The age–velocity dispersion relation of the Galactic discs from LAMOST–Gaia data

Yu, Jincheng; Liu, Chao

doi:10.1093/mnras/stx3204

Cited by 81 publications

(110 citation statements)

References 67 publications

(81 reference statements)

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“…Our result that σ z /σ R increases with age in the low [α/Fe] disc is clearly in-line with this picture of heating by non-stationary processes. A similar scenario was proposed also by Yu & Liu (2018), whose results on the velocity ellipsoid shape are consistent with those presented here. Jenkins & Binney (1990) showed that increasing the importance of spirals over GMCs reduced σ z /σ R , such that models that have the most dominant spiral arm perturbations have the lowest σ z /σ R .…”

Section: Velocity Ellipsoid Shapesupporting

confidence: 93%

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Dynamical heating across the Milky Way disc using APOGEE and Gaia

Mackereth

Bovy

Leung

et al. 2019

Monthly Notices of the Royal Astronomical Society

194

193

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The kinematics of the Milky Way disc as a function of age are well measured at the solar radius, but have not been studied over a wider range of Galactocentric radii. Here, we measure the kinematics of mono-age, mono-[Fe/H] populations in the low and high [α/Fe] discs between 4 R 13 kpc and |z| 2 kpc using 65,719 stars in common between APOGEE DR14 and Gaia DR2 for which we estimate ages using a Bayesian neural network model trained on asteroseismic ages. We determine the vertical and radial velocity dispersions, finding that the low and high [α/Fe] discs display markedly different age-velocity-dispersion relations (AVRs) and shapes σ z /σ R . The high [α/Fe] disc has roughly flat AVRs and constant σ z /σ R = 0.64 ± 0.04, whereas the low [α/Fe] disc has large variations in this ratio which positively correlate with the mean orbital radius of the population at fixed age. The high [α/Fe] disc component's flat AVRs and constant σ z /σ R clearly indicates an entirely different heating history. Outer disc populations also have flatter radial AVRs than those in the inner disc, likely due to the waning effect of spiral arms. Our detailed measurements of AVRs and σ z /σ R across the disc indicate that low [α/Fe], inner disc (R 10 kpc) stellar populations are likely dynamically heated by both giant molecular clouds and spiral arms, while the observed trends for outer disc populations require a significant contribution from another heating mechanism such as satellite perturbations. We also find that outer disc populations have slightly positive mean vertical and radial velocities, likely because they are part of the warped disc.

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Section: Velocity Ellipsoid Shapesupporting

confidence: 93%

“…Combining all the MCMC samples for these bins, we find σ z /σ R = 0.64 ± −0.04. This value is in rough agreement with the measurements of σ R /σ z in LAMOST-TGAS stars by Yu & Liu (2018).…”

Section: The Shape Of the Velocity Ellipsoid As A Function Of Agesupporting

confidence: 90%

Dynamical heating across the Milky Way disc using APOGEE and Gaia

Mackereth

Bovy

Leung

et al. 2019

Monthly Notices of the Royal Astronomical Society

194

193

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“…Since the older stars have been experiencing these interactions for a longer period of time, they should therefore show the largest increase in velocity dispersion. Evidence in favour of such internal mechanisms has come from both observations (Yu & Liu 2018) and simulations (Saha et al 2010;Grand et al 2016;Aumer et al 2016). An alternative explanation is that in the early Universe, conditions were generally more chaotic (Wisnioski et al 2015), so that any stars born at that time were more likely to have higher velocity dispersion.…”

Section: Resolved Studies and Galaxy Formation Simulationsmentioning

confidence: 99%

Combining stellar populations with orbit-superposition dynamical modelling: the formation history of the lenticular galaxy NGC 3115

Poci

McDermid

Zhu

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present a combination of the Schwarzschild orbit-superposition dynamical modelling technique with the spatially-resolved mean stellar age and metallicity maps to uncover the formation history of galaxies. We apply this new approach to a remarkable 5-pointing mosaic of VLT/MUSE observations obtained by Guérou et al. (2016) extending to a maximum galactocentric distance of ∼ 120 (5.6 kpc) along the major axis, corresponding to ∼ 2.5 R e . Our method first identifies 'families' of orbits from the dynamical model that represent dynamicallydistinct structures of the galaxy. Individual ages and metallicities of these components are then fit for using the stellar-population information. Our results highlight components of the galaxy that are distinct in the combined stellar dynamics/populations space, which implies distinct formation paths. We find evidence for a dynamically-cold, metal-rich disk, consistent with a gradual in-situ formation. This disk is embedded in a generally-old population of stars, with kinematics ranging from dispersion-dominated in the centre to an old, diffuse, metal-poor stellar halo at the extremities. We find also a direct correlation between the dominant dynamical support of these components, and their associated age, akin to the relation observed in the Milky Way. This approach not only provides a powerful model for inferring the formation history of external galaxies, but also paves the way to a complete population-dynamical model.

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“…Looking at the age-velocity dispersion relation in the solar neighbourhood (e.g. Yu & Liu 2018, Aumer & Binney 2009), we investigate the signature of an age-rotation relation in the distribution of total space velocities, as defined in Eq.8, as a function of photometric rotation period. Fig.…”

Section: The Age-velocity Dispersion Relationshipmentioning

confidence: 99%

Photometric rotation periods for 107 M dwarfs from the APACHE survey

Giacobbe

Benedetto

Damasso

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We present rotation period measurements for 107 M dwarfs in the mass range 0.15 − 0.70M ⊙ observed within the context of the APACHE photometric survey. We measure rotation periods in the range 0.5-190 days, with the distribution peaking at ∼ 30 days. We revise the stellar masses and radii for our sample of rotators by exploiting the Gaia DR2 data. For ∼ 20% of the sample, we compare the photometric rotation periods with those derived from different spectroscopic indicators, finding good correspondence in most cases. We compare our rotation periods distribution to the one obtained by the Kepler survey in the same mass range, and to that derived by the MEarth survey for stars in the mass range 0.07 − 0.25M ⊙ . The APACHE and Kepler periods distributions are in good agreement, confirming the reliability of our results, while the APACHE distribution is consistent with the MEarth result only for the older/slow rotators, and in the overlapping mass range of the two surveys. Combining the APACHE/Kepler distribution with the MEarth distribution, we highlight that the rotation period increases with decreasing stellar mass, in agreement with previous work. Our findings also suggest that the spin-down time scale, from fast to slow rotators, changes crossing the fully convective limit at ≈ 0.3M ⊙ for M dwarfs. The catalogue of 107 rotating M dwarfs presented here is particularly timely, as the stars are prime targets for the potential identification of transiting small planets with TESS and amenable to high-precision mass determination and further atmospheric characterization measurements.

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The age–velocity dispersion relation of the Galactic discs from LAMOST–Gaia data

Cited by 81 publications

References 67 publications

Dynamical heating across the Milky Way disc using APOGEE and Gaia

Dynamical heating across the Milky Way disc using APOGEE and Gaia

Combining stellar populations with orbit-superposition dynamical modelling: the formation history of the lenticular galaxy NGC 3115

Photometric rotation periods for 107 M dwarfs from the APACHE survey

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