Context. Bulge globular clusters are key to understanding the formation and chemical evolution of the ancient central component of our Galaxy. Thanks to CAPOS, the bulge Cluster APOgee Survey, we can mitigate the observational difficulties limiting access to these objects in the optical and investigate them in more detail in the near-IR. Aims. Our goal is to perform a rigorous abundance analysis on a large number of member stars in the metal-rich bulge globular cluster NGC 6304, using high-resolution spectra, in order to determine its detailed chemical composition and study the relationship of this globular cluster with its halo counterparts. In addition, we investigate chemical patterns that allow us to identify multiple populations. Methods. This analysis is based on spectroscopic data obtained by CAPOS, which uses the APOGEE-2S spectrograph to observe in the H band. The abundances of 17 elements (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, and Ce) were derived using the BACCHUS code, using atmospheric parameters from both APOGEE’s ASPCAP pipeline and those derived independently from photometry (Gaia and 2MASS) to cross validate our results with the ASPCAP values and provide a consistent chemical analysis. Results. We derived a mean iron abundance of [Fe/H] = −0.45 ± 0.05 using the ASPCAP stellar parameters, and [Fe/H] = −0.45 ± 0.08 when using photometric stellar parameters, with no evidence of an intrinsic metallicity spread. NGC 6304 shows a typical enhancement in α elements, with [α/Fe] spec = +0.24 ± 0.07 and [α/Fe] phot = +0.23 ± 0.08, similar to what is observed in other globular clusters. We find a significant spread in [N/Fe], with σspec = 0.54 and σphot = 0.46, along with a clear C–N anticorrelation. Furthermore, we detect a correlation of Ce with both N and Al, consistent with patterns observed in some metal-rich bulge globular clusters but not all. Conclusions. Our study provides the first comprehensive spectroscopic evidence for multiple populations in NGC 6304. We also find a significant star-to-star variation in Na, but a minimal variation in O, in concordance with trends found in other metal-rich bulge clusters. The absence of the Mg–Al anticorrelation supports the evidence that the MgAl cycle is not active in globular clusters at high metallicity. The observed correlation between Ce and both N and Al suggests that the enrichment of these elements may be driven by asymptotic giant branch stars, positioning Ce as an element involved in the multiple population phenomenon in metal-rich globular clusters. We find generally that abundances are consistent with those of bulge field stars of similar metallicity, suggesting a similar origin and chemical evolution.

Context. This study presents detailed elemental abundances in the intermediate-metallicity bulge globular cluster Djorg 2 based on high-resolution near-infrared spectra of six (R ~ 22 500) members obtained through the bulge Cluster APOgee Survey (CAPOS). CAPOS is focused on the study of clusters within the Galactic bulge and uses the APOGEE-2S as part of the Sloan Digital Sky Survey IV (SDSS-IV). Aims. This study was undertaken to chemically explore this poorly studied cluster and to analyze it for the first time using the code BACCHUS, with the main objective of deriving the mean chemical abundances for a number of species and investigating the occurrence of multiple populations. Methods. We employed BACCHUS to provide the line-by-line elemental abundances of a variety of species, including α-elements (O, Mg, Si, Ca, and Ti), light elements (C and N), the odd-Z element Al, the s-process element (Ce), and iron-peak elements (Fe and Ni). Results. We found an average metallicity of [Fe/H] = –1.04 ± 0.06, without an indication of an intrinsic spread. The mean values for the other elements and their standard deviations are [C/Fe] = –0.35 ± 0.18, [N/Fe] = 0.38 ± 0.40, [O/Fe] = 0.22 ± 0.18, [Mg/Fe] = 0.38 ± 0.05, [Al/Fe] = 0.32 ±0.15, [Ca/Fe] = 0.21 ± 0.10, [Si/Fe] = 0.38 ± 0.05, [Ce/Fe] = +0.00 ± 0.06, [Ti/Fe] = +0.12 ± 0.08 and [Ni/Fe] = +0.09 ± 0.06. Conclusions. The typical α-element enrichment in Djorg2 follows the trend of other metal-rich globular clusters. We found evidence for intrinsic spreads in C, N and O, which furthermore show the C:N and N:O anticorrelations that are typical of globular clusters. Ce shows no intrinsic variation, and in particular no correlation with N or Al. We found that Djorg 2 moves in a very elongated and flat orbit, that always remains inside the bulge and does not move far away in altitude above the Galactic plane. Moreover, it moves in a retrograde direction (backward to the rotation of the galaxy) and is not trapped by the galactic bar.

Context. The characterization of globular clusters (GCs) in the Galactic bulge is a challenging task due to high extinction and severe stellar crowding. VVV-CL001 is a poorly studied GC located in the inner bulge, known for its extremely old age, extreme velocity, and low metallicity. Given its unique properties, a detailed study of this cluster can provide valuable insights into the early chemical and dynamical evolution of the Milky Way (MW). Aims. The aim of this study was to derive the fundamental parameters of VVV-CL001 including metallicity, heliocentric radial velocity (RV), proper motions (PMs), structural properties, orbit, and age, in order to improve our understanding of its origin and role in the early evolution of the MW. Methods. We combined spectroscopic, astrometric, and photometric data to characterize VVV-CL001. Metallicity and RV were determined from medium-resolution spectra obtained with FORS2 at the Very Large Telescope. PMs were derived using Gaia DR3 data. Near-infrared photometry from the FourStar instrument on Magellan was used to refine the cluster’s position, construct a radial density profile, and estimate its age, distance, and reddening. Results. Our results confirm that VVV-CL001 is an old 12.1−1.2+1.0 Gyr), metal-poor ([Fe/H] = −2.25 ± 0.05 dex) globular cluster located at a heliocentric position of d⊙ = 7.1−1.1+1.3, with a reddening of E(J − Ks) = 1.40−0.02+0.01. Its mean PMs are μα* = −3.68 ± 0.09 mas yr−1 and µδ = −1.76 ± 0.10 mas yr−1, and it exhibits a RV of −334 ± 4 km s−1. The cluster follows a retrograde-prograde eccentric (e = 0.76−0.14+0.10) orbit, confined within the Galactic plane (|Z|max = 1.0−0.32+0.45 kpc) and inside the bar’s radius of influence (R < 5 kpc), with a pericenter of rperi = 0.6−0.2+0.3 kpc and an apocenter of rapo = 4.5−1.2+2.5 kpc. Conclusions. These orbital properties, combined with its ancient age and low metallicity, strongly support an in situ origin for VVV-CL001 and likely membership of the disk GC system that was captured by the potential of the bar during its formation. Thus, VVV-CL001 emerges as a fossil remnant of the earliest phases of Galactic assembly and a valuable tracer of the population that contributed to the formation of the inner thick disk and bulge, which are likely part of the main progenitor of the MW. Our study highlights the relevance of detailed chemo-dynamical analyses in unveiling the origin of GCs in the inner Galaxy.

We present a detailed chemical abundance analysis of seven red giant branch stars in the very metal-poor globular cluster NGC 4372, based on high-resolution UVES spectra. Our study aims to characterize the chemical evolution of NGC 4372 and investigate the presence of multiple populations. We derived abundances for 17 elements, including light, iron-peak, α, and heavy elements, using both equivalent width and spectral synthesis methods. We find a mean cluster metallicity of [Fe/H]=-2.36 ± 0.03 dex, with no evidence of an intrinsic iron spread. The cluster exhibits a typical α-enhancement of [α/Fe]= 0.33 ± 0.05 dex and a well defined Na-O anticorrelation, confirming that NGC 4372 hosts at least two distinct stellar populations. Furthermore, the measured ratio of [Ba/Eu] =-0.47 ± 0.04 indicates that the synthesis of heavy elements was dominated by r-process, consistent with other very metal-poor environments. We also identify a potential bimodal Mg-Al anticorrelation, which aligns with the patterns observed in GCs of similar mass and metallicity. These results reinforce the status of NGC 4372 as a cornerstone for understanding the early chemical enrichment of the Galactic Halo.

Context. Bulge globular clusters are key to understanding the formation and chemical evolution of the ancient central component of our Galaxy. Thanks to CAPOS, the bulge Cluster APOgee Survey, we can mitigate the observational difficulties limiting access to these objects in the optical and investigate them in more detail in the near-IR. Aims. Our goal is to perform a rigorous abundance analysis on a large number of member stars in the metal-rich bulge globular cluster NGC 6304, using high-resolution spectra, in order to determine its detailed chemical composition and study the relationship of this globular cluster with its halo counterparts. In addition, we investigate chemical patterns that allow us to identify multiple populations. Methods. This analysis is based on spectroscopic data obtained by CAPOS, which uses the APOGEE-2S spectrograph to observe in the H band. The abundances of 17 elements (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, and Ce) were derived using the BACCHUS code, using atmospheric parameters from both APOGEE's ASPCAP pipeline and those derived independently from photometry (Gaia and 2MASS) to cross validate our results with the ASPCAP values and provide a consistent chemical analysis. Results. We derived a mean iron abundance of [Fe/H] = -0.45 +/- 0.05 using the ASPCAP stellar parameters, and [Fe/H] = -0.45 +/- 0.08 when using photometric stellar parameters, with no evidence of an intrinsic metallicity spread. NGC 6304 shows a typical enhancement in alpha elements, with [alpha/Fe] spec = +0.24 +/- 0.07 and [alpha/Fe] phot = +0.23 +/- 0.08, similar to what is observed in other globular clusters. We find a significant spread in [N/Fe], with sigma(spec) = 0.54 and sigma(phot) = 0.46, along with a clear C-N anticorrelation. Furthermore, we detect a correlation of Ce with both N and Al, consistent with patterns observed in some metal-rich bulge globular clusters but not all. Conclusions. Our study provides the first comprehensive spectroscopic evidence for multiple populations in NGC 6304. We also find a significant star-to-star variation in Na, but a minimal variation in O, in concordance with trends found in other metal-rich bulge clusters. The absence of the Mg-Al anticorrelation supports the evidence that the MgAl cycle is not active in globular clusters at high metallicity. The observed correlation between Ce and both N and Al suggests that the enrichment of these elements may be driven by asymptotic giant branch stars, positioning Ce as an element involved in the multiple population phenomenon in metal-rich globular clusters. We find generally that abundances are consistent with those of bulge field stars of similar metallicity, suggesting a similar origin and chemical evolution.

We present the first detailed spectroscopic analysis of the heavily extincted bulge globular cluster Terzan 2 (Ter 2) based on high-resolution near-infrared spectra obtained as part of the CAPOS (bulge Cluster APOgee Survey) project. CAPOS focuses on surveying clusters within the Galactic bulge, using the APOGEE-2S spectrograph, part of the SDSS-IV survey, a component of the second-generation Apache Point Observatory Galactic Evolution Experiment (APOGEE-2). For the spectral analysis, we used the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) code, which provides line-by-line elemental abundances. We derived abundances for the Fe-peak (Fe, Ni), α (O, Mg, Si, Ca, Ti), light (C, N), odd-Z (Al), and s-process element (Ce) for four members of the cluster. Our analysis yields a mean metallicity of [Fe/H] = −0.84 ± 0.04, with no evidence of intrinsic variation. We detect significant abundance variation only in C and N, indicating the presence of multiple populations. Ter 2 exhibits typical α enrichment, which follows the trend of Galactic globular clusters. Additionally, our dynamical analysis reveals that Terzan 2 is a bulge globular cluster with a chaotic orbit that is influenced by the Galactic bar but not trapped by it, displaying both prograde and retrograde motions within the inner bulge region. Overall, the chemical patterns observed in Terzan 2 are in good agreement with those of other CAPOS bulge clusters of a similar metallicity.

Context. The CAPOS project aims to obtain accurate mean abundances for many elements and their mean radial velocities, and it explores the multiple population (MP) phenomenon in Galactic bulge globular clusters (BGCs). NGC 6569 is one of the clusters observed by CAPOS. Aims. This study presents a detailed high-resolution spectroscopic analysis of NGC 6569 to derive high-precision mean abundances for a number of elements with various nucleosynthetic origins and to unveil its MPs by focusing on key spectral features. Our aim is to complement previous suggestions of the presence of MPs in this cluster based on the typical Na-O anticorrelation and the presence of a double horizontal branch. Methods. We analyzed the near-infrared APOGEE-2 spectra of 11 giant member stars in NGC 6569 using the code BACCHUS. We derived abundances for 12 elements, including light elements (C, N), alpha-elements (O, Mg, Si, Ca, Ti), iron-peak elements (Fe, Ni), the odd-Z element (Al), and s-process elements (Ce, Nd). We also performed an isochrone fitting using photometric data (Gaia + 2MASS) to estimate atmospheric parameters, the cluster distance, and its extinction. Results. We derived a mean metallicity of [Fe/H] = -0.91 +/- 0.06, which is consistent with the values from the APOGEE pipeline and slightly more metal poor than previous findings. The scatter lies within the observational uncertainties. The cluster shows enhanced alpha-element abundances ([alpha/Fe] = 0.36 +/- 0.06 dex) similar to other Galactic globular clusters (GCs). We find no significant variation in Al, suggesting a homogeneous distribution within the cluster. In contrast, we find considerable N-enrichment ([N/Fe] = 0.68 +/- 0.34 dex) and a large spread of 0.90 dex, which enabled us to distinguish at least two separate populations based on N that have anticorrelated C abundances. The n-capture elements Ce and Nd are overabundant compared to the Sun, but are similar to those of GCs in this metallicity regime, and also show an average ratio of <[Ce/Nd]> = -0.17 +/- 0.12. Finally, we estimated a mean radial velocity of RV = -49.75 +/- 3.68 km s(-1), which is consistent with previous measurements, but the heliocentric distance (d(circle dot) = 12.4 +/- 1.45 kpc) and interstellar reddening (E(B-V) = 0.68) are higher than reported in the literature. Conclusions. The analysis confirms the presence of MPs in NGC 6569, evidenced by a significant spread in N and a clear C-N anticorrelation. This supports the previously established Na-O anticorrelation. MPs are characterized through this pattern for the first time. NGC 6569 exhibits chemical signatures typical of BGCs, without a significant spread in metallicity. The cluster alpha-element enhancement (consistent with early enrichment by type II supernovae) and the absence of a Mg-Al-Si anticorrelation agree with expectations for relatively high-metallicity GCs and suggests a rapid and homogeneous star formation history. The overabundance of n-capture elements indicates contributions from r-process events and might be linked to neutron star mergers. These n-capture elements are reported in NGC 6569 for the first time.

Context. With CAPOS, we can mitigate the observational difficulties limiting access to bulge globular clusters in the optical and investigate them in more detail in the near-IR. Aims. To perform a rigorous abundance analysis of the metal-rich bulge globular cluster NGC 6304, in order to determine its detailed chemical composition and identify multiple populations. Methods. We analyzed APOGEE-2 near-IR spectra of 27 giant members. The abundances of 17 elements (C, N, O, Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, and Ce) were derived using the BACCHUS code, using atmospheric parameters from both ASPCAP and photometry (Gaia and 2MASS). Results. We derived [ Fe/H] = -0.45±0.05 using the ASPCAP parameters, and [ Fe/H] = -0.45±0.08 when using photometric parameters, with no evidence of an intrinsic metallicity spread. NGC 6304 shows [α/ Fe]_ spec = 0.24±0.07 and [α/ Fe]_ phot = 0.23±0.08. We find a significant spread in [ N/Fe], with σ_ spec = 0.54 and σ_ phot = 0.46, along with a C-N anticorrelation. Furthermore, we detect a correlation of Ce with both N and Al, consistent with patterns observed in some metal-rich bulge globular clusters. Conclusions. We find a significant star-to-star variation in Na, but a minimal variation in O. The absence of the Mg-Al anticorrelation supports the evidence that the MgAl cycle is not active in globular clusters at high metallicity. The observed correlation between Ce and both N and Al suggests that the enrichment of these elements may be driven by asymptotic giant branch stars, positioning Ce as an element involved in multiple populations in metal-rich globular clusters. We find that abundances are consistent with those of bulge field stars of similar metallicity, suggesting a similar origin and chemical evolution.

As part of the bulge Cluster APOgee Survey (CAPOS), high-resolution, high Signal-to-Noise Ratio Near-Infrared spectroscopy, we aim to conduct the most robust chemical study to date for NGC 6316, deriving abundances for a number of elements with a variety of nucleosynthetic origins, most of which have never been studied before in this cluster. We use the Brussels Automatic Code for Characterizing High accuracy Spectra (BACCHUS) with atmospheric parameters photometrically obtained in order to determine, for the first time, abundances for C, N, O, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni and Ce for this cluster. We obtained a mean metallicity [Fe/H]=-0.87±0.02, finding no indication of an intrinsic metallicity spread. Our metallicity agrees with the most recent values from other studies, revising earlier values that were ∼0.5 dex metal-richer. With this new value, this cluster, long believed to be a member of the classical metal-rich group of bulge GCs around -0.5, now falls in the dominant bulge globular cluster peak around [Fe/H]=-1. The cluster presents a clear C-N anticorrelation. We also found a [α/Fe]=0.31±0.02. Our abundances show similar behaviour to other in situ globular clusters with comparable metallicity. An isochrone fitting gave us E(B-V)=0.71, a higher value than any other from the literature for this cluster since we also estimated R_V=2.7, in good agreement with determinations from other works; (M-m)_0=15.32±0.05. We derive an overall metallicity [M/H]=-0.6±0.05, in agreement with our abundance determination.

Context. Bulge globular clusters (BGCs) are exceptional tracers of the formation and chemodynamical evolution of this oldest Galactic component. Until now, observational difficulties have prevented us from taking full advantage of these powerful Galactic archeological tools. Aims. The bulge Cluster APOgee Survey (CAPOS) addresses this key topic by observing a large number of BGCs, most of which have been poorly studied until now. We aim to obtain accurate mean values for metallicity, [alpha/Fe], and radial velocity, as well as abundances for eleven other elements. Here, we present final parameters based on the APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) for all 18 CAPOS BGCs. Methods. We used atmospheric parameters, abundances, and velocities from ASPCAP in DR17. Results. First, we carried out a stringent selection of cluster members, finding a total of 303 with a spectral signal-to-noise value of S/N>70 and an additional 125 with a lower S/N. We confirmed the result of prior ASPCAP multiple population studies, namely, that stars with high [N/Fe] abundances show higher [Fe/H] than their lower [N/Fe] counterparts. Furthermore, the Mg, Ca, and global alpha abundances exhibit similar trends, while Si is well-behaved. The [Fe/H] value of these second-population stars was corrected to derive the mean metallicity. Mean metallicities were determined to a precision of 0.05 dex, [alpha/Fe] to 0.06 dex, and radial velocity to 3.4 km/s. No clusters displayed any strong evidence of internal metallicity variations, including M22. Abundances for eleven other elements using only first-population stars were calculated. Our values are shown to be in good general agreement with the literature. We developed a new chemodynamical GC classification scheme, synthesizing the results of several recent studies. We also compiled a set of up-to-date metallicities. The BGC metallicity distribution is bimodal, with peaks near [Fe/H] = -0.45, and -1.1, with the metal-poor peak displaying a strong dominance. The entire in situ sample, including disk and BGCs, displays the same bimodality, while ex situ GCs are unimodal, with a peak around -1.6. Surprisingly, we see only a small and statistically insignificant difference in the mean [Si/Fe] of in situ and ex situ GCs. The four GCs with the lowest [Si/Fe] values are all ex situ and relatively young, with three belonging to Sagittarius; no other correlations are evident.

Context. The bulge globular cluster (BGC) NGC 6316 has been the subject of few previous chemical studies beyond metallicity. Thanks to the bulge Cluster APOgee Survey (CAPOS), we can now improve our knowledge of the chemistry and nature of this cluster. CAPOS makes use of high-resolution, high signal-to-noise ratio near-infrared spectroscopy, which is capable of penetrating the substantial dust towards the Galactic bulge (a significant optical obstacle for this cluster due to its high reddening).Aims. We aim to conduct the most robust chemical study to date for NGC 6316 by deriving abundances for a number of elements with a variety of nucleosynthetic origins, most of which have never been studied before in this cluster. Methods. We used the Brussels Automatic Code for Characterizing High accuracy Spectra (BACCHUS) with atmospheric parameters photometrically obtained in order to determine the abundances Results. We determined, for the first time, high-resolution spectroscopic abundances for C, N, O, Mg, Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, and Ce for this cluster. We obtained a mean [Fe/H] = -0.87 +/- 0.02, finding no indication of an intrinsic metallicity spread. Our metallicity agrees with the most recent values from other studies, revising earlier values that were similar to 0.5 dex more metal-rich. With this new value, this cluster, long believed to be a member of the classical metal-rich group of BGCs around -0.5, now falls in the dominant BGC peak around [Fe/H] = -1. The cluster presents a clear C-N anti-correlation and [alpha/Fe] = 0.31 +/- 0.02. Our abundances show similar behaviour to other in situ globular clusters with comparable metallicity. An isochrone fitting gave us E(B-V) = 0.71, a higher value than any other from the literature for this cluster since we also estimated R-V = 2.7, which is in good agreement with determinations from other works; (M-m)(0) = 15.32 +/- 0.05. We derive an overall metallicity of [M/H] = -0.6 +/- 0.05, which is in agreement with our abundance determination.

We report the first CO detection in Leo T, representing the most extreme observation of carbon monoxide molecules in the lowest stellar mass gas-rich dwarf galaxy ( M ⋆ ∼ 10 5 M ⊙ ) known to date. We acquired and present new Atacama Compact Array (ACA) 12 CO( J = 1–0) data within our CHIMERA Survey project for the central region of Leo T, a metal-poor ([M/H] ∼ −1.7) dwarf in the Milky Way (MW) outskirts. We identified three compact molecular clouds (< 13 pc) with estimated upper limit virial masses of M mol ∼ 5 × 10 3 M ⊙ each and a total of 1.4 ± 0.4 × 10 4 M ⊙ , corresponding to ∼3% of the total gas mass. We obtained CO-to-H 2 conversion factors ( α CO ) as high as ∼ 155 M ⊙ (K km s −1 pc 2 ) −1 and mean molecular gas surface densities of Σ mol ∼ 9 M ⊙ pc −2 that are consistent with values found in dwarf galaxies with extremely low metal content. All CO clouds are shifted (∼60 pc) from the stellar population centers, and only one cloud appears within the densest HI region. Two clouds have velocity offsets with the HI of Δ v los ∼ + 13 km s −1 being within twice the velocity dispersion (Δ v los / σ HI, los ∼ 2) and probably bound. However, the northern cloud is faster (Δ v los ∼ + 57 km s −1 ); our models with low halo masses ( M h ≲ 10 9 M ⊙ ) result in unbound orbits, suggesting that this material is likely being expelled from the dwarf, providing evidence for molecular gas depletion. These properties reveal a perturbed dynamics intertwined with star formation processes in low-mass dwarf galaxies, supporting a scenario of episodic bursts until they are fully quenched by the MW environment.

We present the first detailed spectroscopic analysis of the heavily extincted bulge globular cluster Terzan 2 (Ter 2) based on high-resolution near-infrared spectra obtained as part of the CAPOS (bulge Cluster APOgee Survey) project. CAPOS focuses on surveying clusters within the Galactic bulge, using the APOGEE-2S spectrograph, part of the SDSS-IV survey, a component of the second-generation Apache Point Observatory Galactic Evolution Experiment (APOGEE-2). For the spectral analysis, we used the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) code, which provides line-by-line elemental abundances. We derived abundances for the Fe-peak (Fe, Ni), alpha (O, Mg, Si, Ca, Ti), light (C, N), odd-Z (Al), and s-process element (Ce) for four members of the cluster. Our analysis yields a mean metallicity of [Fe/H] = -0.84 +/- 0.04, with no evidence of intrinsic variation. We detect significant abundance variation only in C and N, indicating the presence of multiple populations. Ter 2 exhibits typical alpha enrichment, which follows the trend of Galactic globular clusters. Additionally, our dynamical analysis reveals that Terzan 2 is a bulge globular cluster with a chaotic orbit that is influenced by the Galactic bar but not trapped by it, displaying both prograde and retrograde motions within the inner bulge region. Overall, the chemical patterns observed in Terzan 2 are in good agreement with those of other CAPOS bulge clusters of a similar metallicity.

We present the first detailed chemical analysis from APOGEE-2S observations of stars in six regions of recently discovered substructures in the outskirts of the Magellanic Clouds extending to 20 degrees from the LMC center. We also present, for the first time, the metallicity and alpha-abundance radial gradients of the LMC and SMC out to 11 degrees and 6 degrees, respectively. Our chemical tagging includes 13 species including light, alpha, and Fe-peak elements. We find that the abundances of all of these chemical elements in stars populating two regions in the northern periphery - along the northern "stream"-like feature - show good agreement with the chemical patterns of the LMC, and thus likely have an LMC origin. For substructures located in the southern periphery of the LMC, we find more complex chemical and kinematical signatures, indicative of a mix of LMC-like and SMC-like populations. However, the southern region closest to the LMC shows better agreement with the LMC, whereas that closest to the SMC shows a much better agreement with the SMC chemical pattern. When combining this information with 3-D kinematical information for these stars, we conclude that the southern region closest to the LMC has likely an LMC origin, whereas that closest to the SMC has an SMC origin, and the other two southern regions have a mix of LMC and SMC origins. Our results add to the evidence that the southern substructures of the LMC periphery are the product of close interactions between the LMC and SMC, and thus likely hold important clues that can constrain models of their detailed dynamical histories.

ABSTRACT This study presents the results concerning six red giant stars members of the globular cluster NGC 6558. Our analysis utilized high-resolution near-infrared spectra obtained through the CAPOS initiative (the APOgee Survey of Clusters in the Galactic Bulge), which focuses on surveying clusters within the Galactic Bulge, as a component of the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2). We employ the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) code to provide line-by-line elemental-abundances for Fe-peak (Fe, Ni), α-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z (Al), and the s-process element (Ce) for the four stars with high-signal-to-noise ratios. This is the first reliable measure of the CNO abundances for NGC 6558. Our analysis yields a mean metallicity for NGC 6558 of 〈[Fe/H]〉 = −1.15 ± 0.08, with no evidence for a metallicity spread. We find a Solar Ni abundance, 〈[Ni/Fe]〉 ∼ +0.01, and a moderate enhancement of α-elements, ranging between +0.16 and <+0.42, and a slight enhancement of the s-process element 〈[Ce/Fe]〉 ∼ +0.19. We also found low levels of 〈[Al/Fe]〉 ∼ +0.09, but with a strong enrichment of nitrogen, [N/Fe] > +0.99, along with a low level of carbon, [C/Fe] < −0.12. This behaviour of Nitrogen-Carbon is a typical chemical signature for the presence of multiple stellar populations in virtually all GCs; this is the first time that it is reported in NGC 6558. We also observed a remarkable consistency in the behaviour of all the chemical species compared to the other CAPOS bulge GCs of the same metallicity.

We report the first 3D kinematical measurements of 88 stars in the direction of several recently discovered substructures in the southern periphery of the Large Magellanic Cloud (LMC) using a combination of Gaia proper motions and radial velocities from the APOGEE-2 survey. More specifically, we explore stars in assorted APOGEE-2 pointings in a region of the LMC periphery where various overdensities of stars have previously been identified in maps of stars from Gaia and DECam. By using a model of the LMC disk rotation, we find that a sizable fraction of the APOGEE-2 stars have extreme space velocities that are distinct from, and not a simple extension of, the LMC disk. Using N-body hydrodynamical simulations of the past dynamical evolution and interaction of the LMC and Small Magellanic Cloud (SMC), we explore whether the extreme-velocity stars may be accounted for as tidal debris created in the course of that interaction. We conclude that the combination of LMC and SMC debris produced from their interaction is a promising explanation, although we cannot rule out other possible origins, and that these new data should be used to constrain future simulations of the LMC–SMC interaction. We also conclude that many of the stars in the southern periphery of the LMC lie outside of the LMC plane by several kiloparsecs. Given that the metallicity of these stars suggests that they are likely of Magellanic origin, our results suggest that a wider exploration of the past interaction history of the Magellanic Clouds is needed.

ABSTRACT It has been proposed that the globular cluster-like system Terzan 5 is the surviving remnant of a primordial building block of the Milky Way bulge, mainly due to the age/metallicity spread and the distribution of its stars in the α–Fe plane. We employ Sloan Digital Sky Survey data from the Apache Point Observatory Galactic Evolution Experiment to test this hypothesis. Adopting a random sampling technique, we contrast the abundances of 10 elements in Terzan 5 stars with those of their bulge field counterparts with comparable atmospheric parameters, finding that they differ at statistically significant levels. Abundances between the two groups differ by more than 1σ in Ca, Mn, C, O, and Al, and more than 2σ in Si and Mg. Terzan 5 stars have lower [α/Fe] and higher [Mn/Fe] than their bulge counterparts. Given those differences, we conclude that Terzan 5 is not the remnant of a major building block of the bulge. We also estimate the stellar mass of the Terzan 5 progenitor based on predictions by the Evolution and Assembly of GaLaxies and their Environments suite of cosmological numerical simulations, concluding that it may have been as low as ∼3 × 108 M⊙ so that it was likely unable to significantly influence the mean chemistry of the bulge/inner disc, which is significantly more massive (∼1010 M⊙). We briefly discuss existing scenarios for the nature of Terzan 5 and propose an observational test that may help elucidate its origin.

The Planetary Society's LightSail-2 mission successfully validated the orbital maneuvering capability of a solar radiation pressure (SRP) propelled spacecraft. This paper presents a study on two alternative attitude strategies for the orientation of a solar sail. The goal is to increase the effect of the SRP acceleration over the spacecraft's orbital trajectory, with the intention of maintaining or even gaining altitude over time. Furthermore, one of these strategies was employed while varying a few of the mission's parameters to determine if it would be viable to maintain the spacecraft's average altitude. Results show that it is possible to increase the average altitude of the spacecraft over time while still reducing the number of maneuvers necessary to change the spacecraft's attitude. With that result in hand, it is also possible to change some of the mission parameters without compromising the solar sailing performance.

We present results from a study of 15 red giant members of the intermediate-metallicity globular cluster (GC) FSR 1758 using high-resolution, near-infrared spectra collected with the Apache Point Observatory Galactic Evolution Experiment II survey (APOGEE-2) that were obtained as part of CAPOS (the bulge Cluster APOgee Survey). Since its very recent discovery as a massive GC in the bulge region, evoking the name Sequoia, this has been an intriguing object with a highly debated origin, and initially led to the suggestion of a purported progenitor dwarf galaxy of the same name. In this work, we use new spectroscopic and astrometric data to provide additional clues as to the nature of FSR 1758. Our study confirms the GC nature of FSR 1758, and as such we report the existence of the characteristic N-C anticorrelation and Al-N correlation for the first time. We thereby reveal the existence of the multiple-population phenomenon, similar to that observed in virtually all GCs. Furthermore, the presence of a population with strongly enriched aluminum makes it unlikely that FSR 1758 is the remnant nucleus of a dwarf galaxy because Al-enhanced stars are uncommon in dwarf galaxies. We find that FSR 1758 is slightly more metal rich than previously reported in the literature; this source has a mean metallicity [Fe/H] between −1.43 to −1.36, depending on the adopted atmospheric parameters and a scatter within observational error, again pointing to its GC nature. Overall, the α-enrichment (≳ + 0.3 dex), Fe-peak (Fe, Ni), light (C, N), and odd-Z (Al) elements follow the trend of intermediate-metallicity GCs. Isochrone fitting in the Gaia bands yields an estimated age of ∼11.6 Gyr. We used the exquisite kinematic data, including our CAPOS radial velocities and Gaia eDR3 proper motions, to constrain the N-body density profile of FSR 1758, and found that it is as massive (∼2.9 ± 0.6 × 105 M⊙) as NGC 6752. We confirm a retrograde and eccentric orbit for FSR 1758. A new examination of its dynamical properties with the GravPot16 model favors an association with the Gaia-Enceladus-Sausage accretion event. Thus, paradoxically, the cluster that gave rise to the name of the Sequoia dwarf galaxy does not appear to belong to this specific merging event.