Tag: astronomy

Astronomers: If there are artificial Dyson spheres out there, we can detect them

8:55 am

In a preprint science paper published on October 26, 2021, astronomers review the impact a Dyson sphere might have on its central star and conclude that modern astronomical instruments should be able to identify these changes. From the abstract:

The search for signs of extraterrestrial technology, or technosignatures, includes the search for objects which collect starlight for some technological use, such as those composing a Dyson sphere. These searches typically account for a star’s light and some blackbody temperature for the surrounding structure. However, such a structure inevitably returns some light back to the surface of its star, either from direct reflection or thermal re-emission. In this work, we explore how this feedback may affect the structure and evolution of stars, and when such feedback may affect observations. We find that in general this returned light can cause stars to expand and cool. Our MESA models show that this energy is only transported toward a star’s core effectively by convection, so low mass stars are strongly affected, while higher mass stars with radiative exteriors are not. Ultimately, the effect only has significant observational consequences for spheres with very high temperatures (much higher than the often assumed ~300 K) and/or high specular reflectivity. Lastly, we produce color-magnitude diagrams of combined star-Dyson sphere systems for a wide array of possible configurations.

A plain-language description of the paper can be found here, which summarizes this work as follows:

This study shows that Dyson spheres can result in measurable changes to stellar properties. Megastructures have long been confined to science fiction, imagination and certain video games. However, if there are indeed Dyson spheres out there waiting to be found, we could soon be in a position to find them.

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Hubble in safe mode again

10:50 pm

According to NASA’s Twitter feed for the Hubble Space Telescope, it went into safe mode earlier this week because of “issues with internal communications.”

Hubble’s science instruments went into safe mode on Monday after experiencing synchronization issues with internal spacecraft communications. Science observations have been temporarily suspended while the team investigates the issue. The instruments remain in good health.

Much of the press is using that lovely buzzword of bureaucrats, calling this a “glitch.” The goal of that word is to make the problem seem minor and no big deal.

It can’t be minor and no big deal however if the telescope shut down six days ago and remains out of service. This is not a “glitch.” This is a serious issue that is taking time to resolve.

Furthermore, I get more concerned when no further information is provided. As far as I can so far find, the quote above is the only information NASA has released. And that information is remarkably vague and uninformative.

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Water and carbon monoxide detected in exoplanet’s atmosphere

9:54 am

Astronomers, using both the Hubble Space Telescope and the ground-based Gemini Telescope, have detected water and carbon monoxide in the atmosphere of an exoplanet 320 light years away.

Previously hydrogen, helium, hydrogen cyanide, iron, and magnesium have been detected in the atmospheres of a variety of exoplanets. In other cases scientists found exoplanets that were devoid of water.

This detection of water and carbon monoxide is a first for these two materials, and is somewhat significant as it is the first detection that suggests an exoplanet atmosphere that might have similarities to Earth.

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First exoplanet detected in another galaxy?

8:32 am

The uncertainty of science: Using the Chandra X-ray Observatory, astronomers think they may have detected the first exoplanet ever found in another galaxy, the Whirlpool Galaxy, 28 million light years away.

This new result is based on transits, events in which the passage of a planet in front of a star blocks some of the star’s light and produces a characteristic dip. Astronomers using both ground-based and space-based telescopes — like those on NASA’s Kepler and TESS missions — have searched for dips in optical light, electromagnetic radiation humans can see, enabling the discovery of thousands of planets.

Di Stefano and colleagues have instead searched for dips in the brightness of X-rays received from X-ray bright binaries. These luminous systems typically contain a neutron star or black hole pulling in gas from a closely orbiting companion star. The material near the neutron star or black hole becomes superheated and glows in X-rays.

Because the region producing bright X-rays is small, a planet passing in front of it could block most or all of the X-rays, making the transit easier to spot because the X-rays can completely disappear. This could allow exoplanets to be detected at much greater distances than current optical light transit studies, which must be able to detect tiny decreases in light because the planet only blocks a tiny fraction of the star.

The team used this method to detect the exoplanet candidate in a binary system called M51-ULS-1, located in M51. This binary system contains a black hole or neutron star orbiting a companion star with a mass about 20 times that of the Sun. The X-ray transit they found using Chandra data lasted about three hours, during which the X-ray emission decreased to zero. Based on this and other information, the researchers estimate the exoplanet candidate in M51-ULS-1 would be roughly the size of Saturn, and orbit the neutron star or black hole at about twice the distance of Saturn from the Sun.

While this is a tantalizing study, more data would be needed to verify the interpretation as an extragalactic exoplanet. One challenge is that the planet candidate’s large orbit means it would not cross in front of its binary partner again for about 70 years, thwarting any attempts for a confirming observation for decades. [emphasis mine]

As the press release says, this data is tantalizing, but it is really insufficient to prove that an exoplanet has been found. What is known is that for some reason the X-ray emissions from the X-ray binary system disappeared for about three hours. An exoplanet could be one explanation. So could many other things.

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Next Ariane 5 launch postponed

11:39 am

Arianespace today announced that it has postponed its next Ariane 5 launch of two communications satellites, scheduled for October 22nd, because of issues with ground equipment.

Though there appear to be no issues with the rocket, this delay could effect the launch of the James Webb Space Telescope in December on another Ariane 5 rocket. Arianespace has said that it wants to complete this launch first, to make sure the fixes it completed on the rocket’s fairing are truly working.

It was those problems that shut down all Ariane 5 launches for almost a full year.

No new launch date has been set. Normally, ground equipment issues cause short delays, so we should be hopeful all will be fixed quickly and this launch will be quickly rescheduled and take off without problems.

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Early solar system had gap separating its inner and outer regions

9:29 am

New research looking at the make-up of asteroids now suggests that the early solar system had a gap that separated the formation of planets between its inner and outer regions.

Earlier data had suggested that asteroids come in two fundamentally different groups. This new research, looking the magnetic field strength of these two groups, has confirmed this distinction, and provided additional information about the formation process of each.

Surprisingly, they found that their field strength was stronger than that of the closer-in noncarbonaceous meteorites they previously measured. As young planetary systems are taking shape, scientists expect that the strength of the magnetic field should decay with distance from the sun.

In contrast, Borlina and his colleagues found the far-out chondrules had a stronger magnetic field, of about 100 microteslas, compared to a field of 50 microteslas in the closer chondrules. For reference, the Earth’s magnetic field today is around 50 microteslas.

A planetary system’s magnetic field is a measure of its accretion rate, or the amount of gas and dust it can draw into its center over time. Based on the carbonaceous chondrules’ magnetic field, the solar system’s outer region must have been accreting much more mass than the inner region.

In other words, the accretion of planets in the outer region was faster and producing larger objects, while the inner region was slower and producing smaller objects. The data also suggests that gap existed about 4.5 billion years ago, at about the location of the asteroid belt. All in all, this scenario matches the solar system we see today.

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Webb telescope finally arrives at launch site in French Guiana

2:54 pm

Webb deployment

After almost twenty years of construction (a decade behind schedule) and a cost of $10 billion, ($9.5 billion over budget), the James Webb Space Telescope today arrived at the processing facility at Arianespace’s French Guiana spaceport, where it will be prepared for a December 18, 2021 launch on an Ariane 5 rocket.

Once launched the telescope, which is not a replacement for Hubble because it observes in the infrared (not optical) and is optimized for deep space cosmology, will take two weeks to reach its orbital position about a million miles from Earth, as shown in the graphic.

Let us all cross our fingers and toes that it all works as designed, for if it doesn’t this will be the biggest failure ever in the history of NASA.

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As expected, Pluto’s atmosphere is freezing as its orbit takes it from the Sun

10:48 am

Data from ground-based telescopes has now confirmed that Pluto’s nitrogen atmosphere has begun it annual winter freeze out as the planet’s somewhat elliptical 248-year-long orbit takes it away from the Sun.

For about 25 years, Pluto has been moving farther and farther away from the sun, so its surface temperature has been going down. And with these recent observations, the researchers found evidence showing that Pluto’s atmosphere is actually refreezing back onto its surface as the dwarf planet gets colder and colder. Pluto is so far from the sun that, as time goes on, it will get distinctly farther away (and colder) before getting closer to the sun in other regions of its immense orbit.

The astronomers were able to detect this refreezing by observing the planet as it eclipsed a star in 2018.

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New Horizons discovers two binary asteroids in Kuiper Belt

10:32 am

Overview map
Click for full map.

As New Horizons traveled from Pluto to the asteroid Arrokoth in 2018, scientists used it to take images of the relatively nearby asteroids that it was passing, and found that two of those asteroids appeared elongated.

[T]he team fit the shapes with a two-body model: two asteroids in a tight orbit. Even though the individual rocks weren’t resolved, the modeling showed that two bodies were better able to explain the elongation, as well as the brightness seen. The model for 2011 JY31 had two 50-km-wide objects nearly 200 km apart, while for 2014 OS393, the model had slightly smaller bodies (30 km across) that orbited each other 150 km apart.

The map, cropped and further annotated by me, shows New Horizons’ path during this time period, with the two binary asteroids indicated in blue.

This data, combined with the double lobe shape of Arrokoth (formerly named Ultima Thule), strongly suggests that it was not unusual for these primitives asteroids in the early solar system to coalesce from comparably sized partners.

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Orbit of biggest comet ever detected refined

10:59 am

Astronomers have now been able to better refine the orbit and size of Comet Bernardinelli-Bernstein, comet with the largest nucleus ever detected.

A new analysis, led by Bernardinelli and Bernstein themselves, found that the comet nucleus is around 150 km wide, based on its brightness. If so, that makes it the largest comet ever discovered, by quite a margin. Most are only a few kilometers to several dozen kilometers wide, while some particularly big ones, like Hale-Bopp, may be up to 80 km (50 miles) wide. The previous record-holder, Sarabat’s Comet of 1729, has been estimated at about 100 km wide.

The team was also able to calculate the orbit of Comet BB in more detail. This object is on an incredibly long round trip into and out of the solar system – at its most distant point, some 1.5 million years ago, it was about 40,400 AU away. Last time it swung through our neighborhood was about 3.5 million years ago, when it came within 18 AU of the Sun.

But its current inward journey will be its closest so far. Astronomers have already calculated that in 2031, Comet BB will peak at 10.9 AU, almost reaching the orbit of Saturn.

It is presently unclear how bright the comet will be when it reachest its closest point. It will be much farther from the Sun than most bright comets, but its large size may change what is normally expected.

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Galaxies in the early universe don’t fit the theories

9:33 am

The uncertainty of science: New data from both the ALMA telescope in Chile and the Hubble Space Telescope about six massive galaxies in the early universe suggest that there are problems and gaps in the presently accepted theories about the universe’s formation.

Early massive galaxies—those that formed in the three billion years following the Big Bang should have contained large amounts of cold hydrogen gas, the fuel required to make stars. But scientists observing the early Universe with the Atacama Large Millimeter/submillimeter Array (ALMA) and the Hubble Space Telescope have spotted something strange: half a dozen early massive galaxies that ran out of fuel. The results of the research are published today in Nature.

Known as “quenched” galaxies—or galaxies that have shut down star formation—the six galaxies selected for observation from the REsolving QUIEscent Magnified galaxies at high redshift. or the REQUIEM survey, are inconsistent with what astronomers expect of the early Universe.

It was expected that the early universe would have lots of that cold hydrogen for making stars. For some galaxies to lack that gas is inexplicable, and raises questions about the assumptions inherent in the theory of the Big Bang. It doesn’t disprove it, it simply makes it harder to fit the facts to the theory, suggesting — as is always the case — that the reality is far more complicated than the theories of scientists.

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NASA now targets December 18, 2021 for launch of Webb

1:12 pm

NASA today announced that it and the European Space Agency have scheduled the Ariane 5 launch of the James Webb Space Telescope from French Guiana for December 18, 2021.

The agency set the new target launch date in coordination with Arianespace after Webb recently and successfully completed its rigorous testing regimen – a major turning point for the mission. The new date also follows Arianespace successfully launching an Ariane 5 rocket in late July and scheduling a launch that will precede Webb. The July launch was the first for an Ariane 5 since August 2020.

Launching before the end of ’21 will allow NASA to claim that Webb is only be ten years behind schedule, not eleven. The cost overruns however remain astronomical (no pun intended). Initially budgeted at $500 million, Webb is now estimated to have cost $10 billion.

Once launched the telescope will take about six months to slowly move to its Lagrange point location about a million miles from the Earth, in the Earth’s shadow. During that time it will also be steadily deploying its many segmented mirror for infrared observations (an important detail as Webb is not a replacement for Hubble, which does most of its observations in the optical wavelengths).

Should deployment and placement go as planned, Webb will undoubtedly do ground-breaking astronomy, especially in the field of deep space cosmology. If anything should go wrong, any repair mission will take at a minimum five years to mount, if ever.

Keep those fingers and toes crossed!

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Astronomers discover white dwarf stars still burning hydrogen

9:50 am

The uncertainty of science: Using Hubble observations of the white dwarfs in two different globular clusters, astronomers have discovered that — contrary to the consensus opinion — some white dwarf stars are not slowly cooling embers of a dead star, but are still generating nuclear fusion by burning hydrogen in their outer layers.

Using Hubble’s Wide Field Camera 3 the team observed [globular clusters] M3 and M13 at near-ultraviolet wavelengths, allowing them to compare more than 700 white dwarfs in the two clusters. They found that M3 contains standard white dwarfs, which are simply cooling stellar cores. M13, on the other hand, contains two populations of white dwarfs: standard white dwarfs and those which have managed to hold on to an outer envelope of hydrogen, allowing them to burn for longer and hence cool more slowly.

Comparing their results with computer simulations of stellar evolution in M13, the researchers were able to show that roughly 70% of the white dwarfs in M13 are burning hydrogen on their surfaces, slowing down the rate at which they are cooling.

This discovery could have consequences for how astronomers measure the ages of stars in the Milky Way galaxy. The evolution of white dwarfs has previously been modeled as a predictable cooling process. This relatively straightforward relationship between age and temperature has led astronomers to use the white dwarf cooling rate as a natural clock to determine the ages of star clusters, particularly globular and open clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as 1 billion years.

In other words, many past age estimates for star clusters could be very wrong, which in turn could mean the general understanding of the evolution of these objects could be very wrong as well.

These results also illustrate a fact that astronomers seem to always forget. The stars in any one category (white dwarfs, red super giants, yellow stars like the Sun, etc.) are not all identical, and thus their life and death processes will not all follow the predicted stages, like clockwork. Things are always far more complicated. Though the predictions might be broadly right, there will be many variations, so many that it will often be difficult to draw a generalized conclusion.

It seems that with white dwarfs astronomers have made this mistake, and now must rethink many of their conclusions.

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The troubled politics of ground-based astronomy

10:54 am

Link here. The article outlines the politics and negotiations now going on during the writing of the next astronomy decadal survey, the document American astronomers have published every decade since the 1960s to provide the science agencies in the federal government guidance on how to spend the taxpayers’ money on the next decade’s astronomy projects.

The focus is on the problems now faced by the two big American ground-based telescopes, the Thirty Meter Telescope (TMT) and the Giant Magellan Telescope (GMT).

The future of the Giant Magellan Telescope (GMT) and the Thirty Meter Telescope (TMT) likely depends on whether the survey recommends that NSF spend what sources put at $1.8 billion to support a recently forged partnership between the projects. If it does, other proposals could lose out, such as a ­continent-spanning radio array and detectors for neutrinos and other cosmic particles.

While some astronomers are pushing for this $1.8 billion bailout to save both, others are arguing the money can be better spent elsewhere. There is also a third option, not mentioned, which would be to abandon one of these telescopes and instead build just one.

The story is focused entirely on ground-based astronomy, which is remarkably very near-sighted for scientists whose job it is to see a far as possible. The future of astronomy is in space, and to not consider that alternative in this discussion means you aren’t considering all your options. For $1.8 billion, using private rockets and competitive construction approaches, I strongly believe a very large optical telescope could be launched that would provide far more cutting edge astronomy than any larger ground-based telescope. Hubble has proven that endlessly for the past thirty years.

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Webb telescope finally completed, ready for shipment to launchpad

2:15 pm

After more than two decades of construction (ten years behind schedule) and more than $10 billion (20 times the original cost), the infrared James Webb Space Telescope has finally completed its testing and is ready for shipment to its launch site in French Guiana to be mounted on an Ariane 5 rocket.

Now that observatory testing has concluded, shipment operations have begun. This includes all the necessary steps to prepare Webb for a safe journey through the Panama Canal to its launch location in Kourou, French Guiana, on the northeastern coast of South America. Since no more large-scale testing is required, Webb’s clean room technicians have shifted their focus from demonstrating it can survive the harsh conditions of launch and work in orbit, to making sure it will safely arrive at the launch pad. Webb’s contamination control technicians, transport engineers, and logistics task forces are all expertly prepared to handle the unique task of getting Webb to the launch site. Shipping preparations will be completed in September.

If all goes well, NASA and ESA hope to launch the telescope in late October. It will then take about six months for the telescope to unfold and reach its operating position a million miles from Earth in the Earth’s shadow.

Let us all pray that everything works. If it does not, there will be nothing that can be done to fix it for probably at least five years, if then, as it will be out of reach of any maintenance mission, manned or unmanned.

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Spanish judge invalids agreement to build TMT in Canary Islands

9:05 am

The consortium attempting to build the Thirty Meter Telescope (TMT), blocked by protesters in Hawaii, has now had its back-up location in the Canary Islands blocked by a Spanish judge, who last month invalidated the agreement between the consortium and local authorities.

[A]n administrative court in Santa Cruz de Tenerife, the capital of the Spanish archipelago, ruled last month that the 2017 concession by local authorities of public land for the tentative project was invalid. The ruling was dated on July 29, but only became public this week after local media reported about the decision.

In the ruling obtained by The Associated Press, Judge Roi López Encinas wrote that the telescope land allocation was subject to an agreement between the Canary Astrophysics Institute, or IAC, and the telescope’s promoter, the TMT International Observatory (TIO) consortium. But the judge ruled that the agreement was not valid because TIO had not expressed an intention to build on the La Palma site instead of at the Hawaii site.

In other words, it appears the agreement was ruled invalid because the TMT builders had not made a firm commitment about building at the Canary Islands.

At this moment it truly looks like TMT is dead. It has no alternative site, and its political support in Hawaii is nil. While the Democratic Party politicians that rule that state have mouthed support for it, almost all their actions since the protests began has been to help the protesters and stymie construction.

What I think will soon begin happening is that the partners in TMT will begin to back out, switching their support to the other large ground-based telescopes being planned, the Giant Magellan Telescope and the European-Extremely Large Telescope. Since these are both being built in Chile, the loss of TMT means that there will be no large ground-based telescope coverage of the northern sky.

The real solution? Stop building ground-based telescopes. Put them in space, where such political issues won’t exist, and the view will be unimpeded by either the atmosphere or the tens of thousands of new satellites expected to launch in the coming years.

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First hi-res radio wavelength images of metal asteroid Psyche

9:46 am

Psyche in thermal

Using the ALMA telescope in Chile astronomers have obtained the highest resolution radio images of the surface of the metal-rich asteroid Psyche yet obtained. The image to the right is from their just published paper. From the article:

These new images reveal that some regions of the asteroid have surface temperatures different from the average, indicating that Psyche’s composition is not uniform. The researchers also found that Psyche has a relatively high thermal inertia compared to other asteroids, yet it radiates approximately 60% less heat than would be expected for an object with such a high inertia. The researchers hypothesize that this is because the asteroid’s surface is at least 30% metal. However, the light reflecting off Psyche’s surface is unpolarized, which would not be the case for an object with a smooth or solid metallic surface. They therefore hypothesize that metallic grains are spread throughout its surface material, causing the light to scatter.

Though Psyche is large, 178 by 144 by 101 miles, it is not spherical like Ceres, the largest asteroid in the asteroid belt at 580 miles diameter. Thus, somewhere from the size of Psyche to the size of Ceres we move from an irregular asteroid body to a spherical planetary body, as it appears most planetary scientists define planets.

The probe Psyche is scheduled to launch in August ’22 to arrive at Psyche in ’26.

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Asteroid discovered with shortest orbit yet

8:55 am

Astroid's orbit
Click for full image.

Astronomers have discovered an asteroid that circles the Sun with the shortest orbit yet found, flying mostly inside the orbit of Mercury.

The illustration to the right shows the asteroids orbit, which is also tilted 32 degrees from the plane of the solar system.

The orbit of the approximately 1-kilometer-diameter asteroid takes it as close as 20 million kilometers (12 million miles or 0.13 au), from the Sun every 113 days. Asteroid 2021 PH27, revealed in images acquired during twilight, also has the smallest mean distance (semi-major axis) of any known asteroid in our Solar System — only Mercury has a shorter period and smaller semi-major axis. The asteroid is so close to the Sun’s massive gravitational field, it experiences the largest general relativistic effects of any known Solar System object.

Relatively few asteroids have been found with orbits shorter than Earth’s, because to find them astronomers have to turn their telescopes sunward, where viewing is limited to the early evening or early morning. Few space-based telescopes in all wavelengths also don’t look this way much, because of the risk of damage from the intense sunlight.

It is thus unknown exactly how many asteroids exist with similar orbits. There may be many, with many having short eccentric orbits, similar to comets, that extend out to Earth’s orbit and thus pose a risk. Or there may be few, since such orbits so close to the Sun are likely to cause the asteroid’s break-up and destruction over time.

Knowing how many of course is important, in order to obtain a full census of those asteroids in the solar system that might hit the Earth. To get it will likely require placing a probe designed to look for them.

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Hawaiian TMT protesters found not guilty of obstructing the road they obstructed

9:05 am

The law for thee but not for me: An Hawaiian judge has ruled that the protesters of the Thirty Meter Telesecope (TMT) who had obstructed the access road to the top of Mauna Kea are not guilty of obstructing that road.

[I]n announcing her verdict, the judge noted that during the trial, officials testified that the access road was closed and there were no permits issued for oversized vehicles. “Evidence that Mauna Kea access road was closed or restricted to the public, coupled with no permits, equals no obstruction,” Laubach said. “There would be no unreasonable inconvenience or hazard.”

The state failed to meet its burden beyond a reasonable doubt, she said.

This ruling is a joke. The reason the officials closed the road was because the protesters were there. The officials did not want anyone hurt by the oversized trucks that had legal permission to drive through carrying TMT construction equipment.

Such a ruling however is not a surprise. From top to bottom Hawaii’s government in controlled by the Democratic Party. The judge almost certainly was a Democrat. The Democrats favor the bigoted anti-white and anti-technology agenda of the protesters, and have gone out of their way to help them in their protests.

In general, protesters for Democratic Party causes can loot, burn, kill, obstruct traffic, and do all sorts of violent things — including physically attacking women and children in a park in Portland — and are either never arrested, quickly released on dropped charges, or found innocent.

Be a conservative and spend a dozen minutes inside the Capitol Building taking a few selfies, however, and you will find yourself imprisoned for months, with no charges brought and no sign they ever will be brought. You are guilty, and you will be punished. How dare you do anything that opposes the Democratic Party and its storm trooper thugs?

TMT is never going to be built in Hawaii. In fact, I am beginning to doubt it will ever be built anywhere. Considering the increasing difficulty that ground-based astronomy is going to have dealing with the many satellite constellations now being launched, it is very possible the support for the telescope will begin to dry up. And maybe this failure will be a signal to astronomers that they should finally begin spending their money on space-based optical telescopes.

Meanwhile, Hawaii has become a place hostile to science, to new knowledge, and even to tourism. The dark age there has come quite quickly.

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Scientists: Betelgeuse dimmed because of giant dark spot on surface

12:00 pm

The uncertainty of science: A new study by scientists in China now proposes that the dimming of the red giant star Betelgeuse in 2019-2020 was because of a giant dark and cold spot on its surface.

When Betelgeuse was at its dimmest on Jan. 31, 2020, its effective temperature — meaning, the temperature calculated from its emitted radiation — was measured at 3,476 degrees Kelvin (about 5,800 degrees Fahrenheit or 3,200 degrees Celsius.)

But once the star was back to a normal luminosity, measurements indicated an almost 5% temperature rise to 3,646 Kelvin (roughly 6,100 F or 3,370 degrees C.)

…[T]he astronomers … concluded it is unlikely the entire surface cooled temporarily by that amount. Rather, it must have been a sunspot — or rather, a “star spot” — blocking some of Betelgeuse’s radiation from escaping, they said.

This new hypothesis aligns partly with others that say it was a combination of a dark spot and intevening dust that caused the dimming.

None of these hypotheses however “solve” the mystery. Too little concrete information exists at present to do that.

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For the first time astronomers measure the rotation of exoplanets

10:10 am

The uncertainty of science: Using the Keck Telescope in Hawaii astronomers for the first time have measured the rotation of several exoplanets orbiting the star HR8799, about 129 light years away.

Using the state-of-the-art Keck Planet Imager and Characterizer (KPIC) on the Keck II telescope atop Hawaiʻi Island’s Maunakea, astronomers found that the minimum rotation speeds of HR 8799 planets d and e clocked in at 10.1 km/s and 15 km/s, respectively. This translates to a length of day that could be as short as three hours or could be up to 24 hours such as on Earth depending on the axial tilts of the HR 8799 planets, which are currently undetermined. For context, one day on Jupiter lasts nearly 10 hours; its rotation speed is about 12.7 km/s.

As for the other two planets, the team was able to constrain the spin of HR 8799 c to an upper limit of less than 14 km/s; planet b’s rotation measurement was inconclusive.

These results are somewhat uncertain, as are any conclusions theorists try to draw from them. Even if confirmed, the sample is so small it doesn’t tell us anything yet about overall trends in planet formation or the expected spin rate of planets as they form.

Nonetheless, the detection appears valid and thus a scientific triumph. Astronomers have been telling me for years that figuring out ways to find out more about exoplanets is going to become the next hot subject in astronomy. This result illustrates this.

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An astrophysicist explains cosmology’s theoretical failures

8:37 am

Link here. The astrophysicist, Paul Sutter, does a very nice job of outlining the conundrum that has been causing astrophysicists to tear their hair out for the past decade-plus.

In the two decades since astronomers discovered dark energy, we’ve come upon a little hitch: Measurements of the expansion rate of the universe (and so its age) from both the CMB [cosmic microwave background] and supernovas have gotten ever more precise, but they’re starting to disagree. We’re not talking much; the two methods are separated by only 10 million or 20 million years in estimating the 13.77-billion-year history of the universe. But we’re operating at such a level of precision that it’s worth talking about.

If anything, this failure for two measurements of data spanning billions of light years — which is billions in both time and space — is a perfect illustration of the uncertainty of science. Astrophysicists are trying to come up with answers based on data that is quite thin, with many gaps in knowledge, and carries with it many assumptions. It therefore is actually surprising that these two numbers agree as well as they do.

Sutter, being in the CMB camp, puts most of the blame for this failure on the uncertainty of what we know about supernovae. He could very well be right. The assumptions about supernovae used to measure the expansion rate of the universe are many. There is also a lot of gaps in our knowledge, including a full understanding of the process that produces supernovae.

Sutter however I think puts too much faith in theoretical conclusions of the astrophysics community that have determined the age of the universe based on the CMB. The uncertainties here are as great. Good scientists should remain skeptical of this as well. Our knowledge of physics is still incomplete. Physicists really don’t know all the answers, yet.

In the end, Sutter however does pin down the biggest problem in cosmology:

The “crisis” is a good excuse to keep writing papers, because we’ve been stumped by dark energy for over two decades, with a lot of work and not much understanding. In a sense, many cosmologists want to keep the crisis going, because as long as it exists, they have something to talk about other than counting down the years to the next big mission.

In other words, the discussion now is sometimes less about science and theories and cosmology, but instead about funding and career promotion. What a shock!

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The Oort Cloud: what little is known

5:47 pm

Link here. This is one of the best articles on the theorized Oort Cloud, in that right off the bat the author recognizes this important fact:

We know so little about it that its very existence is theoretical — the material that makes up this cloud has never been glimpsed by even our most powerful telescopes, except when some of it breaks free.

The cloud’s existence is extrapolated from the arrival of long period comets, and seems to make sense. Yet, without any direct observations it remains a theory only, and an unproven one at that.

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Astronomers detect for the first time an accretion disk around an exoplanet

8:43 am

The exoplanet and its accretion disk
Click for full image.

Using the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile, astronomers have made the first confirmed images of a moon-forming accretion disk around another a very young exoplanet.

The photo to the right shows this, with the top image the wide view showing the exoplanet in its orbit around the star, in an area inside the star’s own accretion disk (the larger ring) that the planet has apparently cleared of debris as it gathered itself. The bottom image zooms into the planet to show its own disk of material.

From the press release:

The disc in question, called a circumplanetary disc, surrounds the exoplanet PDS 70c, one of two giant, Jupiter-like planets orbiting a star nearly 400 light-years away. Astronomers had found hints of a “moon-forming” disc around this exoplanet before but, since they could not clearly tell the disc apart from its surrounding environment, they could not confirm its detection — until now.

In addition, with the help of ALMA, Benisty and her team found that the disc has about the same diameter as the distance from our Sun to the Earth and enough mass to form up to three satellites the size of the Moon.

The exoplanet’s disk is thus very large compared to our solar system, but that isn’t surprising considering the difficulty of observing it at such distances. Disks comparable in size to our solar system and the Earth-Moon system are simply too small for any telescope to yet image in this way.

The new data also found this interesting fact: The other known Jupiter-like exoplanet in this system does not have its own accretion disk or any visible debris orbiting it. Why one planet still has such debris and the other does not is a mystery related to the formation of solar systems that is at present not understood.

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Hubble returned to science operations

8:49 am

Engineers today completed their testing of their computer hardware fix on the Hubble Space Telescope and took it out of safe mode, allowing science observations to resume after more than a month.

The first observation is scheduled for Saturday afternoon after some instrument calibrations are completed. Most observations missed while science operations were suspended will be rescheduled for a later date.

Now let us all pray that there are no more major failures for the next few years until the U.S. capabilities in space grow and a relatively fast mission to repair the telescope is possible.

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Engineers report Hubble fix appears successfully

8:50 am

Engineers this morning announced that their attempt to switch to backup computer hardware on the Hubble Space Telescope was successful.

The switch included bringing online the backup Power Control Unit (PCU) and the backup Command Unit/Science Data Formatter (CU/SDF) on the other side of the Science Instrument and Command & Data Handling (SI C&DH) unit. The PCU distributes power to the SI C&DH components, and the CU/SDF sends and formats commands and data. In addition, other pieces of hardware onboard Hubble were switched to their alternate interfaces to connect to this backup side of the SI C&DH. Once these steps were completed, the backup payload computer on this same unit was turned on and loaded with flight software and brought up to normal operations mode.

They are now doing tests to make sure everything is working as expected, and preparing the telescope to bring it out of safe mode and resume science operations.

This is great news, but to bring everyone down to Earth, we must remember that Hubble no longer has any redundancy in this area. Should there be another similar computer failure, the telescope will then be dead in the water, with the only way to bring it back a manned or robotic mission — something we presently do not have the capacity to do — to replace these units.

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Hubble update: Engineers pinpoint issue, prepare to fix it

12:38 pm

In an update today on the status for bringing the Hubble Space Telescope back into science operations, the engineers say they think they have pinpointed the failed unit, and are ready to do the switch to a backup.

A series of multi-day tests, which included attempts to restart and reconfigure the computer and the backup computer, were not successful, but the information gathered from those activities has led the Hubble team to determine that the possible cause of the problem is in the Power Control Unit (PCU).

The PCU also resides on the SI C&DH unit. It ensures a steady voltage supply to the payload computer’s hardware. The PCU contains a power regulator that provides a constant five volts of electricity to the payload computer and its memory. A secondary protection circuit senses the voltage levels leaving the power regulator. If the voltage falls below or exceeds allowable levels, this secondary circuit tells the payload computer that it should cease operations. The team’s analysis suggests that either the voltage level from the regulator is outside of acceptable levels (thereby tripping the secondary protection circuit), or the secondary protection circuit has degraded over time and is stuck in this inhibit state.

Because no ground commands were able to reset the PCU, the Hubble team will be switching over to the backup side of the SI C&DH unit that contains the backup PCU. All testing of procedures for the switch and associated reviews have been completed, and NASA management has given approval to proceed. The switch will begin Thursday, July 15, and, if successful, it will take several days to completely return the observatory to normal science operations.

Engineers did a similar switch in 2008, so they are very confident it will work this time also. However, once done, the telescope will no longer have backups for any of these computer modules. The next failure in any of them will shut the telescope down, for good.

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Scientists successfully predict resumption of bursts from magnetar

12:14 pm

The uncertainty of science: Though they have no real idea why it happens, scientists have now successfully predicted the resumption of energetic bursts coming from a magnetar and according to schedule.

The researchers — Grossan and theoretical physicist and cosmologist Eric Linder from SSL and the Berkeley Center for Cosmological Physics and postdoctoral fellow Mikhail Denissenya from Nazarbayev University in Kazakhstan — discovered the pattern last year in bursts from a soft gamma repeater, SGR1935+2154, that is a magnetar, a prolific source of soft or lower energy gamma ray bursts and the only known source of fast radio bursts within our Milky Way galaxy. They found that the object emits bursts randomly, but only within regular four-month windows of time, each active window separated by three months of inactivity.

On March 19, the team uploaded a preprint claiming “periodic windowed behavior” in soft gamma bursts from SGR1935+2154 and predicted that these bursts would start up again after June 1 — following a three month hiatus — and could occur throughout a four-month window ending Oct. 7.

On June 24, three weeks into the window of activity, the first new burst from SGR1935+2154 was observed after the predicted three month gap, and nearly a dozen more bursts have been observed since, including one on July 6.

They made this prediction based on data going back to 2014 that showed the three-month-off/four-month-on pattern.

As to why this pattern exists, they presently have no idea. Theories have been proposed, such as starquakes activated by the magnetar’s fast rotation or blocking clouds of gas, but none are really very convincing, or are backed with enough data.

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Engineers successful complete simulation of Hubble repair

12:30 pm

Though the details released are sparse, engineers working to get the Hubble Space Telescope back in operation since it shut down due to a computer problem in mid-June report today that they have successfully completed a simulation of the procedures they need to do to fix the problem.

This is their entire report:

[The engineers] successfully completed a test of procedures that would be used to switch to backup hardware on Hubble in response to the payload computer problem. This switch could occur next week after further preparations and reviews.

Apparently, because the switch to backup hardware requires switching more than one unit, the sequence is important and following it correctly is critical. It appears they have now determined the correct sequence and will attempt it on Hubble next week.

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