Tag: astronomy

A July 4th Hubble image of Saturn

10:27 am

Saturn as seen by Hubble on July 4, 2020
Click for full image, annotated.

Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope on July 4, 2020, and shows Saturn, its rings, plus several moons, in all their glory.

The dot near the bottom center is Enceladus. The dot at center right is Mimas. If you click on the annotated full image it will show the locations of several other smaller moons much harder to see.

This new Saturn image was taken during summer in the planet’s northern hemisphere.

Hubble found a number of small atmospheric storms. These are transient features that appear to come and go with each yearly Hubble observation. The banding in the northern hemisphere remains pronounced as seen in Hubble’s 2019 observations, with several bands slightly changing color from year to year. The ringed planet’s atmosphere is mostly hydrogen and helium with traces of ammonia, methane, water vapor, and hydrocarbons that give it a yellowish-brown color.

Hubble photographed a slight reddish haze over the northern hemisphere in this color composite. This may be due to heating from increased sunlight, which could either change the atmospheric circulation or perhaps remove ices from aerosols in the atmosphere. Another theory is that the increased sunlight in the summer months is changing the amounts of photochemical haze produced.

The distance across from one end of the rings to the other is about 150,000 miles, about two thirds the distance from the Earth to the Moon.

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First image of multi-exoplanets around young sunlike star

10:00 am

Two exoplanets in one image

Worlds without end: Using the Very Large Telescope (VLT) in Chile, astronomers have taken the first image that captures two different exoplanets circling a young sunlike star.

The star’s light is partly blocked in the upper left of the photo to the right, cropped slightly to post here.

You can read the paper here [pdf]. The star itself, though similar in mass to the Sun, is thought to be only seventeen million years old.

But the system, dubbed TYC 8998-760-1, is nothing like our solar system. One of the star’s companions straddles the line that defines planets, with a mass 14 times Jupiter’s; the other has a mass of six Jupiters. Both orbit far from the star, about 160 and 320 times the average distance between Earth and the Sun. That puts them more than four times farther out than Pluto is from the Sun.

The size and distance of these giant planets were why they could be imaged from the ground.

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After releasing its Ryugu samples Hayabusa-2’s mission will continue

8:33 am

Japan’s space agency JAXA has revealed that it is looking at two fast-spinning asteroids as possible destinations for its Hayabusa-2 spacecraft after it has dropped off its samples from the asteroid Ryugu on December 6.

The candidate asteroids on the agency’s list are asteroid 2001AV43 which Hayabusa2 would reach in November 2029 after flying by Venus, and asteroid 1998KY26 which the probe would reach in July 2031 after passing by another asteroid.

JAXA says both asteroids are rotating on their axis once every 10 minutes. The high-speed spinning indicates that the asteroids’ inner structures are likely different from that of asteroid Ryugu on the first mission, which consists of pieces of rocks.

The spacecraft will no longer have the equipment for returning additional samples, but everything else is functioning and it has the fuel.

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Active volcanoes on Venus?

9:25 am

Using computer models and past radar images from orbiters, scientists now believe that Venus could have as many as 37 active volcanoes.

The type of feature on Venus they think might still be active is called a coronae, circular features detected by radar and distinct to this planet that have been thought to be inactive ancient volcanic features.

In the new study, the researchers used numerical models of thermo-mechanic activity beneath the surface of Venus to create high-resolution, 3D simulations of coronae formation. Their simulations provide a more detailed view of the process than ever before.

The results helped Montési and his colleagues identify features that are present only in recently active coronae. The team was then able to match those features to those observed on the surface of Venus, revealing that some of the variation in coronae across the planet represents different stages of geological development. The study provides the first evidence that coronae on Venus are still evolving, indicating that the interior of the planet is still churning.

Lots of uncertainty here, but nonetheless this is good science. It also reinforces other evidence in recent years that has suggested active volcanism on Venus.

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The magnetic field of a spiral galaxy

9:05 am

Magnetic field of a spiral galaxy
Click for full image.

Using a variety of telescopes, especially the Jansky Very Large Array radio telescope, astronomers have successfully mapped the magnetic field lines of a spiral galaxy seen edge on and 67 million light years away.

The image to the right, cropped and reduced to post here, shows what they have found.

The magnetic field lines extend as much as 22,500 light-years beyond the galaxy’s disk. Scientists know that magnetic fields play an important role in many processes, such as star formation, within galaxies. However, it is not fully understood how such huge magnetic fields are generated and maintained. A leading explanation, called the dynamo theory, suggests that magnetic fields are generated by the motion of plasma within the galaxy’s disk. Ideas about the cause of the kinds of large vertical extensions seen in this image are more speculative, and astronomers hope that further observations and more analysis will answer some of the outstanding questions.

Our understanding of these kinds of gigantic magnetic fields is poor, to put it mildly. This data really only begins the research.

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No TMT construction until 2021, according to its builders

9:19 pm

According to the university consortium building the Thirty Meter Telescope (TMT), they will make no attempt to begin construction until the end of winter in 2021.

According to the official spokesman, the consortium remains committed to building the telescope in Hawaii on Mauna Kea, but I do not see how it will ever happen. The present Democratic government supports the protesters, and there is no chance that government will ever be voted out of power.

Based on this information, I do not think TMT will ever be built, anywhere.

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Comet Neowise: NOW is the time to go see it

8:59 am

Comet Neowise is now visible each evening just after sunset. This article shows a bunch of images produced by people worldwide.

The comet will not be back for thousands of years, so this will be your only chance to see it. And usually good evening-view comets occur only once every few decades, usually not more than once or thrice every century. If you want to see a comet in all its glory, Comet Neowise is giving you a chance, and now is the time to look.

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It appears we will have a comet show in July!

8:55 am

After two other comets this spring suggested they might become bright naked eye objects and then fizzled, it now appears that Comet NEOWISE will deliver, having survived its closest approach to the Sun to now brighten towards first magnitude.

For the northern hemisphere, this is what to expect if you wish to see it:

In the morning sky, the first views of NEOWISE could come as early as July 5 or 6 in the morning sky, very low above the northeast horizon. By around July 11, the comet will reach an altitude of nearly 10 degrees — for comparison, 10 degrees is roughly equal to the width of your fist held at arm’s length. Then over the next 10 days it will gradually slide back down toward the north-northeast horizon, eventually disappearing from dawn visibility.

A far-better viewing perspective will become available in the evening sky starting around July 12, when it will appear low in the northwest sky. In the evenings to follow, the comet will rapidly climb higher in the sky.

On July 22, NEOWISE will make its closest approach to the Earth, a distance of 64 million miles (103 million km). By July 25, the comet will appear 30 degrees (“three fists”) up from the west-northwest horizon as darkness falls. And on July 30-31st, the comet will be passing just to the north of the fine star cluster of Coma Berenices or Berenice’s Hair.

Will this comet brighten more to become comparable to glorious Comet Hale-Bopp in 1997? Keep your fingers crossed.

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New storm outbreak on Jupiter

10:00 am

Clyde's Spot
Click for full image.

A new storm, dubbed Clyde’s spot after its discoverer, developed suddenly in late May on Jupiter, and has been imaged by Juno during its most recent close fly-by of the gas giant planet.

The image to the right, cropped to post here, focuses in on this spot. It is the feature in the center of the full image, with the Great Red Spot to the upper left.

The new feature was discovered by amateur astronomer Clyde Foster of Centurion, South Africa. Early on the morning of May 31, 2020, while imaging Jupiter with his telescope, Foster noticed a new spot, which appeared bright as seen through a filter sensitive to wavelengths of light where methane gas in Jupiter’s atmosphere has strong absorption. The spot was not visible in images captured just hours earlier by astronomers in Australia.

On June 2, 2020, just two days after Clyde Foster’s observations, Juno performed its 27th close flyby of Jupiter. The spacecraft can only image a relatively thin slice of Jupiter’s cloud tops during each pass. Although Juno would not be travelling directly over the outbreak, the track was close enough that the mission team determined the spacecraft would obtain a detailed view of the new feature, which has been informally dubbed “Clyde’s Spot.”

The feature is a plume of cloud material erupting above the upper cloud layers of the Jovian atmosphere. These powerful convective “outbreaks” occasionally erupt in this latitude band, known as the South Temperate Belt

The coolest thing about this is that the storm was spotted by an amateur, using a ground-based telescope, within hours of its inception.

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Calling this exoplanet alien is an understatement

10:03 am

Worlds without end: Using the space telescope TESS astronomers have determined that one of the hottest exoplanets known, with surface temperatures as much as 7,800 degrees Fahrenheit (hotter than our Sun), is even stranger than expected.

Not only does the exoplanet have a polar orbit around its star, that star rotates so fast that its equator bulges out, actually making its poles as much as 1,500 degrees F hotter than the equator.

With each orbit, KELT-9 b twice experiences the full range of stellar temperatures, producing what amounts to a peculiar seasonal sequence. The planet experiences “summer” when it swings over each hot pole and “winter” when it passes over the star’s cooler midsection. So KELT-9 b experiences two summers and two winters every year, with each season about nine hours.

The star, about 670 light years away, is thought to be twice as massive as the Sun, with the exoplanet having a mass 2.9 times that of Jupiter. Whether it is a gas giant like Jupiter or has an atmosphere is entirely unknown. At these temperatures the situation is so alien we really only know the orbit and approximate range of temperatures.

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Giant dark starspots explain Betelgeuse’s dimming last year

9:42 am

Astronomers now think that unusually large dark starspots on the face of the red supergiant star Betelgeuse caused its dimming from October 2019 to April 2020.

“Corresponding high-resolution images of Betelgeuse from December 2019 show areas of varying brightness. Together with our result, this is a clear indication of huge star spots covering between 50% and 70% of the visible surface and having a lower temperature than the brighter photosphere,” said co-author Peter Scicluna from the European Southern Observatory (Eso).

“For comparison, a typical sunspot is the size of the Earth. The Betelgeuse star spot would be a hundred times larger than the Sun. The sudden fading of Betelgeuse does not mean it is going supernova. It is a supergiant star growing a super-sized star spot.” said co-author Prof Albert Zijlstra from The University of Manchester, UK

Starspots have been identified on the surface of Betelgeuse previously, so what is interesting here is how large these spots were.

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Two super-Earths found orbiting nearby red dwarf star

2:40 pm

Worlds without end: Astronomers have detected evidence of two super-Earths orbiting Gliese 887, only 11 light years away and the brightest red dwarf star in the night sky.

They used a technique known as “Doppler wobble”, which enables them to measure the tiny back and forth wobbles of the star caused by the gravitational pull of the planets. The regular signals correspond to orbits of just 9.3 and 21.8 days, indicating two super-Earths – Gliese 887b and Gliese 887c – both larger than the Earth yet moving rapidly, much faster even than Mercury. Scientists estimate the temperature of Gliese 887c to be around 70oC.

Because Gliese 887 is a very constant star, not very active, and with relatively few strong flares, they think these planets have a chance of retaining their atmospheres.

Be aware that these are like most exoplanets only candidate exoplanets. Until their existence is confirmed by other researchers, it is possible the detection is a false one.

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A host of new solar systems

11:20 am

A gallery of baby solar systems

Worlds without end: Astronomers this month released a large collection of images taken during the past four years by the Gemini South Telescope in Chile of young stars that also have debris disks and are likely solar systems in the process of forming.

The image to the right, reduced slightly to post here, is only a sampling of the 26 disk systems found out of 104 young stars photographed. Go to the link to see some higher resolution examples.

Of the 26 images of debris disks obtained by the Gemini Planet Imager (GPI), 25 had “holes” around the central star that likely were created by planets sweeping up rocks and dust. Seven of the 26 were previously unknown; earlier images of the other 19 were not as sharp as those from GPI and often didn’t have the resolution to detect an inner hole. The survey doubles the number of debris disks imaged at such high resolution.

“One of the things we found is that these so-called disks are really rings with inner clearings,” said Esposito, who is also a researcher at the SETI Institute in Mountain View, California. “GPI had a clear view of the inner regions close to the star, whereas in the past, observations by the Hubble Space Telescope and older instruments from the ground couldn’t see close enough to the star to see the hole around it.”

The data strongly confirms most theories about planet formation in these debris disks, as one of the youngest stars did not have any gaps in its disk, suggesting no larger bodies had yet formed to clear out a region.

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Astronomers claim discovery of six exomoons

9:03 am

The uncertainty of science: Astronomers are now claiming they have detected evidence of the existence of six exomoons orbiting different stars with transiting exoplanets.

“These exomoon candidates are so small that they can’t be seen from their own transits. Rather, their presence is given away by their gravitational influence on their parent planet,” Wiegert said.

If an exoplanet orbits its star undisturbed, the transits it produces occur precisely at fixed intervals.

But for some exoplanets, the timing of the transits is variable, sometimes occurring several minutes early or late. Such transit timing variations – known as TTVs – indicate the gravity of another body. That could mean an exomoon or another planet in the system is? affecting the transiting planet.

What they have basically done is applied the technique used to identify exoplanet candidates when the planet does NOT transit the star (the wobble caused by gravity and indicated by spectral changes), and looked to see if they can see the same variations in these exoplanets.

This is fun stuff, but it is so uncertain as to be almost laughable. If you read the press release closely, you will discover that their work has been submitted for publication, but has not yet been even peer reviewed.

Their concept is good, but I would not pay much attention to these “results.”

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Two new multi-wavelength Hubble images of planetary nebulae

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Hubble images of the Butterfly and Jewel Bug planetary nebulae
Click for full image.

Cool images from Hubble! Astronomers have used the Hubble Space Telescope’s entire suite of instruments to produce spectacular new multi-wavelength images of two planetary nebulae, stars that for some reasons not yet entirely understood are surrounded by breath-taking jets and cloud-formations of all shapes and sizes.

The two images are to the right, cropped and reduced to post here.

Planetary nebulas, whose stars shed their layers over thousands of years, can turn into crazy whirligigs while puffing off shells and jets of hot gas. New images from the Hubble Space Telescope have helped researchers identify rapid changes in material blasting off stars at the centers of two nebulas — causing them to reconsider what is happening at their cores.

In the case of NGC 6302, dubbed the Butterfly Nebula, two S-shaped streams indicate its most recent ejections and may be the result of two stars interacting at the nebula’s core. In NGC 7027, a new cloverleaf pattern — with bullets of material shooting out in specific directions — may also point to the interactions of two central stars. Both nebulas are splitting themselves apart on extremely short timescales, allowing researchers to measure changes in their structures over only a few decades.

This is the first time both nebulas have been studied from near-ultraviolet to near-infrared light, a complex, multi-wavelength view only possible with Hubble.

The press release suggests that the most likely and popular explanation for the formation of planetary nebula is the interaction of two closely orbiting stars. While this might be true, it remains only one theory among many, all of which explain some of what we see and none of which explain everything. As I noted in my November 2014 cover story about planetary nebulae for Sky & Telescope:
» Read more

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A fast radio burst that beats every sixteen days

11:59 am

Astronomers have now added to the mystery of fast radio bursts (FRBs), of which about a hundred are known, by discovering one in a nearby galaxy that has a regular outburst every 16.35 days.

Earlier this year CHIME worked with astronomers in Europe to pinpoint the origin of a particular FRB emission — called FRB 180916.J0158+65 — to a galaxy located 500 million light years from Earth.

Now CHIME has determined that FRB 180916 pulses at predictable intervals more than two weeks apart. “It tells us that the origin of at least some FRBs is astrophysically regular in nature, but on long enough time scales that they may be tied to something different than a rotating, compact object — perhaps something like an orbiting system,” said Newburgh, whose lab builds instrumentation for collecting data about the history of the cosmos

Or to put it another way, they really haven’t any idea yet what exactly causes these bursts. The new data however will help formulate better theories, that I guarantee will be contradicted by subsequent new data. At the moment there is so little known about FRBs that any theory must be looked at with great skepticism.

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Astronomers discover giant arc spanning a third of the night sky

9:05 am

Astronomers have discovered a giant arc of hydrogen gas near the Big Dipper that span a third of the night sky and is thought to be the leftover shockwave from a supernova.

Ultraviolet and narrowband photography have captured the thin and extremely faint trace of hydrogen gas arcing across 30°. The arc, presented at the recent virtual meeting of the American Astronomical Society, is probably the pristine shockwave expanding from a supernova that occurred some 100,000 years ago, and it’s a record-holder for its sheer size on the sky.

Andrea Bracco (University of Paris) and colleagues came upon the Ursa Major Arc serendipitously when looking through the ultraviolet images archived by NASA’s Galaxy Evolution Explorer (GALEX). They were looking for signs of a straight, 2° filament that had been observed two decades ago — but they found out that that length of gas was less straight than they thought, forming instead a small piece of a much larger whole.

This is a great illustration of the uncertainty of science. Earlier observations spotted only 2 degrees of this arc, and thus thought it was a straight filament. Newer more sophisticated observations show that this first conclusion was in error, that it was much bigger, and curved.

I wonder what even more and better observations would reveal.

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Antares’ vast blobby atmosphere

9:12 am

The atmosphere of Antares
Click for full image.

Using the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA), astronomers have been able to map out the gigantic atmosphere of gas that surrounds the red gas supergiant star Antares, the closest such star to our solar system.

The ALMA and VLA map of Antares is the most detailed radio map yet of any star, other than the Sun. ALMA observed Antares close to its surface (its optical photosphere) in shorter wavelengths, and the longer wavelengths observed by the VLA revealed the star’s atmosphere further out. As seen in visible light, Antares’ diameter is approximately 700 times larger than the Sun. But when ALMA and the VLA revealed its atmosphere in radio light, the supergiant turned out to be even more gigantic.

“The size of a star can vary dramatically depending on what wavelength of light it is observed with,” explained Eamon O’Gorman of the Dublin Institute for Advanced Studies in Ireland and lead author of the study published in the June 16 edition of the journal Astronomy & Astrophysics. “The longer wavelengths of the VLA revealed the supergiant’s atmosphere out to nearly 12 times the star’s radius.”

The image to the right, cropped and reduced to post here, is what these two telescopes detected. As you can see, the outer atmosphere of the star is very uneven, confirming what other observations of both Antares and Betelgeuse has seen.

These stars are giant gasbags. It appears their shape fluctuates depending on the local “weather” in each star’s atmosphere.

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Lego Antikythera Mechanism

6:01 pm

An evening pause: From the youtube webpage:

The Antikythera Mechanism is the oldest known scientific computer, built in Greece at around 100 BCE. Lost for 2000 years, it was recovered from a shipwreck in 1901. But not until a century later was its purpose understood: an astronomical clock that determines the positions of celestial bodies with extraordinary precision. In 2010, we built a fully-functional replica out of Lego.

Hat tip Shaun Karry.

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New Horizons sees stellar parallax

3:04 pm

New Horizons is now far enough away from Earth that its perspective of the universe shifts at least two nearby stars into slightly different positions than seen on Earth.

On April 22-23, the spacecraft turned its long-range telescopic camera to a pair of the closest stars, Proxima Centauri and Wolf 359, showing just how they appear in different places than we see from Earth. Scientists have long used this “parallax effect” – how a star appears to shift against its background when seen from different locations — to measure distances to stars.

An easy way to see parallax is to place one finger at arm’s length and watch it jump back and forth when you view it successively with each eye. Similarly, as Earth makes it way around the Sun, the stars shift their positions. But because even the nearest stars are hundreds of thousands of times farther away than the diameter of Earth’s orbit, the parallax shifts are tiny, and can only be measured with precise instrumentation. “No human eye can detect these shifts,” Stern said.

But when New Horizons images are paired with pictures of the same stars taken on the same dates by telescopes on Earth, the parallax shift is instantly visible. The combination yields a 3D view of the stars “floating” in front of their background star fields.

The resulting 3D image, available at the link, is very cool. Both stars clearly appear closer than the surrounding background stars, which of course is true as they are among the closest stars to the Sun.

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NASA confirms Webb launch delayed again

9:16 am

NASA officials yesterday confirmed that, due to the new work conditions and the lock down imposed by the Wuhan flu panic, the launch of the James Webb Space telescope will not occur in March 2021.

“We will not launch in March,” said Thomas Zurbuchen, the space agency’s associate administrator for science. “Absolutely we will not launch in March. That is not in the cards right now. That’s not because they did anything wrong. It’s not anyone’s fault or mismanagement.”

Zurbuchen made these comments at a virtual meeting of the National Academies’ Space Studies Board. He said the telescope was already cutting it close on its schedule before the COVID-19 pandemic struck the agency and that the virus had led to additional lost work time. “This team has stayed on its toes and pushed this telescope forward at the maximum speed possible,” he said. “But we’ve lost time. Instead of two shifts fully staffed, we could not do that for all the reasons that we talk about. Not everybody was available. There were positive cases here and there (in the surrounding area, not on site). And so, perhaps, we had only one shift.”

No new target date has been set, though the comments even hinted that they might not be able to do it in 2021.

Webb will cost 20 times more than originally budgeted ($500 million vs $10 billion) and is now more than a decade behind schedule. In the process, those overages and delays wiped out almost all of NASA’s other astronomy projects during the 2010s.

But don’t worry! Once Webb launches the task of wiping out more astronomy projects with overages and delays will be courageously taken up by NASA’s Roman Space Telescope (formerly WFIRST), already behind schedule and over budget, and it is still only in the design phase.

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Rethinking the theories that explain some supernovae

10:30 am

The uncertainty of science: New data now suggests that the previous consensus among astronomers that type Ia supernovae were caused by the interaction of a large red giant star with a white dwarf might be wrong, and that instead the explosion might be triggered by two white dwarfs.

If this new origin theory turns out to be correct, then it might also throw a big wrench into the theory of dark energy.

The evidence that twin white dwarfs drive most, if not all, type Ia supernovae, which account for about 20% of the supernova blasts in the Milky Way, “is more and more overwhelming,” says Dan Maoz, director of Tel Aviv University’s Wise Observatory, which tracks fast-changing phenomena such as supernovae. He says the classic scenario of a white dwarf paired with a large star such as a red giant “doesn’t happen in nature, or quite rarely.”

Which picture prevails has impacts across astronomy: Type Ia supernovae play a vital role in cosmic chemical manufacturing, forging in their fireballs most of the iron and other metals that pervade the universe. The explosions also serve as “standard candles,” assumed to shine with a predictable brightness. Their brightness as seen from Earth provides a cosmic yardstick, used among other things to discover “dark energy,” the unknown force that is accelerating the expansion of the universe. If type Ia supernovae originate as paired white dwarfs, their brightness might not be as consistent as was thought—and they might be less reliable as standard candles.

If type Ia supernovae are not reliable standard candles, then the entire Nobel Prize results that discovered dark energy in the late 1990s are junk, the evidence used to discover it simply unreliable. Dark energy might simply not exist.

What galls me about this possibility is that it was always the case. The certainty in the 1990s about using type Ia supernovae as a standard candle to determine distance was entirely unjustified. Even now astronomers do not really know what causes these explosions. To even consider them to always exhibit the same energy release was just not reasonable.

And yet astronomers in the 1990s did, and thus they fostered the theory of dark energy upon us — that the universe’s expansion was accelerating over vast distances — while winning Nobel Prizes. They still might be right, and dark energy might exist, but it was never very certain, and still is not.

Much of the fault in this does not lie with the astronomers, but with the press, which always likes to sell new theories as a certainty, scoffing over the doubts and areas of ignorance that make the theories questionable. This is just one more example of this, of which I can cite many examples, the worst of all being the reporting about global warming.

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Exoplanet in Earth-like orbit circling Sun-type star

9:54 am

Worlds without end: Astronomers have found evidence suggesting the existence of an exoplanet about twice as massive as the Earth and orbiting a solar-twin star in an orbit almost the same as the Earth’s.

The star, Kepler-160, is about 3,000 light years away, and had previously discovered to have two exoplanets.

“Our analysis suggests that Kepler-160 is orbited not by two but by a total of four planets,” Heller summarizes the new study. One of the two planets that Heller and his colleagues found is Kepler-160d, the previously suspected planet responsible for the distorted orbit of Kepler-160c. Kepler-160d does not show any transits in the light curve of the star and so it has been confirmed indirectly. The other planet, formally a planet candidate, is KOI-456.04, probably a transiting planet with a radius of 1.9 Earth radii and an orbital period of 378 days. Given its Sun-like host star, the very Earth-like orbital period results in a very Earth-like insolation from the star – both in terms of the amount of the light received and in terms of the light color. Light from Kepler-160 is visible light very much like sunlight. All things considered, KOI-456.04 sits in a region of the stellar habitable zone – the distance range around a star admitting liquid surface water on an Earth-like planet – that is comparable to the Earth’s position around the Sun.

“KOI-456.01 is relatively large compared to many other planets that are considered potentially habitable. But it’s the combination of this less-than-double the size of the Earth planet and its solar type host star that make it so special and familiar,” Heller clarifies. As a consequence, the surface conditions on KOI-456.04 could be similar to those known on Earth, provided its atmosphere is not too massive and non-Earth-like. The amount of light received from its host star is about 93 percent of the sunlight received on Earth. If KOI-456.04 has a mostly inert atmosphere with a mild Earth-like greenhouse effect, then its surface temperature would be +5 degrees Celsius on average, which is about ten degrees lower than the Earth’s mean global temperature.

These results have many uncertainties, so we should not be surprised if further research produces significant revisions in these conclusions. Nonetheless, the number of Earth-like planets orbiting Sun-like stars in orbits like the Earth’s continues to rise.

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Second exoplanet confirmed orbiting Proxima Centauri

12:51 pm

Worlds without end: Using archived Hubble data, astronomers have now independently confirmed the existence of a second exoplanet orbiting the nearest star, Proxima Centauri.

Dubbed Proxima c, this is not the same Earth-sized exoplanet confirmed to orbit the star last week. That planet, Proxima b, orbits close to the star every 11.2 days. The new planet is much farther out.

Benedict found a planet with an orbital period of about 1,907 days buried in the 25-year-old Hubble data. This was an independent confirmation of the existence of Proxima Centauri c.

Shortly afterward, a team led by Raffaele Gratton of INAF published images of the planet at several points along its orbit that they had made with the SPHERE instrument on the Very Large Telescope in Chile.

Benedict then combined the findings of all three studies: his own Hubble astrometry, Damasso’s radial velocity studies, and Gratton’s images to greatly refine the mass of Proxima Centauri c. He found that the planet is about 7 times as massive as Earth.

Though I am unaware of any hints of additional planets orbiting Proxima Centauri, the presence of two strongly implies the likelihood of more.

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Smallest satellite yet detects exoplanet

11:06 am

The smallest satellite yet, a cubesat, has demonstrated the potential of cubesats to do real cutting edge astronomy by successfully detected a known exoplanet.

Long before it was deployed into low-Earth orbit from the International Space Station in Nov. 2017, the tiny ASTERIA spacecraft had a big goal: to prove that a satellite roughly the size of a briefcase could perform some of the complex tasks much larger space observatories use to study exoplanets, or planets outside our solar system. A new paper soon to be published in the Astronomical Journal describes how ASTERIA (short for Arcsecond Space Telescope Enabling Research in Astrophysics) didn’t just demonstrate it could perform those tasks but went above and beyond, detecting the known exoplanet 55 Cancri e.

Scorching hot and about twice the size of Earth, 55 Cancri e orbits extremely close to its Sun-like parent star. Scientists already knew the planet’s location; looking for it was a way to test ASTERIA’s capabilities. The tiny spacecraft wasn’t initially designed to perform science; rather, as a technology demonstration, the mission’s goal was to develop new capabilities for future missions. The team’s technological leap was to build a small spacecraft that could conduct fine pointing control – essentially the ability to stay very steadily focused on an object for long periods.

…The CubeSat used fine pointing control to detect 55 Cancri e via the transit method, in which scientists look for dips in the brightness of a star caused by a passing planet. When making exoplanet detections this way, a spacecraft’s own movements or vibrations can produce jiggles in the data that could be misinterpreted as changes in the star’s brightness. The spacecraft needs to stay steady and keep the star centered in its field of view. This allows scientists to accurately measure the star’s brightness and identify the tiny changes that indicate the planet has passed in front of it, blocking some of its light.

This success is mostly a proof of concept, but it lays the groundwork for less expensive future space astronomy, using low cost cubesats capable of doing what the expensive orbiting space telescopes have done so far.

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Chandra captures black hole outburst over eight months

9:32 am

Four-frame movie of black hole outburst

Astronomers using the Chandra X-ray space telescope have documented the motion of two blobs moving away from a stellar-mass black hole over a period of eight months, producing a four-frame movie from their images and estimating the speed of those blobs to be 80% that of the speed of light.

The gif animation to the right shows that short movie.

The black hole and its companion star make up a system called MAXI J1820+070, located in our Galaxy about 10,000 light years from Earth. The black hole in MAXI J1820+070 has a mass about eight times that of the Sun, identifying it as a so-called stellar-mass black hole, formed by the destruction of a massive star. (This is in contrast to supermassive black holes that contain millions or billions of times the Sun’s mass.)

The companion star orbiting the black hole has about half the mass of the Sun. The black hole’s strong gravity pulls material away from the companion star into an X-ray emitting disk surrounding the black hole.

While some of the hot gas in the disk will cross the “event horizon” (the point of no return) and fall into the black hole, some of it is instead blasted away from the black hole in a pair of short beams of material, or jets. These jets are pointed in opposite directions, launched from outside the event horizon along magnetic field lines. The new footage of this black hole’s behavior is based on four observations obtained with Chandra in November 2018 and February, May, and June of 2019, and reported in a paper led by Mathilde Espinasse of the Université de Paris.

Hubble has produced similar movies of the activity around the Crab Nebula. Sadly, we don’t have enough space telescopes like these in orbit to monitor such objects more frequently and thus photograph their behavior more completely. If we did we’d be able to get a much better understanding of their ongoing activity. We would also be able to produce more movies such as this, with much higher resolution and more continuous coverage.

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That Jupiter Trojan comet-like asteroid was neither an asteroid nor a Trojan

9:14 am

Astronomers have now found that the asteroid that had suddenly become active, like a comet, and they had thought was part of the asteroids in Jupiter orbit called Trojans, was neither an asteroid nor a Trojan.

Instead, it is an actual comet captured in a strange unstable orbit around Jupiter.

[W]hen amateur astronomer Sam Deen used software on the Jet Propulsion Laboratory’s solar-system dynamics website to calculate the object’s orbit, he found P/2019 LD2 recently had a close encounter with Jupiter that left its orbit unstable. The model showed that the comet had likely been a Centaur, part of a family of outer solar system asteroids, with an orbit reaching out to Saturn. Then, on February 17, 2017, it passed about 14 million kilometers from Jupiter, an encounter that sent the comet on a wild ride and inserted it into an odd Jupiter-like orbit.

Yet although the swing past Jupiter put P/2019 LD2 into a Jupiter-like orbit, it didn’t move it near to one of the two Lagrange points where the combination of gravitational forces from Jupiter and the Sun hold Trojan asteroids. Instead of being 60° — one-sixth of the giant planet’s orbit — from Jupiter, P/2019 LD2 is only 21° ahead of Jupiter.

The orbit is unstable. It will bring the comet to within 3 million miles of Jupiter in 2063, but beyond that predictions are impossible. The exact closeness of that approach cannot be predicted with much precision, partly because of the chaotic nature of the orbit, and partly because of the random orbital changes that can occur because the comet is venting.

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Poll: Hawaiians favor construction of TMT by wide margins

1:41 pm

A new poll suggests that Hawaii’s general population supports the construction of the Thirty Meter Telescope (TMT) by a 2 to 1 margins, 61% in favor, 32% opposed.

The poll also found wide opposition to the goals and tactics of the protesters, as well as the failure of the state government under Democratic Governor David Ige to stop those protesters from illegally blocking construction.

  • 92 percent of Hawaii residents agree there should be a way for science and Hawaiian culture both to exist on Maunakea
  • 80 percent of Hawaii residents agree that peaceful protests are fine but have no tolerance for protests that result in laws being broken
  • 79 percent of Hawaii residents agree that the government is responsible for providing safe construction access to the TMT site

None of this really matters. Ige and the Democrats who run Hawaii support the bigoted beliefs of the protesters, who want all non-native residents and their projects removed from Hawaii, while imposing a rule controlled solely by these so-called native Hawaiians.

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New observations confirm Earth-like planet orbiting nearest star

9:44 am

Worlds without end: New observations have confirmed the existence of an Earth-sized planet orbiting the nearest star to our Sun, Proxima Centauri, only 4.2 light years away..

The planet, Proxima b, is estimated to have a mass 1.17 of Earth’s, and orbit the star every 11.2 days. Based on that orbit, the planet is also in the star’s habitable zone. Whether there is life there however remains unknown.

Although Proxima b is about 20 times closer to its star than the Earth is to the Sun, it receives comparable energy, so that its surface temperature could mean that water (if there is any) is in liquid form in places and might, therefore, harbour life.

Having said that, although Proxima b is an ideal candidate for biomarker research, there is still a long way to go before we can suggest that life has been able to develop on its surface. In fact, the Proxima star is an active red dwarf that bombards its planet with X rays, receiving about 400 times more than the Earth. “Is there an atmosphere that protects the planet from these deadly rays?” asks Christophe Lovis, a researcher in UNIGE’s Astronomy Department and responsible for ESPRESSO’s scientific performance and data processing. “And if this atmosphere exists, does it contain the chemical elements that promote the development of life (oxygen, for example)? How long have these favourable conditions existed? We’re going to tackle all these questions.

The research data also suggests there might be another planet in orbit around Proxima Centauri, though this conclusion is very preliminary.

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