Astronomisches Rechen–Institut
23 Dec 2008
At least 10-15% of nearby sun-like stars have known Jupiter-mass planets. In contrast, very few planets are found in mature open and globular clusters such as the Hyades and 47 Tuc. We explore here the possibility that this dichotomy is due to the post-formation disruption of planetary systems associated with the stellar encounters in long-lived clusters. One supporting piece of evidence for this scenario is the discovery of freely floating low-mass objects in star forming regions. We use two independent numerical approaches, a hybrid Monte Carlo and a direct NN-body method, to simulate the impact of the encounters. We show that the results of numerical simulations are in reasonable agreement with analytical determinations in the adiabatic and impulsive limits. They indicate that distant stellar encounters generally do not significantly modify the compact and nearly circular orbits. However, moderately close stellar encounters, which are likely to occur in dense clusters, can excite planets' orbital eccentricity and induce dynamical instability in systems which are closely packed with multiple planets. We compute effective cross sections for the dissolution of planetary systems and show that, for all initial eccentricities, dissolution occurs on time scales which are longer than the dispersion of small stellar associations, but shorter than the age of typical open and globular clusters. Although it is much more difficult to disrupt short-period planets, close encounters can excite modest eccentricity among them, such that subsequent tidal dissipation leads to orbital decay, tidal inflation, and even disruption of the close-in planets.
We present photometric and spectroscopic data sets for SN 2020pvb, a Type IIn-P supernova (SN) similar to SNe 1994W, 2005cl, 2009kn and 2011ht, with a precursor outburst detected (PS1 w-band ~ -13.8 mag) around four months before the B-band maximum light. SN 2020pvb presents a relatively bright light curve peaking at M_B = -17.95 +- 0.30 mag and a plateau lasting at least 40 days before it went in solar conjunction. After this, the object is no longer visible at phases > 150 days above -12.5 mag in the B-band, suggesting that the SN 2020pvb ejecta interacts with a dense spatially confined circumstellar envelope. SN 2020pvb shows in its spectra strong Balmer lines and a forest of FeII lines with narrow P Cygni profiles. Using archival images from the Hubble Space Telescope, we constrain the progenitor of SN 2020pvb to have a luminosity of log(L/L_sun) <= 5.4, ruling out any single star progenitor over 50 M_sun. All in all, SN 2020pvb is a Type IIn-P whose progenitor star had an outburst ~ 0.5 yr before the final explosion, the material lost during this outburst is probably playing a role in shaping the physical properties of the supernova.
Giant low-surface-brightness disk galaxies (gLSBGs) are rare objects with disk radii up-to 160 kpc and dynamical masses of an order of up to 1012^{12} MM_{\odot}. Their very existence challenges currently accepted theories of galaxy formation and evolution, as it is difficult to build such large, dynamically cold disks through mergers without destroying them. We present deep MUSE mosaic observations of two nearby gLSBGs with compact elliptical satellites: UGC 1382, which hosts a globally counter-rotating gaseous disk, and AGC 192040, which does not. We analyze properties of ionized gas and present spatially resolved kinematics and metallicity maps; as well as stellar population analysis for the central regions of the galaxies. The radial gradients of gas-phase metallicities are flat for both galaxies. Our estimates of the effective oxygen yield suggest 'passive' gas in the outskirts of both stellar systems that is not involved in star formation. Our observational data indicate that both galaxies experienced mergers several Gyrs ago. However, the scenarios of formation of giant disks appear to be slightly different for these two systems. For AGC 192040 we propose the gas accretion from the filament followed by the intermediate-mass ratio merger with the companion on a prograde orbit. For UGC 1382 multiple gas-rich mergers with companions on retrograde orbits are preferred by the data.
ETH Zurich logoETH ZurichCNRS logoCNRSUniversity of Cambridge logoUniversity of CambridgeTel Aviv University logoTel Aviv UniversityUniversity College London logoUniversity College LondonUniversity of EdinburghUniversidade de LisboaTechnische Universität DresdenKU Leuven logoKU LeuvenRadboud UniversityUniversität HeidelbergUniversity of HelsinkiUppsala UniversityUniversity of Arizona logoUniversity of ArizonaSorbonne Université logoSorbonne UniversitéLeiden University logoLeiden UniversityUniversity of GenevaUniversity of ViennaUniversitat de BarcelonaUniversity of LeicesterObservatoire de ParisUniversité de LiègeINAF - Osservatorio Astrofisico di TorinoUniversité Côte d’AzurUniversity of Groningen logoUniversity of GroningenClemson UniversityLund UniversityUniversidad Nacional Autónoma de MéxicoSwinburne University of TechnologyUniversität HamburgThales Alenia SpaceEuropean Southern Observatory logoEuropean Southern ObservatoryLaboratoire d’Astrophysique de BordeauxSISSACNESUniversity of CalgaryUniversidad de La LagunaIMT AtlantiqueObservatoire de la Côte d’AzurEuropean Space Astronomy Centre (ESAC)Kapteyn Astronomical InstituteObservatoire astronomique de StrasbourgNational Observatory of AthensQueen's University BelfastUniversidade de Santiago de CompostelaINAF – Osservatorio Astronomico di RomaInstituto de Astrofísica de Canarias (IAC)Universidade da CoruñaINAF – Osservatorio Astronomico d’AbruzzoSRON Netherlands Institute for Space ResearchINAF - Osservatorio Astrofisico di CataniaUniversidade de VigoRoyal Observatory of BelgiumINAF- Osservatorio Astronomico di CagliariLeibniz-Institut für Astrophysik Potsdam (AIP)F.R.S.-FNRSTelespazio FRANCEAirbus Defence and SpaceInstituto Galego de Física de Altas Enerxías (IGFAE)Universitat Politècnica de Catalunya-BarcelonaTechSTAR InstituteEuropean Space Agency (ESA)Lund ObservatoryGeneva University HospitalLeiden ObservatoryFinnish Geospatial Research Institute FGICGIAgenzia Spaziale Italiana (ASI)Mullard Space Science LaboratoryInstitut de Ciències del Cosmos (ICCUB)Aurora TechnologyCentro de Supercomputación de Galicia (CESGA)Institut UTINAMGEPISERCOInstitut d’Astronomie et d’AstrophysiqueGMV Innovating Solutions S.L.Space Science Data Center (SSDC)Wallonia Space Centre (CSW)Indra Sistemas S.A.Universit PSL* National and Kapodistrian University of AthensUniversit de ToulouseUniversit Bourgogne Franche-ComtUniversit Libre de BruxellesIstituto Nazionale di Fisica Nucleare INFNMax Planck Institut fr AstronomieUniversit de LorraineUniversit de BordeauxUniversit de StrasbourgUniversit di PadovaINAF Osservatorio Astrofisico di ArcetriINAF Osservatorio Astronomico di PadovaAstronomisches Rechen–InstitutINAF Osservatorio di Astrofisica e Scienza dello Spazio di Bologna
We produce a clean and well-characterised catalogue of objects within 100\,pc of the Sun from the \G\ Early Data Release 3. We characterise the catalogue through comparisons to the full data release, external catalogues, and simulations. We carry out a first analysis of the science that is possible with this sample to demonstrate its potential and best practices for its use. The selection of objects within 100\,pc from the full catalogue used selected training sets, machine-learning procedures, astrometric quantities, and solution quality indicators to determine a probability that the astrometric solution is reliable. The training set construction exploited the astrometric data, quality flags, and external photometry. For all candidates we calculated distance posterior probability densities using Bayesian procedures and mock catalogues to define priors. Any object with reliable astrometry and a non-zero probability of being within 100\,pc is included in the catalogue. We have produced a catalogue of \NFINAL\ objects that we estimate contains at least 92\% of stars of stellar type M9 within 100\,pc of the Sun. We estimate that 9\% of the stars in this catalogue probably lie outside 100\,pc, but when the distance probability function is used, a correct treatment of this contamination is possible. We produced luminosity functions with a high signal-to-noise ratio for the main-sequence stars, giants, and white dwarfs. We examined in detail the Hyades cluster, the white dwarf population, and wide-binary systems and produced candidate lists for all three samples. We detected local manifestations of several streams, superclusters, and halo objects, in which we identified 12 members of \G\ Enceladus. We present the first direct parallaxes of five objects in multiple systems within 10\,pc of the Sun.
Cold gas clouds embedded in a hot, turbulent medium are expected to be short-lived due to disruptive hydrodynamic instabilities. However, radiative cooling might allow such clouds to survive and grow. We present 3D \texttt{Athena++} simulations of clouds with a density contrast of χ=1000\chi = 1000, exploring turbulent Mach numbers M(0.25,0.75)\mathcal{M}\in (0.25, 0.75) and cloud radii chosen to span cooling-to-crushing ratios α[0.001,10]\alpha \in [0.001, 10]. We find a shift in the survival boundary, with cloud survival occurring only when the cooling-to-cloud-crushing ratio (tcool,mix/tcct_{\text{cool,mix}} / t_{\text{cc}}) 0.01\lesssim 0.01, which is lower than the expected boundary of 1\sim 1. This result shows that it is more difficult for higher over-density cold clouds to survive in a turbulent, hot medium, and suggests another `survival criterion'.
We revisit the Quasar Main Sequence (QMS) by investigating the impact of the stellar component from the host galaxy (HG) on the emission line spectra of the active galactic nuclei (AGN). We first detect spectra with broad emission lines using a line ratio method for a sample of \sim3000 high SNR (&gt;20) Black Hole Mapper objects (part of the fifth phase of the Sloan Digital Sky Survey). We then built the Index diagram, a novel diagnostic tool using the zz-corrected spectra, model-free, designed to easily identify spectra with significant stellar HG contributions and to classify the AGN spectra into three categories based on AGN-HG dominance: HG-dominated (HGD), Intermediate (INT), and AGN-dominated (AGND) sources. A colour-zz diagram was used to refine the AGN-HG classification. We subtract the stellar contributions from the HGD and INT spectra before modeling the AGN spectrum to extract the QMS parameters. Our QMS reveals that HGD galaxies predominantly occupy the Population B region with no \rfe, %FWHM\gtrsim4000 \kms, with outliers exhibiting \rfe\ &gt; 1, likely due to HG subtraction residuals and a faint contribution of \hbbc. INT and AGND spectra show similar distributions in the Population A %FWHM(\hbbc)&lt;4000 \kms\ region, while in Population B, %For broader lines, a tail of AGND sources becomes apparent. Cross-matching with radio, infrared, and X-ray catalogs, we find that the strongest radio emitters are associated with HGD and INT groups. Strong X-ray emitters are found in INT and AGND sources, also occupying the AGN region in the WISE colour diagram.
Ionized nebulae provide critical insights into the conditions of the interstellar medium (ISM). Their bright emission lines enable the measurement of physical properties, such as the gas-phase metallicity, across galaxy disks and in distant galaxies. The PHANGS--MUSE survey has produced optical spectroscopic coverage of the central star-forming discs of 19 nearby main-sequence galaxies. Here, we use the H{\alpha} morphology from this data to identify 30,790 distinct nebulae, finding thousands of nebulae per galaxy. For each nebula, we extract emission line fluxes and, using diagnostic line ratios, identify the dominant excitation mechanism. A total of 23,244 nebulae (75%) are classified as HII regions. The dust attenuation of every nebulae is characterised via the Balmer decrement and we use existing environmental masks to identify their large scale galactic environment (centre, bar, arm, interarm and disc). Using strong-line prescriptions, we measure the gas-phase oxygen abundances (metallicity) and ionization parameter for all HII regions. With this new catalogue, we measure the radial metallicity gradients and explore second order metallicity variations within each galaxy. By quantifying the global scatter in metallicity per galaxy, we find a weak negative correlation with global star formation rate and stronger negative correlation with global gas velocity dispersion (in both ionized and molecular gas). With this paper we release the full catalogue of strong line fluxes and derived properties, providing a rich database for a broad variety of ISM studies.
We provide APASS photometry in the Landolt BV and Sloan g'r'i' bands for all the 425,743 stars included in the latest 4th RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as error of the mean of data obtained and separately calibrated over a median of 4 distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014 and 0.021 mag for B, V, g', r' and i' band, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process, and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been chi2 fitted to a densely populated synthetic photometric library designed to widely explore in temperature, surface gravity, metallicity and reddening. Resulting Teff and E(B-V), computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process it is found that the reddening caused by an homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E(B-V,poles)=0.036 +/- 0.002 at the galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b|>=25 deg.
We combine archival HST and new JWST imaging data, covering the ultraviolet to mid-infrared regime, to morphologically analyze the nuclear star cluster (NSC) of NGC 628, a grand-design spiral galaxy. The cluster is located in a 200 pc x 400 pc cavity, lacking both dust and gas. We find roughly constant values for the effective radius (r_eff ~ 5 pc) and ellipticity ({\epsilon} ~ 0.05), while the Sérsic index (n) and position angle (PA) drop from n ~ 3 to ~ 2 and PA ~ 130° to 90°, respectively. In the mid-infrared, r_eff ~ 12pc, {\epsilon} ~ 0.4, and n ~ 1-1.5, with the same PA ~ 90°. The NSC has a stellar mass of log10 (M_nsc / M_Sun) = 7.06 +- 0.31, as derived through B-V, confirmed when using multi-wavelength data, and in agreement with the literature value. Fitting the spectral energy distribution, excluding the mid-infrared data, yields a main stellar population's age of (8 +- 3) Gyr with a metallicity of Z = 0.012 +- 0.006. There is no indication of any significant star formation over the last few Gyr. Whether gas and dust were dynamically kept out or evacuated from the central cavity remains unclear. The best-fit suggests an excess of flux in the mid-infrared bands, with further indications that the center of the mid-infrared structure is displaced with respect to the optical center of the NSC. We discuss five potential scenarios, none of them fully explaining both the observed photometry and structure.
Due to their scarcity, microlensing events in the Galactic disk are of great interest and high-cadence photometric observations, supplemented by spectroscopic follow-up, are necessary for constraining the physical parameters of the lensing system. In particular, a precise estimate of the source characteristics is required to accurately measure the lens distance and mass. We conducted a spectroscopic follow-up of microlensing event Gaia19bld to derive the properties of the microlensing source and, ultimately, to estimate the mass and distance of the lens. We obtained low- and high-resolution spectroscopy from multiple sites around the world during the course of the event. The spectral lines and template matching analysis has led to two independent, consistent characterizations of the source. We found that the source is a red giant located at about 8.5 kpc from the Earth. Combining our results with the photometric analysis has led to a lens mass of Ml=1.1 M at a distance of D l = 5.5 kpc. We did not find any significant blend light in the spectra (with an upper detection limit of V < 17 mag), which is in agreement with photometric observations. Therefore, we cannot exclude the possibility that the lens is a main-sequence star. Indeed, we predict in this scenario a lens brightness of V about 20 mag, a value that would make it much fainter than the detection limit.
We present the Physics at High Angular resolution in Nearby GalaxieS (PHANGS)-AstroSat atlas, which contains ultraviolet imaging of 31 nearby star-forming galaxies captured by the Ultraviolet Imaging Telescope (UVIT) on the AstroSat satellite. The atlas provides a homogeneous data set of far- and near-ultraviolet maps of galaxies within a distance of 22 Mpc and a median angular resolution of 1.4 arcseconds (corresponding to a physical scale between 25 and 160 pc). After subtracting a uniform ultraviolet background and accounting for Milky Way extinction, we compare our estimated flux densities to GALEX observations, finding good agreement. We find candidate extended UV disks around the galaxies NGC 6744 and IC 5332. We present the first statistical measurements of the clumping of the UV emission and compare it to the clumping of molecular gas traced with ALMA. We find that bars and spiral arms exhibit the highest degree of clumping, and the molecular gas is even more clumped than the FUV emission in galaxies. We investigate the variation of the ratio of observed FUV to Hα\alpha in different galactic environments and kpc-sized apertures. We report that 65%\sim 65 \% varation of the log10\log_{10}(FUV/Hα\alpha) can be described through a combination of dust attenuation with star formation history parameters. The PHANGS-AstroSat atlas enhances the multi-wavelength coverage of our sample, offering a detailed perspective on star formation. When integrated with PHANGS data sets from ALMA, VLT-MUSE, HST and JWST, it develops our comprehensive understanding of attenuation curves and dust attenuation in star-forming galaxies.
CNRS logoCNRSUniversity of Cambridge logoUniversity of CambridgeHeidelberg UniversityTel Aviv University logoTel Aviv UniversityUniversity of EdinburghETH Zürich logoETH ZürichKU Leuven logoKU LeuvenSpace Telescope Science Institute logoSpace Telescope Science InstituteEPFL logoEPFLUniversidad Autónoma de MadridStockholm University logoStockholm UniversityUniversity of HelsinkiUppsala UniversityUniversité de GenèveAalto University logoAalto UniversityAristotle University of ThessalonikiLeiden University logoLeiden UniversityMacquarie UniversityUniversity of GlasgowUniversity of Warwick logoUniversity of WarwickUniversitat de BarcelonaUniversity of LeicesterObservatoire de ParisINAF - Osservatorio Astrofisico di TorinoUniversité Côte d’AzurUniversity of Groningen logoUniversity of GroningenINAFInstituto de Astrofísica de CanariasUniversidad de ChileUniversity of AntioquiaUniversidade de São PauloEuropean Space AgencyEuropean Southern Observatory logoEuropean Southern ObservatoryCNESUniversité de MonsNicolaus Copernicus Astronomical CenterObservatoire de la Côte d’AzurFaculdade de Ciências da Universidade de LisboaKapteyn Astronomical InstituteNational Observatory of AthensInstituto de Astrofísica de AndalucíaInstitut d’Estudis Espacials de CatalunyaUniversité de Franche-ComtéESAC, ESAINAF – Osservatorio Astronomico di RomaLeibniz-Institut für Astrophysik PotsdamInstitut d'Astrophysique de ParisINAF - Osservatorio Astrofisico di CataniaU.S. Naval ObservatoryRoyal Observatory of BelgiumFederal University of Technology - ParanáKonkoly ObservatoryTartu ObservatoryLund ObservatoryFinnish Geospatial Research Institute FGISpanish Virtual ObservatoryObservatoire de BesançonUniversité de la SorbonneObservatoire de BordeauxOsservatorio Astrofisico di PadovaTurku Collegium for Science and MedicineUniversité de NiceUniversit di CataniaUniversit catholique de LouvainUniversit Libre de BruxellesINAF Osservatorio Astronomico di CapodimonteMax Planck Institut fr AstronomieUniversit de LorraineUniversit degli Studi di PadovaUniversit de StrasbourgUniversit di TorinoINAF Osservatorio Astrofisico di ArcetriAstronomisches Rechen–InstitutUniversit de MontpellierINAF Osservatorio di Astrofisica e Scienza dello Spazio di BolognaUniversit de Grenoble-AlpesINAF Osservatorio Astronomico di Brera
Gaia DR3 opens a new era of all-sky spectral analysis of stellar populations thanks to the nearly 5.6 million stars observed by the RVS and parametrised by the GSP-spec module. The all-sky Gaia chemical cartography allows a powerful and precise chemo-dynamical view of the Milky Way with unprecedented spatial coverage and statistical robustness. First, it reveals the strong vertical symmetry of the Galaxy and the flared structure of the disc. Second, the observed kinematic disturbances of the disc -- seen as phase space correlations -- and kinematic or orbital substructures are associated with chemical patterns that favour stars with enhanced metallicities and lower [alpha/Fe] abundance ratios compared to the median values in the radial distributions. This is detected both for young objects that trace the spiral arms and older populations. Several alpha, iron-peak elements and at least one heavy element trace the thin and thick disc properties in the solar cylinder. Third, young disc stars show a recent chemical impoverishment in several elements. Fourth, the largest chemo-dynamical sample of open clusters analysed so far shows a steepening of the radial metallicity gradient with age, which is also observed in the young field population. Finally, the Gaia chemical data have the required coverage and precision to unveil galaxy accretion debris and heated disc stars on halo orbits through their [alpha/Fe] ratio, and to allow the study of the chemo-dynamical properties of globular clusters. Gaia DR3 chemo-dynamical diagnostics open new horizons before the era of ground-based wide-field spectroscopic surveys. They unveil a complex Milky Way that is the outcome of an eventful evolution, shaping it to the present day (abridged).
We provide APASS photometry in the Landolt BV and Sloan g'r'i' bands for all the 425,743 stars included in the latest 4th RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as error of the mean of data obtained and separately calibrated over a median of 4 distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014 and 0.021 mag for B, V, g', r' and i' band, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process, and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been chi2 fitted to a densely populated synthetic photometric library designed to widely explore in temperature, surface gravity, metallicity and reddening. Resulting Teff and E(B-V), computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process it is found that the reddening caused by an homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for E(B-V,poles)=0.036 +/- 0.002 at the galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b|>=25 deg.
We present a simple algorithm to switch between NN-body time integrators in a reversible way. We apply it to planetary systems undergoing arbitrarily close encounters and highly eccentric orbits, but the potential applications are broader. Upgrading an ordinary non-reversible switching integrator to a reversible one is straightforward and introduces no appreciable computational burden in our tests. Our method checks if the integrator during the time step violates a time-symmetric selection condition and redoes the step if necessary. In our experiments a few percent of steps would have violated the condition without our corrections. By eliminating them the algorithm avoids long-term error accumulation, of several orders magnitude in some cases.
Context. Galaxies fly inside galaxy clusters and ram pressure by the ICM can remove a large amount of the ISM from the galaxy, and deposit the gas in the ICM. The ISM decoupled from the host galaxy leaves a long trail following the moving galaxy. Such long trails track the galaxy motion and can be detected with sensitive data in Halpha. Aims. We study the Halpha tail trailing NGC 4569 in the Virgo cluster. Methods. The initial discovery was made with the deep Halpha imaging data with CFHT, from the VESTIGE project. The follow-up spectroscopic observations were made with APO/DIS, MMT/Binospec and CFHT/SITELLE. Results. Besides the known 80 kpc Halpha tail downstream of NGC 4569, the deep Halpha imaging data allow the Halpha tail detected to at least 230 kpc from the galaxy. More importantly, the Halpha clumps implied from the imaging data are confirmed with the spectroscopic data. The Halpha clumps show a smooth radial velocity gradient across about 1300 km/s, eventually reaching the velocity of the cluster. We build a simple model to explain the deceleration of stripped clumps and constrain the age to about 0.9 Gyr. Conclusions. This discovery, for the first time, demonstrates the full deceleration process of the stripped ISM. This discovery also showcases the potential with wide-field Halpha survey on galaxy clusters to discover intracluster optical emission-line clouds originated from cluster galaxies. These clouds provide kinematic tracers to the infall history of cluster galaxies and the turbulence in the ICM. They are also excellent multi-phase objects to study the relevant important physical processes.
This paper presents the detailed abundances and r-process classifications of 126 newly identified metal-poor stars as part of an ongoing collaboration, the R-Process Alliance. The stars were identified as metal-poor candidates from the RAdial Velocity Experiment (RAVE) and were followed-up at high spectral resolution (R~31,500) with the 3.5~m telescope at Apache Point Observatory. The atmospheric parameters were determined spectroscopically from Fe I lines, taking into account <3D> non-LTE corrections and using differential abundances with respect to a set of standards. Of the 126 new stars, 124 have [Fe/H]<-1.5, 105 have [Fe/H]<-2.0, and 4 have [Fe/H]<-3.0. Nine new carbon-enhanced metal-poor stars have been discovered, 3 of which are enhanced in r-process elements. Abundances of neutron-capture elements reveal 60 new r-I stars (with +0.3<=[Eu/Fe]<=+1.0 and [Ba/Eu]<0) and 4 new r-II stars (with [Eu/Fe]>+1.0). Nineteen stars are found to exhibit a `limited-r' signature ([Sr/Ba]>+0.5, [Ba/Eu]<0). For the r-II stars, the second- and third-peak main r-process patterns are consistent with the r-process signature in other metal-poor stars and the Sun. The abundances of the light, alpha, and Fe-peak elements match those of typical Milky Way halo stars, except for one r-I star which has high Na and low Mg, characteristic of globular cluster stars. Parallaxes and proper motions from the second Gaia data release yield UVW space velocities for these stars which are consistent with membership in the Milky Way halo. Intriguingly, all r-II and the majority of r-I stars have retrograde orbits, which may indicate an accretion origin.
Gaia Data Release 3 (DR3) provides a wealth of new data products for the astronomical community to exploit, including astrophysical parameters for a half billion stars. In this work we demonstrate the high quality of these data products and illustrate their use in different astrophysical contexts. We query the astrophysical parameter tables along with other tables in Gaia DR3 to derive the samples of the stars of interest. We validate our results by using the Gaia catalogue itself and by comparison with external data. We have produced six homogeneous samples of stars with high quality astrophysical parameters across the HR diagram for the community to exploit. We first focus on three samples that span a large parameter space: young massive disk stars (~3M), FGKM spectral type stars (~3M), and UCDs (~20K). We provide these sources along with additional information (either a flag or complementary parameters) as tables that are made available in the Gaia archive. We furthermore identify 15740 bone fide carbon stars, 5863 solar-analogues, and provide the first homogeneous set of stellar parameters of the Spectro Photometric Standard Stars. We use a subset of the OBA sample to illustrate its usefulness to analyse the Milky Way rotation curve. We then use the properties of the FGKM stars to analyse known exoplanet systems. We also analyse the ages of some unseen UCD-companions to the FGKM stars. We additionally predict the colours of the Sun in various passbands (Gaia, 2MASS, WISE) using the solar-analogue sample.
We present the largest catalog to-date of star clusters and compact associations in nearby galaxies. We have performed a V-band-selected census of clusters across the 38 spiral galaxies of the PHANGS-HST Treasury Survey, and measured integrated, aperture-corrected NUV-U-B-V-I photometry. This work has resulted in uniform catalogs that contain \sim20,000 clusters and compact associations which have passed human inspection and morphological classification, and a larger sample of \sim100,000 classified by neural network models. Here, we report on the observed properties of these samples, and demonstrate that tremendous insight can be gained from just the observed properties of clusters, even in the absence of their transformation into physical quantities. In particular, we show the utility of the UBVI color-color diagram, and the three principal features revealed by the PHANGS-HST cluster sample: the young cluster locus, the middle-age plume, and the old globular cluster clump. We present an atlas of maps of the 2D spatial distribution of clusters and compact associations in the context of the molecular clouds from PHANGS-ALMA. We explore new ways of understanding this large dataset in a multi-scale context by bringing together once-separate techniques for the characterization of clusters (color-color diagrams and spatial distributions) and their parent galaxies (galaxy morphology and location relative to the galaxy main sequence). A companion paper presents the physical properties: ages, masses, and dust reddenings derived using improved spectral energy distribution (SED) fitting techniques.
We present the first spectroscopic abundance determination of iron, alpha-elements (Si, Ca and Ti) and sodium for the Mira variable V1 in the metal-rich globular cluster NGC 5927. We use high-resolution (R~ 28,000), high signal-to-noise ratio (~200) spectra collected with WINERED, a near-infrared (NIR) spectrograph covering simultaneously the wavelength range 0.91--1.35 micron. The effective temperature and the surface gravity at the pulsation phase of the spectroscopic observation were estimated using both optical (V) and NIR time-series photometric data. We found that the Mira is metal-rich ([Fe/H]=-0.55 \pm 0.15) and moderately alpha-enhanced ([alpha/Fe]=0.15 \pm 0.01, sigma=0.2). These values agree quite well with the mean cluster abundances based on high-resolution optical spectra of several cluster red giants available in the literature ([Fe/H]=-0.47 \pm 0.06, [alpha/Fe]=+0.24 \pm 0.05). We also found a Na abundance of +0.35 \pm 0.20 that is higher than the mean cluster abundance based on optical spectra (+0.18 \pm 0.13). However, the lack of similar spectra for cluster red giants and that of corrections for departures from local-thermodynamical equilibrium prevents us from establishing whether the difference is intrinsic or connected with multiple populations. These findings indicate a strong similarity between optical and NIR metallicity scales in spite of the difference in the experimental equipment, data analysis and in the adopted spectroscopic diagnostics.
ETH Zurich logoETH ZurichUniversity of Cambridge logoUniversity of CambridgeUniversity College London logoUniversity College LondonUniversity of EdinburghETH Zürich logoETH ZürichUniversität HeidelbergUppsala UniversityUniversity of ZagrebUniversity of ViennaUniversitat de BarcelonaConsejo Superior de Investigaciones CientíficasUniversity of LeicesterUniversidad Complutense de MadridUniversiteit LeidenObservatoire de ParisUniversité de LiègeINAF - Osservatorio Astrofisico di TorinoUniversity of Groningen logoUniversity of GroningenInstituto de Astrofísica de CanariasUniversidad de ChileEuropean Space AgencyEuropean Southern Observatory logoEuropean Southern ObservatoryInstituto de Astronomía, Universidad Nacional Autónoma de MéxicoObservatoire de la Côte d’AzurInstituto de Astrofísica de Andalucía-CSICUniversité de Franche-ComtéLeibniz-Institut für Astrophysik PotsdamKatholieke Universiteit LeuvenUniversidade da CoruñaINAF - Osservatorio Astrofisico di CataniaUniversidade de VigoRoyal Observatory of BelgiumUniversität BremenTartu ObservatoryLund ObservatoryHungarian Academy of SciencesObservatoire de GenèveINAF–Osservatorio di Astrofisica e Scienza dello Spazio di BolognaWarsaw University ObservatoryUniversidad Nacional de Educaciòn a DistanciaUniversité de BesançonSpace Science Data Center - Italian Space AgencyUniversité PSL, Observatoire de ParisObservatoire de Paris, PSL Research UniversityUniversité LeuvenUniversit catholique de LouvainUniversit de BordeauxUniversit de StrasbourgUniversit de LyonINAF Osservatorio Astrofisico di ArcetriINAF Osservatorio Astronomico di PadovaAstronomisches Rechen–InstitutUniversit de MontpellierUniversit degli Studi di Torino
Gaia Data Release 3 provides novel flux-calibrated low-resolution spectrophotometry for about 220 million sources in the wavelength range 330nm - 1050nm (XP spectra). Synthetic photometry directly tied to a flux in physical units can be obtained from these spectra for any passband fully enclosed in this wavelength range. We describe how synthetic photometry can be obtained from XP spectra, illustrating the performance that can be achieved under a range of different conditions - for example passband width and wavelength range - as well as the limits and the problems affecting it. Existing top-quality photometry can be reproduced within a few per cent over a wide range of magnitudes and colour, for wide and medium bands, and with up to millimag accuracy when synthetic photometry is standardised with respect to these external sources. Some examples of potential scientific application are presented, including the detection of multiple populations in globular clusters, the estimation of metallicity extended to the very metal-poor regime, and the classification of white dwarfs. A catalogue providing standardised photometry for ~220 million sources in several wide bands of widely used photometric systems is provided (Gaia Synthetic Photometry Catalogue; GSPC) as well as a catalogue of 105\simeq 10^5 white dwarfs with DA/non-DA classification obtained with a Random Forest algorithm (Gaia Synthetic Photometry Catalogue for White Dwarfs; GSPC-WD).
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