Tag: astronomy

Astronomers discover galaxy with no dark matter

3:46 pm

The uncertainty of science: Astronomers have detected a galaxy about 250 million light years away that shows no evidence of any dark matter, a phenomenon that defies the accepted theories about dark matter.

The galaxy in question, AGC 114905, is about 250 million light-years away. It is classified as an ultra-diffuse dwarf galaxy, with the name ‘dwarf galaxy’ referring to its luminosity and not to its size. The galaxy is about the size of our own Milky Way but contains a thousand times fewer stars. The prevailing idea is that all galaxies, and certainly ultra-diffuse dwarf galaxies, can only exist if they are held together by dark matter.
Galaxy AGC 114905

The researchers collected data on the rotation of gas in AGC 114905 for 40 hours between July and October 2020 using the VLA telescope. Subsequently, they made a graph showing the distance of the gas from the center of the galaxy on the x-axis and the rotation speed of the gas on the y-axis. This is a standard way to reveal the presence of dark matter. The graph shows that the motions of the gas in AGC 114905 can be completely explained by just normal matter.

“This is, of course, what we thought and hoped for because it confirms our previous measurements,” says Pavel Mancera Piña. “But now the problem remains that the theory predicts that there must be dark matter in AGC 114905, but our observations say there isn’t. In fact, the difference between theory and observation is only getting bigger.”

The evidence for dark matter in almost all galaxies is the motion of gas and stars in the outer perimeter. Routinely they move faster than expected based merely on visible ordinary matter. To account for the faster speed, astronomers beginning in the late 1950s invented dark matter, an invisible material with a mass sufficient to increase the speeds of objects and gas in the outer regions of galaxies.

That increasingly astronomers are finding galaxies with no evidence of dark matter, based on rotation speeds, only makes this mystery all the more baffling.

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Engineers recover a third Hubble instrument

2:39 pm

Engineers have now reactivated a third instrument on the Hubble Space Telescope, bringing the telescope very close to full operations again with only one instrument, a spectrograph, still in safe mode.

The Hubble Space Telescope team recovered the Cosmic Origins Spectrograph instrument on Sunday, Nov. 28, moving the telescope further toward full science operations. Three of Hubble’s four active instruments are now collecting science data once again.

The team also continued work on developing and testing changes to instrument software that would allow them to conduct science operations even if they encounter several lost synchronization messages in the future. Those changes would first be installed on the Cosmic Origins Spectrograph once they’re completed and tested within a few weeks. Hubble’s other instruments would also receive similar changes. The team has not detected further synchronization message issues since monitoring began Nov. 1.

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Engineers: Webb undamaged by “incident”, ready for December 22nd launch

9:46 am

Arianespace engineers have confirmed after testing that the James Webb Space Telescope was undamaged by “incident” that occurred during stacking, and have okayed the resumption of the telescope’s preparation for launch.

On Wednesday, Nov. 24, engineering teams completed these tests, and a NASA-led anomaly review board concluded no observatory components were damaged in the incident. A “consent to fuel” review was held, and NASA gave approval to begin fueling the observatory. Fueling operations will begin Thursday, Nov. 25, and will take about 10 days.

The launch is now set for December 22nd.

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Second camera on Hubble returned to science operations

10:35 am

Engineers working to reactivate the instruments on the Hubble Space Telescope have successfully brought a second camera out of safe mode.

NASA continues bringing the Hubble Space Telescope back to normal science operations, most recently recovering the Wide Field Camera 3 instrument Sunday, Nov. 21. This camera will be the second of Hubble’s instruments, after the Advanced Camera for Surveys, to resume science after suspending the spacecraft’s observations Oct. 25. The Wide Field Camera 3’s first science observation since the anomaly will be Nov. 23.

The team chose to restore the most heavily used Hubble instrument, the Wide Field Camera 3, which represents more than a third of the spacecraft’s observing time. Engineers also began preparing changes to the instrument parameters, while testing the changes on ground simulators. These changes would allow the instruments to handle several missed synchronization messages while continuing to operate normally if they occur in the future. These changes will first be applied to another instrument, the Cosmic Origins Spectrograph, to further protect its sensitive far-ultraviolet detector. It will take the team several weeks to complete the testing and upload the changes to the spacecraft.

The telescope’s other instruments remain in safe mode as the engineers continue to investigate the problem that caused the shut down on October 25th.

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Webb launch delayed four days because of “incident” during stacking

2:18 pm

NASA management has decided to delay the launch of the James Webb Space Telescope for four days while engineers investigate whether an “incident” that occurred during the telescope’s stacking on top of an Ariane 5 rocket could have long term consequences.

Technicians were preparing to attach Webb to the launch vehicle adapter, which is used to integrate the observatory with the upper stage of the Ariane 5 rocket. A sudden, unplanned release of a clamp band – which secures Webb to the launch vehicle adapter – caused a vibration throughout the observatory.

A NASA-led anomaly review board was immediately convened to investigate and instituted additional testing to determine with certainty the incident did not damage any components. NASA and its mission partners will provide an update when the testing is completed at the end of this week.

The launch had been scheduled for December 18th. They have now pushed it back to December 22nd.

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Hubble operations contract extended to 2026, even as engineers work to fix it

3:10 pm

NASA announced today that it has extended the contract for operating the Hubble Space Telescope through 2026, even as it also provided an update on the effort of engineers to bring all the telescope’s science instruments out of safe mode.

[T]he agency has awarded a sole source contract extension to the Association of Universities for Research in Astronomy (AURA) in Washington for continued Hubble science operations support at the Space Telescope Science Institute (STScI) in Baltimore, which AURA operates for NASA. The award extends Hubble’s science mission through June 30, 2026, and increases the value of the existing contract by about $215 million (for a total of about $2.4 billion).

…Currently, the spacecraft team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is investigating an issue involving missed synchronization messages that caused Hubble to suspend science observations Oct. 25. One of the instruments, the Advanced Camera for Surveys, resumed science observations Nov. 7, and continues to function as expected. All other instruments remain in safe mode.

During the week of Nov. 8, the Hubble team identified near-term changes that could be made to how the instruments monitor and respond to missed synchronization messages, as well as to how the payload computer monitors the instruments. This would allow science operations to continue even if several missed messages occur. The team has also continued analyzing the instrument flight software to verify that all possible solutions would be safe for the instruments.

In the next week, the team will begin to determine the order to recover the remaining instruments. The team expects it will take several weeks to complete the changes for the first instrument.

It appears that it is going to take some time to bring all the instruments back in line, considering that they are fixing the instruments one-by-one, in sequence, and that the first fix is taking weeks. Hopefully as they get each instrument back they will be able to move faster once they know what works.

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Hubble camera back in operation

2:16 pm

Good news! As engineers work to fix the problem that caused the Hubble Space Telescope to shut down on October 25th, they have now successfully returned Hubble’s most important camera back to doing science.

The Hubble team successfully recovered the Advanced Camera for Surveys instrument Nov. 7. The instrument has started taking science observations once again. Hubble’s other instruments remain in safe mode while NASA continues investigating the lost synchronization messages first detected Oct. 23. The camera was selected as the first instrument to recover as it faces the fewest complications should a lost message occur.

This success strongly suggests they have pinpointed the software issue that caused the shutdown, and can now step-by-step reactivate all the other instruments in the coming week.

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New catalog of 90 gravitational wave detections published

9:24 am

The scientists operating the world’s three gravitational wave detectors today released a new catalog of all their detections, totaling 90 with 35 never before published.

All signals come from merging black holes and neutron stars. The new catalog contains some surprises, such as an unusual neutron-star–black-hole merger, a massive black hole merger, and binary black holes revealing information about their spins.

…The researchers have also published two papers accompanying their new catalog today. One looks at what the events can tell us about the population of compact objects in our Universe, how often they merge, and how their masses are distributed. In the other paper the researchers employed the gravitational waves to better understand the expansion history of the cosmos by measuring the Hubble constant.

Because of the tiny sample so far detected, these generalized results cannot be taken too seriously, though they do give hints at the larger context.

All three observatories are now undergoing upgrades, and will resume operations in a few weeks.

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Astronomers release fantasy proposals for government telescopes in the 2020s

8:54 am

The astronomical community today released its newest decadal survey, a outline of what major new telescope projects that community recommends the federal government should fund for the next ten years.

More details here.

This is I think the seventh such decadal survey since the first in the early 1960s. In the past these surveys prompted the construction of numerous space telescopes, such as the Hubble Space Telescope, the James Webb Space Telescope, and many others. Until 2000 these survey were enormously influential, which is why space-based astronomy boomed in the 1980s and 1990s.

Now I call it a fantasy because I think it unlikely that most of its proposals — especially the space-based projects — will see fruition, based on the recent history in this century. For example, the 2001 survey recommended the James Webb Space Telescope among many other recommendations. The cost overruns of that project however eventually caused almost all the other space-based proposals to be cancelled, not only in the 2000s but in the 2010s as well. Furthermore, the 2010 survey called for the building of WFIRST, another Webb-like big space telescope that is now called the Roman Telescope, and that project’s high cost and complexity has further forced the elimination of almost all other new space telescopes. Nor has Roman been built and launched in the 2010s as proposed. It is still under development, with the same kinds of cost orverruns and delayed seen with Webb, which means in the 2020s most of the new proposals in this latest decadal survey will have to take a back seat to it, and will likely never get built.

Prove of my analysis is in the report’s press release:

The first mission to enter this program should be an infrared/optical/ultraviolet (IR/O/UV) telescope — significantly larger than the Hubble Space Telescope — that can observe planets 10 billion times fainter than their star, and provide spectroscopic data on exoplanets, among other capabilities. The report says this large strategic mission is of an ambitious scale that only NASA can undertake and for which the U.S. is uniquely situated to lead. At an estimated cost of $11 billion, implementation of this IR/O/UV telescope could begin by the end of the decade, after the mission and technologies are matured, and a review considers it ready for implementation. If successful, this would lead to a launch in the first half of the 2040 decade. [emphasis mine]

Proposing something that won’t be built for two decades is absurd. And the cost is even more absurd, as it is ten times what Hubble cost and seems more designed as a long term jobs program where nothing will get built but money will continue to pour in endlessly to the contractors and astronomers hired. That is what Webb and Roman essentially became.

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Astronomers detect water in the very very early universe

9:14 am

The uncertainty of science: Using the ALMA telescope in Chile, astronomers have detected the molecules of water and carbon monoxide in a galaxy thought to have formed only 780 million years after the Big Bang.

SPT0311-58 is actually made up of two galaxies and was first seen by ALMA scientists in 2017 at its location, or time, in the Epoch of Reionization. This epoch occurred at a time when the Universe was just 780 million years old—roughly 5-percent of its current age—and the first stars and galaxies were being born. Scientists believe that the two galaxies may be merging, and that their rapid star formation is not only using up their gas, or star-forming fuel but that it may eventually evolve the pair into massive elliptical galaxies like those seen in the Local Universe.

“Using high-resolution ALMA observations of molecular gas in the pair of galaxies known collectively as SPT0311-58 we detected both water and carbon monoxide molecules in the larger of the two galaxies. Oxygen and carbon, in particular, are first-generation elements, and in the molecular forms of carbon monoxide and water, they are critical to life as we know it,” said Sreevani Jarugula, an astronomer at the University of Illinois and the principal investigator on the new research. “This galaxy is the most massive galaxy currently known at high redshift, or the time when the Universe was still very young. It has more gas and dust compared to other galaxies in the early Universe, which gives us plenty of potential opportunities to observe abundant molecules and to better understand how these life-creating elements impacted the development of the early Universe.”

Need I say that there are many uncertainties with this result, including the assumption that the universe is only 780 million years old at location of this galaxy. That age is extrapolated from the galaxy’s red shift, a link that depends on some uncertain assumptions. Moreover, the discovery of these molecules so soon after the theorized Big Bang is unexpected. Cosmologists had assumed that at this early age the universe wasn’t old enough yet to form galaxies with such complex molecules.

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Hubble still in safe mode

9:05 am

NASA released a new but relatively terse update on November 1st describing the status of the Hubble Space Telescope, which has been in safe mode since October 25th.

Hubble’s science instruments issued error codes at 1:46 a.m. EDT Oct. 23, indicating the loss of a specific synchronization message. This message provides timing information the instruments use to correctly respond to data requests and commands. The mission team reset the instruments, resuming science operations the following morning.

At 2:38 a.m. EDT, Oct. 25, the science instruments again issued error codes indicating multiple losses of synchronization messages. As a result, the science instruments autonomously entered safe mode states as programmed.

Mission team members are evaluating spacecraft data and system diagrams to better understand the synchronization issue and how to address it. They also are developing and testing procedures to collect additional data from the spacecraft. These activities are expected to take at least one week.

In other words, the engineers presently do not understand the problem, and are working at pinpointing its cause.

This is not a “glitch”. If used properly that word really refers to something that is akin to a short burp in operations. Hubble has been shut down now for ten days, and will remain so for at least one more week. This is a serious problem that remains unsolved.

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Evidence from nearby white dwarfs suggest rocky exoplanets are alien to Earth

10:15 am

The uncertainty of science: Evidence from 23 white dwarfs, all located less than 650 light years from Earth, suggest that the make-up of rocky exoplanets are likely very alien to Earth, with minerals and chemistry that is found nowhere in our solar system.

They found that these white dwarfs have a much wider range of compositions than any of the inner planets in our solar system, suggesting their planets had a wider variety of rock types. In fact, some of the compositions are so unusual that Putirka and Xu had to create new names (such as “quartz pyroxenites” and “periclase dunites”) to classify the novel rock types that must have existed on those planets.

“While some exoplanets that once orbited polluted white dwarfs appear similar to Earth, most have rock types that are exotic to our solar system,” said Xu. “They have no direct counterparts in the solar system.”

Putirka describes what these new rock types might mean for the rocky worlds they belong to. “Some of the rock types that we see from the white dwarf data would dissolve more water than rocks on Earth and might impact how oceans are developed,” he explained. “Some rock types might melt at much lower temperatures and produce thicker crust than Earth rocks, and some rock types might be weaker, which might facilitate the development of plate tectonics.”

The data from the white dwarfs is believed to be the leftover material of exoplanets that were absorbed by the star, sometime in the far past.

First, this result should not be a surprise. To even think for a second that planets in other solar systems would be similar to the planets in our solar system is unrealistic. Even in our solar system we have found that practically every single body — planets, moons, asteroids, comets — is remarkably unique. Other solar systems are sure to be even more alien.

Second, the result here is somewhat uncertain. The scientists were not gathering data of actual exoplanets, but what is believed to be the remains that had been swallowed by the stars. The scientists then extrapolated backwards to come up with these alien rock types. The result, while very suggestive, must be taken with some skepticism.

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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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