bluuebunny/crossref_metadata_2025_split huggingface dataset:
TheGaia-ESO Survey: Preparing the ground for 4MOST and WEAVE galactic surveys
Authors: Nepal S. , Guiglion G. , de Jong R. S. , Valentini M. , Chiappini C. , Steinmetz M. , Ambrosch M. , Pancino E. , Jeffries R. D. , Bensby T. , Romano D. , Smiljanic R. , Dantas M. L. L. , Gilmore G. , Randich S. , Bayo A. , Bergemann M. , Franciosini E. , Jiménez-Esteban F. , Jofré P. , Morbidelli L. , Sacco G. G. , Tautvaišienė G. , Zaggia S. 
Published: January 2023

Context.With its origin coming from several sources (Big Bang, stars, cosmic rays) and given its strong depletion during its stellar lifetime, the lithium element is of great interest as its chemical evolution in the Milky Way is not well understood at present. To help constrain stellar and galactic chemical evolution models, numerous and precise lithium abundances are necessary for a large range of evolutionary stages, metallicities, and Galactic volume.Aims.In the age of stellar parametrization on industrial scales, spectroscopic surveys such as APOGEE, GALAH, RAVE, and LAMOST have used data-driven methods to rapidly and precisely infer stellar labels (atmospheric parameters and abundances). To prepare the ground for future spectroscopic surveys such as 4MOST and WEAVE, we aim to apply machine learning techniques to lithium measurements and analyses.Methods.We trained a convolution neural network (CNN), couplingGaia-ESO Survey iDR6 stellar labels (Teff, log(g), [Fe/H], and A(Li)) and GIRAFFE HR15N spectra, to infer the atmospheric parameters and lithium abundances for ∼40 000 stars. The CNN architecture and accompanying notebooks are available online via GitHub.Results.We show that the CNN properly learns the physics of the stellar labels, from relevant spectral features through a broad range of evolutionary stages and stellar parameters. The lithium feature at 6707.8 Å is successfully singled out by our CNN, among the thousands of lines in the GIRAFFE HR15N setup. Rare objects such as lithium-rich giants are found in our sample. This level of performance is achieved thanks to a meticulously built, high-quality, and homogeneous training sample.Conclusions.The CNN approach is very well adapted for the next generations of spectroscopic surveys aimed at studying (among other elements) lithium, such as the 4MIDABLE-LR/HR (4MOST Milky Way disk and bulge low- and high-resolution) surveys. In this context, the caveats of machine-learning applications should be appropriately investigated, along with the realistic label uncertainties and upper limits for abundances.
Using photometric redshift data to improve the detection of galactic filaments with the Bisous model
Authors: Muru M. M. , Tempel E. 
Published: January 2023

Context. Filament finders are limited, among other things, by the abundance of spectroscopic redshift data. This limits the sky areas and depth where we can detect the filamentary network.
Aims. As there are proportionally more photometric redshift data than spectroscopic, we aim to use data with photometric redshifts to improve and expand the areas where we can detect the large-scale structure of the Universe. The Bisous model is a filament finder that uses only the galaxy positions. We present a proof of concept, showing that the Bisous filament finder can improve the detected filamentary network with photometric redshift data.
Methods. We created mock data from the MULTIDARK-GALAXIES catalogue. Galaxies with spectroscopic redshifts were given exact positions from the simulation. Galaxies with photometric redshifts were given uncertainties along one coordinate. The errors were generated with different Gaussian distributions for different samples. We sample the photometric galaxy positions for each Bisous run based on the uncertainty distribution. In some runs, the sampled positions are closer to the true positions and produce persistent filaments; other runs produce noise, which is suppressed in the post-processing.
Results. There are three different types of samples: spectroscopic only, photometric only, and mixed samples of galaxies with photometric and spectroscopic redshifts. In photometric-only samples, the larger the uncertainty for photometric redshifts, the fewer filaments are detected, and the filaments strongly align along the line of sight. Using mixed samples improves the number of filaments detected and decreases the alignment bias of those filaments. The results are compared against the full spectroscopic sample. The recall for photometric-only samples depends heavily on the size of uncertainty and dropped close to 20%; for mixed samples, the recall stayed between 40% and 80%. The false discovery rate stayed below 5% in every sample tested in this work. Mixed samples showed better results than corresponding photometric-only or spectroscopic-only samples for every uncertainty size and number of spectroscopic galaxies in mixed samples.
Conclusions. Mixed samples of galaxies with photometric and spectroscopic redshifts help us to improve and extend the large-scale structure further than possible with only spectroscopic samples. Although the uncertainty sizes tested in this work are smaller than those for the available photometric data, upcoming surveys, such as J-PAS, will achieve sufficiently small uncertainties to be useful for large-scale structure detection.
26Al gamma rays from the Galaxy with INTEGRAL/SPI
Authors: Pleintinger Moritz M. M. , Diehl Roland , Siegert Thomas , Greiner Jochen , Krause Martin G. H. 
Published: January 2023

Context.The presence of radioactive26Al at 1.8 MeV reveals an ongoing process of nucleosynthesis in the Milky Way. Diffuse emission from its decay can be measured with gamma-ray telescopes in space. The intensity, line shape, and spatial distribution of the26Al emission allow for studies of these nucleosynthesis sources. The line parameters trace massive-star feedback in the interstellar medium thanks to its 1 My lifetime.Aims.We aim to expand upon previous studies of the26Al emission in the Milky Way, using all available gamma-ray data, including single and double events collected with SPI on INTEGRAL from 2003 until 2020.Methods.We applied improved spectral response and background as evaluated from tracing spectral details over the entire mission. The exposure for the Galactic26Al emission was enhanced using all event types measured within SPI. We redetermined the intensity of Galactic26Al emission across the entire sky, through maximum likelihood fits of simulated and model-built sky distributions to SPI spectra for single and for double detector hits.Results.We found an all-sky flux of (1.84±0.03)×10−3ph cm−2s−1in the 1.809 MeV line from26Al, determined via fitting to sky distributions from previous observations with COMPTEL. Significant emission from higher latitudes indicates an origin from nearby massive-star groups and superbubbles, which is also supported by a bottom-up population synthesis model. The line centroid is found at (1809.83±0.04 keV), while the line broadening from source kinematics integrated over the sky is (0.62±0.3) keV (FWHM).
The temperature dependency of Wolf–Rayet-type mass loss
Authors: Sander A. A. C. , Lefever R. R. , Poniatowski L. G. , Ramachandran V. , Sabhahit G. N. , Vink J. S. 
Published: January 2023

Context. The mass loss of helium-burning stars, which are partially or completely stripped of their outer hydrogen envelope, is a catalyst of the cosmic matter cycle and decisive ingredient of massive star evolution. Yet, its theoretical fundament is only starting to emerge with major dependencies still to be uncovered.
Aims. A temperature or radius dependence is usually not included in descriptions for the mass loss of classical Wolf-Rayet (cWR) stars, despite being crucial for other hot star wind domains. We thus aim to determine whether such a dependency will also be necessary for a comprehensive description of mass loss in the cWR regime.
Methods. Sequences of dynamically consistent stellar atmosphere models were calculated with the hydrodynamic branch of the PoWR code along the temperature domain, using different choices for the luminosity, mass, and surface abundances. For the first time, we allowed nonmonotonic velocity fields when solving the hydrodynamic equation of motion. The resulting velocity structures were then interpolated for the comoving-frame radiative transfer, ensuring that the main wind characteristics were preserved.
Results. We find a strong dependence of the mass-loss rate with the temperature of the critical/sonic point which mainly reflects the different radii and resulting gravitational accelerations. Moreover, we obtain a relation between the observed effective temperature and the transformed mass-loss rate Ṁt which seems to be largely independent of the underlying stellar parameters. The relation is shifted when different density contrasts are assumed for the wind clumping. Below a characteristic value of log (Ṁt [M⊙ yr−1]) −4.5, the slope of this relation changes and the winds become transparent for He II ionizing photons.
Conclusions. The mass loss of cWR stars is a high-dimensional problem but also shows inherent scalings which can be used to obtain an approximation of the observed effective temperature. For a more realistic treatment of cWR stars and their mass loss in stellar evolution, we recommend the inclusion of a temperature dependency and ideally the calculation of hydrodynamic structure models.
The aperiodic firehose instability of counter-beaming electrons in space plasmas
Authors: Lazar M. , López R. A. , Moya P. S. , Poedts S. , Shaaban S. M. 
Published: January 2023

Context.Recent studies have revealed new unstable regimes of the counter-beaming electrons specific to hot and dilute plasmas from astrophysical scenarios: an aperiodic firehose-like instability is induced for highly oblique angles of propagation relative to the magnetic field, resembling the fast growing and aperiodic mode triggered by the temperature anisotropyT∥ > T⊥(where ∥, ⊥ denote directions relative to the magnetic field).Aims.The counter-beaming electron firehose instability is investigated here for space plasma conditions, which include not only a specific plasma parameterization but, in particular, the influence of an embedding background plasma of electrons and ions (protons).Methods.We applied fundamental plasma kinetic theory to prescribe the unstable regimes, characterize the wave-number dispersion of the growth rates, and differentiate from the regimes of interplay with other instabilities. We also used numerical particle-in-cell (PIC) simulations to confirm the instability of these aperiodic modes, and their effects on the relaxation of counter-beaming electrons.Results.Linear theory predicts a systematic inhibition of the (counter-)beaming electron firehose instability (BEFI) by reduction of the growth rates and the range of unstable wave-number with increasing relative density of the background electrons. To obtain finite and reasonably high values of the growth rate, the (relative) beam speed does not need to be very high (just comparable to the thermal speed), but the (counter-)beams must be dense enough, with a relative density of at least 15%–20% of the total density. Quantified in terms of the beam speed and the beta parameter, the plasma parametric conditions favorable to this instability are also markedly reduced under the influence of background electrons. Numerical simulations confirm not only that BEFI can be excited in the presence of background electrons, but also the inhibiting effect of this population, especially when this latter is cooler. In the regimes of transition to electrostatic (ES) instabilities, BEFI is still robust enough to develop as a secondary instability, after the relaxation of beams under a quick interaction with ES fluctuations.Conclusions.To the features presented in previous studies, we can add that BEFI resembles the properties of solar wind firehose heat-flux instability triggered along the magnetic field by the anti-sunward electron strahl. However, BEFI is driven by a double (counter-beaming) electron strahl, and develops at highly oblique angles, which makes it potentially effective in the regularization and relaxation of the electron counter-beams observed in expanding coronal loops (with closed magnetic field topology) and in interplanetary shocks.
A recipe for orbital eccentricity damping in the type-I regime for low-viscosity 2D discs
Authors: Pichierri G. , Bitsch B. , Lega E. 
Published: January 2023

Context. It is well known that partial and deep gap opening depends on a disc’s viscosity; however, damping formulas for orbital eccentricities have only been derived at high viscosities, ignoring partial gap opening.
Aims. In this work, we aim to obtain a simple formula to model eccentricity damping of the type-I regime in low-viscosity discs, where even small planets of a few to a few tens of Earth masses may start opening partial gaps in the gas surface density around their orbit.
Methods. We performed high-resolution, 2D, locally isothermal hydrodynamical simulations of planets with varying masses on fixed orbits in discs with varying aspect ratios and viscosities. We determined the torque and power felt by the planet to ultimately derive migration and eccentricity damping timescales.
Results. We first find a lower limit to the gap depths below which vortices appear; this happens roughly at the transition between type-I and classical type-II migration regimes. For the simulations that remain stable, we obtain a fit to the observed gap depth in the limit of vanishing eccentricities that is similar to the one currently used in the literature but accurate down to α = 3.16 × 10−5. We then record the eccentricity damping efficiency as a function of the observed gap depth and the initial eccentricity. When the planet has opened a deep enough gap such that the surface density is less than ~80% of the unperturbed disc surface density, a clear linear trend is observed independently of the planet’s eccentricity; at shallower gaps, this linear trend is preserved at low eccentricities, while it deviates to more efficient damping when e is comparable to the disc’s scale height. Both trends can be understood on theoretical grounds and are reproduced by a simple fitting formula.
Conclusions. Our combined fits for the gap depth and eccentricity damping efficiency yield a simple recipe to implement type-I eccentricity damping in N-body codes in the case of partial gap opening planets that is consistent with high-resolution 2D hydrodynamical simulations. The typical error of the final fit is of the order of a few percent, and at most ~20%, which is the error of type-I torque formulas widely used in the literature. This will allow a more self-consistent treatment of planet-disc interactions of the type-I regime for population synthesis models at low viscosities.
Gaia search for early-formed andesitic asteroidal crusts
Authors: Galinier M. , Delbo M. , Avdellidou C. , Galluccio L. , Marrocchi Y. 
Published: January 2023

Context. Andesitic meteorites are among the oldest achondrites known to date. They record volcanic events and crust formation episodes in primordial planetesimals that took place about 4.565 Myr ago. However, no analogue for these meteorites has been found in the asteroid population to date.
Aims. We searched for spectroscopic analogues of the andesitic meteorite Erg Chech 002 in the asteroid population using the Gaia DR3 spectral dataset.
Methods. In order to identify which asteroids have the most similar spectrum to Erg Chech 002, we first determined the spectral parameters of Gaia DR3 asteroids (spectral slope and Band I depth) and compared them to the spectral parameters of different samples of the meteorite. In addition, we performed a spectral curve matching between Erg Chech 002 and Gaia DR3 asteroid data, and we compared the results of both methods.
Results. We found that 51 main-belt asteroids have a visible spectrum similar to the one of Erg Chech 002, and 91 have a spectrum similar to the space-weathered spectra of the meteorite, corresponding to 0.08% and 0.15% of the whole Gaia DR3 dataset of asteroids with spectra, respectively. The asteroids that best match the laboratory samples of the meteorite are mostly located in the inner main belt, while the objects matching the space-weathered meteorite models show slightly more scattering across the belt.
Conclusions. Despite the fact that we find asteroids that potentially match Erg Chech 002, these asteroids are extremely rare. Moreover, a visible spectrum alone is not completely diagnostic of an Erg Chech 002-like composition. Near-infrared spectra will be important to confirm (or rule out) the spectral matches between Erg Chech 002 and the candidate asteroid population.
Analysis of the first infrared spectrum of quasi-bound H2line emission in Herbig-Haro 7
Authors: Roueff E. , Burton M. G. , Geballe T. R. , Abgrall H. 
Published: January 2023

Context.Highly excited molecular hydrogen (H2) has been observed in many regions of shocked molecular gas. A recently publishedK-band spectrum of Herbig-Haro 7 (HH7) contains several vibration-rotation lines of H2from highly excited energy levels that have not been detected elsewhere, including a line at 2.179 μm identified as arising from thev = 2,  J = 29 level, which lies above the dissociation limit of H2. One emission line at 2.104 μm in this spectrum was unidentified.Aims.We aim to complete the analysis of the spectrum of HH7 by including previously missing molecular data that have been recently computed.Methods.We re-analysed theK-band spectrum, emphasising the physics of quasi-bound upper levels that can produce infrared emission lines in theKband.Results.We confirm the identification of the 2 − 1S(27) line at 2.1785 μm and identify the line at 2.1042 μm as due to the 1−0S(29) transition of H2, whose upper level energy is also higher than the dissociation limit. This latter identification, its column density, and the energy of its upper level further substantiate the existence of a hot thermal component at 5000 K in the HH7 environment.Conclusions.The presence of the newly identified 1 − 0S(29) line, whose quasi-bound upper level (v = 1,J = 31) has a significant spontaneous dissociation probability, shows that dissociation of H2is occurring. The mechanism by which virtually all of the H2in levels with energies from 20 000 K to 53 000 K is maintained in local thermodynamic equilibrium at a single temperature of ∼5000 K remains to be understood.
Resolved near-UV hydrogen emission lines at 40-Myr super-Jovian protoplanet Delorme 1 (AB)b
Authors: Ringqvist Simon C. , Viswanath Gayathri , Aoyama Yuhiko , Janson Markus , Marleau Gabriel-Dominique , Brandeker Alexis 
Published: January 2023

Context. Accretion at planetary-mass companions (PMCs) suggests the presence of a protoplanetary disc in the system, likely accompanied by a circumplanetary disc. High-resolution spectroscopy of accreting PMCs is very difficult due to their proximity to bright host stars. For well-separated companions, however, such spectra are feasible and they are unique windows into accretion.
Aims. We have followed up on our observations of the 40-Myr, and still accreting, circumbinary PMC Delorme 1 (AB)b. We used high-resolution spectroscopy to characterise the accretion process further by accessing the wealth of emission lines in the near-UV.
Methods. We have used the UVES spectrograph on the ESO VLT/UT2 to obtain Rλ ≈ 50 000 spectroscopy, at 3300–4520 Å, of Delorme 1 (AB)b. After separating the emission of the companion from that of the M5 low-mass binary, we performed a detailed emission-line analysis, which included planetary accretion shock modelling.
Results. We reaffirm ongoing accretion in Delorme 1 (AB)b and report the first detections in a (super-Jovian) protoplanet of resolved hydrogen line emission in the near-UV (Hγ, Hδ, Hϵ, H8, and H9). We tentatively detect H11, H12, He I, and Ca II H/K. The analysis strongly favours a planetary accretion shock with a line-luminosity-based accretion rate of Ṁ = 2 × 10−8 MJ yr−1. The lines are asymmetric and are well described by sums of narrow and broad components with different velocity shifts. The overall line shapes are best explained by a pre-shock velocity of v0 = 170 ± 30 km s−1, implying a planetary mass of MP = 13 ± 5 MJ, and number densities of n0 ≳ 1013 cm−3 or n0 ∼ 1011 cm−3. The higher density implies a small line-emitting area of ∼1% relative to the planetary surface. This favours magnetospheric accretion, a case potentially strengthened by the presence of blueshifted emission in the line profiles.
Conclusions. High-resolution spectroscopy offers the opportunity to resolve line profiles, which are crucial for studying the accretion process in depth. The super-Jovian protoplanet Delorme 1 (AB)b is still accreting at ∼40 Myr. Thus, Delorme 1 belongs to the growing family of ‘Peter Pan disc’ systems with (a) protoplanetary and/or circumplanetary disc(s) far beyond the typically assumed disc lifetimes. Further observations of this benchmark companion and its presumed disc(s) will help answer key questions about the accretion geometry in PMCs.
GaiaData Release 3
Authors: Rimoldini Lorenzo , Holl Berry , Gavras Panagiotis , Audard Marc , De Ridder Joris , Mowlavi Nami , Nienartowicz Krzysztof , Jevardat de Fombelle Grégory , Lecoeur-Taïbi Isabelle , Karbevska Lea , Evans Dafydd W. , Ábrahám Péter , Carnerero Maria I. , Clementini Gisella , Distefano Elisa , Garofalo Alessia , García-Lario Pedro , Gomel Roy , Klioner Sergei A. , Kruszyńska Katarzyna , Lanzafame Alessandro C. , Lebzelter Thomas , Marton Gábor , Mazeh Tsevi , Molinaro Roberto , Panahi Aviad , Raiteri Claudia M. , Ripepi Vincenzo , Szabados László , Teyssier David , Trabucchi Michele , Wyrzykowski Łukasz , Zucker Shay , Eyer Laurent 
Published: January 2023

Context.GaiaDR3 contains 1.8 billion sources withG-band photometry, 1.5 billion of which withGBPandGRPphotometry, complemented by positions on the sky, parallax, and proper motion. The median number of field-of-view transits in the three photometric bands is between 40 and 44 measurements per source and covers 34 months of data collection.Aims.We pursue a classification of Galactic and extra-galactic objects that are detected as variable byGaiaacross the whole sky.Methods.Supervised machine learning (eXtreme Gradient Boosting and Random Forest) was employed to generate multi-class, binary, and meta-classifiers that classified variable objects with photometric time series in theG,GBP, andGRPbands.Results.Classification results comprise 12.4 million sources (selected from a much larger set of potential variable objects) and include about 9 million variable stars classified into 22 variability types in the Milky Way and nearby galaxies such as the Magellanic Clouds and Andromeda, plus thousands of supernova explosions in distant galaxies, 1 million active galactic nuclei, and almost 2.5 million galaxies. The identification of galaxies was made possible by the artificial variability of extended objects as detected byGaia, so they were published in thegalaxy_candidatestable of theGaiaDR3 archive, separate from the classifications of genuine variability (in thevari_classifier_resulttable). The latter contains 24 variability classes or class groups of periodic and non-periodic variables (pulsating, eclipsing, rotating, eruptive, cataclysmic, stochastic, and microlensing), with amplitudes from a few milli-magnitudes to several magnitudes.