Systematic errors in Gaia DR2 astrometry and their impact on measurements of internal kinematics of star clusters

Vasiliev, Eugene

doi:10.1093/mnras/stz2100

Cited by 45 publications

(33 citation statements)

References 34 publications

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“…2 of Roccatagliata et al (2018) the authors did not include the systematic errors on the Gaia-DR2 parallaxes in their analysis and derived the distance from the inverse of the parallax. In this study, we derived the distances from Bayesian inference using the Kalkayotl code (Olivares et al 2020) which is designed to deal with some characteristics of the Gaia-DR2 catalogue including the parallax zero-point correction and spatial correlations which are modelled with the covariance function of Vasiliev (2019). The existence of systematic errors in the Gaia-DR2 catalogue does not compromise the valuable astrometry delivered by the Gaia satellite, but needs to be considered to avoid underestimating uncertainties.…”

Section: Distance and Spatial Velocity Of Chamaeleon Starsmentioning

confidence: 99%

Chamaeleon DANCe

Galli

Bouy

Olivares

et al. 2021

A&A

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Context. Chamaeleon is the southernmost low-mass star-forming complex within 200 pc from the Sun. Its stellar population has been extensively studied in the past, but the current census of the stellar content is not complete yet and deserves further investigation. Aims. We take advantage of the second data release of the Gaia space mission to expand the census of stars in Chamaeleon and to revisit the properties of the stellar populations associated to the Chamaeleon I (Cha I) and Chamaeleon II (Cha II) dark clouds. Methods. We perform a membership analysis of the sources in the Gaia catalogue over a field of 100 deg2 encompassing the Chamaeleon clouds, and use this new census of cluster members to investigate the 6D structure of the complex. Results. We identify 188 and 41 high-probability members of the stellar populations in Cha I and Cha II, respectively, including 19 and 7 new members. Our sample covers the magnitude range from G = 6 to G = 20 mag in Cha I, and from G = 12 to G = 18 mag in Cha II. We confirm that the northern and southern subgroups of Cha I are located at different distances (191.4−0.8+0.8 pc and 186.7−1.0+1.0 pc), but they exhibit the same space motion within the reported uncertainties. Cha II is located at a distance of 197.5−0.9+1.0 pc and exhibits a space motion that is consistent with Cha I within the admittedly large uncertainties on the spatial velocities of the stars that come from radial velocity data. The median age of the stars derived from the Hertzsprung-Russell diagram and stellar models is about 1−2 Myr, suggesting that they are somewhat younger than previously thought. We do not detect significant age differences between the Chamaeleon subgroups, but we show that Cha II exhibits a higher fraction of disc-bearing stars compared to Cha I. Conclusions. This study provides the most complete sample of cluster members associated to the Chamaeleon clouds that can be produced with Gaia data alone. We use this new census of stars to revisit the 6D structure of this region with unprecedented precision.

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Section: Distance and Spatial Velocity Of Chamaeleon Starsmentioning

confidence: 99%

Chamaeleon DANCe

Galli

Bouy

Olivares

et al. 2021

A&A

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“…Bellini et al 2014;Watkins et al 2015) while Gaia provides high-quality astrometry in cluster outskirts (e.g. Bianchini et al 2018;Gaia Collaboration 2018;Sollima, Baumgardt & Hilker 2019;Vasiliev 2019). Recent advances in adaptive optics (AO) also provide the potential for useful astrometry in the centres of GCs (e.g.…”

Section: Introductionmentioning

confidence: 99%

MUSE narrow field mode observations of the central kinematics of M15

Usher

Kamann

Gieles

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present observations of the stellar kinematics of the centre of the core collapsed globular cluster M15 obtained with the MUSE integral field spectrograph on the VLT operating in narrow field mode. Thanks to the use of adaptive optics, we obtain a spatial resolution of 0.1 arcsec and are able to reliably measure the radial velocities of 864 stars within 8 arcsec of the centre of M15 thus providing the largest sample of radial velocities ever obtained for the innermost regions of this system. Combined with previous observations of M15 using MUSE in wide field mode and literature data, we find that the central kinematics of M15 are complex with the rotation axis of the core of M15 offset from the rotation axis of the bulk of the cluster. While this complexity has been suggested by previous work, we confirm it at higher significance and in more detail.

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“…Fabricius et al 2014, Ferraro et al 2018, Baumgardt & Hilker 2018, Kamann et al 2018) and/or high-precision proper motion studies based on Gaia and HST data (see e.g. Watkins et al 2015, Bellini et al 2017, Libralato et al 2018a, Bianchini et al 2018b, Jindal et al 2019, Vasiliev 2019, Cordoni et al 2020, Cohen et al 2021) have allowed to investigate the velocity dispersion's variation with the cluster-centric distance, have shown that clusters are often characterized by anisotropy in the velocity distribution and/or internal rotation, and provided the first quantitative measures of the degree of evolution towards energy equipartition.…”

Section: Introductionmentioning

confidence: 99%

Early dynamics and violent relaxation of multimass rotating star clusters

Livernois

Vesperini

Tiongco

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the results of a study aimed at exploring, by means of N-body simulations, the evolution of rotating multi-mass star clusters during the violent relaxation phase, in the presence of a weak external tidal field. We study the implications of the initial rotation and the presence of a mass spectrum for the violent relaxation dynamics and the final properties of the equilibria emerging at the end of this stage. Our simulations show a clear manifestation of the evolution towards spatial mass segregation and evolution towards energy equipartition during and at the end of the violent relaxation phase. We study the final rotational kinematics and show that massive stars tend to rotate more rapidly than low-mass stars around the axis of cluster rotation. Our analysis also reveals that during the violent relaxation phase, massive stars tend to preferentially segregate into orbits with angular momentum aligned with the cluster’s angular momentum, an effect previously found in the context of the long-term evolution of star clusters driven by two-body relaxation.

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Systematic errors in Gaia DR2 astrometry and their impact on measurements of internal kinematics of star clusters

Cited by 45 publications

References 34 publications

Chamaeleon DANCe

Chamaeleon DANCe

MUSE narrow field mode observations of the central kinematics of M15

Early dynamics and violent relaxation of multimass rotating star clusters

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