Odd Star Reveals Magnetic Field Around Milky Way's Monster Black Hole

A strange, pulsing star has revealed a powerful magnetic field around the giant black hole at the heart of Earth’s Milky Way galaxy, scientists say.

The finding may help shed light on how the galaxy's supermassive black hole devours matter around it and spits out powerful jets of super hot matter, the researchers added.

The center of virtually every large galaxy is suspected to host a supermassive black hole with a mass that can range from millions to billions of times the mass of the sun. Astronomers think the Milky Way's core is home to the monster black hole called Sagittarius A* — pronounced "Sagittarius A-star" — that is about 4 million times the mass of Earth's sun. 

Scientists want to learn more about how black holes distort the universe around them, hoping to see if the leading theory regarding black holes, Einstein's theory of general relativity, holds up or if new concepts might be necessary. One way to see how black holes warp space and time is by looking at clocks near them. Cosmic versions of clocks are known as pulsars — rapidly spinning neutron stars that regularly give off pulses of radio waves.

Pulsar tells the tale

Astronomers have been searching for pulsars near Sagittarius A* for the past 20 years.

Earlier this year, NASA's NuSTAR telescope helped confirm the existence of such a pulsar apparently less than half a light-year away from the black hole, one that pulsates radio signals every 3.76 seconds. Scientists quickly analyzed the pulsar using the Effelsberg Radio Observatory of the Max Planck Institute for Radio Astronomy in Bonn, Germany.

"On our first attempt, the pulsar was not clearly visible, but some pulsars are stubborn and require a few observations to be detected," said study lead author Ralph Eatough, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany. "The second time we looked, the pulsar had become very active in the radio band and was very bright. I could hardly believe that we had finally detected a pulsar in the galactic center." 

Additional observations were performed in parallel and subsequently with other radio telescopes around the world. "We were too excited to sleep in between observations," said study co-author Evan Keane from the Jodrell Bank Observatory in England.

The newfound pulsar, named PSR J1745-2900, belongs to a rare kind of pulsars known as magnetars, which only make up about 1 out of every 500 pulsars found to date. Magnetars possess extremely powerful magnetic fields, ones about 1,000 times stronger than the magnetic fields of ordinary neutron stars, or 100 trillion times the Earth's magnetic field.

The radio pulses from magnetars are highly polarized, meaning these signals oscillate along one plane in space. This fact helped the researchers detect a magnetic field surrounding Sagittarius A*.

Black hole magnetic field revealed

Black holes swallow their surroundings, mainly hot ionized gas, in a process of accretion. Magnetic fields threading within this accretion flow can influence how this infalling gas is structured and behaves.

"The magnetic field we measure around the black hole can regulate the amount of matter the black hole eats and could even cause it to spit matter out in so-called jets," Eatough told SPACE.com. "These measurements are therefore of great importance in understanding how supermassive black holes feed, a process that can affect galaxy formation and evolution."

As radio signals traverse the magnetized gas around black holes, the way they are polarized gets twisted depending on the strength of the magnetic fields. By analyzing radio waves from the magnetar, the researchers discovered a relatively strong, large-scale magnetic field pervades the area surrounding Sagittarius A*.

In the area around the pulsar, the magnetic field is about 100 times weaker than Earth's magnetic field. However, "the field very close to the black hole should be much stronger — a few hundred times the Earth's magnetic field," Eatough said.

If the magnetic field generated by the infalling gas is accreted down to the event horizon of the black hole — its point of no return — that could help explain the radio and X-ray glow long associated with Sagittarius A*, researchers added.

"It is amazing how much information we can extract from this single object," said study co-author Adam Deller at the Netherlands Institute for Radio Astronomy in Dwingeloo.

Astronomers predict there should be thousands of pulsars around the center of the Milky Way. Despite that, PSR J1745-2900 is the first pulsar discovered there. "Astronomers have searched for decades for a pulsar around the central black hole in our galaxy, without success. This discovery is an enormous breakthrough, but it remains a mystery why it has taken so long to find a pulsar there," said study co-author Heino Falcke at Radboud Universiteit Nijmegen in the Netherlands.

"It could be the environment is very dense and patchy, making it difficult to see other pulsars," Eatough added.

The researchers cannot test the leading theory regarding black holes using PSR J1745-2900 — they cannot measure the way it warps space-time accurately enough, since the pulsar is slightly too far away from Sagittarius A* and, being relatively young, its spin is too variable. The researchers suggest pulsars that are closer to the black hole and are older with less variable spins could help test the theory.

"If there is a young pulsar, there should also be many older ones. We just have to find them," said study co-author Michael Kramer, director of the Max Planck Institute for Radio Astronomy.

Source of Article: Space.com

NASA Maps Dangerous Asteroids That May Threaten Earth

If you've seen films like "Armageddon," you know the potential threat asteroids can be for Earth. To meet that threat, NASA has built a map like no other: a plot of every dangerous asteroid that could potentially endanger our planet … at least the ones we know about.

NASA released the new map of "potentially hazardous asteroids" on Aug. 2 in a post to its online Planetary Photojournal overseen by the agency's Jet Propulsion Laboratory in Pasadena, Calif. The map shows the orbital paths of more than 1,400 asteroids known creep too close to Earth for comfort. None of the asteroids mapped pose an impact threat to Earth within the next 100 years, agency officials said.

"These are the asteroids considered hazardous because they are fairly large (at least 460 feet or 140 meters in size), and because they follow orbits that pass close to the Earth's orbit (within 4.7 million miles or 7.5 million kilometers)," NASA officials explained in the image description.

The asteroid map shows a dizzying swarm of overlapping blue ellipses (the asteroid orbits) surrounding the sun. The orbits of Earth, Venus, Mercury, Mars and Jupiter are also visible to put the asteroid orbits in perspective on a solar system-wide scale.

If you're worried about a rogue asteroid or comet obliterating life as we know it this week, don't panic just yet. Just because the asteroids in the new NASA map are classified as "potentially hazardous" — scientists call them PHAs in NASA-speak — that doesn't mean they are an imminent threat to the Earth, NASA said.

According to NASA, "being classified as a PHA does not mean that an asteroid will impact the Earth: None of these PHAs is a worrisome threat over the next 100 years. By continuing to observe and track these asteroids, their orbits can be refined and more precise predictions made of their future close approaches and impact probabilities."

NASA scientists and astronomers around the world are constantly searching for asteroids that may pose an impact threat to Earth. NASA has said that roughly 95 percent of the largest asteroids that could endanger Earth — space rocks at least 0.6 miles (1 km) wide — have been identified through these surveys.

At the Jet Propulsion Laboratory, NASA's Asteroid Watch project scientists work to share the latest asteroid discoveries and potential threats with the public. The Asteroid Watch is part of NASA's Near-Earth Object Program that studies asteroids and comets, as well as their potential impact threats to the Earth and other planets.

Source of Article: Space.com

NASA Picks Rocket to Launch Asteroid Sample-Return Mission

NASA has picked the rocket that will launch a spacecraft to a near-Earth asteroid in 2016 to collect samples of the space rock and return them to Earth.

The U.S. space agency has tapped an Atlas 5 rocket built by the Englewood, Colo.-based company United Launch Services to launch the asteroid-sampling OSIRIS-Rex mission. The $800 million asteroid mission will launch from Florida's Cape Canaveral Air Force Station in September 2016. 

The OSIRIS-Rex spacecraft will collect samples of the asteroid 101955 Bennu, which is on the agency's watch list for potentially dangerous asteroids that could pose an impact threat to Earth. The asteroid has a 1-in-1,000 chance of hitting Earth in 2182, so taking a close look at it will help scientists develop deflection methods, should it actually be required.

"OSIRIS-REx will survey near-Earth asteroid 101955 Bennu to understand its physical, mineralogical and chemical properties; assess its resource potential; refine the impact hazard; and return a sample to Earth," NASA officials wrote in a statement. "The spacecraft will rendezvous with the asteroid in 2018. Sample return is planned in 2023. Analysis of the sample returned will reveal the earliest stages of the solar system's evolution and the history of Bennu over the past 4.5 billion years."

Under NASA's $183.5 million contract with the United Launch Services, the launch provider will oversee payload processing, integrated services, telemetry and other launch support requirements.

OSIRIS-REx — which is short for Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer — is scheduled to rendezvous with the 1,840-foot-wide (560 meters) space rock in 2018 and then return the samples to Earth in 2023.

Researchers are also hoping to use the asteroid samples to learn about the earliest stages of the solar system's evolution and what Bennu has been up to over the past 4.5 billion years. The spacecraft will also help scientists study the Yarkovsky effect, a push from the sun's radiation that can alter an asteroid's orbit, NASA said.

Source of Article: Space.com

What Is the 'Hyperloop'? Billionaire Elon Musk to Reveal Futuristic Transportation Idea Monday

The fevered speculation about billionaire entrepreneur Elon Musk's mysterious "Hyperloop" transport system is about to come to an end.

Musk, the visionary behind electric-car firm Tesla and the private spaceflight company SpaceX, has said he will unveil a Hyperloop design on Monday (Aug. 12), after teasing the world about the superfast travel technology for more than a year.

The solar-powered Hyperloop would allow passengers to get from Los Angeles to San Francisco in less than 30 minutes, Musk has said, meaning it must travel at speeds greater than 600 mph (966 km/h). The system would be cheap and convenient, he added, with tickets costing less than a seat aboard a plane or train and Hyperloop vehicles departing frequently from their various stations.

Though we don't know exactly how the Hyperloop will work or what it will look like, Musk has dropped some hints since first disclosing the concept in July 2012. For example, this past May he described the Hyperloop as a "cross between a Concorde and a railgun and an air hockey table."

Using that statement as inspiration, self-described "tinker" John Gardi drew up a design of a system that uses air to blast cars through long tubes. Gardi's concept "is the closest I've seen anyone guess so far," Musk tweeted on July 15. 

Musk has shared some other news about the project lately, revealing that he probably won't have much time to develop the Hyperloop — at least not in the near future.

"I have to focus on core Tesla business and SpaceX business, and that's more than enough," Musk said Tuesday (Aug. 7) during a conference call with Tesla investors, Gizmodo reported.

During the call, Musk expressed hope that the worldwide community of engineers and inventors can make something happen with the Hyperloop design he puts out there. But he didn't close off the possibility of helping out in the future.

"If nothing happens for a few years, with that I mean maybe it could make sense to make the halfway path with Tesla involvement," Musk said, according to Gizmodo. "But [what] I would say is, you shouldn't be speculative."

Source of Article: Space.com

Perseid Meteor Shower: Scientists Will Fire Laser Into Meteor Trails

When the Perseid meteors streak across the sky this weekend, they will leave a trail of celestial pollution in their wake, sprinkling a layer of gases high up in the atmosphere.

This pollution doesn't pose a threat to Earth. If anything, it's a gift to scientists: Astronomers will fire powerful lasers into the gassy Perseid meteor shower debris, creating artificial stars that help researchers snap clearer photos of the cosmos.

"One of the gases left behind by meteors is sodium, which collects in a layer about 60 miles (90 kilometers) above the Earth," Chad Trujillo, head of the Gemini Observatory's adaptive optics program, said in a statement.

"The reason astronomers are so fond of this particular pollution layer is because we can make it glow by using a sodium laser to excite this sodium and produce temporary, artificial stars wherever we like," Trujillo added. "Believe it or not, there aren't enough stars in the sky for astronomers!"

Through adaptive optics systems, scientists can cancel out the hazy interference of Earth's atmosphere during telescope observations from the ground; this allows them to see the universe with remarkable clarity. Artificial stars, also called laser guide stars, can help astronomers correct these adaptive optics systems. They analyze light from guide stars to create a baseline to determine the blurring effects of the atmosphere.

"Perhaps one person's celestial 'pollution' is another's 'natural resource,'" Maria Womack, an astronomy program officer at the U.S. National Science Foundation, said in a statement. "It's this sodium layer, provided courtesy of meteors like the Perseids, that astronomers use to get the clearest views and understand the universe better."

The Gemini South Observatory in Chile uses five separate laser beams to create a "constellation" of laser guide stars to help correct their advanced adaptive optics system. As ground-based telescopes get bigger, they will need more advanced adaptive optics systems like Gemini's to let astronomers see clearly through a wider column of Earth's atmosphere, Trujillo explained.

"The wider the column of air, the more turbulence in the air will distort the observed light," Trujillo said. "Using laser guide stars gives us a reference so we can correct for that turbulence and see things with amazing clarity from the ground."

The Perseid meteor display occurs every year in mid-August when the Earth passes through the dusty from the Comet Swift-Tuttle. This dust burns up in Earth's atmosphere, creating the streaks of meteors visible to observers on the ground. The Perseids will peak overnight between Aug. 11 and 12, and Aug. 12 and 13.

Source of Article: Space.com

Hubble Telescope Finds Source of Cosmic Stream Near Milky Way

For decades, scientists were at a loss to explain the source of the so-called Magellanic Stream, a long ribbon of gas discovered in the early 1970s that extends nearly halfway around the Milky Way.

But new data from NASA's Hubble Space Telescope have helped astronomers crack the case. The observations show that the stream did not form all at once; instead, the ribbon is a combination of material stripped at different times from both the Large Magellanic Cloud and the Small Magellanic Cloud, two satellite galaxies that hover around the Milky Way less than 200,000 light years away.

About 2 billion years ago, material was pulled from the Small Magellanic Cloud, creating part of the gassy filament, while a second region of the stream originated more recently from the Large Magellanic Cloud, the researchers say.

The team determined the source of the ribbon by measuring the abundances of heavy elements at six locations different along the Magellanic Stream using Hubble's Cosmic Origins Spectrograph, according to a statement from NASA. (Scientists can detect theses faraway heavy elements through the way they absorb ultraviolet light.)

Low levels of oxygen and sulfur found throughout most of the stream match the chemical makeup of the Small Magellanic Cloud, the researchers said. But they also found a surprising amount of sulfur in a part of the stream that's closer to the Magellanic Clouds.

"We're finding a consistent amount of heavy elements in the stream until we get very close to the Magellanic Clouds, and then the heavy element levels go up," study researcher Andrew Fox of the Space Telescope Science Institute in Baltimore, Md., said in a statement. "This inner region is very similar in composition to the Large Magellanic Cloud, suggesting it was ripped out of that galaxy more recently."

By studying the stream, researchers could learn more about how larger galaxies affect their surrounding satellite galaxies, Fox explained.

"We want to understand how galaxies like the Milky Way strip the gas from small galaxies that fall into them and then use it to form new stars," he added in a statement. "This seems like it's an episodic process. It's not a smooth process where a slow stream of gas comes in continuously. Instead, once in a while a large gas cloud falls in. We have a way of testing that here, where two galaxies are coming in. We've shown which of them is producing the gas that ultimately will fall into the Milky Way."

Source of Article: Space.com

Pink Alien Planet Is Smallest Photographed Around Sun-Like Star

Astronomers have snapped a photo of a pink alien world that's the smallest yet exoplanet found around a star like our sun.

The alien planet GJ 504b is a colder and bluer world than astronomers had anticipated and it likely has a dark magenta hue, infrared data from the Subaru Telescope in Hawaii revealed.

"If we could travel to this giant planet, we would see a world still glowing from the heat of its formation with a color reminiscent of a dark cherry blossom, a dull magenta," study researcher Michael McElwain, of NASA's Goddard Space Flight Center in Greenbelt, Md., said in a statement from the space agency.

"Our near-infrared camera reveals that its color is much more blue than other imaged planets, which may indicate that its atmosphere has fewer clouds," McElwain added.

The exoplanet orbits the bright star GJ 504, which is 57 light-years from Earth, slightly hotter than the sun and faintly visible to the naked eye in the constellation Virgo. The star system is relatively young at roughly 160 million years old. (For comparison, Earth's system is 4.5 billion years old).

Though it is the smallest alien world caught on camera around a sun-like star, the gas planet around GJ 504 is still huge — about four times the size of Jupiter. It lies nearly 44 Earth-sun distances from its central star, far beyond the system's habitable zone, and it has an effective temperature of about 460 degrees Fahrenheit (237 Celsius), according to the researchers' estimates.

The exoplanet's features challenge the core-accretion model of planet formation, they study's researchers say. Under this widely accepted theory, asteroid and comet collisions produce a core for Jupiter-like planets and when they gets massive enough, their gravitational pull draws in gas from the gas-rich disk of debris that circles their young star. But this model doesn't explain the formation of planets like GJ 504b that are far away from their parent star.

"This is among the hardest planets to explain in a traditional planet-formation framework," study researcher Markus Janson, a Hubble postdoctoral fellow at Princeton University in New Jersey, said in a statement. "Its discovery implies that we need to seriously consider alternative formation theories, or perhaps to reassess some of the basic assumptions in the core-accretion theory."

The discovery of GJ 504b was part of a larger survey, the Strategic Exploration of Exoplanets and Disks with Subaru or SEEDS program, which seeks to explain how planetary systems come together by looking at star systems of many sizes and ages with images at near-infrared wavelengths.

Direct imaging can help scientists measure an alien planet's luminosity, temperature, atmosphere and orbit, but it's difficult to detect faint planets next to their bright parent stars. The study's leader, Masayuki Kuzuhara of the Tokyo Institute of Technology, said the task is "like trying to take a picture of a firefly near a searchlight."

Two of the Subaru Telescope's tools in particular — the High Contrast Instrument for the Subaru Next Generation Adaptive Optics and the InfraRed Camera and Spectrograph — help scientists tease out light from these faint exoplanet sources.

Source of Article: Space.com