Explaining the concept of a dust bunny to small children can be quite amusing. No, it’s not actually alive. It’s moving around because of really small currents of wind that we can’t even see. It’s mainly formed out of dead skin and spider webs. No, the spiders don’t actually eat the dead skin. Most of the time.
Now take that same concept of a bunch of particles stuck together, scale it up a few orders of magnitude, and put it in space. Though it’s still not alive, it would be blown by solar radiation rather than the winds. And instead of being made out of skin and spider webs, it could be made up of cometary dust particles. That is what scientists think our first detected visitor from another star might be – an interstellar dust bunny.
It’s easy to run out of superlatives and adjectives when your puny human language is trying to describe humongously-energetic events in the Universe. So now it’s down to this: a really powerful supernova is a “super-supernova.”
But whatever name we give it, it’s a monster. A monsternova.
Rather than resolving the dispute, additional observations only deepened the mystery, even giving rise to suggestions that it might be an extra-terrestrial solar sail. For this reason, scientists are very interested in finding other examples of ‘Oumuamua-like objects. According to a recent study by a team of Harvard astrophysicists, it is possible that interstellar objects enter our system and end up falling into in our Sun somewhat regularly.
Back in October, the announcement of the first interstellar asteroid triggered a flurry of excitement. Since that time, astronomers have conducted follow-up observations of the object known as 1I/2017 U1 (aka. `Oumuamua) and noted some rather interesting things about it. For example, from rapid changes in its brightness, it has been determined that the asteroid is rocky and metallic, and rather oddly-shaped.
Observations of the asteroid’s orbit have also revealed that it made its closest pass to our Sun back in September of 2017, and it is currently on its way back to interstellar space. Because of the mysteries this body holds, there are those who are advocating that it be intercepted and explored. One such group is Project Lyra, which recently released a study detailing the challenges and benefits such a mission would present. Continue reading “Project Lyra, a Mission to Chase Down that Interstellar Asteroid”
The Solar System is filled with what are known as Trojan Asteroids – objects that share the orbit of a planet or larger moon. Whereas the best-known Trojans orbit with Jupiter (over 6000), there are also well-known Trojans orbiting within Saturn’s systems of moons, around Earth, Mars, Uranus, and even Neptune.
Until recently, Neptune was thought to have 12 Trojans. But thanks to a new study by an international team of astronomers – led by Hsing-Wen Lin of the National Central University in Taiwan – five new Neptune Trojans (NTs) have been identified. In addition, the new discoveries raise some interesting questions about where Neptune’s Trojans may come from.
The team used data obtained by the PS-1 survey, which ran from 2010 to 2014 and utilized the first Pan-STARR telescope on Mount Haleakala, Hawaii. From this, they observed seven Trojan asteroids around Neptune, five of which were previously undiscovered. Four of the TNs were observed orbiting within Neptune’s L4 point, and one within its L5 point.
The newly detected objects have sizes ranging from 100 to 200 kilometers in diameter, and in the case of the L4 Trojans, the team concluded from the stability of their orbits that they were likely primordial in origin. Meanwhile, the lone L5 Trojan was more unstable than the other four, which led them to hypothesize that it was a recent addition.
As Professor Lin explained to Universe Today via email:
“The 2 of the 4 currently known L5 Neptune Trojans, included the one L5 we found in this work, are dynamically unstable and should be temporary captured into Trojan cloud. On the other hand, the known L4 Neptune Trojans are all stable. Does that mean the L5 has higher faction of temporary captured Trojans? It could be, but we need more evidence.”
In addition, the results of their simulation survey showed that the newly-discovered NT’s had unexpected orbital inclinations. In previous surveys, NTs typically had high inclinations of over 20 degrees. However, in the PS1 survey, only one of the newly discovered NTs did, whereas the others had average inclinations of about 10 degrees.
From this, said Lin, they derived two possible explanations:
“The L4 “Trojan Cloud” is wide in orbital inclination space. If it is not as wide as we thought before, the two observational results are statistically possible to generate from the same intrinsic inclination distribution. The previous study suggested >11 degrees width of inclination, and most likely is ~20 degrees. Our study suggested that it should be 7 to 27 degrees, and the most likely is ~ 10 degrees.”
“[Or], the previous surveys were used larger aperture telescopes and detected fainter NT than we found in PS1. If the fainter (smaller) NTs have wider inclination distribution than the larger ones, which means the smaller NTs are dynamically “hotter” than the larger NTs, the disagreement can be explained.”
According to Lin, this difference is significant because the inclination distribution of NTs is related to their formation mechanism and environment. Those that have low orbital inclinations could have formed at Neptune’s Lagrange Points and eventually grew large enough to become Trojans asteroids.
On the other hand, wide inclinations would serve as an indication that the Trojans were captured into the Lagrange Points, most likely during Neptune’s planetary migration when it was still young. And as for those that have wide inclinations, the degree to which they are inclined could indicate how and where they would have been captured.
“If the width is ~ 10 degrees,” he said, “the Trojans can be captured from a thin (dynamically cold) planetesimal disk. On the other hand, if the Trojan cloud is very wide (~ 20 degrees), they have to be captured from a thick (dynamically hot) disk. Therefore, the inclination distribution give us an idea of how early Solar system looks like.”
In the meantime, Li and his research team hope to use the Pan-STARR facility to observe more NTs and hundreds of other Centaurs, Trans-Neptunian Objects (TNOs) and other distant Solar System objects. In time, they hope that further analysis of other Trojans will shed light on whether there truly are two families of Neptune Trojans.
This was all made possible thanks to the PS1 survey. Unlike most of the deep surveys, which are only ale to observe small areas of the sky, the PS1 is able to monitor the whole visible sky in the Northern Hemisphere, and with considerable depth. Because of this, it is expected to help astronomers spot objects that could teach us a great deal about the history of the early Solar System.
Crazy things can happen when galaxies collide, as they sometimes do. Although individual stars rarely impact each other, the gravitational interactions between galaxies can pull enormous amounts of gas and dust into long streamers, spark the formation of new stars, and even kick objects out into intergalactic space altogether. This is what very well may have happened to SDSS1133, a suspected supermassive black hole found thousands of light-years away from its original home.
Seen above in a near-infrared image acquired with the Keck II telescope in Hawaii, SDSS1133 is the 40-light-year-wide bright source observed 2,300 light-years out from the dwarf galaxy Markarian 177, located 90 million light-years away in the constellation Ursa Major (or, to use the more familiar asterism, inside the bowl of the Big Dipper.)
The two bright spots at the disturbed core of Markarian 177 are thought to indicate recent star formation, which could have occurred in the wake of a previous collision.
“We suspect we’re seeing the aftermath of a merger of two small galaxies and their central black holes,” said Laura Blecha, an Einstein Fellow in the University of Maryland’s Department of Astronomy and a co-author of an international study of SDSS1133. “Astronomers searching for recoiling black holes have been unable to confirm a detection, so finding even one of these sources would be a major discovery.”
Interactions between supermassive black holes during a galactic collision would also result in gravitational waves, elusive phenomena predicted by Einstein that are high on astronomers’ most-wanted list of confirmed detections.
Watch an animation of how the suspected collision and subsequent eviction may have happened:
But besides how it got to where it is, the true nature of SDSS1133 is a mystery as well.
The persistently bright near-infrared source has been detected in observations going back at least 60 years. Whether or not SDSS1133 is indeed a supermassive black hole has yet to be determined, but if it isn’t then it’s a very unusual type of extremely massive star known as an LBV, or Luminous Blue Variable. If that is the case though, it’s peculiar even for an LBV; SDSS1133 would have had to have been continuously pouring out energy in a for over half a century until it exploded as a supernova in 2001.
To help determine exactly what SDSS1133 is, continued observations with Hubble’s Cosmic Origins Spectrograph instrument are planned for Oct. 2015.
“We found in the Pan-STARRS1 imaging that SDSS1133 has been getting significantly brighter at visible wavelengths over the last six months and that bolstered the black hole interpretation and our case to study SDSS1133 now with HST,” said Yanxia Li, a UH Manoa graduate student involved in the research.
And, based on data from NASA’s Swift mission the UV emission of SDSS1133 hasn’t changed in ten years, “not something typically seen in a young supernova remnant” according to Michael Koss, who led the study and is now an astronomer at ETH Zurich.
Regardless of what SDSS1133 turns out to be, the idea of such a massive and energetic object soaring through intergalactic space is intriguing, to say the least.
The study will be published in the Nov. 21 edition of Monthly Notices of the Royal Astronomical Society.
A lawn sprinkler in space. That’s one of the descriptions NASA has for the curious P/2013 P5, which is spewing not one, not two, but six comet-like tails at the same time.
“We were literally dumbfounded when we saw it,” stated David Jewitt of the University of California at Los Angeles, who led the research. “Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It’s hard to believe we’re looking at an asteroid.”
UCLA described the asteroid as a “weird and freakish object” in its own press release.
The mystery started when astronomers spotted a really blotchy thing in space Aug. 27 with the Pan-STARRS survey telescope in Hawaii. The Hubble Space Telescope then swung over to take a look on Sept. 10, revealing all these tails of debris flying off the asteroid.
It appears, scientists say, that the asteroid is rotating so quickly that it is ripping its very surface apart. They’ve ruled out a collision because the dust leaves in spurts; calculations by team member Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany estimated this happened on April 15, July 18, July 24, Aug. 8, Aug. 26 and Sept. 4.
Once the dust gets loose, the sun’s continuous stream of particles then pushes the debris into these extraordinary tails. It’s also possible that this “radiation pressure” contributed to the asteroid’s high spin rate. It appears the team is looking to find more of these objects to see if this is a way that smaller asteroids commonly fall apart.
“In astronomy, where you find one, you eventually find a whole bunch more,” Jewitt stated. “This is just an amazing object to us, and almost certainly the first of many more to come.”
That pale white dot up there? No. 10,000 in a list of near-Earth objects. This rock, 2013 MZ5, was discovered June 18. It is 1,000 feet (300 meters) across and will not come anywhere near to threatening Earth, NASA assures us.
But what else is out there? The agency still hasn’t found every asteroid or comet that could come by Earth. To be sure, however, it’s really trying. But is there more NASA and other agencies can do to search? Tell us in the comments.
A bit of history: the first of these objects was discovered in 1898, but in recent decades we’ve been more systematic about finding them. This means we’ve been picking up the pace on discoveries.
Congress asked NASA in 2005 to find and catalog 90 per cent of NEOs that are larger than 500 feet (140 meters) in size, about enough to level a city. The agency says it has also found most of the very largest NEOs, those that are at least six-tenths of a mile (1 kilometer) across (and none so far discovered are a threat.)
Still, NASA says once it achieves its latest goal (which it is supposed to be by 2020), “the risk of an unwarned future Earth impact will be reduced to a level of only one per cent when compared to pre-survey risk levels. This reduces the risk to human populations, because once an NEO threat is known well in advance, the object could be deflected with current space technologies.”
I’m going to try and say this before the Bad Astronomer does: Holy Haleakala! A team of astronomers using the Pan-STARRS1 telescope on Mount Haleakala in Hawaii have found evidence of a black hole ripping a star to shreds. While this isn’t the first time this type of activity has been detected, these new observations are the best views so far of what happens to objects that are consumed by a black hole. Plus, astronomers, for the first time, know what kind of star was destroyed and watched as it happened. This all helps in providing more insight into how black holes behave: They aren’t enormous vacuum cleaners that suck up and destroy everything around them, or sharks that seek out and consume their victims. Instead, like Venus Fly Traps, they wait for objects to come to them.
“Black holes, like sharks, suffer from a popular misconception that they are perpetual killing machines,” said Ryan Chornock of the Harvard-Smithsonian Center for Astrophysics (CfA). “Actually, they’re quiet for most of their lives. Occasionally a star wanders too close, and that’s when a feeding frenzy begins.”
If a star passes too close to a black hole, tidal forces can rip it apart. The remaining gases then swirl in toward the black hole. But just a small fraction of the material near a black hole falls in, while most of it just circles for a while – sometimes forever. The material close the black hole gets superheated, causing it to glow. By searching for newly glowing supermassive black holes, astronomers can spot them in the midst of a feast.
So, kind of like with Junior, the giant Venus Fly Trap in the movie “Little Shop of Horrors,” the feast is evident from what doesn’t get eaten.
This computer simulation shows a star being shredded by the gravity of a massive black hole. Some of the stellar debris falls into the black hole and some of it is ejected into space at high speeds. The areas in white are regions of highest density, with progressively redder colors corresponding to lower-density regions. The blue dot pinpoints the black hole’s location. The elapsed time corresponds to the amount of time it takes for a Sun-like star to be ripped apart by a black hole a million times more massive than the Sun.
The team discovered this type of glow on May 31, 2010, with Pan-STARRS1 and also with NASA’s Galaxy Evolution Explorer (GALEX). The flare brightened to a peak on July 12th before fading away over the course of a year. The event took place in a galaxy 2.7 billion light-years away, and the black hole contains as much mass as 3 million Suns, making it about the same size as the Milky Way’s central black hole.
“We observed the demise of a star and its digestion by the black hole in real time,” said Harvard co-author Edo Berger.
“We’re also witnessing the spectral signature of the ejected gas, said Suvi Gezari of The Johns Hopkins University who lead the research, “which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas we detect from the carnage, we know that the slaughtered star had to have been the helium-rich core of a stripped star.”
Follow-up observations with the MMT Observatory in Arizona showed that the black hole was consuming large amounts of helium. Therefore, the shredded star likely was the core of a red giant star. The lack of hydrogen showed this is likely not the first time the star had encountered the same black hole, and that it lost its outer atmosphere on a previous pass.
The star may have been near the end of its life, the astronomers say. After consuming most of its hydrogen fuel, it had probably ballooned in size, becoming a red giant. The astronomers think the bloated star was looping around the black hole in a highly elliptical orbit, similar to a comet’s elongated orbit around the Sun.
“This is the first time where we have so many pieces of evidence, and now we can put them all together to weigh the perpetrator (the black hole) and determine the identity of the unlucky star that fell victim to it,” Gezari said. “These observations also give us clues to what evidence to look for in the future to find this type of event.”
The team’s results were published today in the online edition of the journal Nature.
The Pan-STARRS PS1 telescope on Haleakala, Maui, discovered 19 near-Earth asteroids on the night of January 29, the most asteroids discovered by one telescope on a single night.
“This record number of discoveries shows that PS1 is the world’s most powerful telescope for this kind of study,” said Nick Kaiser, head of the Pan-STARRS project. “NASA and the U.S. Air Force Research Laboratory’s support of this project illustrates how seriously they are taking the threat from near-Earth asteroids.”
Pan-STARRS software engineer Larry Denneau spent that Saturday night in his University of Hawaii at Manoa office in Honolulu processing the PS1 data as it was transmitted from the telescope over the Internet. During the night and into the next afternoon, he and others came up with 30 possible new near-Earth asteroids.
Asteroids are discovered because they appear to move against the background of stars. To confirm asteroid discoveries, scientists must carefully re-observe them several times within 12-72 hours to define their orbits, otherwise they are likely to be “lost.”
Denneau and colleagues quickly sent their discoveries to the Minor Planet Center in Cambridge, Mass., which collects and disseminates data about asteroids and comets, so that other astronomers can re-observe the objects.
“Usually there are several mainland observatories that would help us confirm our discoveries, but widespread snowstorms there closed down many of them, so we had to scramble to confirm many of the discoveries ourselves,” noted Institute for Astronomy astronomer Richard Wainscoat.
Wainscoat, astronomer David Tholen, and graduate student Marco Micheli spent the next three nights searching for the asteroids using telescopes at Mauna Kea Observatories, Hawaii.
On Sunday night, they confirmed that two of the asteroids were near-Earth asteroids before snow on Mauna Kea forced the telescopes to close. On Monday night, they confirmed nine more before fog set in.
On Tuesday night, they searched for four, but found only one. After Tuesday, the remaining unconfirmed near-Earth asteroids had moved too far to be found again.
Telescopes in Arizona, Illinois, Italy, Japan, Kansas, New Mexico, and the United Kingdom, and the Faulkes Telescope on Haleakala also helped to confirm seven of the discoveries.
Two of the asteroids, it turns out, have orbits that come extremely close to Earth’s. There is no immediate danger, but a collision in the next century or so, while unlikely, cannot yet be ruled out. Astronomers will be paying close attention to these objects.