Gaia Early Data Release 3: Acceleration of the solar system from Gaia astrometry
Gaia Collaboration, S. A. Klioner, F. Mignard, L. Lindegren, U. Bastian, P. J. McMillan, J. Hernández, D. Hobbs, M. Ramos-Lerate, M. Biermann, A. Bombrun, A. de… 展开作者
Gaia Collaboration, S. A. Klioner, F. Mignard, L. Lindegren, U. Bastian, P. J. McMillan, J. Hernández, D. Hobbs, M. Ramos-Lerate, M. Biermann, A. Bombrun, A. de Torres, E. Gerlach, R. Geyer, T. Hilger, U. Lammers, H. Steidelmüller, C. A. Stephenson, A. G. A. Brown, A. Vallenari, T. Prusti, J. H. J. de Bruijne, C. Babusiaux, O. L. Creevey, D. W. Evans, L. Eyer, A. Hutton, F. Jansen, C. Jordi, X. Luri, C. Panem, D. Pourbaix, S. Randich, P. Sartoretti, C. Soubiran, N. A. Walton, F. Arenou, C. A. L. Bailer-Jones, M. Cropper, R. Drimmel, D. Katz, M. G. Lattanzi, F. van Leeuwen, J. Bakker, J. Castañeda, F. De Angeli, C. Ducourant, C. Fabricius, M. Fouesneau, Y. Frémat, R. Guerra, A. Guerrier, J. Guiraud, A. Jean-Antoine Piccolo, E. Masana, R. Messineo, N. Mowlavi, C. Nicolas, K. Nienartowicz, F. Pailler, P. Panuzzo, F. Riclet, W. Roux, G. M. Seabroke, R. Sordo, P. Tanga, F. Thévenin, G. Gracia-Abril, J. Portell, D. Teyssier, M. Altmann, R. Andrae, I. Bellas-Velidis, K. Benson, J. Berthier, R. Blomme, E. Brugaletta, P. W. Burgess, G. Busso, B. Carry, A. Cellino, N. Cheek, G. Clementini, Y. Damerdji, M. Davidson, L. Delchambre, A. Dell'Oro, J. Fernández-Hernández, L. Galluccio, P. García-Lario, M. Garcia-Reinaldos, J. González-Núñez, E. Gosset, R. Haigron, J. -L. Halbwachs, N. C. Hambly, D. L. Harrison, D. Hatzidimitriou, U. Heiter, D. Hestroffer, S. T. Hodgkin, B. Holl, K. Janßen, G. Jevardat de Fombelle, S. Jordan, A. Krone-Martins, A. C. Lanzafame, W. Löffler, A. Lorca, M. Manteiga, O. Marchal, P. M. Marrese, A. Moitinho, A. Mora, K. Muinonen, P. Osborne, E. Pancino, T. Pauwels, A. Recio-Blanco, P. J. Richards, M. Riello, L. Rimoldini, A. C. Robin, T. Roegiers, J. Rybizki, L. M. Sarro, C. Siopis, M. Smith, A. Sozzetti, A. Ulla, E. Utrilla, M. van Leeuwen, W. van Reeven, U. Abbas, A. Abreu Aramburu, S. Accart, C. Aerts, J. J. Aguado, M. Ajaj, G. Altavilla, M. A. Álvarez, J. Álvarez Cid-Fuentes, J. Alves, R. I. Anderson, E. Anglada Varela, T. Antoja, M. Audard, D. Baines, S. G. Baker, L. Balaguer-Nú\-nez, E. Balbinot, Z. Balog, C. Barache, D. Barbato, M. Barros, M. A. Barstow, S. Bartolomé, J. -L. Bassilana, N. Bauchet, A. Baudesson-Stella, U. Becciani, M. Bellazzini, M. Bernet, S. Bertone, L. Bianchi, S. Blanco-Cuaresma, T. Boch, D. Bossini, S. Bouquillon, L. Bramante, E. Breedt, A. Bressan, N. Brouillet, B. Bucciarelli, A. Burlacu, D. Busonero, A. G. Butkevich, R. Buzzi, E. Caffau, R. Cancelliere, H. Cánovas, T. Cantat-Gaudin, R. Carballo, T. Carlucci, M. I Carnerero, J. M. Carrasco, L. Casamiquela, M. Castellani, A. Castro-Ginard, P. Castro Sampol, L. Chaoul, P. Charlot, L. Chemin, A. Chiavassa, G. Comoretto, W. J. Cooper, T. Cornez, S. Cowell, F. Crifo, M. Crosta, C. Crowley, C. Dafonte, A. Dapergolas, M. David, P. David, P. de Laverny, F. De Luise, R. De March, J. De Ridder, R. de Souza, P. de Teodoro, E. F. del Peloso, E. del Pozo, A. Delgado, H. E. Delgado, J. -B. Delisle, P. Di Matteo, S. Diakite, C. Diener, E. Distefano, C. Dolding, D. Eappachen, H. Enke, P. Esquej, C. Fabre, M. Fabrizio, S. Faigler, G. Fedorets, P. Fernique, A. Fienga, F. Figueras, C. Fouron, F. Fragkoudi, E. Fraile, F. Franke, M. Gai, D. Garabato, A. Garcia-Gutierrez, M. García-Torres, A. Garofalo, P. Gavras, P. Giacobbe, G. Gilmore, S. Girona, G. Giuffrida, A. Gomez, I. Gonzalez-Santamaria, J. J. González-Vidal, M. Granvik, R. Gutiérrez-Sánchez, L. P. Guy, M. Hauser, M. Haywood, A. Helmi, S. L. Hidalgo, N. Hładczuk, G. Holland, H. E. Huckle, G. Jasniewicz, P. G. Jonker, J. Juaristi Campillo, F. Julbe, L. Karbevska, P. Kervella, S. Khanna, A. Kochoska, G. Kordopatis, A. J. Korn, Z. Kostrzewa-Rutkowska, K. Kruszyńska, S. Lambert, A. F. Lanza, Y. Lasne, J. -F. Le Campion, Y. Le Fustec, Y. Lebreton, T. Lebzelter, S. Leccia, N. Leclerc, I. Lecoeur-Taibi, S. Liao, E. Licata, H. E. P. Lindstrøm, T. A. Lister, E. Livanou, A. Lobel, P. Madrero Pardo, S. Managau, R. G. Mann, J. M. Marchant, M. Marconi, M. M. S. Marcos Santos, S. Marinoni, F. Marocco, D. J. Marshall, L. Martin Polo, J. M. Martín-Fleitas, A. Masip, D. Massari, A. Mastrobuono-Battisti, T. Mazeh, S. Messina, D. Michalik, N. R. Millar, A. Mints, D. Molina, R. Molinaro, L. Molnár, P. Montegriffo, R. Mor, R. Morbidelli, T. Morel, D. Morris, A. F. Mulone, D. Munoz, T. Muraveva, C. P. Murphy, I. Musella, L. Noval, C. Ordénovic, G. Orrù, J. Osinde, C. Pagani, I. Pagano, L. Palaversa, P. A. Palicio, A. Panahi, M. Pawlak, X. Pe\-nalosa Esteller, A. Penttilä, A. M. Piersimoni, F. -X. Pineau, E. Plachy, G. Plum, E. Poggio, E. Poretti, E. Poujoulet, A. Prša, L. Pulone, E. Racero, S. Ragaini, M. Rainer, C. M. Raiteri, N. Rambaux, P. Ramos, P. Re Fiorentin, S. Regibo, C. Reylé, V. Ripepi, A. Riva, G. Rixon, N. Robichon, C. Robin, M. Roelens, L. Rohrbasser, M. Romero-Gómez, N. Rowell, F. Royer, K. A. Rybicki, G. Sadowski, A. Sagristà Sellés, J. Sahlmann, J. Salgado, E. Salguero, N. Samaras, V. Sanchez Gimenez, N. Sanna, R. Santoveña, M. Sarasso, M. Schultheis, E. Sciacca, M. Segol, J. C. Segovia, D. Ségransan, D. Semeux, H. I. Siddiqui, A. Siebert, L. Siltala, E. Slezak, R. L. Smart, E. Solano, F. Solitro, D. Souami, J. Souchay, A. Spagna, F. Spoto, I. A. Steele, M. Süveges, L. Szabados, E. Szegedi-Elek, F. Taris, G. Tauran, M. B. Taylor, R. Teixeira, W. Thuillot, N. Tonello, F. Torra, J. Torray, C. Turon, N. Unger, M. Vaillant, E. van Dillen, O. Vanel, A. Vecchiato, Y. Viala, D. Vicente, S. Voutsinas, M. Weiler, T. Wevers, Ł. Wyrzykowski, A. Yoldas, P. Yvard, H. Zhao, J. Zorec, S. Zucker, C. Zurbach, T. Zwitter
Context. Gaia Early Data Release 3 (Gaia EDR3) provides accurate astrometry for about 1.6 million compact (QSO-like) extragalactic sources, 1.2 million of which have the best-quality five-parameter astrometric solutions.
Aims. The proper motions of QSO-like sources are used to reveal a systematic pattern due to the acceleration of the solar system barycentre with respect to the rest frame of the Universe. Apart from being an important scientific result by itself, the acceleration measured in this way is a good quality indicator of the Gaia astrometric solution. Methods. The effect of the acceleration is obtained as a part of the general expansion of the vector field of proper motions in Vector Spherical Harmonics (VSH). Various versions of the VSH fit and various subsets of the sources are tried and compared to get the most consistent result and a realistic estimate of its uncertainty. Additional tests with the Gaia astrometric solution are used to get a better idea on possible systematic errors in the estimate.
Results. Our best estimate of the acceleration based on Gaia EDR3 is $(2.32 \pm 0.16) \times 10^{-10}$ m s${}^{-2}$ (or $7.33 \pm 0.51$ km s$^{-1}$ Myr${}^{-1}$) towards $α= 269.1^\circ \pm 5.4^\circ$, $δ= -31.6^\circ \pm 4.1^\circ$, corresponding to a proper motion amplitude of $5.05 \pm 0.35$ $μ$as yr${}^{-1}$. This is in good agreement with the acceleration expected from current models of the Galactic gravitational potential. We expect that future Gaia data releases will provide estimates of the acceleration with uncertainties substantially below 0.1 $μ$as yr${}^{-1}$.
Access to microarcsecond astrometry is now routine in the radio, infrared, and optical domains. In particular the publication of the second data release from the Gaia mission made it possible for every astronomer to work with easily accessible, high-precision astrometry for 1.7 billion sources to 21st magnitude over the full sky. * Gaia provides splendid astrometry but at the limits of the data small systematic errors are present. A good understanding of the Hipparcos/Gaia astrometry concept, and of the data collection and processing, provides insights into the origins of the systematic errors…
We compare the parallaxes of stars from VLBI astrometry in the literature to those in the Gaia DR2 catalog. Our full sample contains young stellar objects, evolved AGB stars, pulsars and other radio stars. Excluding AGB stars, which show significant discrepancies between Gaia and VLBI parallaxes, and stars in binary systems, we obtain an average, systematic, parallax offset of $-75 \pm 29~μ$as for Gaia DR2, consistent with their estimate of a parallax zero-point between $-100$ and 0 $μ$as.
During the Hipparcos mission in September 1992, I presented a concept for using direct imaging on CCDs in scanning mode in a new and very powerful astrometric satellite, Roemer. The Roemer concept with larger aperture telescopes for higher accuracy was developed by ESA and a mission was approved in 2000, expected to be a million times better than Hipparcos. The present name Gaia for the mission reminds of an interferometric option also studied in the period 1993-97, and the evolution of optics and detection in this period is the main subject of the present report. The transition from an interf…
Identifying compact symmetric objects with high-precision VLBI and Gaia astrometry
Shanghai Astronomical Observatory（上海天文台）；Key Laboratory of Radio Astronomy, CAS（中国科学院射电天文重点实验室）；State Key Laboratory of Radio Astronomy and Technology（射电天文与技术国家重点实验室）；Konkoly Observatory（孔科利天文台）；HUN-REN Research Center for Astronomy and Earth Sciences（匈牙利研究与创新天文学与地球科学研究中心）；CSFK（孔科利天文台研究中心）；MTA Centre of Excellence（匈牙利科学院卓越中心）；Institute of Physics and Astronomy, ELTE Eötvös Loránd University（罗兰大学物理与天文研究所）；Xinjiang Astronomical Observatory, CAS（中国科学院新疆天文台）；Netherlands Institute for Radio Astronomy, ASTRON（荷兰射电天文研究所）
In this paper, we present astrophysical parameters of the open cluster King 13 based on the VI CCD and 2MASS JHKs photometric data. This is a poorly studied cluster, for which new results have been found in the present work. To identify probable members, we use proper motion data from Gaia DR2 catalogue. The mean proper motion of the cluster is determined as -2.8 \pm 0.2 and -0.88 \pm 0.14 mas yr{-1} and cluster extent is derived as 3'.2. Using color-magnitude diagrams, we estimate the age and distance of the cluster as 510 \pm 60 Myr and 3.84 \pm 0.15 kpc respectively. Interstellar reddening …
With the publication of Gaia DR2, 1.3 billion stars now have public parallax and proper motion measurements. In this contribution, we compare the results for sources that have both optical and radio measurements, focusing on circumstellar masers. For these large, variable and bright AGB stars, the VLBI astrometry results can be more robust. Moreover, there are a number of applications where VLBI astrometry provides unique data for studying stellar populations and Galactic structure. The BeSSel project not only provides parallax and proper motions at much larger distances than Gaia can reach, b…
We use stellar proper motions (PM) from Gaia Data Release 2 for studying the internal kinematics of Milky Way globular clusters. In addition to statistical measurement errors, there are significant spatially correlated systematic errors, which cannot be ignored when studying the internal kinematics. We develop a mathematically consistent procedure for incorporating the spatial correlations in any model-fitting approach, and use it to determine rotation and velocity dispersion profiles of a few dozen clusters. We confirm detection of rotation in the sky plane for ~10 clusters reported in previo…
Gaia DR2 published positions, parallaxes and proper motions for an unprecedented 1,331,909,727 sources, revolutionising the field of Galactic dynamics. We complement this data with the Astrometry Spread Function (ASF), the expected uncertainty in the measured positions, proper motions and parallax for a non-accelerating point source. The ASF is a Gaussian function for which we construct the 5D astrometric covariance matrix as a function of position on the sky and apparent magnitude using the Gaia DR2 scanning law and demonstrate excellent agreement with the observed data. This can be used to a…
The study of the kinematics of globular clusters (GCs) offers the possibility of unveiling their long term evolution and uncovering their yet unknown formation mechanism. Gaia DR2 has strongly revitalized this field and enabled the exploration of the 6D phase-space properties of Milky Way GCs, thanks to precision astrometry. However, to fully leverage on the power of precision astrometry, a thorough investigations of the data is required. In this contribution, we show that the study of the mean radial proper motion profiles of GCs offers an ideal benchmark to assess the presence of systematics…
We present CCD $UBVI$ photometric study of poorly studied intermediate age open cluster SAI 35 (Juchert 20) for the first time. To accomplish this study, we also used LAMOST DR5, 2MASS, and Gaia EDR3 databases. We identified 214 most probable cluster members with membership probability higher than 50%. The mean proper motion of the cluster is found as μ_αcosδ=1.10 \pm 0.01 and μ_δ=-1.66 \pm 0.01 mas/yr. We find the normal interstellar extinction law using the various two-color diagrams. The age, distance, reddening, and radial velocity of the cluster are estimated to be 360 \pm 40 Myr, 2.9 \pm…
Recent advances in VLBI have led to astrometric accuracy exceeding that of the Gaia mission goals. This chapter describes some important astrophysical problems that can be addressed with sub-milliarcsecond imaging and micro-arcsecond astrometry using the ngVLA with long baselines.
Gaia is the next astrometry mission of the European Space Agency (ESA), following up on the success of the Hipparcos mission. With a focal plane containing 106 CCD detectors, Gaia will survey the entire sky and repeatedly observe the brightest 1,000 million objects, down to 20th magnitude, during its 5-year lifetime. Gaia's science data comprises absolute astrometry, broad-band photometry, and low-resolution spectro-photometry. Spectroscopic data with a resolving power of 11,500 will be obtained for the brightest 150 million sources, down to 17th magnitude. The thermo-mechanical stability of t…
Thanks to its spatial resolution the ESA/Gaia space mission offers a unique opportunity to discover new multiply-imaged quasars and to study the already known lensed systems at sub-milliarcsecond astrometric precisions. In this paper, we address the detection of the known multiply-imaged quasars from the Gaia Data Release 2 and determine the astrometric and photometric properties of the individually detected images found in the Gaia DR2 catalogue. We have compiled an exhaustive list of quasar gravitational lenses from the literature to search for counterparts in the Gaia Data Release 2. We the…
We risk reaching false scientific conclusions if we test our physical theories against subsets of the Gaia catalogue without correcting for the biased process by which stars make it into our sample. In this paper we produce selection functions for three Gaia science samples to enable the community to correct for this bias. We estimate the probability that a source in Gaia EDR3 will have i) a reported parallax and proper motion, ii) an astrometric renormalised unit weight error below 1.4, or iii) a reported radial velocity. These selection functions are estimated as a function of $G$-band appar…
Massive galactic lenses with large Einstein Radii should cause a measurable astrometric microlensing effect, i.e. the light centroid shift due to the motion of the two images. Such a shift in the position of a background star due to microlensing was not included in the $Gaia$ astrometric model, therefore significant deviation should cause $Gaia$'s astrometric parameters to be determined incorrectly. Here we studied one of the photometric microlensing events reported in the $Gaia$ DR3, GaiaDR3-ULENS-001, for which poor goodness of $Gaia$ fit and erroneous parallax could indicate the presence of…
We present reddening, photometric metallicity, age and distance estimates for the Frolov 1 and NGC 7510 open clusters based on CCD UBV photometric and Gaia data. Photometric observations were collected using the 1-m telescope of the TÜBİTAK National Observatory. Gaia DR2 proper motion data in the direction of two groupings were used to identify cluster membership. We determined mean proper motion values ($ μ_α\cosδ, μ_δ$) = ($-3.02\pm 0.10$, $-1.75 \pm 0.08$) and ($-3.66 \pm 0.07$, $-2.17 \pm 0.06$) mas yr$^{-1}$ for Frolov 1 and NGC 7510, respectively. We used two-colour diagrams to obtain $E…
We present a detailed photometric and kinematical analysis of poorly studied open cluster IC 1434 using CCD VRI, APASS, and Gaia DR2 database for the first time. BY determining the membership probability of stars, we identified the 238 most probable members with a probability higher than 60% by using proper motion and parallax data as taken from the Gaia DR2 catalog. The mean proper motion of the cluster is obtained as emu_x= - 3.89 +/- 0.19 and emu_y= - 3.34 +/- 0.19 mas/yr in both the directions of right ascension and declination. The radial distribution of member stars provides cluster exte…
In the second paper of this series we perfected our method of linking high precision Hubble Space Telescope astrometry to the high-accuracy Gaia DR2 absolute reference system to overcome the limitations of relative astrometry with narrow-field cameras. Our test case here is the Y brown dwarf WISE J163940.83-684738.6, observed at different epochs spread over a 6-yr time baseline with the Infra-Red channel of the Wide Field Camera 3. We derived significantly improved astrometric parameters compared to previous determinations, finding: (mu_RAcosDc,mu_DC,parallax) = (577.21+/-0.24mas/yr,-3108.39+/…
The open cluster IC 4996 in Cygnus and its vicinity are investigated by applying a two-dimensional photometric classification of stars measured in the Vilnius seven-color photometric system. Cluster members are identified by applying distances based on the Gaia DR2 parallaxes and the point vector diagram of the Gaia DR2 proper motions. For some B-type stars, spectroscopic MK types are also obtained from the Asiago spectra and collected from the literature. New parameters of the cluster are derived. The interstellar extinction $A_V$ covers a wide range of values, from 1.3 to 2.4 mag; the mean v…
We have used the galaxy modeling algorithm \texttt{GravPot16}, to explore the more probable orbital elements of a sample of 64 selected N-rich stars across the Milky Way. Using the newly measured proper motions from \texttt{Gaia} DR2 with existing line-of-sight velocities from APOGEE-2 survey and spectrophotometric distance estimations from the \texttt{StarHorse}. We adopted a set of high-resolution particle simulations evolved in the same steady-state Galactic potential model with a bar, in order to identify the groups of N-rich stars that have a high probability of belonging to the bulge/bar…
The GPS1 catalog was released in 2017. It delivered precise proper motions for around 350 million sources across three-fourths of the sky down to a magnitude of $r\sim20$\,mag. In this study, we present GPS1+ the extension GPS1 catalog down to $r\sim22.5$\,mag, based on {\it Gaia} DR2, PS1, SDSS and 2MASS astrometry. The GPS1+ totally provides proper motions for $\sim$400 million sources with a characteristic systematic error of less than 0.1\masyr. This catalog is divided into two sub-samples, i.e., the primary and secondary parts. The primary $\sim$264 million sources have either or both of …
We aim to explore the actions of the new Gaia DR3 astrometry to find structures in the Galactic disc. We compute the actions and the orbital parameters of the Gaia DR3 stars with full astrometry and velocities assuming an axisymmetric model for the Milky Way. Using Gaia DR3 photometric data, we select a subset of giants stars with better astrometry as control sample. The maps of the percentiles of the radial action J_R reveal spiral-like shape structures. We find a high J_R region centered at R~10.5 kpc of 1 kpc width, as well as three arc-shape regions dominated by circular orbits at inner ra…
$Context$. Gaia Second Data Release provides precise astrometry and photometry for more than 1.3 billion sources. This catalog opens a new era concerning the characterization of open clusters and test stellar models, paving the way for a better understanding of the disc properties. $Aims$. The aim of the paper is to improve the knowledge of cluster parameters, using only the unprecedented quality of the Gaia photometry and astrometry. $Methods$. We make use of the membership determination based on the precise Gaia astrometry and photometry. We apply anautomated Bayesian tool, BASE-9, to fit st…
In a previous paper, we applied the Gaia DR2 catalog to improve the astrometric accuracy of about 1.7 billion objects in Pan-STARRS1 Data Release 2 (PS1 DR2). We report here on further improvements made by utilizing Gaia EDR3 and correcting for the effects of differential chromatic refraction (DCR) in declination. We extend the correction algorithm in Paper 1 by iteratively subtracting color- and declination-dependent PS1/Gaia EDR3 declination residuals. We determine the astrometric improvement for ~440 million reference objects that are point-like and cross-match to Gaia EDR3. For this set of…
We use the Gaia DR2 catalog to improve the astrometric accuracy of about 1.7 billion objects in Pan-STARRS1 Data Release 2 (PS1 DR2). We also obtain proper motions for these PS1 objects. The cross match between Gaia and PS1 reveals residuals that are correlated on a scale of about 1 arcmin. We apply a spatially adaptive correction algorithm for all PS1 objects having more than two detections to reduce these residuals and align the object positions to Gaia. For point-like PS1 objects that cross match to Gaia, the algorithm reduces PS1/Gaia residuals by 33% in position (median value of 13.5 mas …
In this work we present a method to identify possible members of globular clusters using data from Gaia DR2. The method consists of two stages: the first one based on a clustering algorithm, and the second one based on the analysis of the projected spatial distribution of stars with different proper motions. In order to confirm that the clusters members extracted by the method correspond to actual globular clusters, the spatial distribution, the vector point diagram of the proper motions and the colour-magnitude diagrams are analysed. We apply the developed method to eight clusters: NGC 1261, …
Relativistic models of light propagation adopted for high-precision astrometry are based on the parametrised post-Newtonian formalism, which provides a framework for examining the effects of a hypothetical violation of general relativity on astrometric data. Astrometric observations are strongly affected by the post-Newtonian parameter $γ$ describing the strength of gravitational light deflection. We study both analytically and numerically how a deviation in the PPN parameter $γ$ from unity, which is the value predicted by general relativity, affects the parallax estimations in Gaia-like astro…
This paper presents an investigation on the four open clusters Czernik 14, Haffner 14, Haffner 17 and King 10 located near the Perseus arm of Milky Way Galaxy using Gaia DR2, 2MASS, WISE, APASS and Pan-STARRS1 data sets. We find normal interstellar extinction in twelve photometric bands for these clusters. Likely cluster members are identified as 225, 353, 350 and 395 for Czernik 14, Haffner 14, Haffner 17 and King 10, respectively by using Gaia DR2 proper motion data. Radii are determined as 3.5, 3.7, 6.2 and 5.7 arcmin for Czernik 14, Haffner 14, Haffner 17 and King 10 respectively. Mean pro…
The membership determination for open clusters in noisy environments of the Milky Way is still an open problem. In this paper, our main aim is provide the membership probability of stars using proper motions and parallax values of stars using Gaia EDR3 astrometry. Apart from the Gaia astrometry, we have also used other photometric data sets like UKIDSS, WISE, APASS and Pan-STARRS1 in order to understand cluster properties from optical to mid-infrared regions. We selected 438 likely members with membership probability higher than $50\%$ and G$\le$20 mag. We obtained the mean value of proper mot…
Gaia is a revolutionary space mission developed by ESA and is delivering 5 parameter astrometry, photometry and radial velocities over the whole sky with astrometric accuracies down to a few tens of micro-arcseconds. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centre and the spiral arm regions, important for certain studies, are obscured by interstellar extinction and this makes it difficult for Gaia to deeply probe. This problem can be overcome by switching to the Near Infra-Red (NIR) but this is not possible with silicon CCDs. Additionall…
For stars with unresolved companions, motions of the centre of light and that of mass decouple, causing a single-source astrometric model to perform poorly. We show that such stars can be easily detected with the reduced chi2 statistic, or RUWE, provided as part of Gaia DR2. We convert RUWE into the amplitude of the image centroid wobble, which, if scaled by the source distance, is proportional to the physical separation between companions (for periods up to several years). We test this idea on a sample of known spectroscopic binaries and demonstrate that the amplitude of the centroid perturba…
How very massive stars form is still an open question in astrophysics. VFTS682 is among the most massive stars known, with an inferred initial mass of $\sim$150 $M_\odot$ . It is located in 30 Doradus at a projected distance of 29 pc from the central cluster R136. Its apparent isolation led to two hypotheses: either it formed in relative isolation or it was ejected dynamically from the cluster. We investigate the kinematics of VFTS682 as obtained by Gaia and Hubble Space Telescope astrometry. We derive a projected velocity relative to the cluster of $38 \pm 17 \mathrm{km \ s^{-1}}$ (1$σ$ confi…
This paper presents a comprehensive analysis of two pairs of binary clusters (NGC 5617 and Trumpler 22) and (NGC 3293 and NGC 3324) located in the fourth quadrant of our Galaxy. For this purpose we use different data taken from VVV survey, WISE, VPHAS, APASS, GLIMPSE along with Gaia~EDR3 astrometric data. We identified 584, 429, 692 and 273 most probable cluster members with membership probability higher than 80 % towards the region of clusters NGC 5617, Trumpler 22, NGC 3293 and NGC 3324. We estimated the value of R as ~ 3.1 for clusters NGC 5617 and Trumpler 22, which indicates normal extinc…
Two young open clusters in Cygnus and their vicinity: combining multicolor photometry with Gaia DR3 astrometry
Astronomical Observatory of Vilnius University（维尔纽斯大学天文台）；Vatican Observatory Research Group, Steward Observatory（梵蒂冈天文台研究组，斯图尔德天文台）；Vatican Observatory（梵蒂冈天文台）
The formation of giant planets is best studied through direct imaging by observing planets both during and after formation. Giant planets are expected to form either by core accretion, which is typically associated with low initial entropy (cold-start models) or by gravitational instability, which corresponds to a high initial entropy of the gas (hot-start models). Thus, constraining the initial entropy provides insight into the planet formation mechanism and determines the resultant brightness evolution. We find that, by observing planets in nearby moving groups of known age both through dire…
Mass-dependent multiplicity fraction in low mass stars revealed by Gaia astrometry
Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Fakultät für Physik und Astronomie, Universität Heidelberg（海德堡大学物理与天文学院）；Department of Astronomy, California Institute of Technology（加州理工学院天文学系）
The Gaia mission promises to deliver precision astrometry at an unprecedented level, heralding a new era for discerning the kinematic and spatial coordinates of stars in our Galaxy. Here, we present a new technique for estimating the age of tidally disrupted globular cluster streams using the proper motions and parallaxes of tracer stars. We evolve the collisional dynamics of globular clusters within the evolving potential of a Milky Way-like halo extracted from a cosmological $Λ$CDM simulation and analyze the resultant streams as they would be observed by Gaia. The simulations sample a variet…
A key objective of the ESA Gaia satellite is the realization of a quasi-inertial reference frame at visual wavelengths by means of global astrometric techniques. This requires an accurate mathematical and numerical modeling of relativistic light propagation, as well as double-blind-like procedures for the internal validation of the results, before they are released to the scientific community at large. Aim of this work is to specialize the Time Transfer Functions (TTF) formalism to the case of the Gaia observer and prove its applicability to the task of Global Sphere Reconstruction (GSR), in a…
51 Eri b is one of the only young planets consistent with a wide range of possible initial entropy states, including the cold-start scenario associated with some models of planet formation by core accretion. The most direct way to constrain the initial entropy of a planet is by measuring its luminosity and mass at a sufficiently young age that the initial conditions still matter. We present the tightest upper limit on 51 Eri b's mass yet (M < 11 Mjup at 2$σ$) using a cross-calibration of Hipparcos and Gaia EDR3 astrometry and the orbit-fitting code orvara. We also reassess its luminosity using…
The satellite missions Hipparcos and Gaia by the European Space Agency will together bring a decrease of astrometric errors by a factor 10000, four orders of magnitude, more than was achieved during the preceding 500 years. This modern development of astrometry was at first obtained by photoelectric astrometry. An experiment with this technique in 1925 led to the Hipparcos satellite mission in the years 1989-93 as described in the following reports Nos. 1 and 10. The report No. 11 is about the subsequent period of space astrometry with CCDs in a scanning satellite. This period began in 1992 wi…
Precision astrometry from the second Gaia data release has allowed astronomers to predict 5,787 microlensing events, with 528 of these having maximums within the extended Gaia mission (J2014.5 - J2026.5). Future analysis of the Gaia time-series astrometry of these events will, in some cases, lead to precise gravitational mass measurements of the lens. We find that 61% of events predicted during the extended Gaia mission with sources brighter than G = 18 are likely to be spurious, with the background source in these cases commonly being either a duplicate detection or a binary companion of the …
Context: The current sample of known brown dwarfs (BDs) around FGK-stars is only of the order of a hundred. The ongoing ESA mission Gaia has already collected its nominal 5 yr of mission data and might operate up to 10 yr. Aims: Using detailed simulations, we estimate the number of BDs that could be discovered by Gaia astrometry, radial velocity, and photometric transits around main sequence (V) and subgiants (IV) FGK host stars for a 5 and 10-yr mission. Methods: Using a robust $Δχ^2$ statistic we analyse the BD companion detectability from the Besançon Galaxy population synthesis model compl…
We present a study of six open clusters (Berkeley 67, King 2, NGC 2420, NGC 2477, NGC 2682 and NGC 6940) using the Ultra Violet Imaging Telescope (UVIT) aboard \textit{ASTROSAT} and \textit{Gaia} EDR3. We used combinations of astrometric, photometric and systematic parameters to train and supervise a machine learning algorithm along with a Gaussian mixture model for the determination of cluster membership. This technique is robust, reproducible and versatile in various cluster environments. In this study, the \textit{Gaia} EDR3 membership catalogues are provided along with classification of th…
Gaia GraL X.: The GraL catalogue of gravitationally lensed quasars Matched with \textit{Gaia} data, redshifts, and time delays
Laboratoire d’Astrophysique de Bordeaux, Univ. Bordeaux, CNRS（波尔多天体物理学实验室，波尔多大学，法国国家科学研究中心）；Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo（圣保罗大学天文、地球物理与大气科学研究所）；Donald Bren School of Information and Computer Sciences, University of California, Irvine（加州大学尔湾分校唐纳德·布伦信息与计算机科学学院）；CENTRA/SIM, Faculdade de Ciéncias, Universidade de Lisboa（里斯本大学理学院CENTRA/SIM）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学，蔚蓝海岸天文台，法国国家科学研究中心，拉格朗日实验室）；Sydney Institute for Astronomy, School of Physics, The University of Sydney（悉尼大学物理学院悉尼天文学研究所）；Center for Astrophysics Harvard & Smithsonian（哈佛-史密森尼天体物理中心）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）
While most moving groups are young and nearby, a small number have been identified in the Galactic halo. Understanding the origin and evolution of these groups is an important piece of reconstructing the formation history of the halo. Here we report on our analysis of three putative halo moving groups: G03-37, G18-39, and G21-22. Based on Gaia EDR3 data, the stars associated with each group show some scatter in velocity (e.g., Toomre diagram) and integrals of motion (energy, angular momentum) spaces, counter to expectations of moving-group stars. We choose the best candidate of the three group…
From Very Long Baseline Array (VLBA) observations we previously identified a population of 123 young stellar systems with nonthermal radio emission toward the core of the Orion Nebula Cluster (ONC). We find optical sources in the Gaia DR2 catalog for 34 of them within 0.2" of the radio positions. Most of the radio sources are likely companions of Gaia detections. However, there are 11 stars whose VLBA position differs from Gaia by $<1.6$ mas, and some of these radio sources probably are the direct counterparts of the optical stars. We are able to obtain radio proper motions for 23 stars. Combi…
We characterize twelve young stellar objects (YSOs) located in the Lupus I region, spatially overlapping with the Upper Centaurus Lupus (UCL) sub-stellar association. The aim of this study is to understand whether the Lupus I cloud has more members than what has been claimed so far in the literature and gain a deeper insight into the global properties of the region. We selected our targets using Gaia DR2 catalog, based on their consistent kinematic properties with the Lupus I bona fide members. In our sample of twelve YSOs observed by X-Shooter, we identified ten Lupus I members. We could not …
VLBI astrometry of radio stars to link radio and optical celestial reference frames - II. 11 radio stars
Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Geodesy and Geodynamics, Finnish Geospatial Research Institute (FGI), National Land Survey of Finland（芬兰国家土地测量局芬兰地理研究所大地测量与地球动力学系）；Korea Astronomy and Space Science Institute（韩国天体物理与空间科学研究所）；University of Helsinki（赫尔辛基大学）；Harvard-Smithsonian Center for Astrophysics（哈佛-史密森尼天体物理中心）
In this paper we develop a differential astrometric framework that is appropriate for a scanning space satellite such as Gaia. We apply it to the first of the GAREQ fields, which is the fruit of dedicated efforts within the Gaia project focused on measuring the relativistic deflection of light close to Jupiter's limb. This provides a preliminary assessment of: a) the observability of the relativistic deflection of light close to Jupiter, and, b) Gaia's astrometric capabilities under extremely difficult conditions such as those around a bright extended object. Inputs to our differential astrome…
We present the second Gaia data release, Gaia DR2, consisting of astrometry, photometry, radial velocities, and information on astrophysical parameters and variability, for sources brighter than magnitude 21. In addition epoch astrometry and photometry are provided for a modest sample of minor planets in the solar system. A summary of the contents of Gaia DR2 is presented, accompanied by a discussion on the differences with respect to Gaia DR1 and an overview of the main limitations which are still present in the survey. Recommendations are made on the responsible use of Gaia DR2 results. Gaia…
Context. We have compiled a catalogue of central stars of planetary nebulae (CSPN) with reliable distances and positions obtained from Gaia Data Release 2 (DR2) astrometry. Distances derived from parallaxes allow us to analyse the galactic distribution and estimate other parameters such as sizes, kinematical ages, bolometric magnitudes, and luminosities. Aims. Our objective is to analyse the information regarding distances together with other available literature data about photometric properties, nebular kinematics, and stellar effective temperatures to throw new light on this rapid and rathe…
Aims:We take advantage of the second data release of the Gaia space mission and the state-of-the-art astrometry delivered from very long baseline interferometry observations to revisit the structure and kinematics of the nearby Taurus star-forming region. Methods: We apply a hierarchical clustering algorithm for partitioning the stars in our sample into groups (i.e., clusters) that are associated with the various molecular clouds of the complex, and derive the distance and spatial velocity of individual stars and their corresponding molecular clouds. Results: We show that the molecular clouds …
In light of substantial new discoveries of hot subdwarfs by ongoing spectroscopic surveys and the availability of the Gaia mission Early Data Release 3 (EDR3), we compiled new releases of two catalogues of hot subluminous stars: The data release 3 (DR3) catalogue of the known hot subdwarf stars contains 6,616 unique sources and provides multi-band photometry, and astrometry from Gaia EDR3 as well as classifications based on spectroscopy and colours. This is an increase of 742 objects over the DR2 catalogue. This new catalogue provides atmospheric parameters for 3,087 stars and radial velocitie…
