A short overview of the MW-Gaia COST Action, objectives and outcomes.
A great fraction of stars are born in binary or multiple systems. For a given stellar population, about a third would be products of binary interaction: stripped stellar companions, semi-detached systems, or stellar mergers. A particularly important phase in the life of a binary is the phase of common envelope, which is responsible for the formation of compact binary systems, such as...
Gaia BH1, the first quiescent black hole detected using data from the Gaia mission presents a challenge to existing binary evolution models due to its unusual characteristics, such as a mass ratio of approximately 0.1 and an orbital period that does not align with typical post-common envelope or non-interacting binary systems.
To investigate its formation, we explore the hypothesis that...
The recent discovery of two detached black hole-star (BH-star) binaries from Gaia's third data release has sparkled interest in understanding the formation mechanisms of these systems. We investigate the formation of these systems by dynamical processes in young open star clusters (SCs) and via isolated binary (IB) evolution, using a combination of direct $N$-body models and population...
Open clusters are the place where a large fraction of massive stars form, evolve, and eventually die, giving birth to stellar-mass black holes. If a significant fraction of black holes receives low (≲ km /s) kicks at birth, even open clusters with low escape velocities can efficiently retain them. Thanks to the exquisite astrometric and photometric measurement by Gaia, we have now the...
The death of massive stars can impart an impulse to the remnant black holes (BHs) and neutron stars (NSs) during supernova explosions. This impulse, also known as a natal kick (NK), can propel the compact objects to substantial space velocities. Understanding the motions perturbed by NKs not only sheds light on the underlying supernova physics but also plays a crucial role in the evolution of...
We report on optical observations of transient objects detected by ESA Gaia, DPAC and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts). Ground-based observations contribute significantly to achieving advances in studies of these objects, especially in their classifying. In 2016, we started to observe Gaia transients using the telescopes with diameters up to 2 m. Our...
Gaia Blue (BP) and Red (RP) Photometer low-resolution spectral data is one of the exciting new products in Gaia Data Release 3 (Gaia DR3). However, analogous LDS (low dispersive spectral data) data also available in numerous historical photographic sky surveys (access after digitization).
My estimate is more than 100 mil LDS star spectra covering time period of more than 60 years in these...
Transients can be defined as astrophysical phenomena whose duration is significantly lower than the typical timescale of the stellar and galactic evolution (from seconds to years in contrast to millions or billions of years). Supernovae, novae, gamma-ray burst,..., are some examples of transient events. In most cases, a fast, multiwavelength characterisation is required to properly ...
Despite the classical interpretation of RR Lyrae as old and metal-poor population II stars, it is well known that metal-rich (up to solar values) RR Lyrae stars exist in the solar vicinity. Thanks to the unprecedented Gaia capabilities (Gaia DR2 and Gaia DR3), we found that the metal-rich RR Lyrae stars are present all over the Galactic disc, well beyond the Solar neighbourhood. The...
The MeerKAT Galactic Plane Survey is a radio continuum survey conducted in the L band (~1.4 GHz) in the Galactic plane, covering a wide range of galactic longitudes, spanning from 0 to 60 degrees and 250 to 360 degrees and mostly within a latitude range of |b| ≤ 1.5 degrees. The survey resulted in the detection of approximately 5×105 sources. In this study, we present our analysis of the...
The metallic-line (Am) stars, classified as chemically peculiar A and early F stars, exhibit unique spectral characteristics with weak Ca II K and Sc lines, along with strong Fe-group features compared to their H-line spectral type. These stars are located in the classical instability zone, where pulsating delta Scuti stars lie. For many years, it was believed that classical Am stars cannot...
The Gaia mission has brought an unprecedented revelation in our understanding of the white dwarf population of the Solar neighborhood. The excellent astrometry and photometry provided by DR2 and eDR3 have unveiled unexpected patterns in the Hertzsprung-Russell diagram, such as the bifurcation or the so-called Q-branch. The analysis and comprehension of such features rely on an accurate...
The study of Young Stellar Clusters (YSCs) has gained relevance in modern astrophysics thanks to the role played by large scale surveys with unprecedented precision. In particular, in the solar neighborhood, multiple star-forming regions will be used to characterize YSCs in terms of kinematics, stellar masses and chemical composition, the main ingredients to understand the dynamical evolution...
Sigma Orionis is an open cluster in the nearest giant star formation site - Orion. Its youth (2-4 Myr), little reddening and relative vicinity make it an important benchmark cluster to study stellar and substellar formation. I will present the first detailed kinematic study of the Sigma Orionis cluster with the Gaia DR3 data. It reveals a clear substructure of this complex region with proper...
In this study, we present an analysis of hot subdwarf stars (hot sds) based on the catalogue provided by Solano et al. (2022). Our analysis includes the utilization of the newly available Gaia DR3 data including the treatment of BP/RP spectra using artificial intelligence (AI) techniques. The AI techniques employed in this study involve Self Organized Maps (SOM) and software tools accessible...
Symbiotic stars are interacting binary systems consisting of a red giant and a hot companion, typically a white dwarf or, in some cases, a neutron star. They constitute unique astrophysical laboratories for the study of various phenomena, including mass transfer and accretion, stellar winds and their collision, formation and collimation of jets, production and destruction of dust, stellar...
Chemical tagging is a promising technique for studying and reconstruct the history of our Galaxy by grouping stars based on their similar chemical compositions. To investigate the feasibility and effectiveness of this technique, we utilized high-resolution observations from the Gaia-ESO Survey with Gaia DR3 data to select open clusters and field stars, obtaining additional information on ages...
The third Gaia data release has provided low resolution BP/RP spectra for nearly 100,000 white dwarfs, the most common stellar remnant. The sheer magnitude of this quantity of data precludes the possibility of performing spectral analysis and type determination by human inspection. However, the current development of machine learning techniques allows us to tackle this issue in a satisfactory...
White dwarfs and binary stars can provide a wealth of information about the origin and evolution of the Galaxy and its constituents. Thanks to Gaia, we now have astrometric and photometric data from an immense number of white dwarfs previously unknown, and the number of binary systems has also increased exponentially. Moreover, the completeness of such systems to a distance of 100 pc is higher...
White dwarfs (WDs) are one of the most common objects in the universe. They are stellar remnants of low and intermediate mass stars, such as the Sun. WDs are compact objects, with typical masses around half a solar mass and planetary sizes. The superb astrometric data provided by Gaia has been a revolution in the field, like the discovery of several cooling branches in the Gaia...
White dwarf stars are the most common end-point of stellar evolution. Therefore, these numerous, old and compact objects provide valuable information on the late stages of stellar evolution, and the structure and evolution of our Galaxy. The ESA Gaia space mission has revolutionized this research field, revealing unexpected features on the color-magnitude diagram for white dwarf stars, and...
The dissociative recombination (DR) together with the competing reactions – ro-vibrational excitation/de-excitation of the hydrogen molecular ion plays a decisive role in astrophysical ionized media: stars and interstellar molecular clouds, early Universe.
Using a stepwise method based on Multichannel Quantum Defect Theory (MQDT) [1], cross sections and rate coefficients have been obtained...
Young massive clusters are excellent laboratories to study the star formation process and structures of galaxies as well as massive stellar evolution. Six red supergiant clusters (RSGCs) recently found in the Scutum-Crux arm can provide insights into starburst history and chemical enrichment in the region. We report that RSGs in RSGC4 (Alicante 8) show peculiar radial velocities and action...
A relevant fraction of massive stars are runaway stars, moving with a significant peculiar velocity with respect to their environment. The runaway origin can be explained by kicks produced in supernova explosions or by dynamical ejection of stars from clusters. Runaway stars can be detected using accurate proper motions and parallaxes such as the ones provided by Gaia. We present here a...
The main goal of MW-Gaia is to enhance the scientific exploration of the Gaia satellite results across the community in Europe and beyond. WG5 working group is devoted to impact, inclusiveness and outreach, and one of the workshops organized towards this plan is the WG5 School. The program includes four sessions, workshops, hands-on activities covering topics such as public engagement,...
Open clusters are an ideal laboratory to understand star formation and evolution. Open clusters provide an important contribution to the overall mass budget and stellar population properties of the disk, making their study a crucial element in the understanding of the processes that led to the formation of the disk in the Milky Way and in general in spiral galaxies. Gaia Data Releases...
Most stars from in groups which with time disperse, building the field population of their host galaxy. In the Milky Way, open clusters have been continuously forming in the disk up to the present time, providing it with stars spanning a broad range of ages and masses. Observations of the details of cluster dissolution are, however, scarce. One of the main difficulties is obtaining a detailed...
Most stars are thought to be born in groups which later dissolve into the field population of their host galaxy. This dissolution and integration into the field population has long been a topic of interest. For example, Lamers et al (2005) explored this process using the open cluster (OC) age distribution derived from the Kharchenko et al. (2005) OC catalogue. With the advent of the Gaia...
The particularly abundant presence of blue straggler stars (BSS) in Galactic open clusters offers favorable conditions for detailed studies on the statistical properties and the origin of the blue straggler population. With the help of Gaia DR3, the number of identified open clusters continuously increases, and the determination of star cluster members is more reliable. We performed a...
The scale height of the spatial distribution of open clusters in the Milky Way exhibits a well known increase with age. This increase is usually attributed, in a vague way, to disc heating mechanisms similar to those that act on individual stars. In this contribution, we address the evolution of the scale height of open clusters from a different angle, as an effect of the disruption of...
We investigated the stellar mass function and the binary fraction of 114 nearby (within 500pc) open clusters (OCs) using the high-precision photometric data from Gaia DR3. We estimate the mass of member stars by using ridge lines (RL) that are better in line with the observed CMD, thus obtaining more reasonable stellar mass and the binary mass ratio at the low mass region. By analyzing the...
With the advent of Gaia and its all-sky accurate astrometry and photometry for almost two billion sources, a broad interest in open clusters (OCs) has resurged, having become the subject of active research.
While in pre-Gaia times, there were two main reference catalogues of open clusters (Dias et al. 2002, and Kharchenko et al. 2013), the wealth of Gaia data together with recent...
We calibrated the atmospheric parameters provided by the GSP-Phot module from Gaia DR3 using a deliberately selected sample of open clusters in the solar neighborhood. We used Padova isochrone models to estimate the theoretical atmospheric parameters of cluster members and obtained the calibration expression by fitting the deviation between observed and theoretical values. Our results show...
We systematically searched for open clusters in the solar neighborhood within 500 pc using pyUPMASK and HDBSCAN clustering algorithms based on Gaia DR3. Taking into consideration that the physical size for most open clusters is less than 50 pc, we adopted a slicing approach for different distance shells and identified 324 neighboring open clusters, including 223 reported open clusters and 101...
Open clusters (OCs) play a fundamental role in understanding star formation, evolution, and the Milky Way's structure. The ESA space-based mission Gaia has significantly improved our knowledge of OCs and the Milky Way through precise astrometric and photometric data. The main objective of this research is to construct an extensive sample of estimated OC masses using Gaia DR3. We analyze 2880...
Under various initial conditions, open star clusters serve as valuable laboratories for studying stellar evolution and its outcomes. The Gaia mission has significantly advanced our understanding of the Milky Way through precise astrometric data, while the Javalambre-Photometric Local Universe Survey (J-PLUS) offers extensive multiband photometric information. In this study, we investigate a...
The Gaia third data release (DR3) includes the mean reflectance spectra of 60 518 asteroids at visible wavelengths (0.374–1.05 μm), which is a 10-fold increase in the number of known asteroid spectra (Galluccio et al. 2022). This huge increase in the number of available asteroid spectra provides more detailed distributions of various taxonomies across the Solar System and thus expands our...
Photometric inversion is a technique that has been used for several decades to infer the shape and spin properties of asteroids [1]. Inversion methods have extensively been applied to ground- based observations of asteroids [2], but the high- precision data provided by the Gaia mission has enabled more detailed studies of these objects.
Previous data releases have demonstrated the usefulness...
The recent advancement of observational capabilities, particularly with the addition of Gaia observations, has brought significant improvements in the determination of orbital parameters for Small Solar System bodies. In this study, we investigate the impact of incorporating Gaia Data Release 3 (DR3) into the orbit determination process, with a specific focus on the photocenter-barycenter...
We present the physical models of asteroids, their shapes, sense of
rotation, and spectral classes using Gaia DR3. The shape models were
determined using the lightcurve inversion method with the combination of
dense photometric data from the Astronomical Station Vidojevica in
Serbia and sparse data from the Gaia mission.
For obtaining asteroid low-resolution shapes, using sparse...
Our work aims to determine the shape models of a few asteroids, derived by using a combination of our dense photometric data with the sparse data provided by the database AstDys and as well as by the GAIA mission. These sparse data help us in gaining additional information for the asteroids with a small number of lightcurves and are in favor of the required observational time. Unlike the...
More than fifty years ago, Lin & Shu (1964), Lin & Shu (1966), Lin et al. (1969), and Shu (1970), published their basic, asymptotic theory of spiral sound-like density waves (or a `breathing mode of collective oscillations'), developing in the disk of a rotationally flattened galaxy, by solving both gas-dynamic and Vlasov-Poisson equations for a 2D mass distribution. The theoretical concept of...
The so-called action variables are specific functions of the positions and velocities that remain constant along the stellar orbit. The astrometry provided by Gaia Early Data Release 3 (EDR3), combined with the velocities inferred from the Radial Velocity Spectrograph (RVS) spectra of Gaia DR3, allows for the estimation of the actions and orbital parameters for the largest volume of stars to...
Decoding the key dynamical processes that shape the Galactic disk structure is crucial for reconstructing the Milky Way's evolution history. The second Gaia data release uncovers a new wave pattern in the L_Z-V_R space accompanied by a richness of phase space substructures, signifying the Galactic disk in dynamical disequilibrium. However, its formation mechanism remains elusive due to the...
Galactic stellar populations are good tracers of the history of the Milky Way. Their study via Gaia astrometric and photometric data should allow to pinpoint the star formation history (SFH) in the disc and halo in a self-consistent dynamical model. Population synthesis models are efficient tools to measure the SFH from the distribution of the stars in the Hess diagram, thanks to different...
The Gaia mission has produced an extraordinary amount of high quality photometric data for the whole sky and has contributed dramatically to advancing our understanding of the Milky Way. In particular, its data can be used to calibrate population synthesis models of our galaxy, aiming to reduce the gap between simulations and observations.
We present here a study of the star formation...
The Milky Way (MW) experienced several merger events which left their imprints on the stellar halo. In particular, it is known that a major merger happened during the Galaxy’s first Gyrs. In order to fully understand the effects of such an event, we need to know the chemical and dynamical characteristics of the young MW, i.e. before the major merger event, and the accreted satellite. For this...
Determining the circular velocity curve of a galaxy is a powerful tool for studying its overall properties. One can fit a potential and determine the dark matter distribution and density and the virial mass of the system.
One way of determining the rotation curve is through Jeans equations (Eilers et al. 2019, Ou et al. 2023). However, when using Jeans equations one needs to assume...
New 3D kinematic maps are derived based on Gaia DR3 proper motions and line-of-sight velocities for red giant branch stars, but now, unlike those published in Gaia Collaboration, Drimmel, Romero-Gómez+2022, taking into account the correlations between the proper motions, which contribute to the correlations between the derived kinematic variables. The large-scale correlations between the...
A-type stars are intrinsically bright, moderately numerous and kinetically warm. They trace the Galactic disk evolution at intermediate ages (0.3-1.0 Gyr), so they fill the gap between younger OB stars and older red giants. We present a catalogue of A-type stars selected in the northern Galactic plane (30º≤l≤215º and |b|≤5º) using photometry from the INT Galactic Plane Survey (IGAPS). It...
The vertical phase-space spiral (snail) is a direct sign of dis-equilibrium of Milky Way's disc. Nevertheless, the wrapping of the phase snail contains the information of the vertical potential. We propose a novel method to measure the vertical potential utilizing the intersections between the snail and $z$/$V_{z}$ axes, for which we know the maximum vertical heights ($Z_{max}$) or the maximum...
We use the Besançon Galaxy Model Fast Approximate Simulations (BGM FASt) framework together with the Approximate Bayesian Computation (ABC) algorithm to derive the posterior probability distribution function of the parameters defining the initial mass function (IMF) and the star formation history (SFH) in the solar neighbourhood. We propose new strategies to unveil the influence of some BGM...
Age is arguably the stellar fundamental parameters that is most difficult to obtain for most stars. Over the last few years, many studies have found empirical relationships between the abundance of a star and its isochrone age, known as chemical clocks. We present a new catalogue of spectroscopic stellar ages for 180,000 red-giant stars observed by the APOGEE survey with a median statistical...
The classical Cepheids are variable stars with relatively young ages (<300 Myr). Their tight period-luminosity relation provides highly accurate distance estimates. By combining recent measurements of proper motions from Gaia EDR3, radial velocities from Gaia DR3, and Cepheid distances, it is possible to study the details of the phase space distribution of this population. In my talk, I will...
The warp is a well-known undulation of the Milky Way disc. Its structure has been widely studied, but only since Gaia DR2 has it been possible to reveal its kinematic signature beyond the solar neighbourhood. In this work we will present an analysis of the warp's structure by means of a Fourier decomposition in vertical high ($Z$) and vertical velocity ($V_z$) traced by Cepheids. We find a...
Understanding the structure and formation of our Milky Way galaxy is one of the key goals in the field of Galactic astronomy. The study of disk morphology provides valuable insights into the processes that have shaped our galaxy over time. While our location within the disc allows for detailed observations of stars, this position also limits our ability to gain a clearer view of its structure....
Gaia DR3 provided the community with one million RVS spectra covering the CaII triplet region, similarly to the RAVE spectra. One third of the spectra have a signal-to-noise ratio from 15 to 25 per pixel. Gaia also provides XP spectra/coefficients in DR3. We aim to leverage versatility/capabilities of machine learning techniques for combining
the full set of Gaia products for supercharged...
Stellar ages are of utmost importance for understanding the chemical and dynamical evolution of the Milky (the so called age-metallicity and age-velocity dispersion relations, respectively) as well as to understand the physical properties of its stellar members (e.g. the age-rotation-activity relation of low-mass main sequence stars). However, estimating the ages of stars is a difficult...
We present a chemodynamical analysis of a large sample across the whole disk selected from Gaia-XP-spectra-derived dataset. When dividing the sample into a subsequent of annuluses, a universal chemodynamical trend exists from the disk to the bulge in the row normalized density map in the azimuthal velocity $V_\phi$ and metallicity [M/H] space is found, that is, a V-shaped structure stacked...
The abundance of alpha and neutron-capture elements provide an important fossil signature in Galactic archaeology for tracing the chemical evolution of the Milky Way stellar populations. The combination with the astrometry and photometry from the Gaia data releases allow us to build an accurate time evolving chemodynamical picture of the Galaxy with unprecedented detail. We employ the...
What is the probability that an astronomical object of certain properties enters the Gaia catalogue (or not)? The GaiaUnlimited project aims to enable the full potential of Gaia by characterising its survey selection function, as well as for different subsamples of the data, which are key ingredients in most statistical studies of the Milky Way. By comparing Gaia with deeper imaging from the...
Despite its discovery almost 30 years ago and its subsequent mapping of its core and tidal tails, the progenitor mass of Sagittarius is still highly uncertain/debated, spanning almost two orders of magnitudes!
On the one hand, recent observations of the chemo-dynamical structure of Sgr's stellar stream and structure of the outer disc favour a massive progenitor with $>6\times10^{10}\,...
The Large Magellanic Cloud (LMC) turns out to be a unique and impressive test laboratory thanks to the latest Gaia Data Release 3. Being the closest galaxy in the Local Group, Gaia proper motions and line-of-sight velocities allow it to make 3D velocity maps for the first time (Jiménez-Arranz+23) and endeavour dynamical studies in detail, such as the determination of the LMC bar pattern speed...
Gaia Data Release 2 revealed that the Milky Way contains significant indications of departures from equilibrium in the form of asymmetric features in the phase space density of stars in the Solar neighbourhood. One such feature is the z-vz phase spiral, interpreted as the response of the disc to the influence of a perturbation perpendicular to the disc plane, which could be external (e.g. a...
Radial abundance gradients in the Galactic disc are one of the most important observational constraints to study the chemical evolution of the Milky Way galaxy and also other galaxies in the universe. The radial gradient is the result of many physical processes that occur since the formation of the Galaxy, as e.g. the infalling gas to form the disc, the star formation history, radial gas...
We map chemical inhomogeneities in the Milky Way’s disc out to a distance of ~4 kpc from the Sun, using different samples of bright giant stars in Gaia Data Release 3. The samples are selected using effective temperatures and surface gravities from the GSP-Spec module, and they are expected to trace stellar populations of a different typical age. The cool (old) giants exhibit a relatively...
Our understanding of the Milky Way’s formation history can be refined by analyzing the information encoded in its oldest stellar populations, typically their chemical composition and orbital motion. Having access to such properties is valuable to depict a larger picture of the earliest stages of galactic formation. With the rise of Gaia, an orbital characterization of the different components...
The presence of gaps or regions of small numbers of stars in the main sequence of the Hertzsprung Russell Diagram (HRD) of star clusters has been reported in literature. This is interesting and significant as it could be related to star formation and/or rapid evolution or instabilities. In this paper, using Gaia DR3 photometry and confirmed membership data, we explore the HRD of nine open...
