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Understanding the abundance pattern of metal-poor stars and the production of heavy elements through various nucleosynthesis processes offers crucial insights into the chemical evolution of the Milky Way, revealing primary sites and major sources of rapid neutron-capture process ($r$-process) material in the Universe. In this fifth data release from the $R$-Process Alliance, we present the detailed chemical abundances of 41 faint (down to V = 15.8) and extremely metal-poor (down to [Fe/H] = -3.3) halo stars selected from the R-Process Alliance (RPA). We obtained high-resolution spectra for these objects with the HORuS spectrograph on the Gran Telescopio Canarias. We measure the abundances of light, alpha, Fe-peak, and neutron-capture elements. We report the discovery of five CEMP, one limited-$r$, three $r$-I, and four $r$-II stars, and six Mg-poor stars. We also identify one star of a possible globular cluster origin at an extremely low metallicity at [Fe/H] = -3.0. This adds to the growing evidence of a lower limit metallicity floor for globular cluster abundances. We use the abundances of Fe-peak elements and the alpha-elements to investigate the contributions from different nucleosynthesis channels in the progenitor supernovae. We find the distribution of [Mg/Eu] as a function of [Fe/H] to have different enrichment levels, indicating different possible pathways and sites of their production. We also reveal differences in the trends of the neutron-capture element abundances of Sr, Ba, and Eu of various $r$-I and $r$-II stars from the RPA data releases, which provide constraints on their nucleosynthesis sites and subsequent evolution., Comment: 34 pages, 16 figures, 7 tables; Accepted for publication in The Astrophysical Journal Supplement

The Southern Photometric Local Universe Survey (S-PLUS) is a project to map $\sim9300$ sq deg of the sky using twelve bands (seven narrow and five broadbands). Observations are performed with the T80-South telescope, a robotic telescope located at the Cerro Tololo Observatory in Chile. The survey footprint consists of several large contiguous areas, including fields at high and low galactic latitudes, and towards the Magellanic Clouds. S-PLUS uses fixed exposure times to reach point source depths of about $21$ mag in the $griz$ and $20$ mag in the $u$ and the narrow filters. This paper describes the S-PLUS Data Release 4 (DR4), which includes calibrated images and derived catalogues for over 3000 sq deg, covering the aforementioned area. The catalogues provide multi-band photometry performed with the tools \texttt{DoPHOT} and \texttt{SExtractor} -- point spread function (\PSF) and aperture photometry, respectively. In addition to the characterization, we also present the scientific potential of the data. We use statistical tools to present and compare the photometry obtained through different methods. Overall we find good agreement between the different methods, with a slight systematic offset of 0.05\,mag between our \PSF and aperture photometry. We show that the astrometry accuracy is equivalent to that obtained in previous S-PLUS data releases, even in very crowded fields where photometric extraction is challenging. The depths of main survey (MS) photometry for a minimum signal-to-noise ratio $S/N = 3$ reach from $\sim19.5$ for the bluer bands to $\sim21.5$ mag on the red. The range of magnitudes over which accurate \PSF photometry is obtained is shallower, reaching $\sim19$ to $\sim20.5$ mag depending on the filter. Based on these photometric data, we provide star-galaxy-quasar classification and photometric redshift for millions of objects., Comment: 26 pages, 17 figures, 14 tables, accepted for A&A

With high equilibrium temperatures and tidally locked rotation, ultra-hot Jupiters (UHJs) are unique laboratories within which to probe extreme atmospheric physics and chemistry. In this paper, we present high-resolution dayside spectroscopy of the UHJ WASP-189b obtained with the new Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South Observatory. The observations, which cover three hours of post-eclipse orbital phases, were obtained during the instrument's System Verification run. We detect the planet's atmosphere via the Doppler cross-correlation technique, and recover a detection of neutral iron in the planet's dayside atmosphere at a significance of 7.5$\sigma$ in the red-arm of the data, verifying the presence of a thermal inversion. We also investigate the presence of other species in the atmosphere and discuss the implications of model injection/recovery tests. These results represent the first atmospheric characterization of an exoplanet with GHOST's high-resolution mode, and demonstrate the potential of this new instrument in detecting and studying ultra-hot exoplanet atmospheres., Comment: 21 pages, 12 figures, 3 tables. Accepted for publication in The Astronomical Journal

This paper presents the first public data release of the S-PLUS Ultra-Short Survey (USS), a photometric survey with short exposure times, covering approximately 9300 deg$^{2}$ of the Southern sky. The USS utilizes the Javalambre 12-band magnitude system, including narrow and medium-band and broad-band filters targeting prominent stellar spectral features. The primary objective of the USS is to identify bright, extremely metal-poor (EMP; [Fe/H] $\leq -3$) and ultra metal-poor (UMP; [Fe/H] $\leq -4$) stars for further analysis using medium- and high-resolution spectroscopy.}{This paper provides an overview of the survey observations, calibration method, data quality, and data products. Additionally, it presents the selection of EMP and UMP candidates.}{The data from the USS were reduced and calibrated using the same methods as presented in the S-PLUS DR2. An additional step was introduced, accounting for the offset between the observed magnitudes off the USS and the predicted magnitudes from the very low-resolution Gaia XP spectra.}{This first release contains data for 163 observed fields totaling $\sim$324 deg$^{2}$ along the Celestial Equator. The magnitudes obtained from the USS are well-calibrated, showing a difference of $\sim 15$ mmag compared to the predicted magnitudes by the GaiaXPy toolkit. By combining colors and magnitudes, 140 candidates for EMP or UMP have been identified for follow-up studies.}{The S-PLUS USS DR1 is an important milestone in the search for bright metal-poor stars, with magnitudes in the range 10 $ < r \leq 14$. The USS is an ongoing survey; in the near future, it will provide many more bright metal-poor candidate stars for spectroscopic follow-up., Comment: Accepted for publication in A&A. 17 pages 6 figures. Long table at the end of the paper

We present stellar parameters and chemical abundances of 47 elements detected in the bright (V = 11.63) very metal-poor ([Fe/H] = -2.20 +- 0.12) star 2MASS J22132050-5137385. We observed this star using the Magellan Inamori Kyocera Echelle spectrograph as part of ongoing work by the R-Process Alliance. The spectrum of 2MASS J22132050-5137385 exhibits unusually strong lines of elements heavier than the iron group, and our analysis reveals that these elements were produced by rapid neutron-capture (r-process) nucleosynthesis. We derive a europium enhancement, [Eu/Fe] = +2.45 +- 0.08, that is higher than any other r-process-enhanced star known at present. This star is only the eighth r-process-enhanced star where both thorium and uranium are detected, and we calculate the age of the r-process material, 13.6 +- 2.6 Gyr, from the radioactive decay of these isotopes. This star contains relatively large enhancements of elements that may be produced as transuranic fission fragments, and we propose a new method using this characteristic to assess the r-process yields and gas dilution in samples of r-process-enhanced stars. We conclude that 2MASS J22132050-5137385 exhibits a high level of r-process enhancement because it formed in an environment where the r-process material was less diluted than average. Assuming a canonical baryonic minihalo mass of 10^6 M_sun and a 1 percent metal retention rate, this star formed in a cloud of only ~ 600 M_sun., Comment: Accepted for publication in the Astrophysical Journal (23 pages, 9 figures)

We present a detailed chemical-abundance analysis of a highly $r$-process enhanced (RPE) star, 2MASS J00512646-1053170, using high-resolution spectroscopic observations with $Hubble\ Space\ Telescope$/STIS in the UV and Magellan/MIKE in the optical. We determined abundances for 41 elements in total, including 23 $r$-process elements and rarely probed species such as Al II, Ge I, Mo II, Cd I, Os II, Pt I, and Au I. We find that [Ge/Fe] $= +0.10$, which is an unusually high Ge enhancement for such a metal-poor star and indicates contribution from a production mechanism decoupled from that of Fe. We also find that this star has the highest Cd abundance observed for a metal-poor star to date. We find that the dispersion in the Cd abundances of metal-poor stars can be explained by the correlation of Cd I abundances with the stellar parameters of the stars, indicating the presence of NLTE effects. We also report that this star is now only the 6th star with Au abundance determined. This result, along with abundances of Pt and Os, uphold the case for the extension of the universal $r$-process pattern to the third $r$-process peak and to Au. This study adds to the sparse but growing number of RPE stars with extensive chemical-abundance inventories and highlights the need for not only more abundance determinations of these rarely probed species, but also advances in theoretical NLTE and astrophysical studies to reliably understand the origin of $r$-process elements., Comment: Accepted to MNRAS