The stellar velocity distribution in the solar neighbourhood

Simone, Richard S. De; Wu, Xianghua; Tremaine, Scott

doi:10.1111/j.1365-2966.2004.07675.x

Cited by 173 publications

(162 citation statements)

References 45 publications

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“…Sellwood (2010Sellwood ( , 2011 explored the hypothesis of recurrent short-lived spiral transients. De Simone et al (2004) already showed that the observational features could be reproduced from a succession of strong spiral transients.…”

Section: Introductionmentioning

confidence: 99%

Reliable probabilistic determination of membership in stellar kinematic groups in the young disk

Klutsch

Ferrero

Guillout

et al. 2014

A&A

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Context. Over the last century, the overdensities in the velocity distributions of nearby stars were attributed to stellar kinematic groups or moving groups. Although their reality was initially questioned, their existence is now supported by a confluence of evidence. Aims. To pursue investigations, quantitative methods should be clearly defined to identify new stars belonging to these groups. Here, we present two probabilistic methods to determine the likelihood of kinematic membership for possible candidates in five of the known young stellar kinematic groups -namely, Pleiades, IC 2391, Castor, Ursa Major, and Hyades -in which all are younger than 650 Myr. Methods. We tried different methods to handle kinematic data of their known members. We succeeded in developing two independent procedures able to identify new candidates of these five stellar stream. We tested the robustness of our two approaches by means of extensive Monte Carlo simulations. Results. Our methods are consistent with one another in more than 90% of cases and for almost all the stellar kinematic groups under scrutiny. The IC 2391 supercluster is an exception. Applying our statistical methods to a large sample of young low-mass stars, we confirmed almost all the likely members and good candidates of these stellar streams. We also proposed 39 additional candidates based on the agreement and the high likelihood of age and kinematic membership. Conclusions. These probabilistic methods are very powerful to reliably identify new candidate members of young stellar kinematic groups. However, the kinematic criteria alone are not sufficient to distinguish between coeval stars that are evaporated from open clusters and other field stars trapped by dynamical processes generated by galactic perturbations. The identification of stars belonging to the remnant of a past star-forming event can be possible with the help of additional information, such as indicators of chromospheric activity, age proxies (lithium abundance), and chemical composition.

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Section: Introductionmentioning

confidence: 99%

Reliable probabilistic determination of membership in stellar kinematic groups in the young disk

Klutsch

Ferrero

Guillout

et al. 2014

A&A

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“…Previous studies of heating mechanisms have concentrated on heating from transient spiral density waves (e.g., Carlberg et al 1985;De Simone et al 2004;Jenkins 1992). However in that case changes in the stellar velocity dispersion only occur during the spirals' growth and decay.…”

Section: Stochastic Heating From Multiple Spiral Wavesmentioning

confidence: 99%

Constraining the Milky Way assembly history with Galactic Archaeology

Minchev

2016

Astron Nachr

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The aim of Galactic Archaeology is to recover the evolutionary history of the Milky Way from its present day kinematical and chemical state. Because stars move away from their birth sites, the current dynamical information alone is not sufficient for this task. The chemical composition of stellar atmospheres, on the other hand, is largely preserved over the stellar lifetime and, together with accurate ages, can be used to recover the birthplaces of stars currently found at the same Galactic radius. In addition to the availability of large stellar samples with accurate 6D kinematics and chemical abundance measurements, this requires detailed modeling with both dynamical and chemical evolution taken into account. An important first step is to understand the variety of dynamical processes that can take place in the Milky Way, including the perturbative effects of both internal (bar and spiral structure) and external (infalling satellites) agents. We discuss here (1) how to constrain the Galactic bar, spiral structure, and merging satellites by their effect on the local and global disc phase-space, (2) the effect of multiple patterns on the disc dynamics, and (3) the importance of radial migration and merger perturbations for the formation of the Galactic thick disc. Finally, we discuss the construction of Milky Way chemo-dynamical models and relate to observations.

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“…The timescale between when a star is free from any residual gas from its stellar nursery and when it is kinematically thermalised due to disk-heating mechanisms is similar (De Simone et al 2004). This may indicate that disk-heating has a direct effect on stellar magnetic fields.…”

Section: Residual Molecular Gasmentioning

confidence: 99%

Chromospheric activities and kinematics for solar type dwarfs and subgiants: analysis of the activity distribution and the AVR

Jenkins

Murgas

Rojo

et al. 2011

A&A

111

105

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Aims. In this work we present chromospheric activity indices, kinematics, radial-velocities, and rotational velocities for more than 850 FGK-type dwarfs and subgiant stars in the southern hemisphere and test how best to calibrate and measure S -indices from echelle spectra. Methods. We measured our parameters using the high-resolution and high-S /N FEROS echelle spectra acquired for this purpose. Results. We confirm the bimodal distribution of chromospheric activities for such stars and highlight the role that the more active K-dwarfs play in biasing the number of active stars. We show that the age-activity relationship does appear to continue to ages older than the Sun if we simply compare main sequence stars and subgiant stars with an offset of around 2.5 Gyr between the peaks of both distributions. Also we show evidence of an increased spin-down timescale for cool K dwarfs compared with earlier F and G type stars. We highlight that activities drawn from low-resolution spectra (R < 2500) significantly increase the rms scatter when calibrating onto common systems of measurements like the Mt. Wilson system. Also we show that older and widely used catalogues of activities in the south appear to be offset compared to more recent works at the ∼0.1 dex level in log R HK through calibrator drift. In addition, we show how kinematics can be used to preselect inactive stars for future planet search projects. We see the well known trend between projected rotational velocity and activity, however we also find a correlation between kinematic space velocity and chromospheric activity. It appears that after the Vaughan-Preston gap there is a quick step function in the kinematic space motion towards a significantly broader spread in velocities. We speculate on reasons for this correlation and provide some model scenarios to describe the bimodal activity distribution through magnetic saturation, residual low level gas accretion, or accretion by the star of planets or planetesimals. Finally, we provide a new empirical measurement for the disk-heating law, using the latest age-activity relationships to reconstruct the age-velocity distribution for local disk stars. We find a value of 0.337 ± 0.045 for the exponent of this power law (i.e. σ tot ∝ t 0.337 ), in excellent agreement with those found using isochrone fitting methods and with theoretical disk-heating models.

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The stellar velocity distribution in the solar neighbourhood

Cited by 173 publications

References 45 publications

Reliable probabilistic determination of membership in stellar kinematic groups in the young disk

Reliable probabilistic determination of membership in stellar kinematic groups in the young disk

Constraining the Milky Way assembly history with Galactic Archaeology

Chromospheric activities and kinematics for solar type dwarfs and subgiants: analysis of the activity distribution and the AVR

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