Asteroid 2004 BL86: NEO That Flew Past Earth Has A Companion Moon - Binary

This movie of asteroid 2004 BL86 was generated from data collected by NASA's Deep Space Network antenna at Goldstone, California, on Jan. 26, 2015. Twenty individual images were used.

Credit: NASA

Scientists working with NASA's 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, California, have released the first radar images of asteroid 2004 BL86.

The images show the asteroid, which made its closest approach on Jan. 26, 2015 at 8:19 a.m. PST (11:19 a.m. EST) at a distance of about 745,000 miles (1.2 million kilometers, or 3.1 times the distance from Earth to the moon), has its own small moon.

The 20 individual images used in the movie were generated from data collected at Goldstone on Jan. 26, 2015.

They show the primary body is approximately 1,100 feet (325 meters) across and has a small moon approximately 230 feet (70 meters) across.

In the near-Earth population, about 16 percent of asteroids that are about 655 feet (200 meters) or larger are a binary (the primary asteroid with a smaller asteroid moon orbiting it) or even triple systems (two moons).

The resolution on the radar images is 13 feet (4 meters) per pixel.

The trajectory of asteroid 2004 BL86 is well understood. Monday's flyby was the closest approach the asteroid will make to Earth for at least the next two centuries.

It is also the closest a known asteroid this size will come to Earth until asteroid 1999 AN10 flies past our planet in 2027.

Asteroid 2004 BL86 was discovered on Jan. 30, 2004, by the Lincoln Near-Earth Asteroid Research (LINEAR) survey in White Sands, New Mexico.

Radar is a powerful technique for studying an asteroid's size, shape, rotation state, surface features and surface roughness, and for improving the calculation of asteroid orbits.

Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than if radar observations weren't available.

NASA places a high priority on tracking asteroids in a vain effort that this will somehow protect our home planet from them.

In fact, the U.S. believes it has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs), and report that to date, taking into account all U.S. assets, both civil and military, they have discovered over 98 percent of the known NEOs.

ESO ALMA Observatory: Young binary star system form planets with weird and wild orbits

This is ALMA data of HK Tau shown in a composite image with Hubble infrared and optical data. 

Credit: B. Saxton (NRAO/AUI/NSF); K. Stapelfeldt et al. (NASA/ESA Hubble)

Unlike our solitary Sun, most stars form in binary pairs, two stars that orbit a common center of mass.

Though remarkably plentiful, binaries pose a number of questions, including how and where planets form in such complex environments.

While surveying a series of binary stars with the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers uncovered a striking pair of wildly misaligned planet-forming disks in the young binary star system HK Tau.

These results provide the clearest picture ever of proto-planetary disks around a double star and could reveal important details about the birth and eventual orbit of planets in a multiple star system.

"ALMA has given us an unprecedented view of a main star and its binary companion sporting mutually misaligned protoplanetary disks," said Eric Jensen, an astronomer at Swarthmore College in Pennsylvania.

"In fact, we may be seeing the formation of a solar system that may never settle down."

The two stars in this system, which is located approximately 450 light-years from Earth in the constellation Taurus, are less than 5 million years old and separated by about 58 billion kilometers, or 13 times the distance of Neptune from the Sun.

This system's companion star, dubbed HK Tau, appears fainter to astronomers on Earth because its disk of dust and gas blocks out much of the starlight.

The disk itself, however, can be easily observed by the starlight that it scatters at optical and near-infrared wavelengths.

The key velocity data taken with ALMA that helped the astronomers determine that the disks in HK Tau were misaligned. 

The red areas represent material moving away from Earth and the blue indicates material moving toward us. 

Credit: NASA/JPL-Caltech/R. Hurt (IPAC); ALMA (ESO/NAOJ/NRAO)

The disk around the main star, HK Tau A, is tilted in such a way that the light from its host star shines through unobscured, making it difficult for astronomers to see the disk optically.

This is not a problem for ALMA, however, which can readily detect the millimeter-wavelength light emitted by the dust and gas that comprise the disk.

With its unprecedented resolution and sensitivity, ALMA was able to fully resolve the rotation of HK Tau A's disk for the first time.

This clearer picture enabled the astronomers to calculate that the disks were misaligned, meaning they were out of sync with the orbit of their host stars, by as much as 60 degrees or more.

Rachel Akeson

"This clear misalignment has given us a remarkable look at a young binary star system," said Rachel Akeson of the NASA Exoplanet Science Institute (NEXSCI) at the California Institute of Technology in Pasadena, California.

"Though there have been hints before that this type of misaligned system exists, this is the cleanest and most striking example."

Stars and planets form out of vast clouds of dust and gas. As material in these clouds contracts under gravity, it begins to rotate until most of the dust and gas falls into a flattened proto-planetary disk swirling around a growing central protostar.

Despite forming from a flat, regular disk, planets can end up in highly eccentric orbits, and may be misaligned with the star's equator.

One theory for how planets can migrate to these unusual orbits is that a binary companion star can influence them, but only if its orbit is initially misaligned with the planets.

This is an artist's impression of the misaligned protoplanetary disks around the binary stars in HK Tau. 

Credit: R. Hurt (NASA/JPL-Caltech/IPAC)

"Our results demonstrate that the necessary conditions exist to modify planetary orbits and that these conditions are present at the time of planet formation, apparently due to the binary formation process," noted Jensen.

"We can't rule other theories out, but we can certainly rule in that a second star will do the job."

Since ALMA can see the otherwise invisible dust and gas of protoplanetary disks, it allowed for never-before-seen views of this young binary system.

"Because we're seeing this in the early stages of formation with the protoplanetary disks still in place, we can see better how things are oriented," noted Akeson. "You can simply see gas better than you can see planets."

Looking forward, the researchers want to determine if this type of system is typical or not. They note that this is a remarkable individual case, but additional surveys are needed to determine if this sort of arrangement is common throughout our Galaxy.

More information: Nature DOI: 10.1038/nature13521

ESA Rosetta OSIRIS: Comet 67P/Churyumov-Gerasimenko

Comet 67P/Churyumov-Gerasimenko was imaged on 14 July 2014 by OSIRIS, Rosetta's scientific imaging system, from a distance of approximately 12 000 km. 

This movie uses a sequence of 36 interpolated images each separated by 20 minutes, providing a 360° preview of the complex shape of the comet. 

The images have been processed using 'sub-sampling by interpolation', a technique that removes the pixelisation and makes a smoother image. 

It does not, however, reveal hidden detail and it is therefore important to note that the comet's surface is not very likely to be as smooth as the processing implies. 

The images suggest that the comet may consist of two parts: one segment seems to be rather elongated, while the other appears more bulbous. 

Credits: ESA/Rosetta/MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

Image courtesy ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA.

The European Space Agency's Rosetta probe has been gearing up to attempt a comet landing.

Recently, the craft discovered something surprising about its intended target, Comet Churyumov-Gerasimenko.

The comet is actually two comets in one, conjoined twins, or more technically, a "contact binary."

As seen in the images captured by Rosetta, Churyumov-Gerasimenko's newly discovered sidekick is slightly smaller and looks as if it was just smashed into the side of the larger mass, like two pieces of clay. Together they measure about 2.5 miles around.

And though it looks and sounds pretty exciting, it's going to make landing a spacecraft on the comet quite a bit more difficult.

After entering orbit around the comet next month, Rosetta will release a landing device called Philae onto the comet's surface in November.

"This form restricts potential landing zones," explained Philae navigator Eric Jurado.

France's National Centre for Space Studies apparently jumped the gun in unveiling images of the comet yesterday, along with a press release.

They were quickly removed, but not before they made their rounds on the Internet. ESA released a statement saying more images will be released late Thursday.

The agency explained the need to at least momentarily withhold information collected via its various missions.

"The aim of a proprietary period is to ensure that the academic teams who spent decades developing and running the sophisticated scientific instruments on-board the spacecraft are able to calibrate and verify the data," explained ESA officials, "as well as reap the rewards of their efforts."

ESA XMM-Newton: Unique pair of supermassive black holes discovered

Artist’s impression of a pair of black holes. 

One of them is accreting the 'debris' of the disrupted star, while the second is temporarily interrupting the stream of gas toward the other black hole. 

Credit: ESA /C. Carreau

A pair of supermassive black holes in orbit around one another have been discovered by an international research team including Stefanie Komossa from the Max Planck Institute for Radio Astronomy in Bonn, Germany. This is the first time such a pair could be found in an ordinary galaxy.

Stefanie Komossa

They were discovered because they ripped apart a star when ESA's space observatory XMM-Newton happened to be looking in their direction.

The findings are published in the May 10 issue of the Astrophysical Journal, and appeared online today at the astrophysics preprint server.

Most massive galaxies in the universe are thought to harbor at least one supermassive black hole at their center.

Two supermassive black holes are the smoking gun that the galaxy has merged with another.

Thus, finding binary supermassive black holes can tell astronomers about how galaxies evolved into their present-day shapes and sizes.

To date, only a few candidates for close binary supermassive black holes have been found. All are in active galaxies where they are constantly ripping gas clouds apart, in the prelude to crushing them out of existence.

In the process of destruction, the gas is heated so much that it shines at many wavelengths, including X-rays. This gives the galaxy an unusually bright center, and leads to it being called active.

Fukun Liu

The new discovery, reported by Fukun Liu from Peking University in China, and colleagues, is important because it is the first to be found in a galaxy that is not active.

"There might be a whole population of quiescent galaxies that host binary black holes in their centers," says co-author Stefanie Komossa, Max-Planck-Institut für Radioastronomie, Bonn, Germany.

But finding them is a difficult task because in quiescent galaxies, there are no gas clouds feeding the black holes, and so the cores of these galaxies are truly dark.

The only hope that the astronomers have is to be looking in the right direction at the moment one of the black holes goes to work, and rips a star to pieces. Such an occurrence is called a 'tidal disruption event.'

As the star is pulled apart by the gravity of the black hole, it gives out a flare of X-rays.

In an active galaxy, the black hole is continuously fed by gas clouds. In a quiescent galaxy, the black hole is fed by tidal disruption events that occur sporadically and are impossible to predict.

So, to increase the chances of catching such an event, researchers use ESA's X-ray observatory, XMM-Newton, in a novel way.

ESA's X-ray observatory, XMM-Newton

Artist's impression of XMM-Newton spacecraft in orbit around the Earth. 

The X-ray emission from galaxy SDSS J120136.02+300305.5 was detected in slew modus of the space observatory. 

Credit: ESA /D. Ducros

Usually, the observatory collects data from designated targets, one at a time.

Once it completes an observation, it slews to the next.

The trick is that during this movement, XMM-Newton keeps the instruments turned on and recording.

Effectively this surveys the sky in a random pattern, producing data that can be analyzed for unknown or unexpected sources of X-rays.

On 10 June 2010, a tidal disruption event was spotted by XMM-Newton in galaxy SDSS J120136.02+300305.5, approximately 2 billion light-years away.

NASA's Swift satellite

Komossa and her colleagues were scanning the data for such events and scheduled follow-up observations just days later with XMM-Newton and NASA's Swift satellite.

The galaxy was still spilling X-rays into space.

It looked exactly like a tidal disruption event caused by a supermassive black hole but as they tracked the slowly fading emission day after day something strange happened.

The X-rays fell below detectable levels between days 27 and 48 after the discovery. Then they re-appeared and continued to follow a more expected fading rate, as if nothing had happened.

Now, thanks to Fukun Liu, this behaviour can be explained. "This is exactly what you would expect from a pair of supermassive black holes orbiting one another," says Liu.

More information: "A milliparsec supermassive black hole binary candidate in the galaxy SDSS J120136.02+300305.5," by F. K. Liu, Shuo Li, and S. Komossa, 2014, Astrophysical Journal, Volume 786, Article 103 (May 10). DOI: 10.1088/0004-637X/786/2/103 . Preprint: arxiv.org/abs/1404.4933