Nature Astronomy最新文献

The gravitational waves emitted by neutron star binaries probe the physics of matter at supranuclear densities. During the late inspiral, tidal deformations raised on each star by the gravitational field of its companion depend crucially on the star’s internal properties. The misalignment of a star’s tidal bulge with its companion’s gravitational field encodes the strength of internal dissipative processes, which imprint onto the phase of the gravitational waves emitted. Here, we analyse gravitational wave data from the GW170817 (binary neutron star) event detected by LIGO and Virgo and find a constraint on the dissipative tidal deformability of a neutron star. From this constraint, assuming a temperature profile for each star in the binary, we obtain an order of magnitude bound on the averaged bulk (ζ) and shear (η) viscosity of each star during the inspiral: ζ ≲ 10³¹ g cm⁻¹ s⁻¹ and η ≲ 10²⁸ g cm⁻¹ s⁻¹. We forecast that these bounds could be improved by two orders of magnitude with third-generation detectors, like Cosmic Explorer, using inspiral data. These constraints already inform nuclear physics models and motivate further theoretical work to better understand the interplay between viscosity and temperature in the late inspiral of neutron stars.

Astronomical observatories have been identified as substantial contributors to the carbon footprint of astrophysical research. Being part of the collaboration that is currently developing the medium-sized telescopes in the Cherenkov Telescope Array, a ground-based observatory for very-high-energy γ-rays that will comprise 64 telescopes deployed on two sites, we assessed the environmental impacts of one medium-sized telescope on the northern site with a life-cycle assessment. We identified resource use and climate change as having the most significant impacts due to telescope manufacturing and energy consumption during operations. We estimate life-cycle greenhouse gas emissions of 2,660 ± 274 tCO₂e for the telescope, 44% of which arise from construction, 1% from on-site assembly and commissioning and 55% from operations over 30 yr. The environmental impacts could be reduced by using renewable energy during construction and operations, using fewer electronic components and metal casting and using recycled materials. We propose complementing the project requirements with environmental budgets as an effective measure for impact management and reductions.

The presence and distribution of water on the Moon are fundamental to our understanding of the Earth–Moon system. Despite extensive laboratory research and remote sensing explorations, the origin and chemical form of lunar water have remained elusive. In this study we present the discovery of a hydrated mineral, (NH₄)MgCl₃·6H₂O, in lunar soil samples returned by the Chang’e-5 mission that contains approximately 41 wt% H₂O. The mineral’s structure and composition closely resemble novograblenovite, a terrestrial fumarole mineral formed through the reaction of hot basalt with water-rich volcanic gases, and carnallite, an Earth evaporite mineral. We rule out terrestrial contamination or rocket exhaust as the origin of this hydrate on the basis of its chemical and isotopic compositions and formation conditions. The presence of ammonium indicates a more complex lunar degassing history and highlights its potential as a resource for lunar habitation. Our findings also suggest that water molecules can persist in sunlit areas of the Moon as hydrated salts, providing crucial constraints on the fugacity of water and ammonia vapour in lunar volcanic gases.

Hyperluminous infrared galaxies (HyLIRGs) are the rarest and most extreme starbursts and found only in the distant Universe (z ≳ 1). They have intrinsic infrared (IR) luminosities L_IR ≥ 10¹³ L_⊙ and are commonly found to be major mergers. Recently, the Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts project (PASSAGES) searched ~10⁴ deg² of the sky and found ~20 HyLIRGs. We describe a detailed study of PJ0116-24, the brightest (μL_IR ≈ 2.6 × 10¹⁴ L_⊙, magnified with μ ≈ 17) Einstein-ring HyLIRG in the southern sky, at z = 2.125, with observations from the near-IR integral-field spectrograph VLT/ERIS and the submillimetre interferometer ALMA. We detected Hα, Hβ, [N ii] and [S ii] lines and obtained an extreme Balmer decrement (Hα/Hβ ≈ 8.73 ± 1.14). We modelled the molecular-gas and ionized-gas kinematics with CO(3–2) and Hα data at ~100–300 pc and (sub)kiloparsec delensed scales, respectively, finding consistent regular rotation. We found PJ0116-24 to be highly rotationally supported (v_rot/σ_{0, mol. gas} ≈ 9.4) with a richer gaseous substructure than other known HyLIRGs. Our results imply that PJ0116-24 is an intrinsically massive (M_baryon ≈ 10^11.3 M_⊙) and rare starbursty disk (star-formation rate, SFR = 1,490 M_⊙ yr⁻¹) probably undergoing secular evolution. This indicates that the maximal SFR (≳1,000 M_⊙ yr⁻¹) predicted by simulations could occur during a galaxy’s secular evolution, away from major mergers.

Several potential subsurface openings have been observed on the surface of the Moon. These lunar pits are interesting in terms of science and for potential future habitation. However, it remains uncertain whether such pits provide access to cave conduits with extensive underground volumes. Here we analyse radar images of the Mare Tranquillitatis pit (MTP), an elliptical skylight with vertical or overhanging walls and a sloping pit floor that seems to extend further underground. The images were obtained by the Mini-RF instrument onboard the Lunar Reconnaissance Orbiter in 2010. We find that a portion of the radar reflections originating from the MTP can be attributed to a subsurface cave conduit tens of metres long, suggesting that the MTP leads to an accessible cave conduit beneath the Moon’s surface. This discovery suggests that the MTP is a promising site for a lunar base, as it offers shelter from the harsh surface environment and could support long-term human exploration of the Moon.