Nearby Systems Research Articles

Star Formation Suppression by Tidal Removal of Cold Molecular Gas from an Intermediate-redshift Massive Post-starburst Galaxy

Observations and simulations have demonstrated that star formation in galaxies must be actively suppressed to prevent the formation of overly massive galaxies. Galactic outflows driven by stellar feedback or supermassive black hole accretion are often invoked to regulate the amount of cold molecular gas available for future star formation but may not be the only relevant quenching processes in all galaxies. We present the discovery of vast molecular tidal features extending up to 64 kpc outside of a massive z = 0.646 post-starburst galaxy that recently concluded its primary star-forming episode. The tidal tails contain (1.2 ± 0.1) × 1010 M ⊙ of molecular gas, 47% ± 5% of the total cold gas reservoir of the system. Both the scale and magnitude of the molecular tidal features are unprecedented compared to all known nearby or high-redshift merging systems. We infer that the cold gas was stripped from the host galaxies during the merger, which is most likely responsible for triggering the initial burst phase and the subsequent suppression of star formation. While only a single example, this result shows that galaxy mergers can regulate the cold gas contents in distant galaxies by directly removing a large fraction of the molecular gas fuel, and plausibly suppress star formation directly, a qualitatively different physical mechanism than feedback-driven outflows.

A certified iterative method for isolated singular roots

In this paper we provide a new method to certify that a nearby polynomial system has a singular isolated root and we compute its multiplicity structure. More precisely, given a polynomial system f=(f1,…,fN)∈C[x1,…,xn]N, we present a Newton iteration on an extended deflated system that locally converges, under regularity conditions, to a small deformation of f such that this deformed system has an exact singular root. The iteration simultaneously converges to the coordinates of the singular root and the coefficients of the so-called inverse system that describes the multiplicity structure at the root. We use α-theory test to certify the quadratic convergence, and to give bounds on the size of the deformation and on the approximation error. The approach relies on an analysis of the punctual Hilbert scheme, for which we provide a new description. We show in particular that some of its strata can be rationally parametrized and exploit these parametrizations in the certification. We show in numerical experimentation how the approximate inverse system can be computed as a starting point of the Newton iterations and the fast numerical convergence to the singular root with its multiplicity structure, certified by our criteria.

Microbial Response to Increased Temperatures Within a Lava-Induced Hydrothermal System in Iceland: An Analogue for the Habitability of Volcanic Terrains on Mars.

Fossil hydrothermal systems on Mars are important exploration targets because they may have once been habitable and could still preserve evidence of microbial life. We investigated microbial communities within an active lava-induced hydrothermal system associated with the 2014-2015 eruption of Holuhraun in Iceland as a Mars analogue. In 2016, the microbial composition in the lava-heated water differed substantially from that of the glacial river and spring water sources that fed into the system. Several taxonomic and metabolic groups were confined to the water emerging from the lava and some showed the highest sequence similarities to subsurface ecosystems, including to the predicted thermophilic and deeply branching Candidatus Acetothermum autotrophicum. Measurements show that the communities were affected by temperature and other environmental factors. In particular, comparing glacial river water incubated in situ (5.7°C, control) with glacial water incubated within a lava-heated stream (17.5°C, warm) showed that microbial abundance, richness, and diversity increased in the warm treatment compared with the control, with the predicted major metabolism shifting from lithotrophy toward organotrophy and possibly phototrophy. In addition, thermophilic bacteria isolated from the lava-heated water and a nearby acidic hydrothermal system included the known endospore-formers Geobacillus stearothermophilus and Paenibacillus cisolokensis as well as a potentially novel taxon within the order Hyphomicrobiales. Similar lava-water interactions on Mars could therefore have generated habitable environments for microbial communities.

In-depth direct imaging and spectroscopic characterization of the young Solar System analog HD 95086

Context. HD 95086 is a young nearby Solar System analog hosting a giant exoplanet orbiting at 57 au from the star between an inner and outer debris belt. The existence of additional planets has been suggested as the mechanism that maintains the broad cavity between the two belts. Aims. We present a dedicated monitoring of HD 95086 with the VLT/SPHERE instrument to refine the orbital and atmospheric properties of HD 95086 b, and to search for additional planets in this system. Methods. SPHERE observations, spread over ten epochs from 2015 to 2019 and including five new datasets, were used. Combined with archival observations, from VLT/NaCo (2012-2013) and Gemini/GPI (2013-2016), the extended set of astrometric measurements allowed us to refine the orbital properties of HD 95086 b. We also investigated the spectral properties and the presence of a circumplanetary disk around HD 95086 b by using the special fitting tool exploring the diversity of several atmospheric models. In addition, we improved our detection limits in order to search for a putative planet c via the K-Stacker algorithm. Results. We extracted for the first time the JH low-resolution spectrum of HD 95086 b by stacking the six best epochs, and confirm its very red spectral energy distribution. Combined with additional datasets from GPI and NaCo, our analysis indicates that this very red color can be explained by the presence of a circumplanetary disk around planet b, with a range of high-temperature solutions (1400–1600 K) and significant extinction (Av ≳ 10 mag), or by a super-solar metallicity atmosphere with lower temperatures (800–300 K), and small to medium amount of extinction (Av ≲ 10 mag). We do not find any robust candidates for planet c, but give updated constraints on its potential mass and location.

On the optical properties of resonant drag instabilities: variability of asymptotic giant branch and R Coronae Borealis stars

ABSTRACT In dusty cool-star outflow or ejection events around asymptotic giant branch (AGB) or R Coronae Borealis or RCB-like stars, dust is accelerated by radiation from the star and coupled to the gas via collisional drag forces. It has recently been shown that such dust-gas mixtures are unstable to a super-class of instabilities called the resonant drag instabilities (RDIs), which promote dust clustering. We therefore consider idealized simulations of the RDIs operating on a spectrum of dust grain sizes subject to radiative acceleration (allowing for different grain optical properties), coupled to the gas with a realistic drag law, including or excluding the effects of magnetic fields and charged grains, and calculate for the first time how the RDIs could contribute to observed variability. We show that the RDIs naturally produce significant variations (spatially and temporally) ($\sim 10\!-\!20{{\ \rm per\ cent}}$ 1 σ-level) in the extinction, corresponding to $\sim 0.1\!-\!1\,$mag level in the stellar types above, on time-scales of order months to a year. The fluctuations are surprisingly robust to the assumed size of the source as they are dominated by large-scale modes, which also means their spatial structure could be resolved in some nearby systems. We also quantify how this produces variations in the line-of-sight grain size-distribution. All of these variations are similar to those observed, suggesting that the RDIs may play a key role driving observed spatial and temporal variability in dust extinction within dusty outflow/ejection events around cool stars. We further propose that the measured variations in grain sizes could directly be used to identify the presence of the RDIs in close by systems with observations.

Transit Timing Variations for AU Microscopii b and c

We explore the transit timing variations (TTVs) of the young (22 Myr) nearby AU Mic planetary system. For AU Mic b, we introduce three Spitzer (4.5 μm) transits, five TESS transits, 11 LCO transits, one PEST transit, one Brierfield transit, and two transit timing measurements from Rossiter–McLaughlin observations; for AU Mic c, we introduce three TESS transits. We present two independent TTV analyses. First, we use EXOFASTv2 to jointly model the Spitzer and ground-based transits and obtain the midpoint transit times. We then construct an O − C diagram and model the TTVs with Exo-Striker. Second, we reproduce our results with an independent photodynamical analysis. We recover a TTV mass for AU Mic c of M ⊕. We compare the TTV-derived constraints to a recent radial velocity (RV) mass determination. We also observe excess TTVs that do not appear to be consistent with the dynamical interactions of b and c alone or due to spots or flares. Thus, we present a hypothetical nontransiting “middle-d” candidate exoplanet that is consistent with the observed TTVs and candidate RV signal and would establish the AU Mic system as a compact resonant multiplanet chain in a 4:6:9 period commensurability. These results demonstrate that the AU Mic planetary system is dynamically interacting, producing detectable TTVs, and the implied orbital dynamics may inform the formation mechanisms for this young system. We recommend future RV and TTV observations of AU Mic b and c to further constrain the masses and confirm the existence of possible additional planet(s).

Orbital solution and dynamical masses for the nearby binary system GJ 67 AB

ABSTRACT We report spectroscopic observations of the nearby, 19.5-yr binary system GJ 67AB spanning more than 35 yr. We carry out a global orbital solution combining our radial-velocity measurements with others from the literature going back more than a century, and with all other available astrometric observations. The latter include measurements of the relative position as well as the Hipparcos intermediate data and photographic observations tracing the motion of the photocentre. We derive masses for the primary and the M-dwarf secondary of 0.95 ± 0.11 and 0.254 ± 0.019 M⊙, respectively, as well as a more accurate trigonometric parallax of 79.08 ± 0.63 mas, which accounts for the orbital motion. We provide evidence suggesting that the much smaller parallax from Gaia DR3 is biased. The precision in the masses remains limited mainly by the still few measurements of the relative position.

Evaluation of MPA designs that protect highly mobile megafauna now and under climate change scenarios

Marine protected area (MPA) designs, including large-scale MPAs (LSMPAs; >150,000 km 2 ), mobile MPAs (fluid spatiotemporal boundaries), and MPA networks, may offer different benefits to species and could enhance protection by encompassing spatiotemporal scales of animal movement. We sought to understand how well LSMPAs could benefit nine highly-mobile marine species in the tropics now and into the future by: 1) evaluating current range overlap within a LSMPA; 2) evaluating range overlap under climate change projections; and 3) evaluating how well theoretical MPA designs benefit these nine species. We focused on Palmyra Atoll and Kingman Reef, a 2000 km 2 area within the 1.2 million km 2 U.S. Pacific Remote Islands Marine National Monument (PRIMNM) that contains marine megafauna (reef and pelagic fishes; sea turtles; seabirds; cetaceans) reflecting different behaviors and habitat use. Our approach is useful for evaluating the effectiveness of the Palmyra-Kingman MPA and PRIMNM in protecting these species, and tropical LSMPAs in general, and for informing future MPA design. Stationary MPAs provided protection at varying scales. Reef manta rays ( Mobula alfredi ), grey reef sharks ( Carcharhinus amblyrhynchos ), green sea turtles ( Chelonia mydas ), and bottlenose dolphins ( Tursiops truncatus ) had overall small ranges (<100 km from Palmyra-Kingman) and could benefit from stationary MPAs that contained heterogenous reef habitats. Yellowfin tuna ( Thunnus albacares ), sooty terns ( Onychoprion fuscatus ), red-footed boobies ( Sula sula ), great frigatebirds ( Fregata minor ), and melon-headed whales ( Peponocephala electra ) navigated complex oceanographic processes and may benefit most from mobile MPAs that shift with features including thermal fronts, cyclic regions of elevated productivity, and eddies, if relationships with these features are established and predictable. All species had capacity to travel to nearby reef systems, illustrating potential benefits of MPA networks and protected corridors. Suitable habitats will likely contract for all species as warm water expands under climate change scenarios (species habitats were predicted to decrease by 4–49% at Palmyra-Kingman) and MPAs may not protect suitable habitats into the future. Species habitat requirements and movement ecologies are critical aspects of marine spatial planning, especially with respect to dynamic ocean processes and a changing climate. • How well do large-scale MPAs protect wide-ranging megafauna they claim to protect? • We assessed scales of movement relative to MPA boundaries, designs & climate change. • Protected habitats were greatest for reef-based sharks, manta rays, sea turtles. • Tuna, seabirds, cetaceans less protected offshore or by dynamic ocean processes. • Habitats shifted away from MPAs under climate change.

Parametric Study of Twin Tunneling Effects on Piled Foundations in Stiff Clay: 3D Finite-Element Approach

Due to urbanization, development of society, and growth of population, there are new demands for tunneling technique to facilitate the public transport as well as high-rise buildings to accommodate an increasing population. Piled foundations are commonly preferred for the construction of high-rise buildings. It is, therefore, unavoidable that tunnels must be constructed near extant buildings resting on piled foundations. Inevitable movement of the ground due to stress changes induced by a tunnel can induce additional settlement and reduce the load-carrying capacity of nearby pile foundation systems. This numerical parametric study investigates the responses of two-by-two piled raft to twin side-by-side tunnels either near the mid-depth of the pile shaft or adjacent to or below the pile toe in stiff clay. In addition, it investigates the effects of different group configurations of the piled raft and elevated pile group. The ground in all the finite-element analyses was modeled using the hypoplasticity (clay) model because of its ability to capture degradation of soil stiffness at a small-strain level. Twin tunneling below the pile and near the middepth of the pile shaft caused the largest and smallest settlement of the piled raft, respectively. Unlike induced piled raft settlement, the most significant transverse tilting of the raft is induced after the advancement of the first tunnel. After the twin tunneling near the pile shaft was completed, the raft was separated from the ground, and a portion of the working load carried by the raft was transferred to the piles. The computed results have revealed that the induced settlement of the elevated pile group was significantly larger than that of the piled raft. A significant effect number of piles in the group was found on the piled raft responses to tunneling.

Tongan Volcanic Eruption Intensifies Tropical Cyclone Cody (2022)

The aerosol−cloud impacts of the Tongan volcanic eruptions on the nearby tropical cyclone (TC) Cody on January 14∼15, 2022 are investigated by the MODIS satellite and ERA5 reanalysis data. Both the precipitation and intensity of Cody were obviously enhanced after the main blast of the Tongan volcanic eruption on January 15, although the sea surface temperature and vertical wind shear of the environmental wind did not change much according to ERA5 data. The vision that a large amount of volcanic aerosol flowed from the Tongan eruption into the inflow of Cody was captured by the MODIS observations on January 15. The cloud top temperature dropped, and the cloud particle effective radius decreased in Cody from then on, which indicated the occurrence of deep convection. The analyzed results of ERA5 show that convection was strengthened in the periphery of Cody at the beginning of the volcanic eruption at 03:00 UTC on January 15 and later in Cody’s inner core after the main blast at 06:00 UTC on January 15. This could be because of the microphysical process of aerosol−cloud interactions, which inhibited stratiform precipitation, increased vertical velocity and enhanced convective precipitation further. Since the deep convection in the inner core was conducive to the development of Cody, both the total precipitation and intensity of Cody increased after the main blast of the volcanic eruption. The result also suggests that major volcanic eruptions could increase the convective intensity and induce heavy precipitation in a nearby organized convective system (e.g., TC or mesoscale convective systems).

Calcination temperature induced structural change of red mud and its enhanced catalytic performance for hydrocarbon-based biofuels production

Red mud (RM) is a strongly solid waste from alumina production, and the disposal of RM leads to series of environmental problems such as alkalization of occupied land and pollution of nearby water systems. Using RM as catalyst or carrier is one of the important methods for the comprehensive utilization of RM. Herein, the application of Ni supported RM (Ni/RM) for the efficient hydrodeoxygenation (HDO) of waste oils to produce hydrocarbon-based biofuels is reported. The structural properties of Ni/RM catalysts were investigated. The catalytic performance for HDO of palmitic acid as the model compound was evaluated. The results showed that RM calcinated at low temperature (400–600 °C) has a larger specific surface area and well dispersion of Ni, while the high calcination temperature (700 °C ~ 900 °C) results in sintering of metal oxides and lower dispersion of Ni. Ni/RM-500 shows the largest specific surface area of 77 m2/g. The conversion of palmitic acid over Ni/RM-500 is 100% at 250 °C, and alkanes are the only products at 300 °C. The reaction path of HDO and DCO/DCO2 is related to reaction temperature. The Ni/RM-500 shows the feasibility to different feedstocks. Finally, the catalytic performance of Ni/RM-500 was tested for 135 h, and the main reason causing the deactivation of Ni/RM-500 was revealed.

Seismicity around Southern Lake Erie during 2013–2020 in Relation to Lake Water Level

Abstract The water level change in the Great Lake region can modulate stresses in the nearby fault system and potentially induce earthquakes. We perform a systematic analysis of local seismicity around southern Lake Erie during 2013–2020 to investigate the relation between seismicity and lake water level change. We obtain a newly detected catalog of tectonic earthquakes, which reveals 20–40 M &amp;gt; 0 earthquakes/yr before 2019. The peak seismicity rate in 2019 is dominated by active aftershocks following the 2019 ML 4.0 Ohio earthquake. The clustering analysis reveals both clusters with multiple events and stand-alone events that might represent isolated zones of crustal weakness in this region. The absolute location analysis identifies a group of earthquakes around the epicenter of the 1986 M 5 earthquake, which might be linked to the nearby injection activities. To evaluate the potential interaction with changing water loading of Lake Erie, we then model the coulomb stress change (ΔCSC) caused by elastic lake-water loading and find that ΔCSC strongly depends on effective friction coefficient (μ′). Considering the geometry of the receiver fault, higher lake water level results in positive ΔCSC and would promote failure when μ′≤0.3, and leads to negative ΔCSC and would discourage rupture when μ′&amp;gt;0.3. Further analysis indicates a lack of temporal correlation between long-term seismicity and water level variations before the 2019 Ohio sequence, suggesting that water level fluctuations do not modulate long-term seismicity. However, we cannot fully rule out the impact of increasing water level on reactivating the fault that hosted the 2019 Ohio earthquake sequence because of the uncertainty of μ′. Our results highlight the necessity of denser and closer monitoring of lake seismicity to further investigate the impact of changing water loading on reactivating shallow faults in this region.

Comparison of CIMEL sun-photometer and ground-based GNSS integrated water vapor over south-western European sites

This work analyzes the integrated water vapor (IWV) measured at six Aerosol Robotic Network (AERONET) stations with nearby global navigation satellite system (GNSS) in the Iberian Peninsula for the period 2007–2018. It is shown that both instruments have a high correlation (R2 > 0.91), with small mbe below 1.5 mm and standard deviation (SD) below 2 mm. However, some dependences have been observed when MBE and SD are represented in bins of three variables: IWV, solar zenith angle (SZA), and aerosol optical depth (AOD). The greater or lesser amount of water vapor in the atmosphere seemed to be the more influential variable, increasing dry bias and SD with increasing IWV. Moreover, high SZA values were related to SD increases. A clear seasonal cycle for Cimel–GNSS differences was observed which was mainly related to IWV seasonal cycle. Additionally, AOD did not show a remarkable influence on Cimel–GNSS differences. Finally, the monthly differences are also analyzed with metadata information about Cimel device ID numbers, showing that, for long-term studies, this information can be very valuable.

Gaia, Fundamental Physics, and Dark Matter

The Gaia space astrometry mission is measuring accurate distances and space motions of more than two billion stars throughout our galaxy and beyond. This is a first look at how Gaia is contributing to fundamental physics, and in particular to our understanding of dark matter, for which a few examples are given from the current literature. One of our goals is to illustrate how deep and often surprising insight into very diverse areas of fundamental physics can be extracted from this new and enormous high-accuracy stellar data set. In this spirit, we finish by suggesting a search for a connection between stellar activity, dark matter streams, and planetary configuration in nearby exoplanetary systems, as has been tentatively proposed in the case of the solar system. Dark matter candidates that could be probed by such a test include anti-quark nuggets, which have also been postulated as a possible explanation of the anomalous heating of the solar corona, and of the matter–antimatter asymmetry in the universe.

New palaeontological evidence suggests an early Middle Pleistocene age for the lower levels of Sun Hole Cave, Cheddar, Somerset, UK

Sun Hole, a small fissure cave on the north side of Cheddar Gorge, Somerset, is best known as the site where late Upper Palaeolithic artefacts are associated with human and other mammal remains that immediately pre-date the Lateglacial interstadial. These remains from the upper levels (Unit I) overlie sediments (Unit II) that are thought to have accumulated during a full glacial period, below which are sediments (Unit III) attributed to an interglacial stage. The extinct land snail Retinella (Lyrodiscus) sp., which in Britain was only known from the Hoxnian Stage, had previously been recovered from Unit III. The interglacial at the base of the sequence was therefore assigned to the Hoxnian Stage (Marine Isotope Stage (MIS) 11, 424–374 kyr). Here we provide additional analyses of samples from Unit III, which as well as containing further Retinella (Lyrodiscus), also yielded a specimen of Monachoides incarnatus, its first record from the British Pleistocene. An associated assemblage of small mammals included a few that are rare in the British Pleistocene, such as birch mouse (Sicista cf. betulina) and garden dormouse (Eliomys quercinus). The vole Lasiopodomys gregaloides and the shrew Sorex (Drepanosorex) savini do not occur as late as the Hoxnian and therefore suggest an older age in the early Middle Pleistocene. The record from Sun Hole therefore has parallels with the well-known sequence from the upper Calcareous Member in the nearby cavern system at Westbury-sub-Mendip.

2021 Elijah High-Altitude Balloon Payload

The 2021 WSGC Elijah High-Altitude Balloon Payload Team focused their projects on the upcoming 2024 solar eclipse. These included solar sensing, solar imaging, and the study of cosmic radiation. The solar sensing project involved collecting flight data such as altitude, temperature, and pressure. In addition to this data, quantitative UVA, UVB, light intensity, and solar energy values using various sensors and solar panels. Solar imaging utilized an action camera with solar, IR, and IR cut-off filters in conjunction with a 360-degree camera that captured the entire payload’s flight. The radiation shielding project focused on studying the effectiveness of low-density polyethylene as a radiation shielding material by comparing observations collected by shielded and unshielded Geiger counters. To observe radiation originating from nearby star systems, a particle detector consisting of a scintillator coupled to a silicon photomultiplier was constructed.

Evaluating the impact of increased pollinator habitat on bee visitation and yield metrics in soybean crops

Agricultural intensification has significantly altered ecosystem functioning and aided in the reduction of global biodiversity. While agriculture requires increased reliance on animal pollination, pollinator populations have declined. To combat this, adding pollinator habitat into agricultural landscapes is increasingly common, but many questions remain about its functionality and impact on agroecosystems, particularly in pollinator-independent crops. Our study uses pollinator habitats planted on experimental research stations in the southeastern USA to evaluate their impact on pollinator communities within a nearby cropping system (soybeans) and the resulting yield. We found the species composition of pollinator communities within the habitat to be significantly different than the communities in soybeans. Even still, we identified more than 30 bee species visiting soybean flowers and verified that a subset of these species had actively collected soybean pollen. Bees from soybean fields planted adjacent to the habitat had more habitat pollen types present, while some species had more non-habitat types present when in the negative control sites. The presence of habitat had a positive effect on some yield measurements with adjacent soybean sites having 6.52% heavier seeds per plant on average. These findings demonstrate that pollinator habitat can be an important resource for supporting pollinators and highlights the importance of considering pollinator habitat in pollinator-independent crops, as they may still benefit from and be attractive to pollinator communities.

DC Energy Hubs for Integration of Community DERs, EVs, and Subway Systems

In this paper, a DC microgrid solution is proposed to mitigate the high penetration levels of distributed energy resources (DERs) and electric vehicles (EVs). The microgrid is designed to integrate the regenerative energy available as a result of trains braking at adjacent subway lines. Therefore, the proposed configuration not only helps the distribution network accommodate more renewable energy, but also reduces the energy consumption and peak demand associated with the nearby electrified transportation system. A framework for DC microgrid control has been developed and evaluated using a case study. The results prove the validity and effectiveness of the proposed control framework.

Bioaccumulation and effects of selenium from surface coal mining in an aquatic songbird

Open-pit mining operations are hailed for safe working conditions for miners as well as economically and logistically favourable outcomes for mining companies. However, ecological impacts of these operations may persist for decades. Expansions of open-pit coal mining in British Columbia of Western Canada are planned. Governmental regulation of background contaminants leached from these mines into nearby water systems were established to mitigate environmental impacts associated with these operations. We analyzed water, periphyton, invertebrate, and American dipper (Cinclus mexicanus) blood, egg, and feather samples for selenium and mercury exposure related to mining operations in the Elk Valley. We also quantified effects associated with exposure on clutch size and hatching success. Selenium concentrations in water, periphyton, and invertebrates were significantly higher downstream of mines compared to reference sites within and outside of the Elk River watershed. Selenium concentrations in water from exposed sites exceeded current regulatory levels established to protect wildlife by up to 20 times. Mercury concentrations were below toxic levels for birds in all media and did not factor into determination of selenium exposure or effects. Egg selenium concentrations were on average 0.9 times the regulatory threshold. Our stable isotope analyses showed that diets of nesting females included a negligible proportion of higher order consumers. We did not detect a significant effect of selenium on the rate of hatching success or clutch size of dippers nesting in exposed sites. We conclude that at the time of the investigation, selenium exposure was not impairing hatching of American dippers at the sampled locations.

Highly flexible and ultrathin electromagnetic-interference-shielding film with a sandwich structure based on PTFE@Cu and Ni@PVDF nanocomposite materials.

Light and flexible electromagnetic-interference-shielding materials are of great significance to control electromagnetic pollution and protect the human body and other nearby equipment or systems. In this study, a film of polytetrafluoroethylene wrapped with copper (PTFE@Cu) was prepared by depositing Cu using electroless plating on the surface of a microporous PTFE film modified by dopamine. A Ni@PVDF membrane was fabricated by casting a suspension of Ni nanochains in PVDF. The two kinds of films were hot-pressed into an ultrathin and efficient electromagnetic-shielding film with a sandwich structure. PTFE and PVDF provided high flexibility to the composite film, while the metal-wrapped polymer fiber structure gave the film an excellent electromagnetic-shielding efficiency, and the Ni nanochains and laminated hot-pressing process further enhanced the shielding ability of the film. Through these combined effects, the conductivity of the composite film reached 1117.57 S cm-1 while the thickness was only about 80 μm, and the average shielding efficiency in the X-band range was as high as 57.16 dB with absorption accounting for about 67.2% of the total shielding. At the same time, the composite film had high strength and flexibility, and the tensile strength could reach 43.49 MPa. Even after bending 1000 times, the conductivity could still be maintained at 174.55 S cm-1, while the average shielding effectiveness in the X-band range was retained at 44.29 dB. The film has great latent applications in flexible devices and portable wearable intelligent devices.