C. A. L. Bailer-Jones

Max Planck Institute for Astronomy

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Co-Authors

F. Arenou

Galaxies, Etoiles, Physique et Instrumentation

M. Fouesneau

Max Planck Institute for Astronomy

L. Galluccio

Lagrange Laboratory

J. H. J. de Bruijne

European Space Research and Technology Centre

R. Carballo

Universidad de Cantabria

A. G. A. Brown

Leiden University

E. Brugaletta

Osservatorio Astrofisico di Catania

A. C. Lanzafame

Osservatorio Astrofisico di Catania

A. Ulla

Universidade de Vigo

N. Sanna

Arcetri Astrophysical Observatory

Cooperative Institutions

Max Planck Society

473

Centre National de la Recherche Scientifique

263

European Space Astronomy Centre

147

Université Paris Sciences et Lettres

114

Centre National d'Études Spatiales

111

Observatoire de Paris

108

University of Cambridge

National Institute for Astrophysics

Observatoire de la Côte d’Azur

Universitat de Barcelona

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VizieR Online Data Catalog: Distances of Gaia DR1 TGAS sources (Astraatmadja+, 2016)

VizieR Online Data Catalog (2016)

T. L. Astraatmadja C. A. L. Bailer-Jones

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Finding the imprints of stellar encounters in long-period comets

Monthly Notices of the Royal Astronomical Society (2015)

Fabo Feng C. A. L. Bailer-Jones

The Solar system's Oort cloud can be perturbed by the Galactic tide and by individual passing stars. These perturbations can inject Oort cloud objects into the inner parts of the Solar system, where they may be observed as the long-period comets (periods longer than 200 yr). Using dynamical simulations of the Oort cloud under the perturbing effects of the tide and 61 known stellar encounters, we investigate the link between long-period comets and encounters. We find that past encounters were responsible for injecting at least 5 per cent of the currently known long-period comets. This is a lower limit due to the incompleteness of known encounters. Although the Galactic tide seems to play the dominant role in producing the observed long-period comets, the non-uniform longitude distribution of the cometary perihelia suggests the existence of strong – but as yet unidentified – stellar encounters or other impulses. The strongest individual future and past encounters are probably HIP 89825 (Gliese 710) and HIP 14473, which contribute at most 8 and 6 per cent to the total flux of long-period comets, respectively. Our results show that the strength of an encounter can be approximated well by a simple proxy, which will be convenient for quickly identifying significant encounters in large data sets. Our analysis also indicates a smaller population of the Oort cloud than is usually assumed, which would bring the mass of the solar nebula into line with planet formation theories.

Galactic tide

Interstellar comet

Longitude

10.1093/mnras/stv2222

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Citations (52)

Gaia Focused Product Release: Spatial distribution of two diffuse interstellar bands

arXiv (Cornell University) (2023)

M. Schultheis H. Zhao T. Zwitter C. Ordénovic F. Pailler

Diffuse interstellar bands (DIBs) are absorption features seen in optical and infrared spectra of stars that are probably caused by large and complex molecules in the ISM. Here we investigate the Galactic distribution and properties of two DIBs identified in almost six million stellar spectra collected by the Gaia Radial Velocity Spectrometer. These measurements constitute a part of the Gaia Focused Product Release to be made public between the Gaia DR3 and DR4 data releases. In order to isolate the DIB signal from the stellar features in each individual spectrum, we identified a set of 160 000 spectra at high Galactic latitudes which we consider to be the DIB-free reference sample. Matching each target spectrum to its closest reference spectra in stellar parameter space allowed us to remove the stellar spectrum empirically, without reference to stellar models, leaving a set of six million ISM spectra. Identifying the two DIBs at 862.1 nm and 864.8 nm in the stacked spectra, we modelled their shapes and report the depth, central wavelength, width, and equivalent width (EW) for each, along with confidence bounds on these measurements. Our main results are as follows: (1) the strength and spatial distribution of the DIB $\lambda$862.1 are very consistent with what was found in Gaia DR3, but for this work we attained a higher signal-to-noise ratio in the stacked spectra to larger distances, which allowed us to trace DIBs in the outer spiral arm and beyond the Scutum--Centaurus spiral arm; (2) we produced an all-sky map below ${\pm}65^{\circ}$ of Galactic latitude to $\sim$4000 pc of both DIB features and their correlations; (3) we detected the signals of DIB\,$\lambda$862.1 inside the Local Bubble; and (4) there is a reasonable correlation with the dust reddening found from stellar absorption and EWs of both DIBs.

10.48550/arxiv.2310.06175

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Gaia Focused Product Release: Asteroid orbital solution

Astronomy and Astrophysics (2023)

Patrice David F. Mignard Daniel Hestroffer P. Tanga F. Spoto

Context. We report the exploitation of a sample of Solar System observations based on data from the third Gaia Data Release ( Gaia DR3) of nearly 157 000 asteroids. It extends the epoch astrometric solution over the time coverage planned for the Gaia DR4, which is not expected before the end of 2025. This data set covers more than one full orbital period for the vast majority of these asteroids. The orbital solutions are derived from the Gaia data alone over a relatively short arc compared to the observation history of many of these asteroids. Aims. The work aims to produce orbital elements for a large set of asteroids based on 66 months of accurate astrometry provided by Gaia and to assess the accuracy of these orbital solutions with a comparison to the best available orbits derived from independent observations. A second validation is performed with accurate occultation timings. Methods. We processed the raw astrometric measurements of Gaia to obtain astrometric positions of moving objects with 1D sub-mas accuracy at the bright end. For each asteroid that we matched to the data, an orbit fitting was attempted in the form of the best fit of the initial conditions at the median epoch. The force model included Newtonian and relativistic accelerations to derive the observation equations, which were solved with a linear least-squares fit. Results. Orbits are provided in the form of state vectors in the International Celestial Reference Frame for 156 764 asteroids, including near-Earth objects, main-belt asteroids, and Trojans. For the asteroids with the best observations, the (formal) relative uncertainty σ a / a is better than 10 −10 . Results are compared to orbits available from the Jet Propulsion Laboratory and MPC. Their orbits are based on much longer data arcs, but from positions of lower quality. The relative differences in semi-major axes have a mean of 5 × 10 −10 and a scatter of 5 × 10 −9 .

Astrometry

Orbit Determination

Ephemeris

Orbit (dynamics)

Epoch (astronomy)

Orbital elements

Orbital mechanics

Near-Earth object

Minor planet

10.1051/0004-6361/202347270

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Citations (5)

GaiaData Release 2

Astronomy and Astrophysics (2018)

A. Helmi F. van Leeuwen P. J. McMillan D. Massari T. Antoja

The goal of this paper is to demonstrate the outstanding quality of the second data release of the Gaia mission and its power for constraining many different aspects of the dynamics of the satellites of the Milky Way. We focus here on determining the proper motions of 75 Galactic globular clusters, nine dwarf spheroidal galaxies, one ultra-faint system, and the Large and Small Magellanic Clouds. Using data extracted from the Gaia archive, we derived the proper motions and parallaxes for these systems, as well as their uncertainties. We demonstrate that the errors, statistical and systematic, are relatively well understood. We integrated the orbits of these objects in three different Galactic potentials, and characterised their properties. We present the derived proper motions, space velocities, and characteristic orbital parameters in various tables to facilitate their use by the astronomical community. Our limited and straightforward analyses have allowed us for example to (i) determine absolute and very precise proper motions for globular clusters; (ii) detect clear rotation signatures in the proper motions of at least five globular clusters; (iii) show that the satellites of the Milky Way are all on high-inclination orbits, but that they do not share a single plane of motion; (iv) derive a lower limit for the mass of the Milky Way of 9.8^{+6.7}_{-2.7} x 10^{11} Msun based on the assumption that the Leo I dwarf spheroidal is bound; (v) derive a rotation curve for the Large Magellanic Cloud based solely on proper motions that is competitive with line-of-sight velocity curves, now using many orders of magnitude more sources; and (vi) unveil the dynamical effect of the bar on the motions of stars in the Large Magellanic Cloud. All these results highlight the incredible power of the Gaia astrometric mission, and in particular of its second data release.

Proper motion

Local Group

10.1051/0004-6361/201832698

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Citations (553)

Gaia Early Data Release 3

Astronomy and Astrophysics (2020)

R. L. Smart L. M. Sarro J. Rybizki C. Reylé A. C. Robin

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.

Astrometry

10.1051/0004-6361/202039498

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Citations (239)

Gaia Data Release 2. Observations of solar system objects

Astronomy and Astrophysics (2018)

F. Spoto P. Tanga F. Mignard J. Berthier B. Carry

Context. The Gaia spacecraft of the European Space Agency (ESA) has been securing observations of solar system objects (SSOs) since the beginning of its operations. Data Release 2 (DR2) contains the observations of a selected sample of 14,099 SSOs. These asteroids have been already identified and have been numbered by the Minor Planet Center repository. Positions are provided for each Gaia observation at CCD level. As additional information, complementary to astrometry, the apparent brightness of SSOs in the unfiltered G band is also provided for selected observations.Aims. We explain the processing of SSO data, and describe the criteria we used to select the sample published in Gaia DR2. We then explore the data set to assess its quality.Methods. To exploit the main data product for the solar system in Gaia DR2, which is the epoch astrometry of asteroids, it is necessary to take into account the unusual properties of the uncertainty, as the position information is nearly one-dimensional. When this aspect is handled appropriately, an orbit fit can be obtained with post-fit residuals that are overall consistent with the a-priori error model that was used to define individual values of the astrometric uncertainty. The role of both random and systematic errors is described. The distribution of residuals allowed us to identify possible contaminants in the data set (such as stars). Photometry in the G band was compared to computed values from reference asteroid shapes and to the flux registered at the corresponding epochs by the red and blue photometers (RP and BP).Results. The overall astrometric performance is close to the expectations, with an optimal range of brightness G ~ 12 − 17. In this range, the typical transit-level accuracy is well below 1 mas. For fainter asteroids, the growing photon noise deteriorates the performance. Asteroids brighter than G ~ 12 are affected by a lower performance of the processing of their signals. The dramatic improvement brought by Gaia DR2 astrometry of SSOs is demonstrated by comparisons to the archive data and by preliminary tests on the detection of subtle non-gravitational effects.

Astrometry

Minor planet

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Citations (50)

Gaia DR3 documentation

HAL (Le Centre pour la Communication Scientifique Directe) (2022)

F. van Leeuwen J. de Bruijne C. Babusiaux G. Busso J. Castañeda

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Multiband photometric detection of a huge flare on the M9 dwarf 2MASSW J1707183+643933

Monthly Notices of the Royal Astronomical Society (2006)

B. Rockenfeller C. A. L. Bailer-Jones R. Mundt M. Ibrahimov

We present simultaneous UV-G-R-I monitoring of 19 M dwarfs that revealed a huge flare on the M9 dwarf 2MASSW J1707183+643933 with an amplitude in the UV of at least 6 magnitudes. This is one of the strongest detections ever of an optical flare on an M star and one of the first in an ultracool dwarf (UCD, spectral types later than about M7). Four intermediate strength flares (Delta m_UV < 4 mag) were found in this and three other targets. For the whole sample we deduce a flare probability of 0.013 (rate of 0.018/hr), and 0.049 (0.090/hr) for 2M1707+64 alone. Deviations of the flare emission from a blackbody is consistent with strong Halpha line emission. We also confirm the previously found rotation period for 2M1707+64 (Rockenfeller, Bailer-Jones & Mundt (2006), http://arxiv.org/abs/astro-ph/0511614/) and determine it more precisely to be 3.619 +/- 0.015 hr.

Flare

Flare star

Rotation period

Line (geometry)

10.1111/j.1365-2966.2006.09961.x

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Citations (24)

Classification and Parametrization of Unresolved Galaxies with Gaia

AIP conference proceedings (2008)

P. Tsalmantza M. Kontizas B. Rocca‐Volmerange C. A. L. Bailer-Jones E. Kontizas

The ESA satellite mission Gaia will acquire spectrophotometric observations of several million unresolved galaxies during its five years of operation. Our objective is to design and implement a classification system for these data. For this purpose we need to build a new library of galaxy spectra which covers the necessary parameter space. Using the evolutionary code PÉGASE.2 we have produced a library of 28885 synthetic galaxy spectra at zero redshift covering four general spectral types of galaxies over the wavelength range from 250 to 1050 nm, at a sampling of 1 nm or less. The library was also reproduced for 4 random values of redshift in the range of 0–0.2 and it is computed on a random grid of four key astrophysical parameters (3 for SFR and 1 for timescale of the infall of gas). The synthetic library was compared with various photometric and spectroscopic observations (e.g. from SDSS) and found in good agreement with them. Using simulated Gaia photometry of this library we train and test the performance of Support Vector Machine (SVM) classifiers and parametrizers. The first results are promising, indicating that galaxy types can be reliably predicted and several parameters (e.g. redshift, mass to light ratio, present SFR) can be estimated with low bias and variance from Gaia observations.

Parametrization (atmospheric modeling)

10.1063/1.3059019

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