Astronomers Find Out What Happens to Rocky Planets That Wander too Close to Their Stars

The massive Kepler survey found a treasure trove of exoplanets. But in all that wealth they found three anomalies: what appeared to be rings of dust surrounding stars where planets should be. They were rocky planets in the process of being obliterated. And a team of astronomers that found a way to use these gory sites to understand some of the most mysterious and hard to detect planets in the universe.

We currently know of about 5,000 exoplanets in the galaxy. This represents only a small fraction of the estimated 1 trillion worlds within the Milky Way. But even though we’ve made great strides, we have exceptional difficulty finding one particular class of exoplanet: the small, rocky ones. Our techniques rely on transits. When an exoplanet crosses in front of the face of the star, it causes a small dip in brightness from our point of view. But if the planet is too small, the change in brightness isn’t large enough for us to detect, and so the small planets, roughly the size of the Earth and smaller, remain hidden from us.

But recently a team of researchers recently pointed out that some anomalies in the Kepler data may be a blessing in disguise. Among the data returned from Kepler includes what appears to be rings of dust and debris surrounding a star. Previous researchers had concluded that these are rocky planets in the process of obliteration. They are worlds that got too close to their parent star, and the heat of that star is boiling them alive.

The team of researchers released a paper detailing simulations of how this process could unfold. They found that these small worlds are caught between two extremes. Because they orbit closely to their parent star, they are almost certainly tidally locked, which means that only one side of the planet faces the star at all times. The other side is permanently locked in night. The day side gets blasted to such a degree that instead of a crust it just has a thin shell of pure magma. But the other side is so cold that the rocky crust remains in place.

The night side cools down the planet while the day side heats it up. The astronomers found that there is only a very narrow window where we can observe such situations. If a planet is too big or the star is not bright enough, then it does not evaporate enough material for us to detect it in something like Kepler. However if the planet is too small or the star is too intense, the entire planet obliterates in a short enough time that we are unlikely to see it in a random sample of stars.

Only certain special cases can lead to a ring of debris large enough and visible enough for us to see it. Going from this the astronomers estimate that for every star in the galaxy there is roughly one planet the size of the Earth or smaller. 

Additionally, the astronomers found that these debris trails can give us very important clues as to rocky planetary formation. We don’t normally get to crack open planets and see what’s inside of them. But in these cases the parent star is doing the job for us. They advocate for a follow-up observations with the James Webb Space telescope to study these systems in detail to understand what these rocky planets were made of.

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Forget the Habitable Zone – We Need to Find the Computational Zone

Astronomers are currently searching for signs of life in the “habitable zones” of nearby stars, which is defined as the band around a star where liquid water can potentially exist. But a recent paper argues that we need to take a more nuanced and careful approach, based not on the potential for life, but the potential for computation.

One way to define life itself is as a set of computations that act on information. The information is stored in DNA and the computations are performed by various proteins. The ability to store information and act on its environment allows life to undergo natural selection, which finds ever more complex arrangements.

The traditional searches for life look at how we understand it from an earthly context. Namely, creatures living on the surface of a world just the right distance from a parent star and using liquid water as a solvent for chemical reactions. But it’s easy to imagine much more complex and varied forms of life out there in the universe. Life could use other solvents. Life could be buried underground in icy outer moons. Life may not even require a star. And biological systems could give rise to technological systems that would not meet our current definition for life but might be alive in their own way.

And so a pair of researchers want to rebuild the concept of the habitable zone using a more fundamental concept of computation. They argue that the best chances of finding signs of life are where there is easiest access to computation. The researchers argue that these so-called “computational zones” require three characteristics. One, there must be the capacity for computation, which means that there is a rich set of chemistry available. Two, there must be a raw form of energy, like sunlight or hydrothermal vents. And lastly, computation requires a substrate – something in which the computation can take place.

The traditional view of habitable zones can now be seen as a subset of a much larger concept of computational zones. Where there is life as we currently understand it here on Earth there is computation taking place. But this framework allows us to develop search strategies for concepts of life extending beyond that. For example, if we study individual systems through a lens of computational ability, we might find which systems might be amenable to artificial energy gathering structures like Dyson spheres. Or we could examine how gas clouds around sub-stellar structures could meet all the conditions necessary for computation, and therefore the conditions necessary for a broadened definition of life.

The search for life in our universe in a scientific way has only just begun. And it’s important, as the authors emphasize, to keep an open mind.

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Will the Starship be Ready for an April Launch?

It’s been a long road, but it looks as though SpaceX may finally be ready for an orbital flight test with the Starship and Super Heavy. After months of waiting, static fire tests, stacking, and restacking, Elon Musk announced on March 16th that SpaceX could be ready to go with the SN24 and BN7 prototypes in “a few weeks,” pending approval from the Federal Aviation Administration (FAA). Musk announced via Twitter, saying, “launch timing depends on FAA license approval. Assuming that takes a few weeks, first launch attempt will be near end of third week of April, aka…”

Putting aside the thinly-veiled reference to 4/20, this estimate seems likely to happen and is consistent with recent activity at SpaceX’s Starbase in Boca Chica, Texas. First, there was the rollout of the SN24 Starship prototype in the early morning hours on Saturday, April 1st. This was followed two days later (Monday, April 3rd) with the BN7 Super Heavy booster prototype placed on the orbital launch mount, where crews began performing propellant load tests. These decisions indicated that the prototypes would be stacked and prepped for a launch attempt.

Here's a short thread on three things I think I know about Starship's orbital flight attempt:

1. Elon has been publicly pessimistic about launch dates of late, and April 10 is semi-real. Yes, we are living in an era of negative Elon time. Which is a wild place to be.

— Eric Berger (@SciGuySpace) April 4, 2023

Then, on Tuesday, April 4th, the FAA issued a notice for a potential launch date of April 10th, with backup dates specified for April 11th and 12th. The buzz snowballed from there, with many posting about the likelihood of a launch on Easter Monday – the sixth day of Passover, the twentieth day of Ramadan, or whatever faith is being observed. SpaceX poured gasoline on this fire when, on April 6th, they tweeted images of the SN24 and BN7 stacked on the launch test pad with the caption:

“Starship fully stacked at Starbase. Team is working towards a launch rehearsal next week followed by Starship’s first integrated flight test ~week later pending regulatory approval.”

However, there have been a few indications that this would pass in favor of a later launch date (which appears to be the case). First, the FAA released a statement the same day the license was issued indicating that a decision had not been made. They further clarified that the notice they issued was not to be interpreted as a green light, saying, “The FAA has not made a license determination for the SpaceX Starship Super Heavy operation, and the FAA’s Command Center planning notice should not be interpreted as an indicator that a determination to issue a license has been made or is forthcoming.”

Eric Berger, acclaimed science author and Senior Space Editor at Ars Technica, also took to Twitter to address the growing hype and issue a few reality checks. First, he related how sources within SpaceX and NASA described the situation as it stood on April 4th, tweeting, “For what it’s worth SpaceX has told NASA it is targeting April 10, with backup days on April 11 and 12, for the Starship Orbital Flight Test. None of this is official without a launch license and the usual caveats apply.”

Illustration of SpaceX Starship human lander design that will carry the first NASA astronauts to the surface of the Moon under the Artemis program. Credits: SpaceX

He followed this up by listing three pertinent points about the possible launch, indicating that a flight would happen later in the month. These included:

1. Elon has been publicly pessimistic about launch dates of late, and April 10 is semi-real.
2. A launch license was likely forthcoming, but there might be the risk of the FAA filing a civil suit for environmental reasons at the last minute (leading to a temporary injunction).
3. SpaceX is very close to being ready technically, but it may take a few more days to review data. Barring legal action, a launch attempt will happen this month.

It seems pretty clear at this juncture that Monday (nor the rest of the week) will see the long-awaited orbital launch test. However, there is still the possibility that an attempt will happen on Monday, April 17th, according to an FAA Operations Plan Advisory statement issued on April 8th. While everything is contingent on the FAA giving the go-ahead, SpaceX appears to be as ready as it ever will be to make an orbital launch. This flight, if successful, will validate the totally-reusable super-heavy launch system, which NASA has contracted with SpaceX to provide Human Landing System (HLS) for the Artemis III mission.

The flight test will also open the door to SpaceX’s long-term promise of seeing regular payloads and crews to the Moon, providing intercontinental flights, and delivering Starlink V2 satellites to orbit. It will also bring the company one step closer to realizing the objective Musk has been preaching since he started the company over twenty years ago: to begin sending crewed missions to Mars to create the first self-sustaining city there. And it could all start before this month is over!

Further Reading: FAA

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An Amazing New Map of the Moon, In LEGO

OK, LEGO fans, it’s time to vote this awesome new LEGO Idea into existence! A stunning new 2,360-piece Lego Art space poster called “The Moon: Earth’s Companion” is currently gathering supporters on the LEGO Ideas website. If it gets enough votes, LEGO will review it and possibly create it.

This highly detailed, retro-style brick-built Moon map is not only beautiful, but educational. When put together, it shows the Moon’s craters and terrain features, displaying lunar geology and maria. It also includes geometrical phases of the Moon and a brick-built panorama depicting the Earth rising over the lunar landscape.

Not surprisingly, the idea was chosen as one of the LEGO Ideas Staff Picks, which celebrates “fantastic projects that show off something out of the ordinary.” In just a matter of weeks, the submission has already notched up over 8,800 supporters, and is well on its way to the 10,000-supporter milestone needed for it to be considered for production by Lego. Let’s do this, vote here!

Another view of “The Moon: Earth’s Companion” on the LEGO Ideas site. Image courtesy Marc Sloan.

It measures roughly 15.5 inches (40 cm) wide and 20.2 inches (51 cm) in height and can be hung on a wall.

The idea was submitted by Marc Sloan, aka @Sharky_Bricks who said it took him over a year to design this piece.

“I wanted to find the right balance between artistic license and accuracy, especially on something as familiar as the Moon,” he said via email. “I’m glad that my hard work has paid off, and I’m excited to share my creation with the world.”

Sloan said his inspiration for this design came from a lifelong passion for space travel and astronomy.

“As a child, I was fascinated by all things related to the cosmos, and I vividly remember visiting Cape Canaveral, and feeling in awe of the Apollo rockets and spacecraft on display. In addition to the Apollo missions, I was also inspired by the upcoming Artemis missions, which aim to take humans back to the Moon.”

A detailed look at the design of “The Moon: Earth’s Companion.” Image courtesy Marc Sloan.

Sloan said he has submitted several other 3D map designs to Lego Ideas, so he has a lot of experience using Lego bricks to bring 2D images to life. However, this one is the most popular to date. Sloan said he’s also revised his design after feedback from the LEGO Ideas folks.

“My original design was based around the Moon landings and featured a mini lunar lander that could be placed on all the Apollo landing sites,” he said, “but after some feedback from Lego Ideas, I made it more general to instead highlight the Moon’s geology and topography and its relationship to Earth.”

An alternate idea for the design is to depict a solar eclipse instead of the “Earthrise” panorama.

“I decided to use the Earthrise panorama in my final design after I shared a poll on my Lego Maps community on Facebook and they voted for it,” Sloan told me. “But it’s entirely possible that Lego might include alternative builds in the final product if it makes it through their selection process. It’s usually the case that Lego will modify the original design to improve on it in the final product.”

A possible alternative to the depiction of ‘Earthrise’ is a solar eclipse explainer. Image courtesy Marc Sloan.

The description on the LEGO Ideas site says this piece “celebrates the beauty and mystery of the Moon,” and is “designed in a cool, retro style that will look great on any wall.”

If you agree this beautiful and detailed map of the Moon should become a reality, check out the LEGO Ideas site for The Moon: Earth’s Companion and vote!

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Hubble Sees Two Quasars Side by Side in the Early Universe

When it comes to the brightest, most powerful objects in the Universe, not much can beat a Quasar. A Gamma Ray Burst from a supernova might be more energetic, but doesn’t last very long. Quasars, by comparison, can churn out 1000 times the radiation of the Milky Way, and keep doing it for hundreds of millions of years.

They get all this energy from the supermassive black holes that live at the center of galaxies. As material falls towards the black hole, an accretion disk forms around it: a swirling cloud of energetic material which heats up through friction and releases electromagnetic radiation. The resulting Quasar can be so bright it drowns out the light from the rest of its galaxy from our perspective.

On April 5^th, researchers announced the discovery of a rare double quasar in the early Universe. The two quasars are gravitationally bound, spiraling in towards each other. Their host galaxies are in the process of merging, and the supermassive black holes generating the quasars will also eventually collide and merge.

“We’re starting to unveil this tip of the iceberg of the early binary quasar population,” said Xin Liu, a researcher from the University of Illinois at Urbana-Champaign, in a press release. “This is the uniqueness of this study. It is actually telling us that this population exists, and now we have a method to identify double quasars that are separated by less than the size of a single galaxy.”

A Hubble Space Telescope photograph of a pair of quasars that existed when the universe was just 3 billion years old. Credits: NASA, ESA, Yu-Ching Chen (UIUC), Hsiang-Chih Hwang (IAS), Nadia Zakamska (JHU), Yue Shen (UIUC).

As bright as quasars are, detecting – and interpreting – the signals received from distant quasars is not easy. This pair of quasars existed just three billion years after the Big Bang, during a time period known as cosmic noon: the era between 10 and 11 billion years ago when star formation in the Universe was at its peak. They are very, very distant objects.

It took a large collaboration and a half dozen telescopes to achieve this result. The two objects are named after their Sloan Digital Sky Survey designations J0749 + 2255, and were identified as a double quasar using the European Space Agency’s Gaia spacecraft. Confirming the characterization of the object required observations in infrared from both the Hubble Space Telescope and the W.M. Keck Observatories in Hawaii. Additional information about the objects in other wavelengths were gathered using International Gemini Observatory (optical and near-infrared), the Karl G. Jansky Very Large Array (radio), and NASA’s Chandra X-ray Observatory (X-ray).

Like putting together a puzzle, each wavelength offered different information about the quasars, and helped researchers understand what was going on in this distant binary galaxy system.

Hubble’s powerful resolution also allowed them to rule out the possibility that they were actually just seeing the same quasar twice due to the wonky effects of gravitational lensing.

The double quasars J0749 + 2255 are so close together that they are separated by less than the space of a single galaxy, so resolving them at a distance of 10-11 billion light years away is an incredible feat.

NASA’s upcoming Nancy Grace Roman telescope will be an ideal tool for finding more examples of double quasars. It will have a similar resolution to Hubble, but with a wider field of view to image more of the sky at once.

With a larger sample size, astronomers will be able to make better models of galactic evolution in the early Universe.

Learn More:

“Hubble Unexpectedly Finds Double Quasar in Distant Universe.” NASA.

Yu-Ching Chen et al. “A close quasar pair in a disk–disk galaxy merger at z = 2.17.” Nature.

Featured Image: An artist’s concept of two quasars residing in the cores of two galaxies in the process of merging. Credits: NASA, ESA, Joseph Olmsted (STScI).

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Physicists Discover that Gravity Can Create Light

Researchers have discovered that in the exotic conditions of the early universe, waves of gravity may have shaken space-time so hard that they spontaneously created radiation.

The physical concept of resonance surrounds us in everyday life. When you’re sitting on a swing and want to go higher, you naturally start pumping your legs back and forth. You very quickly find the exact right rhythm to make the swing go higher. If you go off rhythm then the swing stops going higher. This particular kind of phenomenon is known in physics as a parametric resonance.

Your legs act as an external pumping mechanism. When they match the resonant frequency of the system, in this case your body sitting on a swing, they are able to transfer energy to the system making the swing go higher.

These kinds of resonances happen all over the place, and a team of researchers have discovered that an exotic form of parametric resonance may have even occurred in the extremely early universe.

Perhaps the most dramatic event to occur in the entire history of the universe was inflation. This is a hypothetical event that took place when our universe was less than a second old. During inflation our cosmos swelled to dramatic proportions, becoming many orders of magnitude larger than it was before. The end of inflation was a very messy business, as gravitational waves sloshed back and forth throughout the cosmos.

Normally gravitational waves are exceedingly weak. We have to build detectors that are capable of measuring distances less than the width of an atomic nucleus to find gravitational waves passing through the Earth. But researchers have pointed out that in the extremely early universe these gravitational waves may have become very strong. 

And they may have even created standing wave patterns where the gravitational waves weren’t traveling but the waves stood still, almost frozen in place throughout the cosmos. Since gravitational waves are literally waves of gravity, the places where the waves are the strongest represent an exceptional amount of gravitational energy.

The researchers found that this could have major consequences for the electromagnetic field existing in the early universe at that time. The regions of intense gravity may have excited the electromagnetic field enough to release some of its energy in the form of radiation, creating light.

This result gives rise to an entirely new phenomenon: the production of light from gravity alone. There’s no situation in the present-day universe that could allow this process to happen, but the researchers have shown that the early universe was a far stranger place than we could possibly imagine.

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Do Repeating Radio Signals Indicate an Exoplanet with a Magnetosphere?

There’s an interesting problem in exoplanet studies: how to tell if a planet has a magnetosphere. It’s not like we can visibly see it unless we find a different way of looking. A pair of scientists may have found one. They used radio telescopes to track emissions given off by magnetic star-planet interactions. These happen when a planet with a magnetic field plows through star stuff caught its star’s magnetic field.

Sebastian Pineda (the University of Colorado Laboratory for Atmospheric and Space Physics) and Jackie Villadsen (Bucknell University) used the Karl G. Jansky Very Large Array to search for those emissions at a star called YZ Ceti and its planet, YZ Ceti b. Over the course of several observation runs, they found a repeating radio signal from the star. It was a first.

“I’m seeing this thing that no one has seen happen before,” said Villadsen, describing the moment she first isolated the radio signal while pouring over data at her home on a weekend.

“We saw the initial burst and it looked beautiful,” said Pineda. “When we saw it again, it was very indicative that, OK, maybe we really have something here.”

That something looks like proof of a magnetosphere (the region around a planet dominated by the planet’s magnetic field) around YZ Ceti b. The search method could give astronomers another way to confirm the existence of exoplanetary magnetic fields. And, finding one at this planet has interesting implications in the search for habitable worlds.

Radio Waves Give Away the Existence of a Planetary Magnetosphere

YZ Ceti is a small red dwarf star with a known rocky exoplanet orbiting around it in a two-day orbit. It’s a good target to determine if a planetary magnetic field collides with its star’s magnetic field to provide outbursts. That’s because the exoplanet is very close to the star and can easily encounter material given off during a flare or other outburst. As plasma from YZ Ceti bounces off the planet’s magnetosphere it interacts with the star’s magnetic field. That action generates radio waves strong enough to be observed on Earth. The researchers then use the intensity of the radio waves to figure out the strength of the planetary magnetic field.

An artist’s conception of YZ Ceti b, a terrestrial-type exoplanet orbiting an M-type star. Its mass is 0.7 Earths. Scientists may have found a way to detect a possible magnetosphere around it. Courtesy NASA Exoplanet Exploration.

If the method works out well, it will provide a way to detect magnetic fields at other stars, according to Villadsen. “What we’re doing is looking for a way to see them,” she said. “We’re looking for planets that are really close to their stars and are a similar size to Earth. These planets are way too close to their stars to be somewhere you could live, but because they are so close the planet is kind of plowing through a bunch of stuff coming off the star. If the planet has a magnetic field and it plows through enough star stuff, it will cause the star to emit bright radio waves.”

The study also provides a look at the environment around stars and how they interact with planetary magnetic fields. “This idea is what we’re calling “extrasolar space weather'” said Pineda. “We have been doing this radio monitoring of stellar systems like these in the hope of gathering evidence of the magnetic interaction of the star and planet.”

Extrasolar Space Weather and Magnetospheres

Using extrasolar space weather to look for magnetospheres around exoplanets is quite new, said Pineda in a follow-up email. “That interaction hasn’t really been demonstrated in the literature before, so discovering it would also be significant. However, the reason to pursue this sort of physics is precisely because it is a unique observable that has a clear dependence on the exoplanetary magnetic field. If we can measure these bursts, prove that they are planet-induced, and know the star sufficiently well, then we have real concrete constraints on an exoplanet’s magnetic field.”

Interestingly, during the interactions between YZ Ceti b and its star, aurorae get produced. But, as Pineda points out, they’re not planetary aurorae as we see on Earth. “We’re actually seeing the aurora on the star — that’s what this radio emission is,” he said. “There should also be aurora on the planet if it has its own atmosphere.”

This discovery will need to be confirmed by a great many other observations in the coming years, according to Pineda and Villadsen. “This could really plausibly be it,” says Villadsen. “But I think it’s going to be a lot of follow-up work before a really strong confirmation of radio waves caused by a planet comes out.”

Why is a Magnetosphere Important?

On Earth, our magnetic field protects us from the solar wind and some aspects of flares and coronal mass ejections. Of course, we are affected by some space weather. We see auroral displays during milder events. If a solar storm is particularly strong, our magnetosphere shields us from the worst effects. But, even then, space weather can still pose a threat to our satellites, power grids, and other technology.

Earth’s magnetosphere isn’t a sphere at all. The solar wind deforms it into an asymmetrical shape. Image Credit: NASA

However, we can thank our magnetosphere for our very existence. It’s very likely that life on Earth wouldn’t be here if our planet didn’t have its protective magnetic field. So, in the hunt for habitable worlds in the galaxy, the presence of a magnetosphere could be a good sign. It not only tells scientists something about a world’s physical characteristics, but it might be a clue to that world’s habitability.

If a distant world doesn’t have a magnetosphere, it’s probably not hospitable to life. If it does have one, then it—and any life it harbors—would have an umbrella of protection from outbursts by its star. That adds a new dimension to the search for exoplanets, particularly those that might be harboring life.

For More Information

Do Earth-like exoplanets have magnetic fields? Far-off radio signal is promising sign
Coherent radio bursts from known M-dwarf planet-host YZ Ceti

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