Category: 7. Science

Martian glaciers are mostly pure ice across the Red Planet, suggesting they might potentially be useful resources for any explorers that might land there one day, a new study finds.

For decades, scientists have often seen glaciers coated in dust on the slopes of the mountains of Mars. Previous research suggested these were either glaciers that were comprised mostly of rock and as little as 30% ice, or debris-covered glaciers that were more than 80% ice.

Editor’s note: Astronaut Thomas Pesquet carries out investigations with the spectrometer associated with the ESA Electronic FieldBook

A key aspect to understanding a new location during an Away Team Mission is understanding the local atmosphere and mineralogy.

In the case of examining minerals and life forms in locations such as caves, wells, or other isolated locations, the atmosphere may cary considerably from what is seen on the surface. Having a system that can do in situ analysis can be vital – not only for science but also for crew safety.

Using a common smartphone platform allows adaptation of this technology by a broader number of users here on Earth by virtue of using a easily obtained smartphone platform.

Astrobiology, Astrogeology

Some of the rainiest places on Earth could see their annual precipitation nearly halved if climate change continues to alter the way ocean water moves around the globe.

In a new CU Boulder-led study published July 30 in Nature, scientists revealed that even a modest slowdown of a major Atlantic Ocean current could dry out rainforests, threaten vulnerable ecosystems and upend livelihoods across the tropics.

“That’s a stunning risk we now understand much better,” said lead author Pedro DiNezio, associate professor in CU Boulder’s Department of Atmospheric and Oceanic Sciences, adding that parts of the Amazon rainforest could see up to a 40% reduction in annual precipitation.

The ocean conveyor belt

The Atlantic Meridional Overturning Circulation (AMOC) is a massive system of ocean currents that moves water through the Atlantic Ocean, transporting warm, salty water from the tropics to the North Atlantic. The AMOC plays an important role in regulating the climate by redistributing heat from the southern to the northern hemisphere. It also makes sure the tropical rain belt, a narrow band of heavy precipitation near the equator, stays north of it.

As the climate warms, melting polar ice and increasing rainfall will dilute the ocean’s surface waters, making them less dense and potentially slowing down the circulation. The impact of a weakened AMOC on the tropics remains uncertain, because scientists have only been monitoring the system directly for two decades.

As a technician at a National Oceanic and Atmospheric Administration (NOAA) lab in Miami in 2005, DiNezio helped calibrate some of the earliest measurements of AMOC. At the time, he had no idea that he’d be studying that very same system two decades later.

“A few years ago, this monitoring system recorded signs of a decline in the AMOC, but it later rebounded. So we weren’t sure if it was just a fluke. The problem is, we haven’t been measuring the ocean long enough to detect meaningful long-term change,” DiNezio said.

While scientists are uncertain whether the AMOC has already begun to decline, climate models predict the system will eventually weaken because of climate change.

Predicting the future

DiNezio and his team set out to explore how a future slowing of these critical ocean currents could impact global precipitation patterns.  

“Changes in rainfall are very difficult to predict, because so many factors are involved in making rain, like moisture, temperature, wind and clouds. Many models struggle to predict how the pattern will change in a warming world,” DiNezio said.

The team turned to climate records from about 17,000 years ago, when the AMOC last slowed down significantly due to natural causes. Evidence of precipitation preserved in cave formations, as well as lake and ocean sediments revealed how rainfall patterns responded to the slowdown during that period.

Drawing on that data, DiNezio’s team identified the computer models that best captured those ancient rainfall shifts and used them to predict how the patterns could change in the future.

Their best models predict that as the AMOC weakens and cools the northern Atlantic, this temperature drop would spread toward the tropical Atlantic and into the Caribbean. This change, on top of rising global temperatures, will lead to significant reductions in precipitation over Central America, the Amazon, and West Africa.

“This is bad news, because we have these very important ecosystems in the Amazon,” said DiNezio. The Amazon rainforest contains almost two years of global carbon emissions, making it a major carbon sink on Earth. “Drought in this region could release vast amounts of carbon back into the atmosphere, forming a vicious loop that could make climate change worse.”

While DiNezio said the AMOC is unlikely to stop completely, even a small reduction in its strength could lead to changes across the entire tropical region, increasing the risk of reaching a tipping point. But how fast and how much it slows depends on the degree of future climate change.

“We still have time, but we need to rapidly decarbonize the economy and make green technologies widely available to everyone in the world. The best way to get out of a hole is to stop digging,” DiNezio said. 

Temperate sub-Neptune exoplanets could contain large inventories of water in various phases, such as water-worlds with water-rich atmospheres or even oceans.

Both space-based and ground-based observations have shown that many exoplanets likely also contain photochemically-generated hazes. Haze particles are a key source of organic matter and may impact the evolution or origin of life.

In addition, haze layers could provide a mechanism for lower-atmospheric shielding and ultimately atmospheric retention. Often orbiting close to M-dwarf stars, these planets receive large amounts of radiation, especially during flaring events, which may strip away their atmospheres.

M-dwarf stars are known to have higher stellar activity than other types of stars, and stellar flares have the potential to accelerate atmospheric escape. In this work, we present results on laboratory investigations of UV radiation effects simulating two different stellar flare energies on laboratory-produced exoplanet hazes made under conditions analogous to water-world atmospheres.

We find that both simulated flares altered the overall transmittance and reflectance of the hazes, and higher energy “flares” make those alterations more pronounced. On a larger scale, these laboratory-made hazes show potential signs of degradation over the simulated flaring period. Our results provide insight into the effects that stellar flaring events have on potential exoplanet haze composition and the ability for water-world-like exoplanets to retain their atmospheres.

Lori Huseby, Sarah E. Moran, Neil Pearson, Tiffany Kataria, Chao He, Cara Pesciotta, Sarah M. Hörst, Pierre Haenecour, Travis Barman, Vishnu Reddy, Nikole K. Lewis, Véronique Vuitton

Comments: 19 pages, 11 figures, Accepted for publication in PSJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2505.13692 [astro-ph.EP] (or arXiv:2505.13692v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2505.13692
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From: Lori Huseby
[v1] Mon, 19 May 2025 19:51:01 UTC (6,941 KB)
https://arxiv.org/abs/2505.13692

Astrobiology,

Scientists have discovered a previously-undetected flood under the Greenland ice sheet that spilled out with such force that it burst through nearly 300 feet (91 meters) of solid ice.

The phenomenon occurred in 2014 and caused 24 billion gallons (90 billion liters) of meltwater to punch out from a subglacial lake under the ice sheet. It is the first time such an event has ever been documented in the country.

We determine optimal requirements for the joint detection of habitable-zone planets and cold giant planets with the Habitable Worlds Observatory (HWO).

Analysis of 164 nearby stars shows that a coronagraph outer working angle (OWA) of 1440 milliarcseconds (mas) is necessary to achieve 80-90% visibility of cold giants. Approximately 40 precursor radial velocity measurements with 1 m/s precision are required to adequately constrain orbital parameters before HWO observations.

We demonstrate that 6-8 astrometric measurements distributed across the mission timeline, compared to radial velocity constraints alone and to astrometry constraints alone, significantly improve orbital parameter precision, enabling direct determination of orbital inclination with uncertainties of 0.8-3 degrees.

For habitable-zone planet characterization, 4-5 epochs provide moderate confidence, while high-confidence (95%) confirmation requires 8+ observations.

These specifications are essential for the comprehensive characterization of planetary system architectures and understanding the potential habitability of terrestrial exoplanets.

Sabina Sagynbayeva, Asif Abbas, Stephen R. Kane, Eric L. Nielsen, William Thompson, Sarah Blunt, Malena Rice, Jessie L. Christiansen, Caleb K. Harada, Elisabeth R. Newton, Yasuhiro Hasegawa, Philip J. Armitage, Tansu Daylan

Comments: In review in ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2507.21443 [astro-ph.EP] (or arXiv:2507.21443v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.21443
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From: Sabina Sagynbayeva
[v1] Tue, 29 Jul 2025 02:32:25 UTC (13,631 KB)
https://arxiv.org/abs/2507.21443

Astrobiology,

Interstellar ices play a fundamental role in the physical and chemical evolution of molecular clouds and star-forming regions, yet their large-scale distribution and abundance remain challenging to map.

In this work, I present the ice color excess method, which parametrizes the peak optical depth (τ_max3.0) of the prominent 3μm absorption feature, which is predominantly caused by the presence of solid H₂O.

The method builds on well-established near-infrared color excess techniques and uses widely available infrared broadband photometry. Through detailed evaluation of passband combinations and a comprehensive error analysis, I construct the ice color excess metric Λ(W1−I1). This parameter emerges as the optimal choice that minimizes systematic errors while leveraging high-quality, widely available photometry from Spitzer and WISE data archives.

To calibrate the method, I compile from the literature a sample of stars located in the background of nearby molecular clouds, for which spectroscopically measured optical depths are available. The empirical calibration yields a remarkably tight correlation between τ_max3.0 and Λ(W1−I1).

This photometric technique opens a new avenue for tracing the icy component of the interstellar medium on Galactic scales, providing a powerful complement to spectroscopic surveys and enabling new insights into the environmental dependence of the formation and evolution of icy dust grains.

Stefan Meingast

Comments: Accepted for publication in Astronomy & Astrophysics on July 24, 2025
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.18688 [astro-ph.GA] (or arXiv:2507.18688v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2507.18688
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From: Stefan Meingast
[v1] Thu, 24 Jul 2025 18:00:00 UTC (1,293 KB)
https://arxiv.org/abs/2507.18688

Astrobiology, Astrochemistry,

Tracing dense molecular gas, the fuel for star formation, is essential for the understanding of the evolution of molecular clouds and star formation processes.

We compare the emission of HCN(1-0), HNC(1-0) and HCO⁺(1-0) with the emission of N₂H⁺(1-0) at cloud-scales (125 pc) across the central 5×7 kpc of the Whirlpool galaxy, M51a, from “Surveying the Whirlpool galaxy at Arcseconds with NOEMA” (SWAN).

We find that the integrated intensities of HCN, HNC and HCO⁺ are more steeply correlated with N₂H+ emission compared to the bulk molecular gas tracer CO, and we find variations in this relation across the center, molecular ring, northern and southern disk of M51.

Compared to HCN and HNC emission, the HCO⁺ emission follows the N₂H⁺ emission more similarly across the environments and physical conditions such as surface densities of molecular gas, stellar mass, star-formation rate, dynamical equilibrium pressure and radius. Under the assumption that N2H⁺ is a fair tracer of dense gas at these scales, this makes HCO⁺+ a more favorable dense gas tracer than HCN within the inner disk of M51.

In all environments within our field of view, even when removing the central 2 kpc, HCN/CO, commonly used to trace average cloud density, is only weakly depending on molecular gas mass surface density. While ratios of other dense gas lines to CO show a steeper dependency on the surface density of molecular gas, it is still shallow in comparison to other nearby star-forming disk galaxies.

The reasons might be physical conditions in M51 that are different from other normal star-forming galaxies. Increased ionization rates, increased dynamical equilibrium pressure in the central few kpc and the impact of the dwarf companion galaxy NGC 5195 are proposed mechanisms that might enhance HCN and HNC emission over HCO⁺ and N₂H⁺ emission at larger-scale environments and cloud scales.

Sophia K. Stuber, Eva Schinnerer, Antonio Usero, Frank Bigiel, Jakob den Brok, Jerome Pety, Lukas Neumann, María J. Jiménez-Donaire, Jiayi Sun, Miguel Querejeta, Ashley T. Barnes, Ivana Bešlic, Yixian Cao, Daniel A. Dale, Cosima Eibensteiner, Damian Gleis, Simon C. O. Glover, Kathryn Grasha, Ralf S. Klessen, Daizhong Liu, Sharon Meidt, Hsi-An Pan, Toshiki Saito, Mallory Thorp, Thomas G. Williams

Comments: Accepted for publication in A&A
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.19439 [astro-ph.GA] (or arXiv:2507.19439v1 [astro-ph.GA] for this version)
https://doi.org/10.48550/arXiv.2507.19439
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From: Sophia Stuber
[v1] Fri, 25 Jul 2025 17:15:59 UTC (6,415 KB)
https://arxiv.org/abs/2507.19439

Astrobiology, Astrochemistry,