Tag: astronomy

Comet 67P from 1000 k

11:06 pm

67P from 1000 kilometers

Above is a new image of Comet 67P as seen from about 1000 kilometers, or about 620 miles, released by the Rosetta science team today. The image was taken on August 1 and has been processed somewhat to bring out the details. The black spot near the junction between the nucleus’s two sections is not real but an artifact of the camera’s CCD.

This image is the first real clear and sharp look at the nucleus, and what it shows us is a surface quite different from the many other asteroids that science probes have imaged close-up in the past. From this angle there are far few craters visible then is normally seen on asteroids, and the surface has complex roughness and pitted look that I suspect the planetary geologists are right now scratching their heads about and waving their arms trying to explain. My first guess, which no one should take too seriously, is that as material vents off the comet when it gets close to the Sun it leaves behind these scars.

One more thing: If you go here you can see a number of additional image releases in the last 24 hours, all fascinating. This link explains that the features that looked like craters in earlier images were actually artifacts from the camera’s CCD.

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A Hubble Space Telescope status report

4:48 pm

Five years after the last shuttle repair mission, the Hubble Space Telescope continues to operate almost perfectly.

Jeletic said other than a single gyro failure, the observatory is operating in near-flawless fashion five years after the final shuttle crew departed. “Batteries are fine, solar arrays are fine, all the communications equipment is fine, we don’t see any glitches with the computers, the instruments are all fine,” he said. “In fact, an interesting statistic, the Advanced Camera for Surveys, which was repaired by the astronauts during the last servicing mission, that’s actually now run longer on the repair than it did originally for the Wide Field Camera part of it.”

The ACS, like the repaired Space Telescope Imaging Spectrograph, no longer has any internal redundancy. “It’s amazing. It truly is,” Jeletic said. “Given all the things that can fail, a lot of people were hoping for one or two years of continued work with it. Now we’ve gotten over five.” Likewise, the Space Telescope Imaging Spectrograph, which also is operating in “single-string” mode, is still going strong.

When they completed the 2009 servicing mission, the goal was to give Hubble five more years of operation. They’ve done that, and are now looking to keep the telescope going till at least 2020, marking 30 years in orbit.

The only issue, not surprisingly, is the failure of one of the six gyros on board. These have traditionally been the telescope’s biggest problem, and have been replaced twice over during shuttle missions. Three of today’s six however are using a new design which will hopefully extend their life significantly.

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Fermi proves that novae produce gamma rays

12:56 pm

The Fermi Gamma-Ray Space Telescope has discovered that novae, small scale stellar explosions similar to some supernovae but far less powerful, also produce gamma rays when they explode.

A nova is a sudden, short-lived brightening of an otherwise inconspicuous star caused by a thermonuclear explosion on the surface of a white dwarf, a compact star not much larger than Earth. Each nova explosion releases up to 100,000 times the annual energy output of our sun. Prior to Fermi, no one suspected these outbursts were capable of producing high-energy gamma rays, emission with energy levels millions of times greater than visible light and usually associated with far more powerful cosmic blasts.

What is significant about this is that it demonstrates a solid link between novae and supernovae, since only recently have scientists shown that some supernovae also produce gamma ray bursts. It suggests that the two explosions are produced by somewhat similar processes, but at very different scales. This fact will have important ramifications in the study of stellar evolution and the death of stars. For example, some nova stars often go nova repeatedly. Other data suggest that some more powerful eruptions can be recurrent as well. Extending this recurrent pattern to supernova suggests many new theoretical possibilities.

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The Milky Way shrinks

9:49 pm

The uncertainty of science: New research by astronomers suggests that the Milky Way is about half as massive as previously estimated.

In the sixties I remember astronomers claiming that the Milky Way was twice as big as Andromeda. Then it was considered half as big. Most recently it was considered about the same size. This new research makes it half as big as Andromeda again.

In other words, the data is very uncertain, and the scientists really don’t have a good handle on it. None of these conclusions should be taken very seriously. All we really know at this point is that the Milky Way and Andromeda are approximately comparable.

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Gaia commissioning complete

9:47 am

After several months of in-orbit analysis, engineers have declared the European space telescope Gaia ready to begin research.

There have been several issues that had raised concerns, but from the article it sounds as if the engineers have either corrected the problems or have found ways to overcome or mitigate them.

Gaia will measure the movement and location of a billion stars, allowing astronomers to map the Milky Way better than ever before.

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New Rosetta comet images

6:34 pm

New images from Rosetta have a resolution of 100 meters per pixel and are finding that the neck connecting the comet’s two sections is apparently much brighter than the rest of the nucleus.

As earlier images had already shown, 67P may consist of two parts: a smaller head connected to a larger body. The connecting region, the neck, is proving to be especially intriguing. “The only thing we know for sure at this point is that this neck region appears brighter compared to the head and body of the nucleus”, says OSIRIS Principal Investigator Holger Sierks from the Max-Planck-Institute for Solar System Research (MPS) in Germany. This collar-like appearance could be caused by differences in material or grain size or could be a topographical effect.

It looks like this comet is going to turn out to be one of the most fascinating objects any space probe has visited in a long time.

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More images from Rosetta

5:24 pm

67P

The comet that Rosetta will orbit is getting stranger and stranger, with new images suggesting that it is really two objects stuck together.

The pictures show that 67P/Churyumov-Gerasimenko appears to be not one but two objects joined together. It is what scientists call a “contact binary”. How the comet came to take this form is unknown. It is possible that 67P suffered a major fracture at some point in its past; it is also possible the two parts have totally different origins.

What is clear is that the European Space Agency (Esa) mission team now has additional and unexpected considerations as it plans how to land on the comet later this year – not least, which part of the comet should be chosen for contact?

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Fast radio pulses exist, come from outside the galaxy, and no one knows what they are

9:32 am

A new astronomical mystery: The Arecibo radio telescope has confirmed the existence of fast radio pulses.

Fast radio bursts (FRBs) are bright flashes of radio waves that last only a few thousandths of a second. Scientists using the Parkes Observatory in Australia have recorded such events for the first time, but the lack of any similar findings by other facilities led to speculation that the Australian instrument might have been picking up signals originating from sources on or near Earth. The discovery at Arecibo is the first detection of a fast radio burst using an instrument other than the Parkes radio telescope. The position of the radio burst is in the direction of the constellation Auriga in the Northern sky. …

“Our result is important because it eliminates any doubt that these radio bursts are truly of cosmic origin,” continues Victoria Kaspi, an astrophysics professor at McGill University in Montreal and Principal Investigator for the pulsar-survey project that detected this fast radio burst. “The radio waves show every sign of having come from far outside our galaxy – a really exciting prospect.”

Exactly what may be causing such radio bursts represents a major new enigma for astrophysicists. Possibilities include a range of exotic astrophysical objects, such as evaporating black holes, mergers of neutron stars, or flares from magnetars — a type of neutron star with extremely powerful magnetic fields.

Be warned: All of the above theories could also be wrong. These fast radio flashes could just as easily turn out to be something entirely unpredicted.

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Rosetta snaps more comet pictures

9:23 am

rotating comet nucleus

Rosetta’s new images of Comet 67P/Churyumov-Gerasimenko show the very irregular shape and rotation of its nucleus.

These images were taken on July 4 from a distance of only 23,000 miles. The rendezvous is expected in early August, with the touchdown of Rosetta’s landing probe Philae sometime in November after they have done a reconnaissance of the nucleus to pick a landing spot.

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A source for the most powerful cosmic rays?

8:58 am

Astronomers think they have discovered a region in the sky, within or near the Milky Way, which might be the source of the most energetic cosmic rays

Nobody knows how ultra–high-energy cosmic rays—mainly protons or heavier atomic nuclei—acquire energies millions of times higher than have been achieved with humanmade particle accelerators. (Physicists dubbed one of the first ones observed the “Oh-My-God particle.”) Lower energy cosmic rays are thought to spring from the lingering remnants of stellar explosions called supernovas. But such clouds are far too small to produce the highest energy cosmic rays. Instead, theorists generally expect that the most energetic cosmic rays rev up over millions of years in unidentified accelerators the size of galaxies.

The Telescope Array aims to help solve that mystery. When a high-energy cosmic array strikes the atmosphere, it disappears in an avalanche of lower energy particles. Those particles trigger the detectors in the array, enabling researchers to deduce the direction and energy of the original cosmic ray. From 2008 to 2013, researchers spotted 72 cosmic rays with energies above 57 exaelectron volts—15 million times the highest energy achieved with a particle accelerator. And 19 of them appear to cluster in a hotspot in the sky about 20° in radius, as Hiroyuki Sagawa, a co-representative for the Telescope Array team from the University of Tokyo, reported today in a press conference at the university. [emphasis mine]

The low number of detections, 19 out of 72 total, that seem to come from this wide 20 degree region, suggests that this report falls most certainly under the heading of “the uncertainty of science.” I would not be surprised at all if this conclusion does not stand up after further research.

Nonetheless, the article is worth reading because it outlines nicely this astronomical mystery. Something out there accelerates these particles to these high energies, and astronomers do not yet know what that something is.

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Problems with the European Gaia space telescope

7:43 pm

Shades of Hubble: The first data from Europe’s Gaia space telescope, launched to map a billion Milky Way stars, will be delayed 9 months while engineers grapple with several problems.

Gaia managers started taking test images early this year, but soon noticed three issues. For one, more light than anticipated is bending around the 10-metre sunshield and entering the telescope.

Small amounts of water trapped in the spacecraft before launch are being released now that the telescope is in the vacuum of space, and more ice than calculated is accumulating on the telescope’s mirrors. In addition, the telescope itself is expanding and contracting by a few dozen nanometres more than expected because of thermal variations.

Mission managers say the number of stars detected will remain the same even if these complications remain untreated, but the accuracy in measurements of the fainter stars will suffer.

Unlike Hubble, however, there is no way to send a shuttle and a team of astronauts to Gaia to fix it. And it sounds like these issues will have an impact on the telescope’s abilities to gather its intended data.

This story raises my hackles for another reason. Gaia was a very technically challenging space telescope to build, but it was far easier and less cutting edge than the James Webb Space Telescope. It also cost far less. What will happen when Webb gets launched later this decade? How likely is it to have similar issues? Based on a story I just completed for Sky & Telescope on the difficulties of building ground-based telescopes, I’d say Webb is very likely to have similar problems, with no way to fix them. The American astronomy community could then be faced with the loss of two decades of research because they had put all the eggs into Webb’s basket, and thus had no money to build anything else.

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Two exoplanets disappear

4:53 pm

The uncertainty of science: Two exoplanets orbiting Gliese 581, both thought to be in the habitable zone, have now been proven to not even exist.

“We’ve proven that some of the controversial signals from Gliese 581 don’t come from two proposed Goldilocks planets, but instead are coming from activity within the star itself masquerading as planets,” lead study author Paul Robertson, an astronomer at Pennsylvania State University in University Park, told Space.com.

This result should serve as a strong reminder: Though it is likely that many if not most of the so far discovered exoplanets are real, it is also likely that many will turn out to be false positives. We won’t have solid real knowledge about them until we can actually get a close look at them, which will require far better telescopes in space, and maybe even interstellar missions to them.

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Telescope teamwork produces spectacular galaxy image

11:55 am

M106

Combining images from a host of space and ground-based telescopes, astronomers have created a spectacular image of the galaxy M106.

This galactic fireworks display is taking place in NGC 4258 (also known as M106), a spiral galaxy like the Milky Way. This galaxy is famous, however, for something that our Galaxy doesn’t have – two extra spiral arms that glow in X-ray, optical, and radio light. These features, or anomalous arms, are not aligned with the plane of the galaxy, but instead intersect with it.

The anomalous arms are seen in this new composite image of NGC 4258, where X-rays from NASA’s Chandra X-ray Observatory are blue, radio data from the NSF’s Karl Jansky Very Large Array are purple, optical data from NASA’s Hubble Space Telescope are yellow and blue, and infrared data from NASA’s Spitzer Space Telescope are red.

A new study of these anomalous arms made with Spitzer shows that shock waves, similar to sonic booms from supersonic planes, are heating large amounts of gas – equivalent to about 10 million Suns. What is generating these shock waves? Radio data shows that the supermassive black hole at the center of NGC 4258 is producing powerful jets of high-energy particles. Researchers thinkthat these jets strike the disk of the galaxy and generate shock waves. These shock waves, in turn, heat some of the gas – composed mainly of hydrogen molecules – to thousands of degrees.

The astronomers also used the Herschel Space Observatory to confirm the data from Spitzer.

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A trio of supermassive black holes

9:20 am

Astronomers have discovered a trinary of supermassive black holes at the center of a distant collision of multiple galaxies.

Astronomer Roger Deane of the University of Cape Town in South Africa and his colleagues have been watching a particular quasar, known as SDSS J1502+1115, in the constellation Boötes. Other astronomers had found that the object, located 4.3 billion light-years from Earth, possessed two supermassive black holes, each the center of a large galaxy smashing into another. The black holes are at least 24,000 light-years apart.

Deane wanted to confirm their existence, so he used an intercontinental array of radio dishes that yields even sharper views than the Hubble Space Telescope. Lo and behold, one of the black holes turned out to be two. “We were incredibly surprised,” says Deane, whose team reports its findings online today in Nature.

While the discovery of this system is incredibly cool, this article in the journal Science is surprisingly incorrect on some points, while also missing the main story.
» Read more

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Groundbreaking — the literally blasting off of a mountaintop — took place today in Chile at the eventual site of the European Extremely Large Telescope (E-ELT).

2:45 pm

Groundbreaking — the literally blasting off of a mountaintop — took place today in Chile at the eventual site of the European Extremely Large Telescope (E-ELT).

Once completed in 2024 this telescope will have a segmented mirror with a total diameter of 39 meters or 128 feet, the largest ever built.

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The astronomers who allocate time on the Hubble Space Telescope have decided to devote a large block for finding a Kuiper Belt object that the probe New Horizons might fly past.

5:52 pm

The astronomers who allocate time on the Hubble Space Telescope have decided to devote a large block for finding a Kuiper Belt object that the probe New Horizons might fly past.

This allocation is still contingent upon a test observation to see if Hubble will be able to spot enough objects to make the long observations worthwhile.

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Engineers have returned to full operation the x-ray instrument on the Swift gamma-ray burst space telescope.

11:58 pm

Engineers have returned to full operation the x-ray instrument on the Swift gamma-ray burst space telescope.

They are still investigating what went wrong this week, but have figured out how to get the instrument back in full automatic robotic mode so that it can gather x-ray data on gamma ray bursts within seconds of their occurence.

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A new analysis of Apollo lunar rocks provides strong new evidence for the theory that the Moon was formed when the Earth was hit by a Mars’ sized planet.

9:14 am

A new analysis of Apollo lunar rocks provides strong new evidence for the theory that the Moon was formed when the Earth was hit by a Mars’ sized planet.

The abstract from this just released science paper summarizes the scientific problem.

Earth formed in a series of giant impacts, and the last one made the Moon. This idea, an edifice of post-Apollo science, can explain the Moon’s globally melted silicate composition, its lack of water and iron, and its anomalously large mass and angular momentum. But the theory is seriously called to question by increasingly detailed geochemical analysis of lunar rocks. Lunar samples should be easily distinguishable from Earth, because the Moon derives mostly from the impacting planet, in standard models of the theory. But lunar rocks are the same as Earth in O, Ti, Cr, W, K, and other species, to measurement precision. Some regard this as a repudiation of the theory; others say it wants a reformation. Ideas put forward to salvage or revise it are evaluated, alongside their relationships to past models and their implications for planet formation and Earth.

The new analysis has found that lunar rocks do differ from Earth in certain ways. Not surprisingly, however, the results have uncertainties.

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The rupture of a drum at a nuclear waste site in New Mexico has shut down a neutrino experiment.

9:00 am

The rupture of a drum at a nuclear waste site in New Mexico has shut down a neutrino experiment.

This article, from Nature, focuses on the harm done to the science experiment, which is considerable and very unfortunate. However, scroll to the end of the article to learn a little about the drum rupture, which has serious implications for the storage of nuclear waste anywhere.

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The predicted new meteor shower last night was less than hoped but intriguing nonetheless.

9:18 am

The predicted new meteor shower last night was less than hoped but intriguing nonetheless.

Based on a few reports via e-mail and my own vigil of two and a half hours centered on the predicted maximum of 2 a.m. CDT (7 UT) Saturday morning the Camelopardalid meteor shower did not bring down the house. BUT it did produce some unusually slow meteors and (from my site) one exceptional fireball with a train that lasted more than 20 minutes.

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