Astronomy

Similar craters are found on Earth and the Moon, and are the product of volcanic, tectonic or even fluvial activity.

Red dwarf stars, also known as M-dwarfs, dominate the Milky Way’s stellar population. They can last for 100 billion years or longer. Since these long-lived stars make up the bulk of the stars in our galaxy, it stands to reason that they host the most planets.

Astronomers examined one red dwarf star named SPECULOOS-3, a Jupiter-sized star about 55 light-years away, and found an Earth-sized exoplanet orbiting it. It’s an excellent candidate for further study with the James Webb Space Telescope.

SPECULOOS stands for the Search for habitable Planets EClipsing ULtra-cOOl Stars. It’s a European Southern Observatory effort that searches for terrestrial planets orbiting cool stars like red dwarfs. (Its odd name is an homage to a Belgian sweet biscuit.) Its goal is to find planets that are good targets for spectroscopy with the JWST and the ELT.

The new planet is named SPECULOOS-3b, and its discovery was presented in a recent paper in Nature Astronomy. The paper is titled “Detection of an Earth-sized exoplanet orbiting the nearby ultracool dwarf star SPECULOOS-3.” The lead author is Michaël Gillon from the Astrobiology Research Unit, Université de Liège, Belgium.

SPECULOOS is an automated search using four telescopes around the world: one at the Paranal Observatory in Chile, one at the Teide Observatory in Tenerife, one at the La Silla Observatory in Chile, and one at the Oukaïmden Observatory in Morocco. The project is searching 1,000 ultra-cool stars and brown dwarfs for terrestrial planets.

One of the problems in detecting planets around these stars is their low luminosity. Since they’re so dim, transiting exoplanets are difficult to detect, making their planetary populations difficult to characterize and study. So far, astronomers have found only one planetary system around one of these stars, and it’s rather well-known: the TRAPPIST-1 system. When it began, the SPECULOOS program expected to find at least one dozen systems similar to TRAPPIST-1.

“We designed SPECULOOS specifically to explore nearby ultra-cool dwarf stars in search of rocky planets,” lead author Gillon said. “With the SPECULOOS prototype and the crucial help of the NASA Spitzer Space Telescope, we discovered the famous TRAPPIST-1 system. That was an excellent start!”

The dimness of these stars can’t be understated. “Though this particular red dwarf is more than a thousand times dimmer than the Sun, its planet orbits much, much closer than the Earth, heating up the planetary surface,” said co-author Catherine Clark, a postdoctoral researcher at NASA’s JPL in Southern California.

The new planet is an Earth-sized world that orbits its star in only 17 hours. The star has a spectral type M6.5, and it delivers 16.5 more solar irradiation to its planet than the Sun does to Earth. That may sound surprising since the star is much cooler than the Sun. The Sun’s surface temperature is 5,772 K (5,500 C), while SPECULOOS-3’s temperature is only 2,900 K (2,627 C.) But SPECULOOS 3 bombards the planet with radiation due to the small distance separating them.

Since the irradiation is largely infrared and the star is only Jupiter-sized, it makes the planet an exceptional candidate for follow up observations, which is exactly what the SPECULOOS program is all about. The SPECULOOS Program 1 has found about 365 temperate, Earth-sized targets for further study with the JWST.

This chart shows the classifications by spectral type for main sequence stars according to the Harvard classification. Image Credit: By Pablo Carlos Budassi – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=92588077

The SPECULOOS-3 system is about 6.6 billion years old. Its luminosity, mass and radius are 0.084%, 10.1% and 12.3% of those of the Sun. “Just slightly larger than TRAPPIST-1, SPECULOOS-3 is the second-smallest main sequence star found to host a transiting planet,” the authors explain in their paper.

Two different telescopes observed the planetary transits around the star in 2021 and 2022 over eight nights. “Visual inspection of the 2021 and 2022 light curves showed some transit-like structures that motivated future intensive monitoring of the star,” the authors explain. The star was re-observed in 2023.

This figure from the study shows the transit of SPECULOOS-3b around its dim, cool star. Image Credit: Gillon et al. 2024.

The researchers determined that SPECULOOS-3b is about the same size as Earth, about 96% of our planet’s radius. But the planet’s density and mass are so far unconstrained. “Nevertheless,” the authors write in their paper, “several factors strongly suggest a rocky composition.”

There are two empirical reasons why the planet is likely rocky, though. The first is that its radius is on the rocky side of the radius gap. The second is that “all of the known Earth-sized planets in the NASA exoplanet archive have masses that imply rocky compositions,” Gillon and his co-authors explain.

This figure from the research compares SPECULOOS-3b to other transiting terrestrial exoplanets with less than 1.6 Earth radii. All of these planets are also cool enough to have rocky daysides rather than molten daysides. The shaded green area highlights planetary radii most similar to Earth’s (0.9–1.1R). Image Credit: Gillon et al. 2024.

But the big question concerns the planet’s potential atmosphere.

“From a theoretical point of view, the intense extreme ultraviolet emission of low-mass stars during their early lives makes it unlikely that such a small planet on such a short orbit could have maintained a substantial envelope of hydrogen.” the authors explain.

Red dwarfs are known to emit extreme radiation that strips away planetary atmospheres. However, there is some evidence that some planets can hold on to their atmospheres despite intense radiation, as with the recently discovered TIC365102760 b. Only time and more observations can tell us if the planet has an atmosphere and what type it has.

The researchers watched closely to see if there was a second planet around the star but didn’t find one. They also examined the planet spectroscopically with ground-based facilities. But we’ll have to wait for the JWST to examine the planet before we can really understand its atmosphere. The two most likely types of atmospheres for hot rocky planets are CO2-dominated and H2O-dominated.

The JWST will be able to examine SPECULOOS-3b with emission spectroscopy. This means it can examine the light the planet is emitting rather than just the light from the star as it passes through the atmosphere, which is called transmission spectroscopy. Emission spectroscopy is unaffected by irregular stellar behaviour, which red dwarfs are known to exhibit. JWST emission spectroscopy can also help determine the surface mineralogy if there’s no atmosphere. There’s a potential wealth of information waiting to be uncovered.

“We’re making great strides in our study of planets orbiting other stars,” said Steve B. Howell, one of the planet’s discoverers at NASA Ames Research Center. “We have now reached the stage where we can detect and study Earth-sized exoplanets in detail. The next step will be to determine whether any of them are habitable or even inhabited.”

The post An Earth-sized Exoplanet Found Orbiting a Jupiter-Sized Star appeared first on Universe Today.

Despite being extraordinarily difficult to detect for the first time, gravitational waves can be found using plenty of different techniques. The now-famous first detection at LIGO in 2015 was just one of the various ways scientists had been looking. A new paper from researchers from Europe and the US proposes how scientists might be able to detect some more by tracking the exact position of the upcoming Uranus Orbiter and Probe (UOP).

Initially suggested by NASA’s Planetary Science and Astrobiology Decadal Survey, UOP will be the first mission to Uranus since Voyager visited the system in 1986. When it finally arrives in 2044, after a 2031 launch date, it will be almost 60 years since humanity last had an up-close look at the Uranian system.

But 13 years in transit sure is a long time. Part of that time will be spent getting a gravitational boost from Jupiter, but most will be spent coasting between planetary bodies. And that much time spent in between planets is what the paper’s authors want to utilize to do non-Uranian science.

Fraser has long been a proponent of returning to Uranus, as he explains here.

Gravitational waves can disrupt the fabric of space-time, causing discernible distortions, especially over long distances. If the instruments in question are sensitive enough, the massive distance between UOP and the Earth would be a viable way to detect them.

This isn’t the first time using the distance between a spacecraft and Earth has been considered for detecting gravitational waves. Pioneer 11, Cassini, and a triangulation of Galileo, Ulysses, and Mars Orbiter all had entertained suggestions of being utilized for gravitational wave detection while on their journey to their final destinations. However, the equipment they were designed with was not sensitive enough to pick up the minute fluctuations required for an actual detection.

UOP will have the added advantages of decades of improved equipment, especially communications and timing electronics, which are critical to any gravitational wave detection. It also benefits that we’ve already officially detected a gravitational wave, so we know at least what to look for.

Long distance communication is hard, as Fraser explains in this video, but it’s also key to capturing data on gravitational waves.

The underlying mechanism is simple enough – consistently track the exact established position of UOP during its 13-year cruise to Uranus and cross-reference any anomalies in its position against what could be expected from known causes. These include the gravitational pull of some of the planets, or even asteroids, and solar radiation pressure on the spacecraft itself. As the authors note, some or even all of these could impact the spacecraft’s exact position; for the calculations to work effectively to find gravitational waves, better accounting for what, if any, impact they have must be completed.

But there is another potentially scientifically interesting cause of slight positional drift for the UOP: ultra-light dark matter. In theory, UOP could be used to test or even directly detect a form of dark matter known as ultra-light dark matter if it happens to exist in the solar system. Theorists have numerous models showing how it would work if it did exist. UOP could also use the same sort of exact positional calculation to contribute to that scientific research.

Best of all, UOP can do all this with literally no change to its primary functional mission – exploring the Uranian system. All that would have to be changed about the mission would be to update Earth with consistent positional data about once every 10 seconds for the duration of the 13-year trip to UOP’s final destination. Suppose there’s a chance that those more frequent check-ins with home could help detect gravitational waves or potentially dark matter. In that case, it seems well worth the consideration of the UOP mission planners – but it remains to be seen whether it will be included or not. The paper’s authors have made a persuasive argument about why it should be.

Learn More:
Zwick et al. – Bridging the micro-Hz gravitational wave gap via Doppler tracking with the Uranus Orbiter and Probe Mission: Massive black hole binaries, early universe signals and ultra-light dark matter
UT – It’s Time to Go Back to Uranus. What Questions do Scientists Have About the Ice Giants?
UT – We Could SCATTER CubeSats Around Uranus To Track How It Changes
UT – What Mission Could Detect Oceans at Uranus’ Moons?

Lead Image:
Proposed Uranus orbiter mission.
Credit – NASA Decadal Survey

The post A Mission to Uranus Could Also be a Gravitational Wave Detector appeared first on Universe Today.

The mystery of how a single-celled predator extends its "neck" by more than 30 times its overall length has finally been solved

The mystery of how a single-celled predator extends its "neck" by more than 30 times its overall length has finally been solved

Reid Wiseman felt a little jealous about the tree that he and his crewmates helped dedicate on the grounds of the U.S. Capitol. The NASA astronaut was, in a way, beaten to the moon by the sapling.

Astronomers using the JWST have discovered tiny stars may be better suited at birthing small, rocky planets with atmospheres dominated by carbon.

The Artemis II crew, NASA astronauts Victor Glover, Reid Wiseman, and Christina Koch, and Canadian Space Agency (CSA) astronaut Jeremy Hansen, pose for a photo after a Moon tree dedication ceremony, Tuesday, June 4, 2024, at the United States Capitol in Washington. The American Sweetgum tree planted on the southwestern side of the Capitol, was grown from a seed that was flown around the Moon during the Artemis I mission.

SpaceX conducted the fourth flight test of its Starship megarocket on June 6, putting on quite the show for photographers gathered near its Starbase facility in Texas.

The wait until nightfall can make observing cosmic wonders all the sweeter.

The post Why We Look Up: Anticipation appeared first on Sky & Telescope.

Boeing's Starliner capsule arrived at the ISS on its second try today (June 6), overcoming a problem with several of its reaction-control system thrusters.

SpaceX’s Starship earned high marks today in its fourth uncrewed flight test, making significant progress in the development of a launch system that’s tasked with putting NASA astronauts on the moon by as early as 2026.

The Super Heavy booster blasted off from SpaceX’s Starbase complex in South Texas at 7:50 a.m. CT (12:50 p.m. UTC), rising into the sky with 32 of its 33 methane-fueled Raptor engines blazing. Super Heavy is considered the world’s most powerful launch vehicle, with 16.7 million pounds of thrust at liftoff.

Minutes after launch, the rocket’s upper stage — known as the Ship — separated from the first stage, firing up its own set of six Raptor engines. Meanwhile, Super Heavy flew itself to a controlled splashdown in the Gulf of Mexico.

The soft splashdown marked a new achievement for Starship. During the third flight test, which took place in March, only a few of Super Heavy’s engines were able to light up again for a crucial landing burn. As a result, the booster hit the water with an uncontrolled splat.

Eventually, SpaceX plans to have the Super Heavy booster fly itself back to its base after doing its job.

The upper stage reached orbital-scale altitudes in excess of 200 kilometers (125 miles), but completing a full orbit wasn’t part of today’s plan. Instead, SpaceX aimed to have Ship make its own soft splashdown in the Indian Ocean.

Streaming video, relayed via SpaceX’s Starlink satellite network, showed the rocket’s protective skin glowing with the heat of atmospheric re-entry. Burning debris broke off from one of Ship’s control fins, damaging the camera’s lens — but the fuzzy view nevertheless confirmed that the spacecraft successfully hit the mark. That represented another advance over the third test, when the Ship broke up during its descent to the ocean.

“Despite loss of many tiles and a damaged flap, Starship made it all the way to a soft landing in the ocean!” SpaceX founder Elon Musk exulted in a posting to his X social-media platform.

NASA Administrator Bill Nelson added his congratulations on X, and noted that the successful test was a plus for the space agency’s Artemis moon program. “We are another step closer to returning humanity to the moon through Artemis — then looking onward to Mars,” he wrote.

A customized version of Ship is slated to serve as the lunar lander for Artemis 3, which would mark the first crewed mission to the moon’s surface since Apollo 17 in 1972. That mission is currently scheduled for 2026, but the timing depends in part on when the Starship system will be ready.

SpaceX’s uncrewed flight tests are following a step-by-step path to get Starship in shape for a wide variety of missions — including the deployment of hundreds of Starlink satellites, point-to-point travel between spaceports on Earth, and crewed odysseys to the moon, Mars and beyond.

Starship rockets aren’t carrying payloads for these early tests. “We said it before, we’re going to say it 9,000 times: The data is the payload,” SpaceX commentator Dan Huot said during today’s flight test.

But as the development program proceeds, the envelope for the flight tests will be widened to include multi-orbit operations, payload deployments and precision touchdowns on landing pads. Before today’s test, SpaceX and the Federal Aviation Administration worked out an arrangement that’s expected to streamline the regulatory process for future flights.

The post Success! SpaceX’s Starship Makes a Splash in Fourth Flight Test appeared first on Universe Today.

A genetic analysis of ancient horses reveals that breeding techniques developed by people in the Pontic-Caspian steppes enabled the rapid spread of horse-powered travel

A genetic analysis of ancient horses reveals that breeding techniques developed by people in the Pontic-Caspian steppes enabled the rapid spread of horse-powered travel

The dark skies of the new moon of June 2024 will allow some of the naked eye planets to stand out late in the night after midnight.

Scientists say it’s likely that at least one of the next five years will exceed an average increase of 1.5 degrees Celsius above preindustrial temperatures

Why are bears both adorable and deadly? Scientific American investigates why these apex predators are “friend-shaped”

The UK government has set limits on the capabilities of quantum computers that can be exported from the country and has declined to explain these limits on the grounds of national security. Experts say this make no sense

The UK government has set limits on the capabilities of quantum computers that can be exported from the country and has declined to explain these limits on the grounds of national security. Experts say this make no sense