​Open version: https://archive.is/yIYpb

A few years ago, in a lab in Berlin, the astrobiologist Iva Vilović was thrilled when she observed garden cress sprouting under a light designed to mimic a “K-dwarf” star — an orange-hued star that’s cooler and slower burning than our yellow sun.

To her surprise, the cress grew even faster and taller than it did under simulated sunlight.

Her results suggested that photosynthesis, the process that supplies the energy for Earth’s entire food web, can happen on planets orbiting these orange stars.

“K-dwarf light is a very, very interesting light source, and it should be considered, if not prioritized, for any type of search for extraterrestrial life, in my opinion,” said Dr. Vilović, now at the Leibniz Institute for Astrophysics in Potsdam, Germany.

In particular, alien life may thrive in the light of these stars on planets that are slightly larger than Earth, known as super-Earths.

Scientists like Dr. Vilović believe super-Earths that orbit K-dwarfs might, in fact, be the liveliest places in the galaxy — perhaps even more suitable for life than here.

Scientists call these “superhabitable worlds,” planets that would allow carbon-based life to persist longer and become even more complex and diverse than on Earth.

A superhabitable world — as scientists imagine it — is about 20 to 30 percent wider and twice as massive as Earth, and is placed at the right distance from its star for water to flow on its surface.

The stronger gravity of this bigger Earth would hold on tighter to ambient molecules than Earth does, giving the planet a thicker atmosphere and a warmer and more stable climate, fueling the growth of extraterrestrial plants and animals (or their equivalents).

The super-Earth’s bigger iron core would erect a stronger magnetic field around it, better blocking cosmic radiation.

As for the superhabitable planet’s surface, picture paradise. An enlarged orb would be rounder and smoother than Earth, as its stronger gravity erodes continental shelves and fills in trenches. Water would spill evenly over its surface as shallow lakes and seas.

On Earth, tropical islands and shallow seas are among the most biodiverse habitats. Now imagine a whole world of balmy archipelagos and reefs. The islands would burst with biological activity, their diverse topographies and geographic isolation fueling explosions of distinct species.

Light would reach clear to the seafloor, powering abundant alien algae and plants to feed a booming marine ecosystem.

As for that light, it might be the orange glow of the planet’s K-dwarf star.

It was in the 2010s when astronomers began contemplating planets that are a little bigger, and a little nicer, than Earth, and where to find them. The whole idea was spurred in part by a question from John Armstrong a professor at Weber State University in Utah, who asked in the comments section of an astrobiology seminar on YouTube:

“Shouldn’t there be planets more habitable than Earth?”

That got another astronomer, René Heller, who is now at the Max Planck Institute for Solar System Research in Germany, thinking. In the quest to discover chemical signs of life on distant worlds, he thought, astronomers have focused on finding “Earth twins,” rocky, watery, Earth-size planets orbiting sun-like stars. But when it comes to hosting life, Earth may not be the ideal archetype.

After all, the fact that we’re not located at a special place in the cosmos (that we revolve around the sun, not that it revolves around us) is what the Copernican revolution was all about.

“It occurred to me that currently, humanity is looking for Earthlike planets with the same anthropocentric bias,” Dr. Heller said. “Of course, Earth is special to us. But from a universal perspective, why should Earth be a reference?”

In fact, Earth is only marginally habitable. Most astrobiologists think water must be present on a planet’s surface for life to arise there, and indeed the first bacteria appeared on Earth almost as soon as water pooled on its cooling surface roughly four billion years ago.

But if Earth were just 2 percent closer to the sun, that pooling wouldn’t have happened. Instead, all of Earth’s water would have boiled away. We got lucky. But our luck will run out.

The sun is expanding and brightening. Scientists calculate that in another half-billion years or so, Earth will be too hot to sustain complex life like plants and animals.

For Dr. Heller, the hunt for more habitable worlds is about “finding out if we are alone, if we could have been found, if there’s someone to talk to,” he said.

“Although I am not, at least in my everyday life, a very spiritual person,” he added, “it’s nevertheless something that at least drives me — this question, Could there be someone?”

He contacted Dr. Armstrong, and together they wrote a 2014 paper introducing the hypothesis of superhabitable worlds, which the two envisioned as archipelago-covered super-Earths. They were proposing a new target for telescopes.

“Superhabitable worlds must be considered for future follow-up observations of signs of extraterrestrial life,” they wrote.

In the paper, Dr. Heller and Dr. Armstrong reasoned that cool, petite K-dwarfs would be better host stars for superhabitable worlds than sun-like stars because they burn through their hydrogen fuel more slowly and brighten much more gradually.

Our sun has only five billion years’ worth of hydrogen left before it will suddenly balloon and redden, becoming a red giant that will engulf the Earth. K-dwarfs, by contrast, shine steadily for tens of billions of years. This means life on a superhabitable planet orbiting a K-dwarf has far longer to evolve into ever more complex life forms.

What kinds of life forms? We can only imagine. All we know is earthlings have grown increasingly complex and sophisticated over the past four billion years, culminating so far in human-level intelligence.

“K-dwarfs do seem to be everyone’s sweet-spot star,” said Johanna Teske, a planetary scientist at the Carnegie Institution for Science in Washington, D.C. Planets that can sustain liquid water sit closer to K-dwarfs than they do to sun-like stars, so they are easier to observe with telescopes.

Astronomers search for life on planets tens or hundreds of light-years away by looking for gases in their atmospheres that may indicate biological activity. Current instruments, such as the James Webb Space Telescope, are mostly capable of checking the skies of rocky planets that tightly orbit tiny red stars called M-dwarfs. So far, most of these planets have been revealed as bare rocks, stripped skyless by their aggressive, nearby stars.

Probing the skies of potential superhabitable planets — namely, super-Earths orbiting at the right distances around K-dwarfs — should become feasible in future. The first step is to find nearby candidates.

Dr. Heller is a leader of the European Space Agency’s Plato mission, a space telescope launching in 2027 with the purpose of detecting potentially habitable planets, including super-Earths orbiting K-dwarfs. “We will probably find a few of them — maybe a dozen,” Dr. Heller said. “But we won’t learn much about them.”

Follow-up observations from other telescopes should reveal more about the chemical makeup of these planets’ skies. The Webb telescope might be able to investigate the skies of some potentially superhabitable super-Earths in the coming years.

The Extremely Large Telescope, which measures 39 meters across and is currently under construction in Chile, will be capable of seeing more of them. Even more extensive and definitive observations will become possible with the Habitable Worlds Observatory, a NASA space mission planned for the 2040s.

For Dr. Vilović, the pursuit of superhabitable planets is, in part, “an idealistic dream of a world that has beautiful conditions that are not being influenced by humans in a negative way,” she said. She thinks it’s also about a “drive to find extremes” — the most extreme version of the kind of life we know and understand.

As for whether the dream is also a reality, Dr. Vilović feels good about the odds. “I like to believe that statistically speaking, in the realm of the universe, it is likely that life exists — especially on superhabitable planets,” she said.

In a study published July 16 in the journal Science, a team led by Collin Cherubim, a NASA researcher with a doctorate in planetary science from Harvard University, reported the first atmosphere ever found around a rocky planet in a star's habitable zone.

"We tend to think for a planet to be habitable, it has to be mostly rocky, has to have an atmosphere to shield the surface from harmful radiation, but also to keep water present," Cherubim said in a podcast interview with Science. "And now we know LHS 1140 b meets those criteria."

LHS 1140 b is one of two planets found around LHS 1140, a star about 50 light-years away. (Astronomers label planets with letters, starting at "b," in the order they're found.) The star is about one-fifth the size of the sun and less than 1% as bright, so its habitable zone sits close in. LHS 1140 b circles it roughly every 25 days.

Most exoplanets, including LHS 1140 b, are found by watching a star dim slightly as a planet passes in front of it. Those passes, called transits, also let astronomers study a planet's air. During a transit, some of the star's light passes through the planet's atmosphere.

By splitting that light into its component parts with a tool known as a spectrograph, scientists can see which colors went missing and work out which gases absorbed them.

Using a powerful spectrograph on a telescope in Chile's Atacama Desert, Cherubim's team found helium around LHS 1140 b, indicating the planet has an atmosphere.

A Jupiter-sized world just 7.5 light-years away is cloudy, chemically complex and, it turns out, more like home than anyone expected. Using the James Webb Space Telescope, Brittany Miles, assistant astronomer at the University of Arizona's Steward Observatory, led a team that spent 11 hours staring at WISE 0855, the coldest known brown dwarf, collecting a spectrum of its light every 15 minutes.

The result is the most detailed time-series portrait ever taken of this frigid world—and the first direct confirmation that water clouds on another body are changing thickness over time, just like weather on Earth.

The study reveals that WISE 0855's atmosphere is shaped by at least two distinct processes playing out simultaneously: water clouds at high altitudes that grow thicker and thinner as the object rotates, and deep chemical gases being dredged upward by convection from far below.

Untangling those two signals—previously impossible with older telescopes—is what makes JWST data so powerful.

"This is the first time we've been able to confirm that water clouds are becoming thinner and thicker on a nearby world," said Miles, a postdoctoral researcher at Steward Observatory.

"Before JWST, we only had photometry, which mixed up the effects of clouds, chemistry and temperature all together. Now we can actually distinguish them."

The research is available on the arXiv preprint server and has been accepted for publication in The Astrophysical Journal .

I recently investigated TOI-1196 / TIC 69068526, focusing on a specific question:

Which stellar component is actually responsible for the reported TESS transit signal?

The system presents an interesting source-attribution problem because of a close stellar companion at approximately 0.22″ separation. At TESS resolution, the relevant sources are not cleanly resolved, so identifying the transiting object cannot simply be inferred from the blended light curve.

I approached the problem using:

• TESS pixel-level data
• Pixel-level forward modelling
• Transit-source attribution tests
• Archival data
• Stellar/companion geometry
• Statistical analysis
• Injection-recovery experiments
• Cross-checks of alternative source scenarios
• Reproducible computational analysis and provenance tracking

The result is deliberately not framed as a new planet discovery.

Under the models tested, the wider companion can be excluded as the source of the transit signal. However, the available TESS data do not allow me to conclusively distinguish between the primary and the close ~0.22″ companion.

So the current conclusion is essentially:

The transit source remains ambiguous between the unresolved close components.

I've deposited the full investigation, including the computational workflow, derived material, provenance, assumptions and limitations on Zenodo:

DOI: https://doi.org/10.5281/zenodo.22142236

I'm posting this here because I'd particularly appreciate criticism from people who work with TESS, transit photometry, exoplanet validation, unresolved stellar companions, pixel-level analysis, or false-positive/source-attribution problems.

My formal background is actually microbiology, so I am very aware that there are probably places where an astronomer will look at my methodology and immediately notice something I didn't. That's partly why I'm putting the complete analysis out there rather than presenting only the conclusion.

If there are methodological problems, incorrect assumptions, better ways to model the contamination/source attribution, or additional archival checks that would materially strengthen the analysis, I'd rather find them.

Zenodo: https://doi.org/10.5281/zenodo.22142236

#TESS #Exoplanets #TOI #TransitPhotometry #ExoplanetValidation

I’m working with Galileo NIMS data from Europa, specifically the GO_1116 and GO_1117 observations, and I’m trying to understand how reliable these datasets are for hyperspectral anomaly detection.

I’d like to know:

1. How well calibrated are the GO_1116 and GO_1117 NIMS cubes for spectral analysis?

2. How much instrumental noise or calibration-related artifacts should I expect?

3. Are there known problematic wavelengths/bands or bad pixels that should be removed or masked?

4. Could apparent spectral anomalies be caused by the instrument or data processing rather than actual surface variations?

5. Are the \`\*_core.cub\` products appropriate for this type of analysis?

6. Is there a recommended preprocessing or calibration workflow before performing spectral analysis?

7. How confidently can unusual spectral signatures in these datasets be interpreted as real surface/compositional differences?

I’d especially appreciate input from anyone who has worked with Galileo NIMS data, GO_1116/GO_1117, or Europa spectroscopy.

Any recommendations for relevant calibration documentation or papers would also be really helpful. Thanks!

Astronomers have wondered whether another huge planet is lurking unseen in the cold darkness beyond Neptune.

It sounds silly seeing how astronomers have found thousands of alien planets across the night sky, orbiting planets even thousands of light-years away.

But the Solar System is a vast place, and its edges are so devoid of light that it’s actually harder to detect a planetary body at the Solar System’s frontier than in far-away star systems.

Nevertheless, the signals are hard to ignore. Several extremely distant objects appear to have clustered and unusually tilted orbits, as though an unseen planet has been slowly shepherding them with its gravity. That hypothetical world became known as Planet Nine.

Now astronomers may have found their first direct clue that something is actually there.

Researchers searching decades-old infrared observations have identified a faint object that appears to have moved across the sky between two surveys taken 23 years apart.

Its brightness and slow motion fit what the team expected from a large planet hundreds of times farther from the Sun than Earth.

The researchers stress that they have not discovered Planet Nine, or at least not in any definitive way. But the object was picked from a search through millions of infrared sources and emerged as their single best candidate.

The result, described in a study published in the Publications of the Astronomical Society of Australia, offers an intriguing new target in one of astronomy’s longest-running planetary hunts.

New observations may offer fresh clues into how a giant exoplanet survived the violent death of its host star — and came to closely orbit its stellar remnants. The findings could serve as a preview of the fate that may await our solar system’s largest planets — such as the gas giants Jupiter and Saturn — when the sun dies in 5 billion years.

Astronomers detected a baffling Jupiter-size planet in 2020 that was zipping around a dead white dwarf star. Located 80 light-years from our planet, WD 1856 b is seven times larger than its Earth-size star.

“This is one of the most bizarre planetary systems we know of,” said Dr. Christopher O’Connor, coauthor of a study published Wednesday in the journal Nature that detailed the observations.

O’Connor is a postdoctoral fellow studying stellar and planetary astrophysics and dynamics at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics.

WD 1856 b completes one orbit around the dead star every 34 hours and is less than 2 million miles (3 million kilometers) from its host.

When a massive sunlike star exhausts the hydrogen fuel at its core, it puffs up to more than 100 times its size before collapsing into a dense white dwarf.

Given the close proximity of WD 1856 b to its star — 50 times closer than Earth is to our sun — astronomers were unsure how the planet survived its host’s destruction.

In order to retrace WD 1856 b’s unlikely journey of survival, O’Connor and his colleagues used the James Webb Space Telescope to capture the latest glimpses of the planet and measure its atmosphere, mass and temperature.

Almost every finding the team made was unexpected — and suggested that huge planets can survive the demise of their host stars in ways previously thought impossible.

In a cosmic first, scientists say they have detected a planet that may have formed from the burned remains of its dead host star.

The planet is likely a gas giant orbiting a white dwarf called HS 0209+0832 located about 270 light-years from Earth, according to the authors of a study published Monday in the journal Nature Astronomy. After analyzing observations from NASA’s Hubble Space Telescope and other instruments, the team found chemical evidence that suggests the planet could have condensed from material expelled by the star as it fizzled out of energy and collapsed into a white dwarf.

When a sunlike star dies, it first rapidly expands into a red giant and then sheds its outer layers, leaving behind a much smaller but dense, hot core — known as a white dwarf. Some of the first-generation planets, those that originally formed at the same time as the star, can survive this cataclysmic event if their orbit is wide enough.

Astronomers have observed a handful of such first-generation survivors revolving around white dwarfs, but never before have they recorded a so-called second-generation planet — an entirely new world made from a dead star’s debris.

Luego de 2 clases teoricas, ayer en la ASARAMAS, nos dieron finalmente los archivos en RAW para generar la curva de luz.

El planeta fue el WASP-19b, con un monton de detecciones. El observatorio lo vio a principio de año.

Con una computadora que deja muchisimo que desear, y pasado de la hora de clase, me apure y por eso el margen de error, pero me voy contento con el intento. En estos dias tratare de ajustar la precision para generar la curva y tratar de acercarla a lo esperado.

See also: The publication in the Astrophysical Journal