Tag: astronomy

Getting India’s first space telescope working

9:12 am

A moment of terror: During the first week of successful operation, there was an initial moment of terror when the engineers checking out Astrosat, India’s first space telescope, thought the spacecraft was unable to point at its target accurately.

During the first orbit, there was a difficulty in detecting this Crab Nebula as the satellite happened to pass through the South Atlantic Anomaly (SAA) region when Crab was in the field of view. SAA avoidance zone was deliberately kept wide to protect the instruments, and detectors were switched OFF in this interval during the initial days of Astrosat operation. When all the data were systematically analysed and data were selected based on the availability of Crab in the detector field of view, one could see the Crab emerging from Earth’s shadow (Fig 3).

Using the Crab Nebula as Astrosat’s first target, the check-out has been proceeding well, with full research operations expected to begin in the next few weeks.

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Judge rules in favor of telescope protesters

9:30 pm

A Hawaiian judge has ruled that the state’s emergency order that had forbid camping on the mountain was invalid.

The state says that it will still prohibit anyone from blocking the road, but I don’t know how they will be able to do that if a large number of protesters camp on the mountain, ready to move and block any construction vehicles trying to get to the mountaintop.

I think it is time for the makers of the Thirty Meter Telescope to consider a move out of Hawaii. I believe they will never be able to get the telescope built as planned.

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A planet-forming disk with mysterious ripples

11:40 am

cropped image of dust disk and ripples

The mysteries of science: Astronomers have detected ripples and blobs moving outward through the dust disk surrounding a nearby star, and have no idea what is causing them.

The images reveal a train of wave-like arches, resembling ripples in water. After spotting the features in the SPHERE data the team turned to earlier Hubble images of the disk, taken in 2010 and 2011. The wave-like nature of some of these features were not recognized in the initial Hubble observations. But once astronomers reprocessed the Hubble images they not only identified the features but realized that they had changed over time. The researchers report that these ripples are moving β€” and they are moving very fast. “We ended up with enough information to track the movement of these strange features over a 3- to 4-year period,” explained team member Christian Thalmann of the Swiss Federal Institute of Technology in Zurich, Switzerland. “By doing this, we found that the arches are racing away from the star at speeds of up to 10 kilometers per second (22,000 miles per hour)!” Co-investigator Carol Grady of Eureka Scientific in Oakland, California, added, “Because nothing like this has been observed or predicted in theory we can only hypothesize when it comes to what we are seeing and how it came about.”

The one theory that is still not refuted is that the star’s flaring activity, which is significant, causes the ripples somehow.

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Comet 67P/C-G was formed by a soft collision

9:04 am

Scientists, using data from Rosetta, have concluded that Comet 67P/C-G’s double lobed shape was caused by the slow-motion collision of two distinct comets.

By using high-resolution images taken between 6 August 2014 and 17 March 2015 to study the layers of material seen all over the nucleus, they have shown that the shape arose from a low-speed collision between two fully fledged, separately formed comets. β€œIt is clear from the images that both lobes have an outer envelope of material organised in distinct layers, and we think these extend for several hundred metres below the surface,” says Matteo Massironi, lead author from the University of Padova, Italy, and an associate scientist of the OSIRIS team. β€œYou can imagine the layering a bit like an onion, except in this case we are considering two separate onions of differing size that have grown independently before fusing together.”

While erosion continues to eat away at the comet’s surface, changing its shape, the two lobes formed separately, though in much the same way.

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India launches its first space observatory

8:46 am

The competition heats up: India today successfully launched Astrosat, its first space telescope.

ASTROSAT, with a mission life of five years, is armed with telescopes that will simultaneously study the space in visible light, ultraviolet (UV) rays and low- and high-energy X-rays, plus an X-ray scanning sky monitor to detect transient X-ray emissions and Ξ³-ray bursts. The observatory aims to study star-birth regions and high-energy processes, including binary star systems of neutron stars and black holes.

This space observatory fills several gaps that have existed in astronomical research since the shut down of NASA’s Rossi X-Ray Timing Explorer in 2012 as well as the International Ultraviolet Explorer in 1996.

The launch also put six other small satellites into orbit, demonstrating once again the reliability of India’s smaller Polar Satellite Launch Vehicle (PSLV).

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Milky Way’s central black hole is getting active

1:03 pm

The uncertainty of science: Sagittarius A* (pronounced A-Star), the Milky Way’s supermassive central black hole, has shown signs of increased activity in recent months.

The new study reveals that Sagittarius A* (Sgr A* for short) has been producing one bright X-ray flare about every ten days. However, within the past year, there has been a ten-fold increase in the rate of bright flares from Sgr A*, at about one every day. This increase happened soon after the close approach to Sgr A* by a mysterious object called G2.

“For several years, we’ve been tracking the X-ray emission from Sgr A*. This includes also the close passage of this dusty object” said Gabriele Ponti of the Max Planck Institute for Extraterrestrial Physics in Germany. β€œA year or so ago, we thought it had absolutely no effect on Sgr A*, but our new data raise the possibility that that might not be the case.”

G2 was first thought to be a cloud that would be ripped apart as it passed close to Sgr A*, causing an outburst of activity. When it wasn’t ripped apart and there was no immediate increase in activity astronomers concluded that G2 was a star surrounded by dust which was generally unaffected by its close fly-by of the black hole.

The timing of this new activity now is puzzling. It comes much later than it should have if it was caused by G2, but astronomers don’t have any other explanation for it. It might be because of G2’s fly-by, or maybe the activity is just the natural variability of this poorly understand object. Either way it illustrates how little we really know about the behavior of giant black holes.

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Hawaii arranges to schedule next TMT protest

8:34 am

The Hawaiian government, after allowing the protesters of the Thirty Meter Telescope (TMT) to live for months on Mauna Kea in defiance of an emergency order closing the mountain, has agreed to give the protesters advance warning when TMT plans to restart construction so they can get there to block it.

The short article spins things to favor the protest and to hide the fact that the state is acting as their supporter. Similar media spin here. Because of this, the protesters have decided there is no need for them to continue their 24 hour vigil on the mountain. They left without removing their structures, and the state has said it will likely not remove them. How convenient!

As I’ve said earlier, it is time that the TMT seriously consider other sites for this telescope. Hawaii doesn’t want them.

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Road crews remove stone altar built by TMT protesters on Mauna Kea

8:52 am

According to state officials, a crew needing access to materials for grading the roads on Mauna Kea removed last week one of three stone altars built by the protesters to the Thirty Meter Telescope.

The altar known as an ahu (AH’-hoo) was built June 24, the day hundreds of protesters prevented construction crews from reaching the telescope site on Mauna Kea (mow-NAH’ kay-AH’). “About a hundred people or so contributed to this ahu I would guess,” Lakea Trask, one of the protester leaders, said Tuesday in describing how stones were passed person-to-person to erect the 4-foot-high structure at an elevation of 11,000 feet. “Basically, it’s a religious altar or shrine. It’s not just a stack of rocks. It’s the focus of the energies of our pule β€” our prayers β€” our spiritual connection to the land,” Trask said. “It’s like a hate crime to us.”

The group of people who have been camping regularly on the mountain to prevent crews from returning hadn’t checked on the ahu for a while, Trask said. Every second Sunday or so, some of them visit the altar to give offerings, usually water or bundles of leaves from the Hawaiian ti plant, he said. On Sunday, “when they went up there to check on it, there was no ahu,” Trask said. “And in its place there was a bulldozer.”

Forgive me if I express extreme skepticism about the religious nature of these stone structures. If they are so significant, why were none built before the protests? And why, before the protests, did we hear so little of people going up to the top of Mauna Kea to pray? When I was there in 2003, I saw zero evidence of religious pilgrims or sites. The mountaintop was then open to visitation by all, and the only people I saw visiting it were astronomers, telescope engineers, road crews, amateur astronomers, and tourists.

These structures are purely political, built to put a wedge between the mountain and the astronomers. I am certain that the instant these protesters get their way, shutting down TMT and possibly gaining some financial reward from the state, these so-called Sunday prayer visits will stop.

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Astronomers find no evidence of nearby alien civilizations

8:33 am

New observations of the best candidate galaxies now suggests that very advanced civilizations are very rare or don’t exist in the local universe.

They looked at several hundred nearby galaxies that emitted a high amount of mid-infrared radiation, which could possibly be produced as the waste heat from civilizations using energy on galactic scales.

Professor Michael Garrett (ASTRON & University of Leiden) has used radio measurements of the very best candidate galaxies and discovered that the vast majority of these systems present emission that is best explained by natural astrophysical processes. In particular, the galaxies as a sample, follow a well-known global relation that holds for almost all galaxies – the so-called “Mid-Infrared Radio correlation”. The presence of radio emission at the levels expected from the correlation, suggests that the mid-IR emission is not heat from alien factories but more likely emission from dust – for example, dust generated and heated by regions of massive star formation.
As Professor Garrett explains: “the original research at Penn State has already told us that such systems are very rare but the new analysis suggests that this is probably an understatement, and that advanced Kardashev Type III civilisations basically don’t exist in the local Universe. In my view, it means we can all sleep safely in our beds tonight – an alien invasion doesn’t seem at all likely!”.

Joking aside, Professor Garrett is still looking at a few candidate galaxies that lie off of the astrophysical correlation: “Some of these systems definitely demand further investigation but those already studied in detail turn out to have a natural astrophysical explanation too. It’s very likely that the remaining systems also fall into this category but of course it’s worth checking just in case!”

Obviously, the uncertainty of these results is quite high. Nonetheless, the results indicate that either humanity really is the only intelligent species in this part of the universe, or advanced civilizations are far more efficient in their use of energy than is reasonable to assume.

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Police arrest 8 protesters camping illegally on Mauna Kea

8:54 am

Last night police arrested 8 protesters who were camping illegally on Mauna Kea in opposition to the construction of the Thirty Meter Telescope.

I have posted below the fold a video of the arrests. To me, the significant take-away from this video is the scale and permanence of the tent structures that these people have built opposite the Mauna Kea visitors center. The emergency order forbidding camping had gone into effect on July 14. Yet, the impressive buildings they have made of wood and poles have clearly been allowed to stand. This suggests that the state is really not serious about enforcing the law and stopping the protesters from camping on the mountain.

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