Metal Lines Research Articles

Metal accretion scars may be common on magnetic, polluted white dwarfs

More than 30% of white dwarfs exhibit atmospheric metals, which are understood to be from recent or ongoing accretion of circumstellar debris. In cool white dwarfs, surface motions should rapidly homogenise photospheric abundances, and the accreted heavy elements should diffuse inward on a timescale much longer than that for surface mixing. The recent discovery of a metal scar on WD 0816–310 implies its B ≈ 140 kG magnetic field has impeded surface mixing of metals near the visible magnetic pole. Here, we report the discovery of a second magnetic, metal-polluted white dwarf, WD 2138–332, which exhibits periodic variability in longitudinal field, metal line strength, and broadband photometry. All three variable quantities have the same period, and show remarkable correlations: the published light curves have a brightness minimum exactly when the longitudinal field and line strength have a maximum, and a maximum when the longitudinal field and line strength have a minimum. The simplest interpretation of the line strength variability is that there is an enhanced metal concentration around one pole of the magnetic field; however, the variable line-blanketing cannot account for the observed multi-band light curves. More theoretical work is required to understand the efficiency of horizontal mixing of the accreted metal atoms, and the origin of photometric variability. Because both magnetic, metal-polluted white dwarfs that have been monitored to date show that metal line strengths vary in phase with the longitudinal field, we suggest that metal scars around magnetic poles may be a common feature of metal-polluted white dwarfs.

Multifunctional PDMS/Schiff base/SiO2 gel assisted fabrication of printed, stretchable and straight copper conductors

Printable, stretchable, and highly conductive metal conductors have emerged as potentially promising interconnects in the field of soft electronics. However, current techniques relying on geometric engineering have been criticized for complicated fabrication process and defective geometric structure. Here, we report a printed, straight, and omnidirectionally stretchable copper conductor, which is facilely fabricated on a flat substrate without requiring prestretching, assisted by a multifunctional gel medium layer. The PSS gel, composited by polydimethylsiloxane, Schiff base and fumed SiO2, offers a unique combination of stretchability, printability, and moldability. Additionally, this gel enables the reduction of silver ions directly on its surface by partially bonded crosslinker molecules. The fully exposed catalyst exhibits excellent activity in catalyzing electroless copper deposition reaction, on which high-quality copper coating is facilely achieved. The produced copper patterns exhibit high conductivity (4.93 × 107 S m−1) and excellent stretchability with fracture strains of ∼ 191 % and ∼ 135 % for the uni- and omni-directionally stretchable patterns respectively, which are superior to the majority of stretchable metals in published literature. The stretchable wrinkles derive form the gel medium layer molded by templates, realizing straight metal lines on flat substrate. This process combines the advantages of traditional in-plane and out-of-plane strategies, demonstrating great potential in practical application.

Strong nebular emissions associated with Mg ii absorptions detected in the SDSS spectra of background quasars

ABSTRACT We present long-slit spectroscopic observations of 40 Galaxy On Top of Quasars (GOTOQs) at ${0.37 \leqslant z \leqslant 1.01}$ using the South African Large Telescope. Using this and available photometric data, we measure the impact parameters of the foreground galaxies to be in the range of 3–16 kpc with a median value of 8.6 kpc. This is the largest sample of galaxies producing Mg ii absorption at such low impact parameters. These quasar–galaxy pairs are ideal for probing the disc–halo interface. At such impact parameters, we do not find any anticorrelation between rest equivalent width (REW) of Ca ii, Mn ii, Fe ii, Mg ii, and Mg i absorption and impact parameter. These sight lines are typically redder than those of strong Mg ii absorbers, with the colour excess, E(B − V) for our sample ranging from −0.191 to 0.422, with a median value of 0.058. In the E(B − V) versus W3935 plane, GOTOQs occupy the same region as Ca ii absorbers. For a given E(B − V), we find larger W3935 than what has been found in the Milky Way, probably due to a smaller dust-to-gas ratio in GOTOQs. Galaxy parameters could be measured for twelve cases, and their properties seem to follow the trends found for strong Mg ii absorbers. Measuring the host galaxy properties for the full sample using HST photometry or AO-assisted ground-based imaging is important to gain insights into the relationship between the stellar mass of galaxies and the metal line REW distributions at low impact parameters.

JADES

Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (PopIII) stars, is one of the most important goals of modern astrophysics. Recent models have suggested that PopIII stars may form in pockets of pristine gas in the halo of more evolved galaxies. We present NIRSpec integral field spectroscopy and micro-shutter array spectroscopic observations of the region around GN-z11, an exceptionally luminous galaxy at z = 10.6, that reveal a greater than 5σ detection of a feature consistent with being HeIIλ1640 emission at the redshift of GN-z11. The very high equivalent width of the putative HeII emission in this clump (log(EWrest(HeII)/Å) = 1.79−0.25+0.15) and a lack of metal lines can be explained in terms of photoionisation by PopIII stars, while photoionisation by PopII stars is inconsistent with the data. The high equivalent width would also indicate that the putative PopIII stars likely have an initial mass function with an upper cutoff reaching at least 500 M⊙. The PopIII bolometric luminosity inferred from the HeII line would be ∼7 × 109 L⊙, which would imply a total stellar mass formed in the burst of ∼2 × 105 M⊙. We find that photoionisation by the active galactic nucleus (AGN) in GN-z11 cannot account for the HeII luminosity observed in the clump but can potentially be responsible for an additional HeII emission observed closer to GN-z11. We also consider the possibility of in situ photoionisation by an accreting direct collapse black hole hosted by the HeII clump. We find that this scenario is less favoured, but it remains a possible alternative interpretation. We also report the detection of a Lyα halo stemming out of GN-z11 and extending out to ∼2 kpc as well as resolved funnel-shaped CIII emission likely tracing the ionisation cone of the AGN.

A new measurement of the mean transmitted flux in the Ly α and Ly β forest

ABSTRACT We present new measurements of the mean transmitted flux in the hydrogen $\rm {Ly\,\alpha }$ and a relative transmitted flux measurement in $\rm {Ly\,\beta }$ using 27 008 quasar spectra from the Fourteenth Data Release (DR14) of the Extended Baryon Oscillation Spectroscopic Survey. Individual spectra are first combined into 16 composites with mean redshifts in the range of $2.8\lt z\lt 4.9$. We then apply Markov Chain Monte Carlo (MCMC) inference to produce a piecewise fit of the effective $\tau _{\rm {Ly\,\alpha }}$ (corrected for metal lines and optically thick absorption) assuming a spline point distribution. We also perform a relative $\Delta \tau _{\rm {Ly\,\beta }}$ measurement with the same data set, finding $\Delta \tau _{\rm {Ly\,\beta }}\lt 0.35$ at $z\lt 4.8$. The 6–8 per cent precision measurements in the rest frame 1075–1150 Å at ${\it z} \ \lt \rm {4.0}$ and 10–12 per cent precision measurements in the same region at ${\it z} \ \gt \rm {4.0}$ on $\tau _{\rm {Ly\,\alpha }}$, and our determinations of $\Delta \tau _{\rm {Ly\,\beta }}$, are dominated by systematic errors, likely arising from bias and uncertainties in estimates of the quasar continuum. Our $\tau _{\rm {Ly\,\alpha }}$ values show a smooth increase by a factor of 5 over the redshift range $z=2.4-4.4$.

HR 10 as seen by CHEOPS and TESS. Revealing delta Scuti pulsations, granulation-like signal and hint for transients

HR 10 has only recently been identified as a binary system. Previously thought to be an A-type shell star, it appears that both components are fast-rotating A-type stars, each presenting a circumstellar envelope. Although showing complex photometric variability, spectroscopic observations of the metallic absorption lines reveal variation explained by the binarity, but not indicative of debris-disc inhomogeneities or sublimating exocomets. On the other hand, the properties of the two stars make them potential delta Scuti pulsators. The system has been observed in two sectors by the TESS satellite, and was the target of three observing visits by CHEOPS. Thanks to these new data, we aim to further characterise the stellar properties of the two components. In particular, we aim to decipher the extent to to which the photometric variability can be attributed to a stellar origin. In complement, we searched in the lightcurves for transient-type events that could reveal debris discs or exocomets. We analysed the photometric variability of both the TESS and CHEOPS datasets in detail. We first performed a frequency analysis to identify and list all the periodic signals that may be related to stellar oscillations or surface variability. The signals identified as resulting from the stellar variability were then removed from the lightcurves inorder to search for transient events in the residuals. We report the detection of delta Scuti pulsations in both the TESS and CHEOPS data, but we cannot definitively identify which of the components is the pulsating star. In both datasets, we find flicker noise with the characteristics of a stellar granulation signal. However, it remains difficult to firmly attribute it to actual stellar granulation from convection, given the very thin surface convective zones predicted for both stars. Finally, we report probable detection of transient events in the CHEOPS data, without clear evidence of their origin.

Logic Gates Based on 3D Vertical Junctionless Gate-All-Around Transistors with Reliable Multilevel Contact Engineering.

Vertical gate-all-around (V-GAA) represents the ultimate configuration in the forthcoming transistor industry, but it still encounters challenges in the semiconductor community. This paper introduces, for the first time, a dual-input logic gate circuit achieved using 3D vertical transistors with nanoscale sub-20-nm GAA, employing a novel technique for creating contacts and patterning metallic lines at the bottom level without the conventional lift-off process. This involves a two-step oxidation process: patterning the first field oxide to form bottom metal lines and then creating the gate oxide layer on nanowires (NWs), followed by selective removal from the top and bottom of the nanostructures. VGAA-NW transistors, fabricated using the lift-off-free approach, exhibit improved yield and reduced access resistance, leading to an enhanced drive current while maintaining good immunity against short-channel effects. Finally, elementary two-input logic gates within a single cell, using VNW transistors, demonstrate novel possibilities in advanced logic circuitry design and routing options in 3D.

Study on plasma-polymerized 1-(trimethylsilyl)pyrrolidine films deposited by plasma-enhanced chemical vapor deposition for use as a Cu diffusion barrier in multilevel metallization process

As integration continues in the modern semiconductor industry, copper (Cu) is used for metal lines and low dielectric constant (low-k) films are used for intermetal dielectrics (IMD) to reduce signal delays occurring in device interconnects. A diffusion barrier is essential between the Cu metal lines and the IMD to prevent Cu diffusion, and silicon carbon-nitride (SiCN) films with relatively low dielectric constants are being widely studied. In this study, SiCN films deposited from 1-(trimethylsilyl)pyrrolidine (TSPD) precursor by plasma-enhanced chemical vapor deposition (PECVD) were investigated for use as a Cu diffusion barrier in multilevel metallization process. This plasma-polymerized TSPD (ppTSPD) monolayer film as SiCN was deposited in plasma powers ranging from 15 to 30 W. The electrical properties of ppTSPD were measured and the chemical properties were analyzed by Fourier-transform infrared spectroscopy (FTIR). The dielectric constant increased with increased plasma power. The lowest dielectric constant of 3.70 and leakage current density at 1 MV/cm of 2.27×10−8 A/cm2 were found for ppTSPD film deposited at 15 W. To verify the Cu diffusion barrier characteristics of the ppTSPD films, a ppTSPD/ppOMCTS bilayer was introduced by using plasma-polymerized octamethylcyclotetrasiloxane (ppOMCTS) as porous low-k SiCOH films. The time-dependent dielectric breakdown (TDDB) characteristic was enhanced around five times than ppOMCTS monolayer used as a reference. The ppTSPD was suggested for fabricating SiCN films for use as a Cu diffusion barrier in multilevel metallization process.

A conclusive non-detection of magnetic field in the Am star o Peg with high-precision near-infrared spectroscopy

The A-type metallic-line (Am) stars are typically considered to be non-magnetic or to possess very weak sub-G magnetic fields. This view has been repeatedly challenged in the literature; most commonly for the bright hot Am star Several studies claim to have detected 1--2 kG field of unknown topology in this object, possibly indicating a new process of magnetic-field generation in intermediate-mass stars. In this study, we revisit the evidence of a strong magnetic field in using new high-resolution spectropolarimetric observations and advanced spectral fitting techniques. We estimated the mean magnetic field strength in from the high-precision CRyogenic InfraRed Echelle Spectrograph $) measurement of near-infrared (NIR) sulphur lines. We modelled this observation with a polarised radiative transfer code, including treatment of the departures from local thermodynamic equilibrium. In addition, we used the least-squares deconvolution multi-line technique to derive longitudinal field measurements from archival optical spectropolarimetric observations of this star. Our analysis of the NIR S i lines reveals no evidence of Zeeman broadening, ruling out magnetic field with a strength exceeding 260 G. This null result is compatible with the relative intensification of Fe ii lines in the optical spectrum, taking into account blending and uncertain atomic parameters of the relevant diagnostic transitions. Longitudinal field measurements on three different nights also yield null results with a precision of 2 G. This study refutes the claims of kG-strength dipolar or tangled magnetic field in This star therefore appears to be non-magnetic, with surface magnetic field characteristics no different from those of other Am stars.

Analysis of the Impact of the Blazhko Effect Both on the Van Hoof Effect and Radial Velocity Amplitude in the Star RR Lyr

The Van Hoof effect is a phase shift existing between the radial velocity curves of hydrogen and metallic lines within the atmosphere of pulsating stars. In this article, we present a study of this phenomenon through the spectra of the brightest pulsating star RR Lyr of RR Lyrae stars recorded for 22 yr. We based ourselves, on the one hand, on 1268 spectra (41 nights of observation) recorded between the years 1994 and 1997 at the Observatory of Haute Provence (OHP, France) previously observed by Chadid and Gillet, and on the other hand on 1569 spectra (46 nights of observation) recorded at our Oukaimeden Observatory (Morocco) between 2015 and 2016. Through this study, we have detected information on atmospheric dynamics that had not previously been detected. Indeed, the Van Hoof effect which results in a clear correlation between the radial velocities of hydrogen and those of the metallic lines has been observed and analyzed at different Blazhko phases. A correlation between the radial velocities of different metallic lines located in the lower atmosphere has been observed as well. For the first time, we were able to show that the amplitude of the radial velocity curves deduced from the lines of hydrogen and that of Fe ii (λ4923.921 Å) increases toward the minimum of the Blazhko cycle and decreases toward the maximum of the same Blazhko cycle. Furthermore, we found that the Van Hoof effect is also modulated by the Blazhko effect. Thus, toward the minimum of the Blazhko cycle the Van Hoof effect is more visible and at the maximum of the Blazhko cycle, this effect is minimal. We also observed the temporal evolution of the amplitudes of the radial velocities of the lower and upper atmosphere. When observed over a long time, we can interpret it as a function of the Blazhko phases.

48‐4: Distinguished Paper: Backside Bonding for Extremely Narrow Bezel at the Bottom of Flexible Displays

We developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65 ℃) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the nextgeneration flexible displays.

Bulge-Free and Homogeneous Metal Line Jet Printing with StarJet Technology.

The technology to jet print metal lines with precise shape fidelity on diverse substrates is gaining higher interest across multiple research fields. It finds applications in additively manufactured flexible electronics, environmentally friendly and sustainable electronics, sensor devices for medical applications, and fabricating electrodes for solar cells. This paper provides an experimental investigation to deepen insights into the non-contact printing of solder lines using StarJet technology, eliminating the need for surface activation, substrate heating, curing, or post-processing. Moreover, it employs bulk metal instead of conventional inks or pastes, leading to cost-effective production and enhanced conductivity. The effect of molten metal temperature, substrate temperature, standoff distance, and printing velocity was investigated on polymer foils (i.e., PET sheets). Robust printing parameters were derived to print uniform, bulge-free, bulk metal lines suitable for additive manufacturing applications. The applicability of the derived parameters was extended to 3D-printed PLA, TPU, PA-GF, and PETG substrates having a much higher surface roughness. Additionally, a high aspect ratio of approx. 16:1 wall structure has been demonstrated by printing multiple metal lines on top of each other. While challenges persist, this study contributes to advancing additively manufactured electronic devices, highlighting the capabilities of StarJet metal jet-printing technology.

A Strong He ii λ1640 Emitter with an Extremely Blue UV Spectral Slope at z = 8.16: Presence of Population III Stars?

Cosmic hydrogen reionization and cosmic production of the first metals are major phase transitions of the Universe occurring during the first billion years after the Big Bang; however, these are still underexplored observationally. Using the JWST/NIRSpec prism spectroscopy, we report the discovery of a sub-L * galaxy at z spec = 8.1623 ± 0.0007, dubbed RX J2129–z8He II, via the detection of a series of strong rest-frame UV/optical nebular emission lines and the clear Lyman break. RX J2129–z8He II shows a pronounced UV continuum with an extremely steep (i.e., blue) spectral slope of β=−2.53−0.07+0.06 , the steepest among all spectroscopically confirmed galaxies at z spec ≳ 7, in support of its very hard ionizing spectrum that could lead to a significant leakage of its ionizing flux. Therefore, RX J2129–z8He II is representative of the key galaxy population driving the cosmic reionization. More importantly, we detect a strong He II λ1640 emission line in its spectrum, one of the highest redshifts at which such a line is robustly detected. Its high rest-frame equivalent width (EW = 21 ± 4 Å) and extreme flux ratios with respect to UV metal and Balmer lines raise the possibility that part of RX J2129–z8He II’s stellar population could be Pop III (Pop III)-like. Through careful photoionization modeling, we show that the physically calibrated phenomenological models of the ionizing spectra of Pop III stars with strong mass loss can successfully reproduce the emission line flux ratios observed in RX J2129–z8He II. Assuming the Eddington limit, the total mass of the Pop III stars within this system is estimated to be 7.8 ± 1.4 × 105 M ⊙. To date, this galaxy presents the most compelling case in the early Universe where trace Pop III stars might coexist with metal-enriched populations.

Extreme magnetic field modulus variability of the Bp star HD 57372

In chemically peculiar Ap/Bp stars with large-scale organised magnetic fields of simple centred dipole configuration, the ratio between the maximum and the minimum of the mean magnetic field modulus is on the order of 1.25. Values of two or more are observed only for very few Ap/Bp stars and are indicative of a very unusual magnetic field geometry. Determining the magnetic field structure of Ap/Bp stars is bound to provide a different insight into the physics and the origin of the magnetic fields in early-type stars. In this respect, the Bp star HD\,57372 is of particular interest because strongly variable magnetically split lines have been observed in HARPS and APOGEE spectra. We obtained and analysed measurements of the mean magnetic field modulus and of the mean longitudinal magnetic field using near-infrared spectra and optical polarimetric spectra distributed over the stellar rotation period. The mean magnetic field modulus bm of HD\,57372, as estimated from absorption lines that are split via the Zeeman effect and resolved in both optical and near-infrared spectra, is found to vary by an extraordinary amount: about 10\,kG. The exceptional value of three for the ratio between the maximum and the minimum of the field modulus is indicative of a very unusual geometry for HD\,57372's magnetic field. All observable quantities were found to vary in phase with the photometric period of 7.889\,days. This includes the longitudinal magnetic field bz , which varies from $-6$\,kG up to $1.7$\,kG in FORS2 spectra, as well as the metal line strengths, whose equivalent widths change by up to 50<!PCT!> of their mean values over the course of the rotation period. The B8 temperature class of HD\,57372 also places it among the hottest stars known to exhibit resolved, magnetically split lines.

Unveiling the complex circumgalactic medium: a comparative study of merging and non-interacting galaxy groups

ABSTRACT While most galaxies live in group environments where they undergo an accelerated evolution, the characteristics of their circumgalactic medium (CGM) remain uncertain. We present an analysis of the CGM of two galaxy groups in different stages of interaction: (G1) a close pair of galaxies (z = 0.043) separated by 87 kpc that do not show signs of interactions and (G2) four merging galaxies (z = 0.098) separated by 10 kpc. We present spatially resolved Keck/Keck Cosmic Web Imager galaxy observations and Hubble Space Telescope (HST)/COS quasar spectra (G1 at 48 kpc and G2 at 100 kpc away) to quantify both the resolved galaxy and CGM properties in these two different group environments. G1 contains two typical star-forming galaxies with no evidence of strong outflows. G2 contains two star-forming, one post-starburst and one quiescent galaxy. Both groups have a range of CGM-detected metal lines (H i, C ii, Si ii, Si iii, N v, and O vi). Despite G2 being twice as far from the quasar, G2 has $\log (N({{{\rm H}{\small I}}})/{\rm cm}^{-2})=17.33$, compared to $\log (N({{{\rm H}{\small I}}})/{\rm cm}^{-2})=16.43$ for G1. We find that the CGM of the merging galaxies (G2) is more kinematically complex, is in a higher ionization state, spans a wider range of metallicities and column densities, has smaller cloud sizes, and is inconsistent with the simple superposition model that seems to match well with G1. We conclude that the complexity of the CGM in merging galaxies surpasses that of not strongly interacting galaxies, suggesting that mergers play a significant role in shaping the intricate structure of the CGM.

Stellar Atmospheric Parameters of ∼11,000 RR Lyrae Stars from LAMOST Spectra

Accurate determination of the stellar atmospheric parameters of RR Lyrae stars (RRLs) requires short individual exposures of the spectra to mitigate pulsation effects. We present improved template-matching methods to determine the stellar atmospheric parameters of RRLs from single-epoch spectra of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also known as the Guoshoujing Telescope (LAMOST). We determine the radial velocities and stellar atmospheric parameters (effective temperature T eff, surface gravity logg , and metallicity [M/H]) of 10,486 and 1027 RRLs from 42,729 LAMOST low-resolution spectra (LRS) and 7064 LAMOST medium-resolution spectra (MRS), respectively. Our results are in good agreement with the parameters of other databases, where the external uncertainties of T eff, logg , and [M/H] for LRS/MRS are estimated to be 207/142 K, 0.21/0.16 dex, and 0.24/0.18 dex, respectively. We conclude with the variation characteristics of the radial velocities (RV) and stellar atmospheric parameters for RRLs during the pulsation phase. There is a significant difference of 28 ± 21 km s−1 between the peak-to-peak amplitude (A ptp) of RV from the Hα line (RVHα ) and from metal lines (RVmetal) for RRab, whereas it is only 4 ± 17 km s−1 for RRc. The A ptp of T eff is 930 ± 456 and 409 ± 375 K for RRab and RRc, respectively. The logg of RRab shows a mild variation of approximately 0.22 ± 0.42 dex near the phase of φ = 0.9, while that of RRc almost remains constant. The [M/H] of RRab and RRc show a minor variation of about 0.25 ± 0.50 and 0.28 ± 0.55 dex, respectively, near the phase of φ = 0.9. We expect that the determined stellar atmospheric parameters would shed new light on the study of stellar evolution and pulsation, the structure of the Milky Way, as well as other research fields.

Variations in Line Profiles of Atomic Transitions in RR Lyrae Stars

We have investigated the absorption shapes of atomic lines and Hα in RR Lyrae stars. We used the database of high-resolution spectra gathered with the Las Campanas Observatory du Pont Telescope, analyzing a set of about 2700 short exposure spectra of 17 RRab and 5 RRc variables. To increase the signal-to-noise ratio of the spectra for each star, we first coadded spectra in small photometric phase bins, and then coadded metallic line profiles in velocity space. The resulting line absorption shapes vary with photometric phase in a consistent manner for all RRab stars, while exhibiting no obvious phase-related variations for the RRc stars. We interpret these line profile variations in terms of velocity gradients in the photospheric layers that produce absorption line profiles. The Hα profiles are much broader, indicative of shock temperatures of order 100,000 K.

Backside bonding for extremely narrow bezel at the bottom of flexible displays

AbstractWe developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65°C) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the next‐generation flexible displays.

Post-AGB candidate IRAS 02143+5852: Cepheid-like variability, three-layer circumstellar dust envelope and spectral features

ABSTRACT We present the results of multicolour UBVRCICJHK photometry, spectroscopic analysis and spectral energy distribution (SED) modelling for the post-AGB candidate IRAS 02143+5852. We detected Cepheid-like light variations with the full peak-to-peak amplitude ΔV ∼ 0.9 mag and the pulsation period of about 24.9 d. The phased light curves appeared typical for the W Vir Cepheids. The period–luminosity relation for the Type II Cepheids yielded the luminosity logL/L⊙ ∼ 2.95. From a low-resolution spectrum, obtained at maximum brightness, the following atmospheric parameters were determined: Teff ∼ 7400 K and logg ∼ 1.38. This spectrum contains the emission lines H α, ${\rm Ba\, {\small II}}$ λ6496.9, ${\rm He\, {\small I}}$λ10830, and Pa β. Spectral monitoring performed in 2019–2021 showed a significant change in the H α profile and appearance of CH and CN molecular bands with pulsation phase. The metal lines are weak. Unlike typical W Vir variables, the star shows a strong excess of infrared radiation associated with the presence of a heavy dust envelope around the star. We modelled the SED using our photometry and archival data from different catalogues and determined the parameters of the circumstellar dust envelope. We conclude that IRAS 02143+5852 is a low-luminosity analogue of dusty RV Tau stars.

Discovery of Magnetically Guided Metal Accretion onto a Polluted White Dwarf

Dynamically active planetary systems orbit a significant fraction of white dwarf stars. These stars often exhibit surface metals accreted from debris disks, which are detected through infrared excess or transiting structures. However, the full journey of a planetesimal from star-grazing orbit to final dissolution in the host star is poorly understood. Here, we report the discovery that the cool metal-polluted star WD 0816–310 has cannibalized heavy elements from a planetary body similar in size to Vesta, and where accretion and horizontal mixing processes have clearly been controlled by the stellar magnetic field. Our observations unveil periodic and synchronized variations in metal line strength and magnetic field intensity, implying a correlation between the local surface density of metals and the magnetic field structure. Specifically, the data point to a likely persistent concentration of metals near a magnetic pole. These findings demonstrate that magnetic fields may play a fundamental role in the final stages of exoplanetary bodies that are recycled into their white dwarf hosts.