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The Gaia-ESO Survey: Calibrating the lithium–age relation with open clusters and associations. II. Expanded cluster sample and final membership selection
Get PDFContext. The Li abundance observed in pre-main sequence and main sequence late-type stars is strongly age-dependent, but also shows a complex pattern depending on several parameters, such as rotation, chromospheric activity, and metallicity. The best way to calibrate these effects, and with the aim of studying Li as an age indicator for FGK stars, is to calibrate coeval groups of stars, such as open clusters (OCs) and associations. Aims. We present a considerable target sample of 42 OCs and associations – with an age range from 1 Myr to 5 Gyr – observed within the Gaia-ESO survey (GES), and using the latest data provided by GES iDR6 and the most recent release of Gaia that was then available, EDR3. As part of this study, we update and improve the membership analysis for all 20 OCs presented in our previous article. Methods. We perform detailed membership analyses for all target clusters to identify likely candidates, using all available parameters provided by GES, complemented with detailed bibliographical searches, and based on numerous criteria: from radial velocity distributions, to the astrometry (proper motions and parallaxes) and photometry provided by Gaia, to gravity indicators (log g and the ? index), [Fe/H] metallicity, and Li content in diagrams of (Li equivalent widths) EW(Li) versus Teff. Results. We obtain updated lists of cluster members for the whole target sample, as well as a selection of Li-rich giant contaminants obtained as an additional result of the membership process. Each selection of cluster candidates was thoroughly contrasted with numerous existing membership studies using data from Gaia to ensure the most robust results. Conclusions. These final cluster selections will be used in the third and last paper of this series, which reports the results of a comparative study characterising the observable Li dispersion in each cluster and analysing its dependence on several parameters, allowing us to calibrate a Li–age relation and obtain a series of empirical Li envelopes for key ages in our sample
Hollows on Mercury: A Comprehensive Analysis of Spatial Patterns and Their Relationship to Craters and Structures
Get PDFWe acknowledge funding from the ItalianSpace Agency (ASI) under ASI‐INAFagreement 2017‐47‐H.0. The authorsgratefully acknowledge Susan Conwayand David T. Blewett for the helpful andconstructive revisions.Hollows on Mercury are small (hundreds of meters - few kilometers), shallow (tens of meters), irregular depressions typically found in clusters, often associated with impact craters, and likely formed by the loss of volatile materials. While their exact formation process remains debated, various hypotheses suggest sublimation or space weathering. In this study, we analyzed the global distribution of hollows, exploring their spatial patterns and relationships with key geological features. Our findings challenge the idea that hollows arise from a single volatile-rich surface layer, suggesting instead that volatiles are dispersed throughout the crust. Hollows show no correlation with specific geological units or elevations, indicating no singular volatile source. Moreover, the transitory nature of hollows is suggested as they are rare in older, degraded craters but common in younger ones or older craters with deep-seated features, hinting at a link to the reworking of materials through impacts or volcano-tectonic activity
Automating the Process of Document Submission in the IVOA Document Repository
Get PDFThe International Virtual Observatory Alliance (IVOA) produces standards to enable the interoperability of astronomical data and services for the global astrophysical community. The working groups and the interest groups submit the documents following the promotion process described by the IVOA document for Standards and Processes. This process is currently managed mostly manually by the IVOA Document Coordinator. We are developing a web application to automate this process. This tool will help users submit the document alongside their metadata information, which will then be stored in the IVOA database. The application will use the metadata to dynamically generate both the individual document landing pages and the global repository landing page. Other features of this application will be the addition of Errata, Requests for Comments (RFC) phases, and other related features, which are currently manually managed by the IVOA Document Coordinator or other IVOA organization’s roles. This web application is built using the Python Flask framework, SQLite3 as the database, SQLAlchemy as the Object Relational Mapper (ORM), and various front-end tools. The application is designed to accept metadata and different formats of documents through a form interface. The uploaded documents are then processed, renamed, and saved in a structured document tree. The accompanying metadata is stored in SQLite3 database and used to dynamically generate individual document landing pages for ease of access and organization. This document provides a step-by-step explanation of the architecture, technology and
implementation involved in the development of this application
Discovery of a dormant 33 solar-mass black hole in pre-release Gaia astrometry
Get PDFContext. Gravitational waves from black-hole (BH) merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models-And also higher than known stellar-origin black holes in our Galaxy. It has been proposed that those high-mass BHs are the remnants of massive metal-poor stars. Aims. Gaia astrometry is expected to uncover many Galactic wide-binary systems containing dormant BHs, which may not have been detected before. The study of this population will provide new information on the BH-mass distribution in binaries and shed light on their formation mechanisms and progenitors. Methods. As part of the validation efforts in preparation for the fourth Gaia data release (DR4), we analysed the preliminary astrometric binary solutions, obtained by the Gaia Non-Single Star pipeline, to verify their significance and to minimise false-detection rates in high-mass-function orbital solutions. Results. The astrometric binary solution of one source, Gaia BH3, implies the presence of a 32.70a ±a 0.82aM- BH in a binary system with a period of 11.6 yr. Gaia radial velocities independently validate the astrometric orbit. Broad-band photometric and spectroscopic data show that the visible component is an old, very metal-poor giant of the Galactic halo, at a distance of 590 pc. Conclusions. The BH in the Gaia BH3 system is more massive than any other Galactic stellar-origin BH known thus far. The low metallicity of the star companion supports the scenario that metal-poor massive stars are progenitors of the high-mass BHs detected by gravitational-wave telescopes. The Galactic orbit of the system and its metallicity indicate that it might belong to the Sequoia halo substructure. Alternatively, and more plausibly, it could belong to the ED-2 stream, which likely originated from a globular cluster that had been disrupted by the Milky Way
The AGILEScience mobile application for the AGILE space mission
Get PDFAGILE is a space mission launched in 2007 to study X-ray and gamma-ray phenomena through data acquired by different payload instruments. The AGILE Team developed an application called AGILEScience that allows to visualize information about the AGILE space mission from mobile devices, such as smartphones and tablets. The AGILEScience application can be downloaded freely for iOS and Android devices. Beside sharing information about the AGILE space mission with the public for outreach purposes, similarly to what other applications do, the AGILEScience app offers some new and unique features in gamma-ray astrophysics: (i) it gives public access in nearly real-time to the sky view of a gamma-ray satellite for the first time, (ii) it interacts with the AGILE remote gamma-ray data storage and analysis system, allowing data analysis to be sent and results to be visualized, and (iii) it allows the AGILE Team to access a password-protected section of the app to view detailed AGILE pipeline results and submit advanced analyses. The last two features are critical to allow remote and easy access to the results of the AGILE automated pipelines. In particular, the ability to visualize results and execute manual data analysis from mobile devices is key during the follow-up of transient events and to easily monitor the satellite status via smartphone
The GAPS programme at TNG LII. Spot modelling of V1298 Tau using the SpotCCF tool
Get PDFContext. The intrinsic variability due to the magnetic activity of young active stars is one of the main challenges in detecting and characterising exoplanets. The stellar activity is responsible for jitter effects observed both in photometric and spectroscopic observations that can impact our planetary detection sensitivity. Aims. We present a method able to model the stellar photosphere and its surface inhomogeneities (starspots) in young, active, and fast-rotating stars based on the cross-correlation function (CCF) technique, and we extract information about the spot configuration of the star. Methods. We developed Spot CCF, a tool able to model the deformation of the CCF profile due to the presence of multiple spots on the stellar surface. Within the Global Architecture of Planetary Systems (GAPS) Project at the Telescopio Nazionale Galileo, we analysed more than 300 spectra of the young planet-hosting star V1298 Tau provided by the HARPS-N high-resolution spectrograph. By applying the SpotCCF model to the CCFs, we extracted the spot configuration (latitude, longitude, and projected filling factor) of this star, and provide a new radial velocity (RV) time series for this target. Results. We find that the features identified in the CCF profiles of V1298 Tau are modulated by the stellar rotation, supporting our assumption that they are caused by starspots. The analysis suggests a differential rotation velocity of the star with lower rotation at higher latitudes. Also, we find that SpotCCF provides an improvement in RV extraction, with a significantly lower dispersion with respect to the commonly used pipelines. This allows mitigation of the stellar activity contribution modulated with stellar rotation. A detection sensitivity test, involving the direct injection of a planetary signal into the data, confirms that the SpotCCF model improves the sensitivity and ability to recover planetary signals. Conclusions. Our method enables us to model the stellar photosphere and extract the spot configuration of young, active, and rapidly rotating stars. It also allows the extraction of optimised RV time series, thereby enhancing our detection capabilities for new exoplanets and advancing our understanding of stellar activity
A pulsar in a binary with a compact object in the mass gap between neutron stars and black holes
Get PDFSome compact objects observed in gravitational wave events have masses in the gap between known neutron stars (NSs) and black holes (BHs). The nature of these mass gap objects is unknown, as is the formation of their host binary systems. We report pulsar timing observations made with the Karoo Array Telescope (MeerKAT) of PSR J0514‑4002E, an eccentric binary millisecond pulsar in the globular cluster NGC 1851. We found a total binary mass of 3.887 ± 0.004 solar masses (M⊙), and multiwavelength observations show that the pulsar's binary companion is also a compact object. The companion's mass (2.09 to 2.71 M⊙, 95% confidence interval) is in the mass gap, indicating either a very massive NS or a low-mass BH. We propose that the companion formed in a merger between two earlier NSs...
Type Ia supernovae from chemically segregated white dwarfs
Get PDFType Ia supernovae are the outcome of the explosion of a carbon-oxygen white dwarf in a close binary system. They are thought to be the main contributors to the galactic nucleosynthesis of iron-peak elements, with important contributions to the yields of intermediate-mass elements. Recent analyses of the phase diagram of carbon and oxygen containing impurities such as 22Ne and 56Fe in conditions relevant to white dwarf interiors suggest that both isotopes can partially separate when the temperature of the star is low enough to start solidifying. The purpose of the present paper is to examine the impact of this separation on the yields of the different chemical species synthesized during explosions. We used a one-dimensional supernova code to evaluate the impact of the sedimentation assuming different degrees of chemical separation. We find that the main properties of the ejecta, the kinetic energy, and the ejected mass of 56Ni only vary slightly when the separation is taken into account. However, the yields of important isotopes that are used as diagnostic tools, such as manganese, can be strongly modified. Furthermore, the chemical separation studied here is able to change several indicators related to the metallicity of the progenitor (such as the mass ratio of calcium to sulphur in the ejecta or the UV flux of the supernova) and to its mass, whether it is a Chandrasekhar-mass white dwarf or a substantially lighter one (such as the imprint of stable nickel on late-time infrared spectra or that related to the presence of radioactive nickel at the center of the ejecta)
Upgrading the AZT24 telescope at the Campo Imperatore high-altitude observatory: design and installation of a new, seeing-enhanced NIR imager
Get PDFThe AZT24 is a 1.1m telescope installed at the Campo Imperatore observing station, in Central Italy, at an elevation of 2200 m a.s.l. Since the 2nd half of 1990s, its focal plane has been equipped with SWIRCAM, a 1-2.5 micron camera based on an LN2-cooled, HgCdTe detector, able to exploit the excellent observing conditions offered by the site, especially at those wavelengths. After almost 30 years of operation, this system will now be upgraded with a new IR imager, based on an InGaAs detector, TEC-cooled at around -80 °C. Even with a reduced spectral coverage, the NIR imager will cover a wider field-of-view and will benefit from the seeing-enhancement capability produced by a devoted Tip-Tilt (TT) corrector. The overall project is presented in this paper, with emphasis on a commercial InGaAs detector for astronomical applications. The opto-mechanical layout is optimized to reduce the instrumental thermal background, while the TT-correction system produces a significant narrowing of the PSF, increasing the signal-to-noise ratio of the detected sources. Simulations of the expected performances are reported: they show that the upgraded system is suitable for a number of science cases, ranging from extragalactic Astronomy to stellar Astrophysics and Solar System studies. In addition, it represents an interesting testbench for some technological investigations, both in the field of Adaptive Optics and in that of data acquisition and processing techniques
No Redshift Evolution in the Fe ii/Mg ii Flux Ratios of Quasars across Cosmic Time
Get PDFThe Fe ii/Mg ii emission line flux ratio in quasar spectra serves as a proxy for the relative Fe to α-element abundances in the broad-line regions of quasars. Due to the expected different enrichment timescales of the two elements, they can be used as a cosmic clock in the early Universe. We present a study of the Fe ii/Mg ii ratios in a sample of luminous quasars exploiting high-quality near-IR spectra taken primarily by the XQR-30 program with VLT XSHOOTER. These quasars have a median bolometric luminosity of log(L bol[erg s−1]) ∼ 47.3 and cover a redshift range of z = 6.0-6.6. The median value of the measured Fe ii/Mg ii ratios is ∼7.9 with a normalized median absolute deviation of ∼2.2. In order to trace the cosmic evolution of Fe ii/Mg ii in an unbiased manner, we select two comparison samples of quasars with similar luminosities and high-quality spectra from the literature, one at intermediate redshifts (z = 3.5-4.8) and the other at low redshifts (z = 1.0-2.0). We perform the same spectral analysis for all these quasars, including the usage of the same iron template, the same spectral fitting method, and the same wavelength fitting windows. We find no significant redshift evolution in the Fe ii/Mg ii ratio over the wide redshift range from z = 1 to 6.6. The result is consistent with previous studies and supports the scenario of a rapid iron enrichment in the vicinity of accreting supermassive black holes at high redshift