Category: 7. Science

Since the discovery of the first exoplanet orbiting a Sun-like star, the confirmation of nearly 6000 exoplanets to date – and their diversity – has revolutionized our knowledge of planetary systems in the past three decades.

Nevertheless, the majority of these planets are around mature stars (≳1 Gyr), where the planet birth environments have already dissipated. Indeed, we have only confirmed 2 forming planets (i.e., protoplanets; ≲10 Myr) residing in one single system. In comparison, we have imaged over 200 protoplanetary disks in the past decade, with many of them hosting substructures such as spirals and gaps which suggest the existence of protoplanets.

To understand the early stages of planet formation, the Habitable Worlds Observatory (HWO) – with its high-contrast imaging and integral field spectroscopy capabilities – presents a unique opportunity to explore the demographics of the natal stages of planet formation and their birth environments.

We propose to image protoplanets within substructured protoplanetary disks using HWO via direct imaging, and characterize them (i.e., protoplanets, protoplanetary disks, circumplanetary disks) using integral field spectroscopy and spectropolarimetry. This effort will dramatically extend current population of protoplanets, probing and characterizing over 200 protoplanets.

By expanding the number of protoplanets by two orders of magnitude, these observations will test and refine planet formation theory and planet-disk interaction theory, and further motivate planet migration studies together with existing mature planets. The results will offer critical insight into planetary system formation and evolution, and help understand the origin of our own Solar System.

Bin B. Ren

Comments: 9 pages, 3 figures, 2 tables. HWO Science Case #SCDD-SSiC-8 for HWO25 proceedings
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2506.24129 [astro-ph.IM] (or arXiv:2506.24129v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2506.24129
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Submission history
From: Bin Ren Dr.
[v1] Mon, 30 Jun 2025 17:59:59 UTC (1,388 KB)
https://arxiv.org/abs/2506.24129
Astrobiology,

Extremophilic bacteria from extreme environments, such as the Atacama Desert, Salar de Huasco, and Antarctica, exhibit adaptations to intense UV radiation. In this study, we investigated the genomic and structural mechanisms underlying UV resistance in three bacterial isolates identified as Bacillus velezensis PQ169, Pseudoalteromonas sp. AMH3-8, and Rugamonas violacea T1-13.

Through integrative genomic analyses, we identified key genes involved in DNA-repair systems, pigment production, and spore formation. Phylogenetic analyses of aminoacidic sequences of the nucleotide excision repair (NER) system revealed conserved evolutionary patterns, indicating their essential role across diverse bacterial taxa.

Structural modeling of photolyases from Pseudoalteromonas sp. AMH3-8 and R. violacea T1-13 provided further insights into protein function and interactions critical for DNA repair and UV resistance. Additionally, the presence of a complete violacein operon in R. violacea T1-13 underscores pigment biosynthesis as a crucial protective mechanism.

In B. velezensis PQ169, we identified the complete set of genes responsible for sporulation, suggesting that sporulation may represent a key protective strategy employed by this bacterium in response to environmental stress.

Our comprehensive approach underscores the complexity and diversity of microbial adaptations to UV stress, offering potential biotechnological applications and advancing our understanding of microbial resilience in extreme conditions.

Phylogenetic tree based on the amino acid sequences of UvrA, UvrB, and UvrC proteins (NER system). Multiple sequence alignment was performed using MUSCLE on the Phylogeny.fr platform, followed by tree construction with PhyML and visualization using TreeDyn. The resulting tree was further arranged and refined using the Interactive Tree of Life (iTOL v7) tool. The maximum likelihood method was employed with 1000 bootstrap replicates, where the node sizes reflect the level of bootstrap support. Each label includes the gene name, the bacterial species, and the corresponding NCBI accession number. Three environmental strains are highlighted: Bacillus velezensis PQ-169 (green), Pseudoalteromonas sp. AMH3-8 (yellow), and Rugamonas violacea T1-13 (purple). These strains, along with other extremophilic, UV-resistant, and pathogenic bacteria, were included to compare UvrA (red clade), UvrB (blue clade), and UvrC (green clade) variations under extreme environmental conditions. — Int J Mol Sci via PubMed

Isolation sites, genomic assembly characteristics, and ANI-based taxonomic assignment of three extremophilic bacterial isolates. (a–c) Representative sampling sites of bacterial isolates: (a) Atacama Desert, (b) Salar de Huasco, and (c) Antarctic soil. (d–f) Circular genome representations illustrating variability in genome size, contiguity, and genetic content: (d) Bacillus velezensis PQ169 (76 contigs, 4.18 Mb), (e) Pseudoalteromonas sp. AMH3-8 (single contig, 4.74 Mb), and (f) Rugamonas violacea T1-13 (171 contigs, 6.85 Mb). Rings (outer to inner) represent predicted CDSs, RNA genes (rRNA, tRNA, and tmRNA), GC content, and GC skew. (g–i) Heatmaps depicting average nucleotide identity based on MUMmer (ANIm) analysis between each isolate and closely related reference strains, supporting definitive taxonomic assignment: (g) Bacillus velezensis PQ169, (h) Pseudoalteromonas sp. AMH3-8, and (i) Rugamonas violacea T1-13. Color gradients indicate similarity percentages, with red color representing higher ANI values, and blue lower values. — Int J Mol Sci via PubMed

astrobiology, genomics, extremophiles,

Carbon dioxide is one of the three most abundant species within the ice mantles around dust grains inside molecular clouds.

Since a substantial amount of interstellar grains is made of siliceous materials, we have studied the infrared profile of CO₂ deposited on top of a bare and ice-coated amorphous silicate (MgFeSiO₄) film using reflection absorption infrared spectroscopy (RAIRS).

In contrast to a metal surface, the CO₂ IR profile shows a relaxation of the metal surface selection rule in the presence of the bare MgFeSiO₄ dust grain analog, which brings the IR profile closer to the observational spectra while maintaining the sensitivity of RAIRS. Experiments with the underlying CO and CH₄ ices show that their presence facilitates structural changes toward crystalline ice for the deposited CO₂ at much lower temperatures than on the polar ice layers.

Warming-up experiments of CO₂ showed that it tends to stay on the silicate surface for much longer than on the gold surface without the silicate layer. We noticed for the first time a split in the ¹³CO₂ IR feature on the pure or ice-covered silicate grain as a marker for the onset of diffusion.

The laboratory ¹³CO₂ profile then closely resembles recent JWST observations of this feature around young and embedded protostars, suggesting that it can be linked to the observed feature.

Tushar Suhasaria, Vanessa Leuschner, Cornelia Jaeger, Caroline Gieser, Thomas Henning

Comments: 13 pages, 6 figures, 2 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.00836 [astro-ph.GA] (or arXiv:2507.00836v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2507.00836
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Submission history
From: Tushar Suhasaria Dr
[v1] Tue, 1 Jul 2025 15:08:11 UTC (363 KB)
https://arxiv.org/abs/2507.00836
Astrobiology,

A bombardment of comets is thought to have occurred in the inner solar system as a result of a dynamical instability among the giant planets after gas disk dispersal.

Vesta, the second largest asteroid in the main asteroid belt, likely differentiated before gas disk dispersal, implying its crust witnessed the cometary bombardment. The composition of HED meteorites, which represent fragments of Vesta’s crust, could therefore have been altered by cometary impacts.

Here we combine noble gas mass spectrometry measurements, N-body simulations, collision rate calculations, and impact simulations to estimate the cometary contribution to Vesta.

While our dynamical simulations indicate that Vesta likely underwent a significant number of collisions with large comets, we find no xenon cometary signature in HED meteorites. This apparent contradiction arises due to the fact that cometary impacts were at high speeds and Vesta’s weak gravitational attraction made it incapable of retaining cometary material.

Smaller asteroids are even less likely to retain such material. Therefore, if a cometary xenon signature is ever detected in an asteroid belt object, it must have been acquired during formation, within the same source region as comet 67P/Churyumov-Gerasimenko, and have been implanted later into the asteroid belt.

Sarah Joiret, Guillaume Avice, Ludovic Ferrière, Zoë M. Leinhardt, Simon Lock, Alexandre Mechineau, Sean N. Raymond

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.00753 [astro-ph.EP] (or arXiv:2507.00753v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.00753
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Related DOI:
https://doi.org/10.3847/PSJ/ade990
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Submission history
From: Sarah Joiret
[v1] Tue, 1 Jul 2025 13:57:44 UTC (350 KB)
https://arxiv.org/abs/2507.00753
Astrobiology, Astrochemistry, Astrogeology,

Sea spiders (Pycnogonida) have a very strange body shape. They’re tiny marine animals with super skinny trunks and legs so long that some of their organs stretch into them! Their belly is so reduced it’s barely visible. They belong to the same group as spiders and scorpions: chelicerates, named after their special claw-like mouthparts called chelicerae.

Because sea spiders look so different, researchers are exploring their genome to understand what genes create such unusual bodies and what this reveals about their evolutionary history.

Researchers from the University of Vienna and the University of Wisconsin- Madison have created the first chromosome-level genome of the sea spider Pycnogonum litorale. This breakthrough helps explain the species’ unusual body structure and offers new insights into the evolution of chelicerates—a group that includes spiders, scorpions, and horseshoe crabs.

To assemble the sea spider genome, researchers used two advanced sequencing techniques. First, they applied long-read sequencing to one individual, which captured long stretches of DNA and helped piece together tricky parts of the genome. Then, with a second individual, they studied how DNA is arranged inside the cell, figuring out which pieces sit close together.

Scientists revealed the oldest known scorpion on Earth

By combining these approaches, they successfully built 57 pseudochromosomes, covering nearly the whole genome with high precision. They also added data on gene activity across different developmental stages, giving an even deeper look into how this unique animal develops and functions.

The team mainly focused on the so-called Hox cluster, a gene family that is evolutionarily conserved across the animal kingdom. In arthropods like sea spiders, Hox genes are crucial for defining where different body segments go—head, thorax, abdomen, etc. But their role isn’t limited to creepy crawlies! Across many animal groups, Hox genes act as master regulators, guiding the overall layout during development.

In a fascinating twist, scientists discovered that Pycnogonum litorale, a sea spider, is missing a key Hox gene called abdominal-A (Abd-A), a gene normally responsible for shaping the rear end of arthropods. Its absence may explain why sea spiders have extremely reduced abdomens, a trait also seen in mites and barnacles.

This supports a broader evolutionary pattern: when certain Hox genes disappear, the body parts they control often shrink or vanish. Sea spiders now join the list of species showing this gene-body connection.

Unlike spiders and scorpions, which show signs of ancient whole-genome duplications, P. litorale has no such genetic echoes. Since sea spiders are considered the sister group to all other chelicerates, this suggests that genome duplications occurred later, in specific subgroups, not in the earliest chelicerate ancestors.

The newly completed genome of P. litorale gives scientists a powerful tool for comparing chelicerate species—like spiders, scorpions, and horseshoe crabs—and studying how their body plans evolved.

Identifying the genes behind venom production

Why sea spiders stand out:

• Their development may reflect how early arthropods grew.
• They have unique body features not seen in other species.
• They can regenerate parts of their body, which is rare and exciting for research.

With the genome and gene activity data now in hand, researchers like Georg Brenneis can explore these traits in detail at the molecular level.

Journal Reference:

1. Papadopoulos, N., Kulkarni, S.S., Baranyi, C., et al. The genome of a sea spider corroborates a shared Hox cluster motif in arthropods with a reduced posterior tagma. BMC Biol 23, 196 (2025). DOI: 10.1186/s12915-025-02276-x

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Can animals share the same space peacefully high above the ground in the treetops? A research team at the University of Göttingen has found that forests combining both deciduous and conifer trees make it easier for red squirrels and dormice to coexist. Using cameras placed high in the canopy, scientists discovered that red squirrels tend to prefer coniferous forests, while dormice are more commonly found in beech forests. However, in mixed forests that include both tree types, both species were observed living side by side. This suggests that mixed forests could play an important role in supporting biodiversity. The findings were published in the European Journal of Wildlife Research.

The study took place in northern Germany and used 80 cameras placed between 2 and 30 meters above the ground in the trees.  The researchers, with the help of professional climbers, had to climb up each tree to install, inspect and retrieve the cameras in the forest canopy. Cameras automatically recorded animals, being activated by movement and heat when animals passed through their field of view. During seven months of observation in 20 different forests, the researchers recorded 468 sightings of red squirrels and 446 of dormice. Among the dormice sightings were 249 edible dormice and 197 hazel dormice. These observations allowed the team to analyze how the presence of each species was linked to the number of beech trees and the presence of other tree-dwelling mammal species.

“Our results show that dormice and red squirrels are not avoiding each other. In fact, they can live together quite well in mixed forests,” says lead author Pedro Mittelman, a PhD researcher in Wildlife Sciences at the University of Göttingen. “This is great news – it shows that forestry management systems combining tree species can benefit wildlife.” The research team highlights the value of cultivating a mixture of trees as a way to support biodiversity, even in areas managed for timber production.

This study is part of the graduate programme EnriCo (“Enrichment of European beech forests with conifers: impacts of functional traits on ecosystem functioning”) at the University of Göttingen. It is funded by the German Research Foundation (DFG) and contributes to ongoing efforts to better understand the functioning of pure and mixed forest ecosystems.

Reference: Mittelman P, Pineda M, Balkenhol N. Mixed broadleaf-conifer forests promote coexistence of red squirrels and doormice. Euro J Wildlife Res. 2025. doi: 10.1007/s10344-025-01947-y

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A sneak preview of the first batch of deep space imagery from the new Vera C. Rubin Observatory in Chile made its way to news sites and social media last week, followed by a livestream event.

“(The Rubin Observatory is) going to build the greatest time-lapse movie of the cosmos ever made,” the observatory said in a post.

The observatory is named for the American scientist widely credited for finding some of the first evidence of dark matter, with the project being funded by the National Science Foundation and the US Department of Energy’s Office of Science. 

The scientists and officials from the NSF and DOE participated in a news conference and Q&A about the findings last week. You can watch the stream below.

Millions of galaxies, big images

Though the livestream was plagued by a few technical issues, it still offered some context on what data is being captured at the Rubin Observatory and why.

“Starting today, our ability to understand dark matter, dark energy and planetary defense will grow even faster than ever before,” said Brian Stone, the NSF’s chief of staff.

The observatory’s 3,200-megapixel camera is used for a full-sky scan that happens every three to four days. Stunning images that the observatory shares are only a fraction of what is being captured, in some cases showing only 2 percent of the full view, which would require 400 HDTVs to show. 

One image can capture 10 million galaxies. Closer to Earth, astronomers have discovered 1 million asteroids in our solar system and expect to discover 5 million more in the next few years.

During this upcoming week, skywatchers across most of the U.S. and southern Canada will get an opportunity to view the two largest space vehicles now in orbit around the Earth within minutes of each other.

They are the International Space Station (ISS) and China’s space station, Tiangong. If you are up during the predawn hours, you’ll probably be able to make a sighting of both within less than a half hour of each other.