The Oort Cloud: what little is known

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.

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

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.

Hubble returned to science operations

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.

Engineers report Hubble fix appears successfully

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.

Hubble update: Engineers pinpoint issue, prepare to fix it

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.

Scientists successfully predict resumption of bursts from magnetar

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.

Engineers successful complete simulation of Hubble repair

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.

Hubble update: Engineers narrow possible failed hardware to one of two units

Engineers working to pinpoint the cause of the computer hardware issue that has placed the Hubble Space Telescope in safe mode since June 13th have now narrowed the possible failed hardware to one of two units.

The source of the computer problem lies in the Science Instrument Command and Data Handling (SI C&DH) unit, where the payload computer resides. A few hardware pieces on the SI C&DH could be the culprit(s).

The team is currently scrutinizing the Command Unit/Science Data Formatter (CU/SDF), which sends and formats commands and data. They are also looking at a power regulator within the Power Control Unit, which is designed to ensure a steady voltage supply to the payload computer’s hardware. If one of these systems is determined to be the likely cause, the team must complete a more complicated operations procedure to switch to the backup units. This procedure would be more complex and riskier than those the team executed last week, which involved switching to the backup payload computer hardware and memory modules. To switch to the backup CU/SDF or power regulator, several other hardware boxes on the spacecraft must also be switched due to the way they are connected to the SI C&DH unit.

Over the next week or so, the team will review and update all of the operations procedures, commands and other related items necessary to perform the switch to backup hardware. They will then test their execution against a high-fidelity simulator.

The team performed a similar switch in 2008, which allowed Hubble to continue normal science operations after a CU/SDF module failed.

That such a switch was done successfully in the past is a very hopeful sign. However, it sounds as though they are not 100% sure they have pinpointed the actual issue, which means that this switch still might not fix the problem.

We can only wait and hope. And even if the fix works, Hubble will no longer have working backup units for these pieces of hardware. Should any of the backup that are now being activated fail, the telescope will fail, and this time it won’t be fixable with the equipment on board.

Astronomers detect a white dwarf that is both the smallest and most massive ever found

Using an array of telescopes on the ground and in space, astronomers have discovered a white dwarf star that is both the smallest ever found while also being the most massive.

White dwarfs are the collapsed remnants of stars that were once about eight times the mass of our Sun or lighter. Our Sun, for example, after it first puffs up into a red giant in about 5 billion years, will ultimately slough off its outer layers and shrink down into a compact white dwarf. About 97 percent of all stars become white dwarfs.

While our Sun is alone in space without a stellar partner, many stars orbit around each other in pairs. The stars grow old together, and if they are both less than eight solar-masses, they will both evolve into white dwarfs.

The new discovery provides an example of what can happen after this phase. The pair of white dwarfs, which spiral around each other, lose energy in the form of gravitational waves and ultimately merge. If the dead stars are massive enough, they explode in what is called a type Ia supernova. But if they are below a certain mass threshold, they combine together into a new white dwarf that is heavier than either progenitor star. This process of merging boosts the magnetic field of that star and speeds up its rotation compared to that of the progenitors.

Astronomers say that the newfound tiny white dwarf, named ZTF J1901+1458, took the latter route of evolution; its progenitors merged and produced a white dwarf 1.35 times the mass of our Sun. The white dwarf has an extreme magnetic field almost 1 billion times stronger than our Sun’s and whips around on its axis at a frenzied pace of one revolution every seven minutes (the zippiest white dwarf known, called EPIC 228939929, rotates every 5.3 minutes).

Based on their present understanding of stellar evolution, single white dwarfs do not form from stars with more than 1.3 solar masses. Stars with greater masses instead become neutron stars, or black holes. To get a white dwarf of 1.35 masses thus requires a merger of two white dwarfs, but it also means that the resulting dwarf could be unstable and could collapse into a neutron star at some point. The data also suggests that this merger process might be how a large number of neutron stars actually form.

The dwarf is also the smallest ever found, with a diameter of 2,670 miles, because the larger masses squeezes it into a tighter space.

Gravitational wave detectors see two different black holes as they swallowed a neutron star

Astronomers using three different gravitational wave detectors have seen the gravity ripples caused when two different black holes swallowed a nearby neutron star.

The two gravitational-wave events, dubbed GW200105 and GW200115, rippled through detectors only 10 days apart, on January 5, 2020, and January 15, 2020, respectively.

Each merger involved a fairly small black hole (less than 10 Suns in heft) paired with an object between 1½ and 2 solar masses — right in the expected range for neutron stars. Observers caught no glow from the collisions, but given that both crashes happened roughly 900 million light-years away, spotting a flash was improbable, even if one happened — and it likely didn’t: The black holes are large enough that they would have gobbled the neutron stars whole instead of ripping them into bite-size pieces.

Note the time between the detection, in early 2020, and its announcement now, in mid-2021. The data is very complex and filled with a lot of noise, requiring many months of analysis to determine if a detection was made. For example, in a third case one detector was thought to have seen another such merger but scientists remain unsure. It might simply be noise in the system. I point this out to emphasize that thought they are much more confident in these new detections, there remains some uncertainty.

Hubble update: Still no solution

An update today from the engineers trouble-shooting the problem on the Hubble Space Telescope that put it into safe mode on June 13 continue to show the problem is complex, and has not yet been traced to its source.

Additional tests performed on June 23 and 24 included turning on the backup computer for the first time in space. The tests showed that numerous combinations of [a number of] hardware pieces from both the primary and backup payload computer all experienced the same error – commands to write into or read from memory were not successful.

Since it is highly unlikely that all individual hardware elements have a problem, the team is now looking at other hardware as the possible culprit, including the Command Unit/Science Data Formatter (CU/SDF), another module on the SI C&DH [the module that holds the telescope’s computers]. The CU formats and sends commands and data to specific destinations, including the science instruments. The SDF formats the science data from the science instruments for transmission to the ground. The team is also looking at the power regulator to see if possibly the voltages being supplied to hardware are not what they should be. A power regulator ensures a steady constant voltage supply. If the voltage is out of limits, it could cause the problems observed.

They remain hopeful they can find the problem and fix it, though the longer it takes the more worrisome it becomes.

Astronomers discover “comet” bigger than the largest comets approaching inner solar system

Astronomers have discovered an object 80 to 100 miles in diameter, larger than the largest comets, approaching the inner solar system and coming from the theorized Oort Cloud of material thought to exist between a tenth and a third of a light year from the Sun.

The object is probably rich in ice like a comet and is currently around three billion kilometres from the Sun. It will reach its closest point, known as perihelion, in 2031. At that time, it will be positioned below the plane of the solar system, near the orbit of Saturn.

Part of the interest in C/2014 UN271 is that it may be something of a transition object. Astronomers believe that many of the long period comets, that occasionally appear with bright tails, actually come from the Oort Cloud. Stars wandering near the Sun can nudge these objects from their positions and over millennia they work their way inwards, with the gravity of the giant planets tweaking their paths on each visit until they reside where we see them today.

“The fact that [C/2014 UN271] has a perihelion so far away from the Sun might be telling us that it’s done this a couple of times but is still in that process of eventually becoming some of those long period comets we know and love,” explains Meg Schwamb a Kuiper Belt and Oort Cloud expert at Queen’s University Belfast.

Initially astronomers thought because of its size that it was not a comet, but new observations have detected the first signs of a coma, suggesting that it will provide us a very interesting and extended show when it reaches its closest point in 2031. Because that perihelion is around the orbit of Saturn, the object will not be traveling very fast, so its passage through the inner solar system will take several years. Its size also suggests it will have a lot of material that can sublimate off to produce a tail.

The object was discovered by two astronomers, Gary Bernstein and Pedro Bernardinelli. If it turns out to be a comet it will then be named Comet Bernardinelli-Bernstein, or Comet B-B for short.

UPDATE: It is official. The object is now officially a comet, and named Comet Bernardinelli-Bernstein.

2,000 nearby stars found that see the Earth cross in front of the Sun

Astronomers have identified 2,134 nearby stars that at some point in the past, present, or future are properly positioned along the solar system’s ecliptic so that the Earth can be seen transiting in front of the Sun.

From their paper’s abstract:

[W]e report that 1,715 stars within 100 parsecs from the Sun are in the right position to have spotted life on a transiting Earth since early human civilization (about 5,000 years ago), with an additional 319 stars entering this special vantage point in the next 5,000 years. Among these stars are seven known exoplanet hosts, including Ross-128, which saw Earth transit the Sun in the past, and Teegarden’s Star and Trappist-1, which will start to see it in 29 and 1,642 years, respectively. We found that human-made radio waves have already swept over 75 of the closest stars on our list. [emphasis mine]

I like the detail highlighted. Of the stars that could definitely identify the Earth by transits, 75 are also now close enough to have also heard our radio broadcasts. Should any of those stars also have a sufficiently advanced alien civilization, they could know of our existence. These same stars in turn make for very good targets of study for us to see if there is alien life there.

Update on attempts to bring Hubble back to life

Engineers have released an update on their attempts to bring Hubble out of safe mode that are indicating that they are honing in on the cause of the problem.

After performing tests on several of the computer’s memory modules, the results indicate that a different piece of computer hardware may have caused the problem, with the memory errors being only a symptom. The operations team is investigating whether the Standard Interface (STINT) hardware, which bridges communications between the computer’s Central Processing Module (CPM) and other components, or the CPM itself is responsible for the issue. The team is currently designing tests that will be run in the next few days to attempt to further isolate the problem and identify a potential solution.

This step is important for determining what hardware is still working properly for future reference. If the problem with the payload computer can’t be fixed, the operations team will be prepared to switch to the STINT and CPM hardware onboard the backup payload computer. The team has conducted ground tests and operations procedure reviews to verify all the commanding required to perform that switch on the spacecraft.

It appears that no matter what solution they arrive at, they will still require several days to test the solution to make sure it works. This update however is very hopeful, as it does appear they are locating the cause and have avenues for fixing it.

Hubble went into safe mode on June 13, which means it has now been out of operation for more than ten days.

Hubble remains out of commission, with no repair date in sight

According to a statement to Space.com provided by the engineers trying to fix the Hubble Space Telescope, “there is no definitive timeline for bringing the computer back online.”

The Hubble operations team is working to solve the payload computer issue onboard the Hubble Space Telescope. The team is working to collect all the data available to them to isolate the problem and determine the best path forward for bringing the computer back to operations. At this time, there is no definitive timeline for bringing the computer back online. However, the team has multiple options available to them and are working to find the best solution to return the telescope to science operations as soon as possible.

…Assuming that this problem is corrected via one of the many options available to the operations team, Hubble is expected to continue yielding amazing discoveries into the late 2020s or beyond,” the operations team at NASA’s Goddard Space Flight Center in Maryland told Space.com in an email. However, “there is no definitive timeline yet as to when this will be completed, tested and brought back to operational status,

I gather from this that they do have options to might fix the problem, but they have also found the problem to be more complex than expected.

While I honestly am confident these engineers can bring the telescope back to life, we must all be prepared for the strong possibility that this might be the moment when such a repair is impossible. If so, our vision of the heavens will once again be blinded by the poor vision available to us from inside the Earth’s atmosphere. And that vision will not be cleared in the foreseeable future by an American or western optical space telescope, as none are being designed, no less built.

The Chinese however are building one, for their purposes, which will be better than Hubble and is set to launch within the next few years to fly in formation with their new space station, close by so that astronauts can do repairs if necessary.

First attempts to fix Hubble fail

An attempt to switch the Hubble Space Telescope to a different backup computer module in order to bypass a broken unit failed last week, leaving the telescope in safe mode.

A payload computer on Hubble stopped working June 13, the agency said in a June 16 statement. Engineers speculated that the computer, used to manage operations of Hubble’s science instruments, malfunctioned because of a degrading memory module, putting the instruments into a safe mode.

The agency said at the time that it would switch of a backup memory module that day and, after about a day of testing, restart the instruments and resume science observations.

However, in a June 18 statement, NASA said those efforts to switch to a backup memory module failed because “the command to initiate the backup module failed to complete.” An attempt to restore the computer with both the original memory module and the backup unit also failed.

While the engineers at the Space Telescope Science Institute, that operates Hubble, have expressed confidence they can overcome these issues, the failures this week are truly troublesome. We may truly be facing the end of the telescope,

New data confirms lack of dark matter in one galaxy

The uncertainty of science: Astronomers have strengthened their evidence that one particular nearby galaxy is completely devoid of dark matter, a situation that challenges the existing theories about dark matter which suggest it comprises the bulk of all matter in the universe.

The astronomers had made their first claim that this galaxy, NGC 1052-DF2, lacked dark matter back in 2018, a claim that was strongly disputed by others.

The claim however would only hold up if the galaxy’s distance from Earth was as far away as they then estimated, 65 million light years (not the 42 million light years estimated by others). If it were closer, as other scientists insisted, then NCC 1052-DF2 likely did have dark matter, and the theorists could sleep at night knowing that their theory about dark matter was right.

To test their claim, the astronomers used the Hubble Space Telescope to get a better, more tightly constrained estimate of the distance, and discovered the galaxy was even farther away then previously believed.

Team member Zili Shen, from Yale University, says that the new Hubble observations help them confirm that DF2 is not only farther from Earth than some astronomers suggest, but also slightly more distant than the team’s original estimates.

The new distance estimate is that DF2 is 72 million light-years as opposed to 42 million light-years, as reported by other independent teams. This places the galaxy farther than the original Hubble 2018 estimate of 65 light-years distance.

So, does this discovery invalidate the theories about dark matter? Yes and no. The theories now have to account for the existence of galaxies with no dark matter. Previously it was assumed that dark matter was to be found as blobs at the locations of all galaxies. Apparently it is not.

However, the lack of dark matter at this one galaxy does not prove that dark matter is not real. As noted by the lead astronomer in this research,

“In our 2018 paper, we suggested that if you have a galaxy without dark matter, and other similar galaxies seem to have it, that means that dark matter is actually real and it exists,” van Dokkum said. “It’s not a mirage.

Ah, the uncertainty of science. Isn’t it wonderful?

Astronomers propose explanation the dimming of Betelgeuse in 2020

The uncertainty of science: New data has allowed astronomers to propose a more detailed explanation for the dimming of Betelgeuse in 2020 by almost two-thirds.

[T]he dimming was likely to be caused by [one of two] mechanisms, such as a blob of unusually cold matter appearing on the surface of the star in what’s known as a convective cell, or a cloud of dust crossing the line of sight to it.

Now, astrophysicist Miguel Montargès at the Paris Observatory and his collaborators have found that the reason for the ‘great dimming’ was probably a combination of both of those factors

The data suggest that the star spewed out material from a convection cell, which then quickly condensed into dust which acted to block the star’s light. The growing cell itself also was darker, which also contributed to the dimming.

The results, while robust, are still uncertain. While a number of mainstream news sources are claiming the mystery of Betelgeuse’s dimming has been “solved”, that is not how it works. The data now points to an answer, but the data is far from complete, and future observations could very easily change that answer.

Hubble in safe mode due to computer problem

A computer failure on June 13th put the Hubble Space Telescope in safe mode, with engineers hoping to have the problem resolved and the telescope back in operation by tomorrow.

NASA is working to resolve an issue with the payload computer on the Hubble Space Telescope. The computer halted on Sunday, June 13, shortly after 4 p.m. EDT. After analyzing the data, the Hubble operations team is investigating whether a degrading memory module led to the computer halt. The team is preparing to switch to one of several backup modules on Wednesday, June 16. The computer will then be allowed to run for approximately one day to verify that the problem has been solved. The team would then restart all science instruments and return the telescope to normal science operations.

The unit itself, while built in the 1980s, was only launched to Hubble in 2009 as part of the last shuttle repair mission.

Third set of new results from Parker released

The scientists using the Parker Solar Probe on June 2nd released their third set of new results as part of a special issue of the journal Astronomy & Astrophysics.

The latest articles include data analysis, theory, and modeling. Among the major topics covered are magnetic switchbacks first discovered by Parker Solar Probe, the role of waves in heating solar plasma, solar angular momentum, the near-Sun dust environment, and the diversity of small energetic-particle events.

The most interesting paper I think is the one describing data that lends strong weight to the theory, proposed in 1929 by astronomer Henry Norris Russell, that a dust-free zone exists close to the Sun and all stars. From the abstract:

The observed brightness decrease in the axis of symmetry is interpreted as the signature of the existence of a dust density depletion zone between about 19 [solar radii] and 3 [solar radii] which at the inner limit of WISPR’s field of view of 7.65 [solar radii] has a dust density that is ~5% lower than the density at 19 [solar radii], instead of the expected density which is three times if no depletion zone exists.

In plain English, the data shows that from about 1.3 million to 8.2 million miles from the Sun Parker found far less dust than predicted by other models. As the probe continues to lower its orbit and get closer to the Sun with each fly-by these numbers will be better refined, and are likely to in the end prove Russell’s hypothesis.

Problem with Ariane 5 rocket causes Arianespace to delay Webb telescope launch

As first revealed in mid-May, Arianespace has been forced to delay the launch of the James Webb Space Telescope by at least one month because of a problem with the fairing on its Ariane 5 rocket, found during an August 2020 launch.

There have been no Ariane 5 launches since. According to yesterday’s press briefing, however:

“The origin of the problem has been found. Corrective actions have been taken,” Daniel de Chambure, acting head of Ariane 5 adaptations and future missions at ESA, said. “The qualification review has started, so we should be able to confirm all that within a few days or weeks.” He did not elaborate on the problem or those corrective actions, beyond stating that the problem took place during separation of the payload fairing. Industry sources said in May that, on the two launches, the separation system imparted vibrations on the payload above acceptable limits, but did not damage the payloads.

It appears this new delay to Webb’s launch is because two commercial payloads must lift off first before Webb, with the first now scheduled for July. According to Arianespace, it will take two months prep for the next commercial launch, followed by two months prep for the Webb launch. That puts the launch of Webb in November.

Overall this particular delay is slight, only a few weeks, and pales in comparison to the ten years of delays experienced by NASA during development and construction of Webb. It also will add very little to the telescope’s overall budget, which has grown from an original price of $500 million to now about $10 billion.

A lopsided spiral galaxy

Losided spiral galaxy
Click for full image.

For a change, today’s cool image is not from Mars, but instead goes deep into space. The photo to the right, reduced to post here, was taken by the Hubble Space Telescope of the relatively nearby spiral galaxy NGC 2276, located about 120 million light years away. As the caption explains:

The magnificent spiral galaxy NGC 2276 looks a bit lopsided in this Hubble Space Telescope snapshot. A bright hub of older yellowish stars normally lies directly in the center of most spiral galaxies. But the bulge in NGC 2276 looks offset to the upper left.

In reality, a neighboring galaxy to the right of NGC 2276 (NGC 2300, not seen here) is gravitationally tugging on its disk of blue stars, pulling the stars on one side of the galaxy outward to distort the galaxy’s normal fried-egg appearance. This sort of “tug-of-war” between galaxies that pass close enough to feel each other’s gravitational pull is not uncommon in the universe. But, like snowflakes, no two close encounters look exactly alike.

The scientists also note that the bright edge along the galaxy’s north and west perimeter mark regions of intense star-formation. In those same regions astronomers six years ago identified the first medium-sized black hole ever found.

New Chandra mosaic of galactic center reveals spider-web of magnetism

Magnetic field line at the galactic center
Click for full image.

Scientists today released a spectacular panorama of the center of the Milky Way using X-ray data from the Chandra X-ray Observatory and radio data from the MeerKAT radio telescope in South Africa. The panorama reveals a complex web of magnetic field lines emanating out from the supermassive black hole at the center, Sagittarius A* (pronounced A-star).

Below the fold are reduced versions of the full panorama, unlabeled on the left and labeled on the right. The image to the right, reduced to post here, shows just one single example of those magnetic field lines, dubbed G0.17-0.41 and about 20 light years long. This particular filament is the subject of a paper just published in connection with the release of this panorama. From the press release.

A new study of the X-ray and radio properties of this thread by Q. Daniel Wang of the University of Massachusetts at Amherst suggests these features are bound together by thin strips of magnetic fields. This is similar to what was observed in a previously studied thread. (Both threads are labeled with red rectangles in the [full labeled panorama]. The newly studied one in the lower left, G0.17-0.41, is much farther away from the plane of the Galaxy.) Such strips may have formed when magnetic fields aligned in different directions, collided, and became twisted around each other in a process called magnetic reconnection. This is similar to the phenomenon that drives energetic particles away from the Sun and is responsible for the space weather that sometimes affects Earth.

The image below is fascinating to study because of the wealth of detail it includes, not only of magnetic filaments but of other nearby gas clouds and Sagittarius A* itself.
» Read more

More delays for Webb telescope?

An issue with the fairing release on the last two Ariane 5 launches has not only paused use of that rocket since August 2020, it might cause another delay in the planned October 31, 2021 launch of the James Webb Space Telescope.

In a statement to SpaceNews, Arianespace acknowledged that “post-flight analyses conducted on two recent Ariane 5 launches have indicated the occurrence of a less than fully nominal separation of the fairing, however with no adverse impact on the Ariane 5 flights in question.”

The company did not elaborate on the problem, but industry sources familiar with the issue said that, on both the August 2020 launch and the previous Ariane launch in February 2020, the separation of the faring induced vibrations into the payload stack well above acceptable limits. Neither incident damaged any of the payloads, but raised concerns about the effect on future missions, including JWST.

Moreover, Arianespace has two Ariane 5 launches on its schedule that are supposed to launch before Webb. If those are delayed it puts a further squeeze on the Webb launch date.

Meanwhile, the final checkouts of the Webb telescope have been proceeding, including a successful test of the unfolding of the telescope’s segmented mirror.

After a more than decade of delays and budget overruns — raising this telescope’s budget from 1/2 billion to $10 billion — it appears that Webb’s final schedule delay might occur not because of the telescope but because of the rocket.

In addition, the issue at Arianespace appears to be seriously impacting that company’s ’21 launch schedule, having failed to launch any Ariane 5 rockets so far this year.

Breakthrough Listen finds no signs of alien transmissions from 60 million stars

Where are those alien civilizations? Breakthrough Listen, a privately funded project searching for evidence of alien life, has released the first results from its survey of 60 million stars in an area looking towards the galactic center, noting that it found no evidence of any technological transmissions signaling an alien civilization from any of those stars.

The paper can be downloaded here [pdf].

The kind of signals they were looking for were not beacons sent out intentionally by alien civilizations, such as television or radio broadcasts, but unintentional transmissions, such as radar transmissions meant for other purposes but still beamed into space. They found none.

Jupiter’s changing and unchanging Great Red Spot

The changing Great Red Spot of Jupiter
Click for full figure.

In a paper published in March in the Journal of Geophysical Research: Planets, scientists (using images from amateurs, the Hubble Space Telescope, and Juno, scientists) have mapped out the interactions between Jupiter’s Great Red Spot, the longest known storm on the gas giant, and the smaller storms that interact with it as they zip past.

The series of images to the right come from figure 5 of their paper, showing the Spot over a period of three days. The Spot in these images is about 9,000 miles across, less than half the size it had been back in the late 1800s.

The black arrows mark the shifting location and shape of one smaller vortice as it flowed past the Spot from east to west along its northern perimeter, ripping off portions of the Spot as it passed. From the paper’s absract:

During its history, the [Great Red Spot] has shrunk to half its size since 1879, and encountered many smaller anticyclones and other dynamical features that interacted in a complex way. In 2018–2020, while having a historically small size, its structure and even its survival appeared to be threatened when a series of anticyclones moving in from the east tore off large fragments of the red area and distorted its shape. In this work, we report observations of the dynamics of these interactions and show that as a result the [Spot] increased its internal rotation velocity, maintaining its vorticity but decreasing its visible area, and suffering a transient change in its otherwise steady 90‐day oscillation in longitude.

…From the analysis of the reflectivity of the [Spot] and flakes and model simulations of the dynamics of the interactions we find that these events are likely to have been superficial, not affecting the full depth of the [Spot]. The interactions are not necessarily destructive but can transfer energy to the [Spot], maintaining it in a steady state and guaranteeing its long lifetime.

In other words, the changes seen only involved the Spot’s cloud tops, even if those tops were many miles thick. The storm itself is much deeper, with its base embedded strongly inside Jupiter and largely unaffected by these passing smaller storms.

Why the Spot exists and remains so long-lived remains an unsolved mystery.

Astronomers detect largest flare ever, on Proxima Centauri

In May 2019 astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected the largest flare ever seen from any star, including our Sun, on the nearest star, the red dwarf Proxima Centauri.

The detection was 100 times stronger than the Sun’s typical flares.

In May 2019, Proxima Centauri ejected a violent flare that lasted just seven seconds, but generated a surge in both ultraviolet and millimeter wavelengths. The flare was characterized by a strong, impulsive spike never before seen at these wavelengths. The event was recorded by five of the nine telescopes involved in the study, including the Hubble Space Telescope (HST) in ultraviolet, and ALMA in millimeter wavelengths. “The star went from normal to 14,000 times brighter when seen in ultraviolet wavelengths over the span of a few seconds,” said MacGregor, adding that similar behavior was captured in millimeter wavelengths by ALMA at the same time.

Red dwarfs are known to issue very powerful flares, a high solar activity that would likely make life as we know it impossible on any Earth-sized planet in its habitable zone, since the star’s small size and dimness requires that zone to be so close to the star. This powerful flare only cements this reality. The exoplanets that have been found circling Proxima Century will therefore not be great places for life, though building the first interplanetary colony there might make sense.

X-rays from Uranus detected for the 1st time

Composite Uranus image of X-ray and optical data

Astronomers using the Chandra X-ray Observatory in orbit have for the first time detected X-rays coming from the planet Uranus.

In the new study, researchers used Chandra observations taken in Uranus in 2002 and then again in 2017. They saw a clear detection of X-rays from the first observation, just analyzed recently, and a possible flare of X-rays in those obtained fifteen years later. The main graphic [posted to the right] shows a Chandra X-ray image of Uranus from 2002 (in pink) superimposed on an optical image from the Keck-I Telescope obtained in a separate study in 2004. The latter shows the planet at approximately the same orientation as it was during the 2002 Chandra observations.

What could cause Uranus to emit X-rays? The answer: mainly the Sun. Astronomers have observed that both Jupiter and Saturn scatter X-ray light given off by the Sun, similar to how Earth’s atmosphere scatters the Sun’s light. While the authors of the new Uranus study initially expected that most of the X-rays detected would also be from scattering, there are tantalizing hints that at least one other source of X-rays is present.

One explanation could be that the X-rays could be coming from Uranus’s rings, as such X-rays do from Saturn. This is not confirmed as yet however. More data will be needed.

Radar images of Apophis during its March close approach of Earth

Apophis as seen by radar March 9, 2021
Click for full image.

Using two radar dishes, Green Bank in West Virginia and Goldstone in California, astronomers were able to produce radar images of the asteroid Apophis during its most recent close fly-by of Earth on March 10th.

The image to the right, cropped and reduced to post here, shows Apophis on March 9th. If you go to the full image you can also see the March 10th and 11th images, which appear to show the asteroid in different orientations as it rotated.

These images represent radar observations of asteroid 99942 Apophis on March 8, 9, and 10, 2021, as it made its last close approach before its 2029 Earth encounter that will see the object pass our planet by less than 20,000 miles (32,000 kilometers). The 70-meter radio antenna at the Deep Space Network’s Goldstone Deep Space Communications Complex near Barstow, California, and the 100-meter Green Bank Telescope in West Virginia used radar to precisely track Apophis’ motion. At the time of these observations, Apophis was about 10.6 million miles (17 million kilometers) from Earth, and each pixel has a resolution of 127 feet (38.75 meters).

The data obtained has firmly removed any chance Apophis will impact the Earth in the next 100 years. However, it still could hit us late in the 22nd century.

These observations were originally planned to also include data from the Arecibo Observatory, but that telescope was destroyed in December when its instrument platform collapsed. If it had been operational, these radar images would have had much better resolution.

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