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Context - Around the year 2000, Triton's south pole experienced an extreme summer solstice that occurs every about 650 years, when the subsolar latitude reached about 50{\deg}. Bracketing this epoch, a few occultations probed Triton's atmosphere in 1989, 1995, 1997, 2008 and 2017. A recent ground-based stellar occultation observed on 6 October 2022 provides a new measurement of Triton's atmospheric pressure which is presented here. Aims- The goal is to constrain the Volatile Transport Models (VTMs) of Triton's atmosphere that is basically in vapor pressure equilibrium with the nitrogen ice at its surface. Methods - Fits to the occultation light curves yield Triton's atmospheric pressure at the reference radius 1400 km, from which the surface pressure is induced. Results - The fits provide a pressure p_1400= 1.211 +/- 0.039 microbar at radius 1400 km (47 km altitude), from which a surface pressure of p_surf= 14.54 +/- 0.47 microbar is induced (1-sigma error bars). To within error bars, this is identical to the pressure derived from the previous occultation of 5 October 2017, p_1400 = 1.18 +/- 0.03 microbar and p_surf= 14.1 +/- 0.4 microbar, respectively. Based on recent models of Triton's volatile cycles, the overall evolution over the last 30 years of the surface pressure is consistent with N2 condensation taking place in the northern hemisphere. However, models typically predict a steady decrease in surface pressure for the period 2005-2060, which is not confirmed by this observation. Complex surface-atmosphere interactions, such as ice albedo runaway and formation of local N2 frosts in the equatorial regions of Triton could explain the relatively constant pressure between 2017 and 2022., Comment: 8 pages, 4 figures, accepted for publication in Astronomy and Astrophysics

Binary molecules such as CO, OH, CH, CN, and C$_2$ are often used as abundance indicators in stars. These species are usually assumed to be formed in chemical equilibrium. The time-dependent effects of hydrodynamics can affect the formation and dissociation of these species and may lead to deviations from chemical equilibrium. We aim to model departures from chemical equilibrium in dwarf stellar atmospheres by considering time-dependent chemical kinetics alongside hydrodynamics and radiation transfer. We examine the effects of a decreasing metallicity and an altered C/O ratio on the chemistry when compared to the equilibrium state. We used the radiation-(magneto)hydrodynamics code CO5BOLD, and its own chemical solver to solve for the chemistry of 15 species and 83 reactions. The species were treated as passive tracers and were advected by the velocity field. The steady-state chemistry was also computed to isolate the effects of hydrodynamics. In most of the photospheres in the models we present, the mean deviations are smaller than $0.2$ dex, and they generally appear above $\log{\tau} = -2$. The deviations increase with height because the chemical timescales become longer with decreasing density and temperature. A reduced metallicity similarly results in longer chemical timescales and in a reduction in yield that is proportional to the drop in metallicity; a decrease by a factor $100$ in metallicity loosely corresponds to an increase by factor $100$ in chemical timescales. As both CH and OH are formed along reaction pathways to CO, the C/O ratio means that the more abundant element gives faster timescales to the constituent molecular species. Overall, the carbon enhancement phenomenon seen in very metal-poor stars is not a result of an improper treatment of molecular chemistry for stars up to a metallicity as low as [Fe/H] = $-3.0$., Comment: 29 pages

In this work, we present a photospheric solar silicon abundance derived using CO5BOLD model atmospheres and the LINFOR3D spectral synthesis code. Previous works have differed in their choice of a spectral line sample and model atmosphere as well as their treatment of observational material, and the solar silicon abundance has undergone a downward revision in recent years. We additionally show the effects of the chosen line sample, broadening due to velocity fields, collisional broadening, model spatial resolution, and magnetic fields. CO5BOLD model atmospheres for the Sun were used in conjunction with the LINFOR3D spectral synthesis code to generate model spectra, which were then fit to observations in the Hamburg solar atlas. We present a sample of 11 carefully selected lines (from an initial choice of 39 lines) in the optical and infrared, made possible with newly determined oscillator strengths for the majority of these lines. Our final sample includes seven optical Si I lines, three infrared Si I lines, and one optical Si II line. We derived a photospheric solar silicon abundance of $\log \epsilon_\mathrm{Si} = 7.57 \pm 0.04$, including a $-0.01$ dex correction from Non-Local Thermodynamic Equilibrium (NLTE) effects. Combining this with meteoritic abundances and previously determined photospheric abundances results in a metal mass fraction Z/X = $0.0220 \pm 0.0020$. We found a tendency of obtaining overly broad synthetic lines. We mitigated the impact of this by devising a de-broadening procedure. The over-broadening of synthetic lines does not substantially affect the abundance determined in the end. It is primarily the line selection that affects the final fitted abundance., Comment: 24 pages

We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z=4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z=0.87, associated with a 1.2 mm source which is at a 2.07+/-0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths lambda < 2 microns, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z=4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (~ 10^7-10^{10} Msun) and star formation rates (SFRs) of 0.4-24 Msun/yr, resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar-mass doubling times of only ~ 2x10^7 years). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/millimetre continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR~200-300 Msun/yr) and lies on the star-formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts., Comment: 13 pages including 7 figures and 1 table. Accepted for publication at the ApJ. Minor changes with respect to version 1. Figure 6 has been expanded to broaden comparison with the literature

We search for bright Ly$\rm \alpha$ emitters among Spitzer SMUVS galaxies at z > 2.9 with homogeneous MUSE data. Although it only covers a small region of COSMOS, MUSE has the unique advantage of providing spectral information over the entire field, without the need of target pre-selection. This gives an unbiased detection of all the brightest Ly$\rm \alpha$ emitters among SMUVS sources, which by design are stellar-mass selected galaxies. Within the studied area, ~14% of the SMUVS galaxies at z > 2.9 have Ly$\rm \alpha$ fluxes F$\rm _\lambda$ > 7 x 10$^{-18}$ erg s$^{-1}$ cm$^{-2}$. These Ly$\rm \alpha$ emitters are characterized by three types of emission, 47% show a single line profile, 19% present a double peak or a blue bump and 31% show a red tail. One object (3%) shows both a blue bump and a red tail. We also investigate the spectral energy distribution (SED) properties of the SMUVS MUSE-detected galaxies and MUSE non-detections. After stellar-mass matching both populations, we find that MUSE detected galaxies have generally lower extinction than SMUVS-only objects, while there is no clear intrinsic difference in the mass and age distributions. For the MUSE-detected SMUVS galaxies, we compare the instantaneous SFR lower limit given by Ly$\rm \alpha$ flux with its past average derived from SED fitting, and find evidence for rejuvenation in some of our oldest objects. We also study the spectra of those Ly$\rm \alpha$ emitters which are not detected in SMUVS in the same field. We find different distributions of the emission line profiles, which could be ascribed to the fainter Ly$\rm \alpha$ luminosities of the MUSE-only sources and an intrinsically different mass distribution. Finally, we search for the presence of galaxy associations. MUSE's integral coverage is 20 times more likely to find associations than all other existing spectral data in COSMOS, biased by target pre-selection., Comment: 14 pages, 7 figures, 5 tables, re-submitted to A&A after addressing the referee's report

Transition metal dichalcogenides (TMDs) are layered semiconducting van der Waal crystals and promising materials for a wide range of electronic and optoelectronic devices. Realizing practical electrical and optoelectronic device applications requires a connection between a metal junction and a TMD semiconductor. Hence, a complete understanding of electronic band alignments and the potential barrier heights governing the transport through a metal-TMD-metal junction is critical. But, there is a knowledge gap; it is not clear how the energy bands of a TMD align while in contact with a metal as a function of the number of layers. In pursuit of removing this knowledge gap, we have performed conductive atomic force microscopy (CAFM) of few layered (1-5) MoS2 immobilized on ultra-flat conducting Au surfaces (root mean square (RMS) surface roughness <0.2 nm) and indium tin oxide (ITO) substrate (RMS surface roughness <0.7 nm) forming a vertical metal (conductive-AFM tip)-semiconductor-metal device. We have observed that the current increases as the number of layers increases up to 5 layers. By applying Fowler-Nordheim tunneling theory, we have determined the barrier heights for different layers and observed that the barrier height decreases as the number of layers increases. Using density functional theory (DFT) calculation, we successfully demonstrated that the barrier height decreases as the layer number increases. By illuminating the TMDs on a transparent ultra-flat conducting ITO substrate, we observed a reduction in current when compared to the current measured in the dark, hence demonstrating negative photoconductivity. Our study provides a fundamental understanding of the local electronic and optoelectronic behaviors of TMD-metal junction, and may pave an avenue toward developing nanoscale electronic devices with tailored layer-dependent transport properties., Comment: 11 pages, 5 figures

The Spitzer Matching Survey of the UltraVISTA Ultra-deep Stripes (SMUVS) has obtained the largest ultra-deep Spitzer maps to date in a single field of the sky. We considered the sample of about 66,000 SMUVS sources at $z=2-6$ to investigate the evolution of dusty and non-dusty galaxies with stellar mass through the analysis of the galaxy stellar mass function (GSMF). We further divide our non-dusty galaxy sample with rest-frame optical colours to isolate red quiescent (`passive') galaxies. At each redshift, we identify a characteristic stellar mass in the GSMF above which dusty galaxies dominate, or are at least as important as non-dusty galaxies. Below that stellar mass, non-dusty galaxies comprise about 80% of all sources, at all redshifts except at $z=4-5$. The percentage of dusty galaxies at $z=4-5$ is unusually high: 30-40% for $M_{*}=10^9 - 10^{10.5} \, \rm M_\odot$ and $>80\%$ at $M_*>10^{11} \, \rm M_\odot$, which indicates that dust obscuration is of major importance in this cosmic period. The overall percentage of massive ($\log_{10} (M_*/M_\odot)>10.6$) galaxies that are quiescent increases with decreasing redshift, reaching $>30\%$ at $z\sim2$. Instead, the quiescent percentage among intermediate-mass galaxies (with $\log_{10} (M_*/M_\odot)=9.7-10.6$) stays roughly constant at a $\sim 10\%$ level. Our results indicate that massive and intermediate-mass galaxies clearly have different evolutionary paths in the young Universe, and are consistent with the scenario of galaxy downsizing., Comment: Final version accepted for publication at the ApJ. Several test results and corresponding figures added. No conclusions changed. 27 pages, 20 figures

We study a large galaxy sample from the Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) to search for sources with enhanced 3.6 micron fluxes indicative of strong Halpha emission at z=3.9-4.9. We find that the percentage of "Halpha excess" sources reaches 37-40% for galaxies with stellar masses log10(M*/Msun) ~ 9-10, and decreases to <20% at log10(M*/Msun) ~ 10.7. At higher stellar masses, however, the trend reverses, although this is likely due to AGN contamination. We derive star formation rates (SFR) and specific SFR (sSFR) from the inferred Halpha equivalent widths (EW) of our "Halpha excess" galaxies. We show, for the first time, that the "Halpha excess" galaxies clearly have a bimodal distribution on the SFR-M* plane: they lie on the main sequence of star formation (with log10(sSFR/yr^{-1})<-8.05) or in a starburst cloud (with log10(sSFR/yr^{-1}) >-7.60). The latter contains ~15% of all the objects in our sample and accounts for >50% of the cosmic SFR density at z=3.9-4.9, for which we derive a robust lower limit of 0.066 Msun yr^{-1} Mpc^{-3}. Finally, we identify an unusual >50sigma overdensity of z=3.9-4.9 galaxies within a 0.20 x 0.20 sq. arcmin region. We conclude that the SMUVS unique combination of area and depth at mid-IR wavelengths provides an unprecedented level of statistics and dynamic range which are fundamental to reveal new aspects of galaxy evolution in the young Universe., Comment: 18 pages, 11 figures, 1 table. Re-submitted to the ApJ, after addressing referee report. Main changes with respect to v1: a new section and a new appendix have been added to investigate further the origin and robustness of the sSFR bimodality. No conclusion changed

We present multi-wavelength imagery of the merger remnant galaxy NGC 1316 with an objective to study the content of dust and its association with the other phases of the ISM. Color-index maps as well as extinction maps derived for this galaxy reveal an intricate and complex dust morphology in NGC 1316, i.e., in the inner part it exists in the form of a prominent lane while at about 6--7\,kpc it apparently takes an arc-like pattern extended along the North-East direction. In addition to this, several other dust clumps and knots are also evident in this galaxy. Dust emission mapped using \textit{Spitzer} data at 8 $\mu$m indicates even more complex morphological structures of the dust in NGC1316. The extinction curve derived over the optical to near-IR bands closely follows the standard Galactic curve suggesting similar properties of the dust grains. The dust content of NGC 1316 estimated from optical extinction is $\sim$ 2.13$\times\, 10^5$ \Msun. This is a lower limit compared to that estimated using the IRAS flux densities $\sim$ 5.17$\times\, 10^6$ \Msun\, and flux densities at 24$\mu$m, 70$\mu$m and 160 $\mu$m from MIPS $\sim$ 3.2$\times\, 10^7$ \Msun. High resolution \textit{Chandra} observations of this merger remnant system have provided with an unprecedented view of the complex nature of hot gas distribution in NGC 1316 which closely matches the morphology of ionized gas and to some extent with the dust also. X-ray color-color plot for the resolved sources within optical D$_{25}$ extent of NGC 1316 has enabled us to separate them in different classes., Comment: 17 pages, 8 figures, Accepted for publication in the RAA

In this paper a tool called RDBNorma is proposed, that uses a novel approach to represent a relational database schema and its functional dependencies in computer memory using only one linked list and used for semi-automating the process of relational database schema normalization up to third normal form. This paper addresses all the issues of representing a relational schema along with its functional dependencies using one linked list along with the algorithms to convert a relation into second and third normal form by using above representation. We have compared performance of RDBNorma with existing tool called Micro using standard relational schemas collected from various resources. It is observed that proposed tool is at least 2.89 times faster than the Micro and requires around half of the space than Micro to represent a relation. Comparison is done by entering all the attributes and functional dependencies holds on a relation in the same order and implementing both the tools in same language and on same machine., Comment: 22 pages and international journal