Tuesday, November 7, 2017

The Most Powerful Magnets in the Universe Are Collapsed Stars

When a large star dies, sometimes it becomes a neutron star, a tiny, 12 mile across ball that's made almost entirely out of neutrons. These dead stars are incredibly dense, and spin incredibly fast. Just one thimbleful of neutron star would weigh 100 million tons. Magnetars are a variation of neutron stars, and they somehow manage to be even scarier. Neutron stars already have extremely strong magnetic fields--about 2 trillion times more powerful than Earth's. Yet magnetars have magnetic fields 1,000 times stronger than that. Yeah, that's a pretty intense field. Magnetars are not just insanely powerful--they're also very, very dangerous. If you were a mere 1,000 kilometers from a magnetar, your entire body would dissolve as the magnetic field rearranged the sequence of atoms in your body. 

In addition to their terrifying magnetic powers, magnetars also have something called starquakes, which function similarly to earthquakes here on Earth--except with much more intense results. A crack in the crust of a magnetar is responsible for the brightest light we've ever observed from space. And if a magnetar was closer to us, like 10 light years away, and blasted us with the radiation from a starquake, it would destroy our ozone layer and probably kill all life on Earth.

But don't worry--thankfully, there aren't any magnetars near Earth. The closest one is about 9,000 light years away. Let's pray that it stays that way.

Tuesday, October 31, 2017

Three New Gas Giants May Provide Hint Into Major Astronomical Mystery

European astronomers with the Super Wide Angle Search for Planets (SuperWASP) consortium of planet hunters have detected three new gas giant alien worlds.The SuperWASP is an international effort to use the Roque de los Muchachos Observatory in Spain and the South African Astronomical Observatory to discover exoplanets. Both observatories are equipped with eight wide-angle cameras that monitor the sky for planetary transit events (when planets pass in front of their stars, allowing them to be imaged by human telescopes). The three planets were discovered orbiting three stars also discovered by the SuperWASP program: WASP-151, WASP-153 and WASP-156. "In this paper, we report the discovery of three transiting exoplanets by the SuperWASP survey and the SOPHIE spectrograph with mass and radius determined with a precision better than 15 percent," wrote the astronomers, led by a team out of the University of Porto in Portugal.

Two of the planets are "hot Saturns," large but low-density gas giants that are very close to their stars. The larger of the two, WASP-153b, has a radius 1.86 times that of Saturn and is 1.3 times as dense. The smaller hot Saturn, WASP-151b, is 1.36 times larger than Saturn and is 1.03 times as dense. Both of them have orbital periods of less than a week.

Meanwhile, the third planet is a "super-Neptune:" a planet appreciably bigger than Neptune (2.5 times more massive in this case) but smaller than Saturn, which is about five times more massive than Neptune. This third planet, WASP-156b, only needs 3.83 days to complete a revolution around its star.

This third find is the exciting one to astronomers, as shockingly few super-Neptunes have been discovered — a dearth named the so-called "Neptunian Desert." Many terrestrial planets (like Earth and Venus), gas giants (like Jupiter and Saturn), and super-Earths (like Uranus and Neptune) have been discovered. Meanwhile 156b is only the ninth-ever super-Neptune to be found of the thousand-plus exoplanets confirmed — and nobody is sure why.

"These three planets also lie close to (WASP-151b and WASP-153b) or below (WASP-156b) the upper boundary of the Neptunian desert. (…) While a detailed analysis of the origin of the Neptunian desert is beyond the scope of this paper, it is still interesting to look into the similarities and differences between WASP-156b and WASP-151b/WASP-153b since they might provide useful hints on the nature of this desert," the paper reads.

Monday, October 30, 2017

SpaceX to Launch Korean Communications Satellite Today: Watch It Live

SpaceX aims to pull off another launch-and-landing double play today (Oct. 30), and you can watch all the spaceflight action live. A SpaceX two-stage Falcon 9 rocket is scheduled to launch the KoreaSat 5A communications satellite at 3:34 p.m. EDT (1934 GMT) today from Florida's Cape Canaveral Air Force Station. You can courtesy of SpaceX, or directly via the company at http://www.spacex.com/webcast. If all goes according to plan, the booster's first stage will return to Earth for a soft landing less than 10 minutes after liftoff, settling vertically onto a SpaceX "drone ship" stationed off the Florida coast. Such landings are part of SpaceX's plan to develop fully and rapidly reusable rockets and space vehicles, a key priority for the company and its billionaire founder and CEO, Elon Musk. To date, SpaceX has aced 18 Falcon 9 touchdowns and re-launched landed boosters on three different occasions.

SpaceX has also re-flown a Dragon cargo capsule once and aims to do so again on its next resupply run to the International Space Station for NASA, which will launch no earlier than December.

KoreaSat 5A is owned by the South Korean company KTSat. The satellite will provide TV and other communications services to people in South Korea, Japan and Southeast Asia, according to the company's website. The satellite will also aid maritime communications from East Africa to East Asia.

KoreaSat 5A will replace KoreaSat 5, which launched in 2006.

Friday, October 27, 2017

We may have just seen the first comet from another solar system

The solar system may be hosting a visitor from the stars. A newly discovered comet is screaming away from Earth, and based on its weird orbital trajectory astronomers think it might be the first comet ever observed that came from interstellar space. A sky-surveying telescope in Hawaii spotted the fast-moving object, now called C/2017 U1, on 18 October, after its closest approach to the sun. During the next week, astronomers made 34 separate observations of the object and found it has a strange trajectory that is at an angle to the orbits of the planets and does not circle the sun. Now, astronomers are hoping more skywatchers will take a look and pin down whether it’s from our neighborhood or an interloper from beyond. Most comets follow ellipse-shaped orbits around the sun, swooping in from the distant Oort Cloud to kiss the inner solar system before heading back out again. This one, by contrast, will never return. Its orbital path suggests it sailed in from the direction of the constellation Lyra above the relatively flat plane of the solar system, looped around the sun, and is headed back out for eternity.

Lyra is near the direction the sun is moving within the Milky Way, says Luke Dones at the Southwest Research Institute in Boulder, Colorado. “That’s exactly what you’d expect; there should be more interstellar comets coming from the direction the sun is heading toward,” he says.
Just popping in

“It’s coming from very far away, but we can’t actually backtrack how far away it started. It could be that it’s coming from outside the solar system, but it’s really hard to tell,” says Simon Porter, also at the Southwest Research Institute. Further observations in the next couple weeks will make the picture clearer.

What’s more, a comet on such an extreme path doesn’t necessarily have to come from interstellar space. “It could have interacted with Jupiter or another planet in such a way that changed its orbit,” says Maria Womack at the University of South Florida in Tampa.

The comet’s origins are hard to pin down in part because of the nature of comets. “When you think of photos of comets, they’re a fuzzy blob. People have to make determinations of where they think the center is. Someone who is at the telescope has to make a call,” Womack says.

This necessary guesswork makes the measurements less precise, so astronomers want lots of observations before they’ll be convinced the comet really is from beyond our solar system, she adds.

Luckily, there are plenty of opportunities left to take a peek. The comet should be visible in powerful telescopes for at least another couple weeks, allowing amateurs and professionals alike to survey the icy visitor and determine its history.

Wednesday, June 28, 2017

Success of Gravity-Wave Satellite Paves Way for 3-Craft Mission

Europe’s gravitational-wave hunters are celebrating. On July 1, a satellite will wrap up its mission to test technology for the pioneering quest to measure gravitational ripples in the stillness of space. Over the past year, the craft has performed much better than many had hoped. That success has convinced the European Space Agency (ESA) to give the go-ahead to a full-scale version able to sense cataclysmic events that can’t be felt on Earth. The LISA Pathfinder mission, launched in late 2015, beat its precision target by a factor of 1,000 and quieted critics who have doubted its potential, says project scientist Paul McNamara, an astrophysicist at ESA in Noordwijk, the Netherlands. “This is not the impossible task that some people believed it was.” Currently set to fly in 2034, the full-scale Laser Interferometer Space Antenna (LISA) will be the space analogue of the Laser Interfero-meter Gravitational-Wave Observatory (LIGO), two machines in the United States—each with a pair of 4-kilometre-long arms—that first detected the ripples by ‘hearing’ the merger of two black holes.

LISA Pathfinder—shown before being encapsulated into a rocket for launch—allowed scientists to test technology for detecting gravitational waves. 

 LISA’s three probes will fly in a triangle, millions of kilometres apart, making the mission sensitive to much longer gravitational waves, such as the ripples produced by the collisions of even larger black holes.

The mission will bounce laser beams between the three LISA craft—or, more precisely, between test masses suspended in a vacuum inside each satellite. Taking advantage of the vibration-free conditions of space, it will measure tiny variations in the distances between the test masses that reveal the passage of space-warping gravitational waves.

LISA Pathfinder’s goal was to show that such variations could be measured in zero gravity and with a precision of one pico-metre, or one-billionth of a millimetre. High-precision thrusters adjusted Pathfinder’s route so that it would closely follow the gravitational free fall of two test masses inside the craft and not interfere with their orbit. At the same time, the probe bounced a laser beam between the two masses—a pair of 2-kilogram cubes made of a gold and platinum alloy—and measured fluctuations in their separation.

The €400-million (US$447-million) probe was declared a success in February 2016, two weeks after LIGO announced its first detection. Pathfinder did not detect gravitational waves—which would not have appreciable effects over the short distance inside the probe—but it showed that it could detect motions 100 times smaller than the pico-metre requirement. Since then, the experiment’s performance has improved by another order of magnitude (M. Armano et al. Phys. Rev. Lett. 118,171101; 2017).

By early June this year, LISA Pathfinder had almost run out of thruster fuel, and mission control used what was left to nudge the spacecraft out of its operating orbit and into its final orbit around the Sun. On 1 July, Pathfinder will stop collecting data, and the spacecraft will be put to sleep for good on 18 July.

Pathfinder was “a triumph”, says William Klipstein, a physicist at NASA’s Jet Propulsion Laboratory in Pasadena, California, who works on LISA development but was not involved in ESA’s Pathfinder mission. Its performance “removes the last major technical barrier for proceeding with a long-planned ESA-led gravitational-wave mission”, he says.

In a unanimous decision on June 20, ESA’s Science Programme Committee officially selected LISA as the third of the agency’s large, or €1-billion-class, mission in its current science programme. The approval was long-awaited but had been in little doubt after Pathfinder’s success and LIGO’s gravitational-wave discoveries, says Karsten Danzmann, a director of the Max Planck Institute for Gravitational Physics in Hanover, Germany, and Pathfinder’s co-principal investigator.

The decision is not final, but it means that industrial partners will now be involved in detailed design and cost projections. Once those are finished, ESA will decide whether to ‘adopt’ the mission and commit the funding to build it. The United States—which was an equal partner in the mission until 2011, when it reduced its participation to save costs—is expected to provide important components.

ESA has chosen two other large missions to go ahead before LISA—one to the moons of Jupiter, slated to launch in 2022, and an X-ray observatory for 2028. This puts LISA on schedule to be launched in 2034. But Pathfinder principal investigator Stefano Vitale, a physicist at the University of Trento in Italy, and others hope that its schedule can be accelerated. ESA’s call for proposals to lead the gravitational-wave observatory—won by Vitale’s team—was put out in late 2016, instead of late 2019 as the agency had planned. Vitale and other gravitational-wave researchers hope the agency will push the launch date forward so that LISA can start sending back data before too many of the current key researchers have retired.

Sunday, June 25, 2017

Hubble Captures Massive Dead Disk Galaxy that Challenges Theories of Galaxy Evolution

By combining the power of a "natural lens" in space with the capability of NASA's Hubble Space Telescope, astronomers made a surprising discovery—the first example of a compact yet massive, fast-spinning, disk-shaped galaxy that stopped making stars only a few billion years after the big bang. Finding such a galaxy early in the history of the universe challenges the current understanding of how massive galaxies form and evolve, say researchers. When Hubble photographed the galaxy, astronomers expected to see a chaotic ball of stars formed through galaxies merging together. Instead, they saw evidence that the stars were born in a pancake-shaped disk.

Acting as a “natural telescope” in space, the gravity of the extremely massive foreground galaxy cluster MACS J2129-0741 magnifies, brightens, and distorts the far-distant background galaxy MACS2129-1, shown in the top box. The middle box is a blown-up view of the gravitationally lensed galaxy. In the bottom box is a reconstructed image, based on modeling that shows what the galaxy would look like if the galaxy cluster were not present. The galaxy appears red because it is so distant that its light is shifted into the red part of the spectrum.
Credits: NASA, ESA, S. Toft (University of Copenhagen), M. Postman (STScI), and the CLASH team

This is the first direct observational evidence that at least some of the earliest so-called "dead" galaxies — where star formation stopped — somehow evolve from a Milky Way-shaped disk into the giant elliptical galaxies we see today.

This is a surprise because elliptical galaxies contain older stars, while spiral galaxies typically contain younger blue stars. At least some of these early "dead" disk galaxies must have gone through major makeovers. They not only changed their structure, but also the motions of their stars to make a shape of an elliptical galaxy.

"This new insight may force us to rethink the whole cosmological context of how galaxies burn out early on and evolve into local elliptical-shaped galaxies," said study leader Sune Toft of the Dark Cosmology Center at the Niels Bohr Institute, University of Copenhagen, Denmark. "Perhaps we have been blind to the fact that early "dead" galaxies could in fact be disks, simply because we haven't been able to resolve them."

This artist's concept shows what the young, dead, disk galaxy MACS2129-1, right, would look like when compared with the Milky Way galaxy, left. Although three times as massive as the Milky Way, it is only half the size. MACS2129-1 is also spinning more than twice as fast as the Milky Way. Note that regions of Milky Way are blue from bursts of star formation, while the young, dead galaxy is yellow, signifying an older star population and no new star birth.
Credits: NASA, ESA, and Z. Levy (STScI)

Previous studies of distant dead galaxies have assumed that their structure is similar to the local elliptical galaxies they will evolve into. Confirming this assumption in principle requires more powerful space telescopes than are currently available.

However, through the phenomenon known as "gravitational lensing," a massive, foreground cluster of galaxies acts as a natural "zoom lens" in space by magnifying and stretching images of far more distant background galaxies. By joining this natural lens with the resolving power of Hubble, scientists were able to see into the center of the dead galaxy.

The remote galaxy is three times as massive as the Milky Way but only half the size. Rotational velocity measurements made with the European Southern Observatory's Very Large Telescope (VLT) showed that the disk galaxy is spinning more than twice as fast as the Milky Way.

Using archival data from the Cluster Lensing And Supernova survey with Hubble (CLASH), Toft and his team were able to determine the stellar mass, star-formation rate, and the ages of the stars.

Why this galaxy stopped forming stars is still unknown. It may be the result of an active galactic nucleus, where energy is gushing from a supermassive black hole. This energy inhibits star formation by heating the gas or expelling it from the galaxy. Or it may be the result of the cold gas streaming onto the galaxy being rapidly compressed and heated up, preventing it from cooling down into star-forming clouds in the galaxy's center.

But how do these young, massive, compact disks evolve into the elliptical galaxies we see in the present-day universe? "Probably through mergers," Toft said. "If these galaxies grow through merging with minor companions, and these minor companions come in large numbers and from all sorts of different angles onto the galaxy, this would eventually randomize the orbits of stars in the galaxies. You could also imagine major mergers. This would definitely also destroy the ordered motion of the stars."

The findings are published in the June 22 issue of the journal Nature. Toft and his team hope to use NASA's upcoming James Webb Space Telescope to look for a larger sample of such galaxies.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

The Very Large Telescope is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of Northern Chile.

Tuesday, May 30, 2017

VLT snaps an exotic exoplanet

Astronomers hunt for planets orbiting other stars (exoplanets) using a variety of methods. One successful method isdirect imaging; this is particularly effective for planets on wide orbits around young stars, because the light from the planet is not overwhelmed by light from the host star and is thus easier to spot. This image demonstrates this technique. It shows a T-Tauri star named CVSO 30, located approximately 1200 light-years away from Earth in the 25 Orionis group (slightly northwest of Orion’s famous Belt). In 2012, astronomers found that CVSO 30 hosted one exoplanet (CVSO 30b) using a detection method known as transit photometry, where the light from a star observably dips as a planet travels in front of it. Now, astronomers have gone back to look at the system using a number of telescopes. The study combines observations obtained with the ESO’s Very Large Telescope (VLT) in Chile, the W. M. Keck Observatory in Hawaii, and the Calar Alto Observatory facilities in Spain.

Using the data astronomers have imaged what is likely to be a second planet! To produce the image, astronomers exploited the astrometry provided by VLT’s NACO and SINFONI instruments.

This new exoplanet, named CVSO 30c, is the small dot to the upper left of the frame (the large blob is the star itself). While the previously-detected planet, CVSO 30b, orbits very close to the star, whirling around CVSO 30 in just under 11 hours at an orbital distance of 0.008 au, CVSO 30c orbits significantly further out, at a distance of 660 au, taking a staggering 27 000 years to complete a single orbit. (For reference, the planet Mercury orbits the Sun at an average distance of 0.39 au, while Neptune sits at just over 30 au.)

If it is confirmed that CVSO 30c orbits CVSO 30, this would be the first star system to host both a close-in exoplanet detected by the transit method and a far-out exoplanet detected by direct imaging. Astronomers are still exploring how such an exotic system came to form in such a short timeframe, as the star is only 2.5 million years old; it is possible that the two planets interacted at some point in the past, scattering off one another and settling in their current extreme orbits.