illustrates the precession of the star’s orbit, with the effect exaggerated for easier visualisation.

Observations made with ESO’s Very Large Telescope (VLT) have revealed for the first time that a star orbiting the supermassive black hole at the centre of the Milky Way moves just as predicted by Einstein’s general theory of relativity. Its orbit is shaped like a rosette and not like an ellipse as predicted by Newton’s theory of gravity. This long-sought-after result was made possible by increasingly precise measurements over nearly 30 years, which have enabled scientists to unlock the mysteries of the behemoth lurking at the heart of our galaxy.

“Einstein’s General Relativity predicts that bound orbits of one object around another are not closed, as in Newtonian Gravity, but precess forwards in the plane of motion. This famous effect — first seen in the orbit of the planet Mercury around the Sun — was the first evidence in favour of General Relativity. One hundred years later we have now detected the same effect in the motion of a star orbiting the compact radio source Sagittarius A* at the centre of the Milky Way. This observational breakthrough strengthens the evidence that Sagittarius A* must be a supermassive black hole of 4 million times the mass of the Sun,”

says Reinhard Genzel, Director at the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching, Germany and the architect of the 30-year-long programme that led to this result.

Located 26 000 light-years from the Sun, Sagittarius A* and the dense cluster of stars around it provide a unique laboratory for testing physics in an otherwise unexplored and extreme regime of gravity. One of these stars, S2, sweeps in towards the supermassive black hole to a closest distance less than 20 billion kilometres (one hundred and twenty times the distance between the Sun and Earth), making it one of the closest stars ever found in orbit around the massive giant. At its closest approach to the black hole, S2 is hurtling through space at almost three percent of the speed of light, completing an orbit once every 16 years.

“After following the star in its orbit for over two and a half decades, our exquisite measurements robustly detect S2’s Schwarzschild precession in its path around Sagittarius A*,”

says Stefan Gillessen of the MPE, who led the analysis of the measurements published today in the journal Astronomy & Astrophysics.

Most stars and planets have a non-circular orbit and therefore move closer to and further away from the object they are rotating around. S2’s orbit precesses, meaning that the location of its closest point to the supermassive black hole changes with each turn, such that the next orbit is rotated with regard to the previous one, creating a rosette shape. General Relativity provides a precise prediction of how much its orbit changes and the latest measurements from this research exactly match the theory. This effect, known as Schwarzschild precession, had never before been measured for a star around a supermassive black hole.

This simulation shows the orbits of stars very close to the supermassive black hole at the heart of the Milky Way. One of these stars, named S2, orbits every 16 years and is passing very close to the black hole in May 2018. This is a perfect laboratory to test gravitational physics and specifically Einstein’s general theory of relativity. Research into S2’s orbit was presented in a paper entitled “Detection of the Gravitational Redshift in the Orbit of the Star S2 near the Galactic Centre Massive Black Hole“, by the GRAVITY Collaboration, which appeared in the journal Astronomy & Astrophysics on 26 July 2018.

The study with ESO’s VLT also helps scientists learn more about the vicinity of the supermassive black hole at the centre of our galaxy.

“Because the S2 measurements follow General Relativity so well, we can set stringent limits on how much invisible material, such as distributed dark matter or possible smaller black holes, is present around Sagittarius A*. This is of great interest for understanding the formation and evolution of supermassive black holes,”

say Guy Perrin and Karine Perraut, the French lead scientists of the project.

This result is the culmination of 27 years of observations of the S2 star using, for the best part of this time, a fleet of instruments at ESO’s VLT, located in the Atacama Desert in Chile. The number of data points marking the star’s position and velocity attests to the thoroughness and accuracy of the new research: the team made over 330 measurements in total, using the GRAVITY, SINFONI and NACO instruments. Because S2 takes years to orbit the supermassive black hole, it was crucial to follow the star for close to three decades, to unravel the intricacies of its orbital movement.

The research was conducted by an international team led by Frank Eisenhauer of the MPE with collaborators from France, Portugal, Germany and ESO. The team make up the GRAVITY collaboration, named after the instrument they developed for the VLT Interferometer, which combines the light of all four 8-metre VLT telescopes into a super-telescope (with a resolution equivalent to that of a telescope 130 metres in diameter). The same team reported in 2018 another effect predicted by General Relativity: they saw the light received from S2 being stretched to longer wavelengths as the star passed close to Sagittarius A*.

“Our previous result has shown that the light emitted from the star experiences General Relativity. Now we have shown that the star itself senses the effects of General Relativity,”

says Paulo Garcia, a researcher at Portugal’s Centre for Astrophysics and Gravitation and one of the lead scientists of the GRAVITY project.

With ESO’s upcoming Extremely Large Telescope, the team believes that they would be able to see much fainter stars orbiting even closer to the supermassive black hole.

“If we are lucky, we might capture stars close enough that they actually feel the rotation, the spin, of the black hole,”

says Andreas Eckart from Cologne University, another of the lead scientists of the project. This would mean astronomers would be able to measure the two quantities, spin and mass, that characterise Sagittarius A* and define space and time around it.

“That would be again a completely different level of testing relativity,” says Eckart.

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Carnival of Space #657 – NextBigFuture.com

NextBigFuture.com hosts the latest Carnival of Space.

Analysis of the images of black holes will provide characterization of the rings of photons surrounding them, which in turn will produce information about the black holes themselves . Credits: CFA via Universe Today and Carnival of Space

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