The distribution of low-mass stars in the Galactic disc

Kroupa, Pavel; Tout, Christopher A.; Gilmore, G.

doi:10.1093/mnras/262.3.545

Cited by 1,633 publications

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“…In this work, we solve equation (8) for oxygen, silicon and iron, by assuming yO = 1.022 × 10 −2 , ySi = 8.5 × 10 −4 , yFe = 5.6 × 10 −4 and R = 0.285, which can be obtained by assuming the Kroupa et al (1993) IMF (see also Vincenzo et al 2016a). We adopt the so-called 3/8-rule forth-order Runge-Kutta method to solve equation (8).…”

Section: The Delay Time Distribution Of Type Ia Supernovaementioning

confidence: 99%

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

Vincenzo

Matteuccí²,

Spitoni³

2016

Mon. Not. R. Astron. Soc.

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We present a theoretical method for solving the chemical evolution of galaxies, by assuming an instantaneous recycling approximation for chemical elements restored by massive stars and the Delay Time Distribution formalism for the delayed chemical enrichment by Type Ia Supernovae. The galaxy gas mass assembly history, together with the assumed stellar yields and initial mass function, represent the starting point of this method. We derive a simple and general equation which closely relates the Laplace transforms of the galaxy gas accretion history and star formation history, which can be used to simplify the problem of retrieving these quantities in the galaxy evolution models assuming a linear Schmidt-Kennicutt law. We find that -once the galaxy star formation history has been reconstructed from our assumptions -the differential equation for the evolution of the chemical element X can be suitably solved with classical methods. We apply our model to reproduce the [O/Fe] and [Si/Fe] vs. [Fe/H] chemical abundance patterns as observed at the solar neighborhood, by assuming a decaying exponential infall rate of gas and different delay time distributions for Type Ia Supernovae; we also explore the effect of assuming a nonlinear Schmidt-Kennicutt law, with the index of the power law being k = 1.4. Although approximate, we conclude that our model with the single degenerate scenario for Type Ia Supernovae provides the best agreement with the observed set of data. Our method can be used by other complementary galaxy stellar population synthesis models to predict also the chemical evolution of galaxies.

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Section: The Delay Time Distribution Of Type Ia Supernovaementioning

confidence: 99%

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

Vincenzo

Matteuccí²,

Spitoni³

2016

Mon. Not. R. Astron. Soc.

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“…The initial mass of each model is 6 × 10 4 M⊙ and has 96000 single stars and 4000 binaries. Stellar masses are drawn from a Kroupa, Tout, & Gilmore (1993) initial mass function between 0.1M⊙ and 30M⊙, with each star assigned a metallicity of Z = 0.001. The distribution of stellar positions and velocities follow a Plummer density profile with a cutoff at 10rm (Plummer 1911;Aarseth et al 1974).…”

Section: The Modelsmentioning

confidence: 99%

The effects of orbital inclination on the scale size and evolution of tidally filling star clusters

Webb

Sills

Harris

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We have performed N -body simulations of tidally filling star clusters with a range of orbits in a Milky Way-like potential to study the effects of orbital inclination and eccentricity on their structure and evolution. At small galactocentric distances R gc , a non-zero inclination results in increased mass loss rates. Tidal heating and disk shocking, the latter sometimes consisting of two shocking events as the cluster moves towards and away from the disk, help remove stars from the cluster. Clusters with inclined orbits at large R gc have decreased mass loss rates than the non-inclined case, since the strength the disk potential decreases with R gc . Clusters with inclined and eccentric orbits experience increased tidal heating due to a constantly changing potential, weaker disk shocks since passages occur at higher R gc , and an additional tidal shock at perigalacticon. The effects of orbital inclination decrease with orbital eccentricity, as a highly eccentric cluster spends the majority of its lifetime at a large R gc . The limiting radii of clusters with inclined orbits are best represented by the r t of the cluster when at its maximum height above the disk, where the cluster spends the majority of its lifetime and the rate of change in r t is a minimum. Conversely, the effective radius is independent of inclination in all cases.

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“…The input stellar spectra are based on the library of Lejeune et al (1998), as we are mostly interested in broad band photometry. The SMF is taken from Kroupa (1993), and extends from 0.1 to 120 M . Nebular emission (lines and continuum) is included in the calculated spectra of young objects under the assumption that no ionizing photon escapes.…”

Section: Synthetic Populationsmentioning

confidence: 99%

Accounting for stochastic fluctuations when analysing the integrated light of star clusters

Fouesneau¹,

Lançon²

2010

A&A

111

132

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Context. Star clusters are studied widely both as benchmarks for stellar evolution models and in their own right. Cluster age distributions and mass distributions within galaxies are probes of star formation histories and of cluster formation and disruption processes. The vast majority of clusters in the Universe are small, and it is well known that the integrated fluxes and colours of all but the most massive ones have broad probability distributions, owing to small numbers of bright stars. Aims. This paper goes beyond describing predicted probability distributions to present results of the analysis of cluster energy distributions in an explicitly stochastic context. Methods. The method developed is Bayesian. It provides posterior probability distributions in the age-mass-extinction space, using multi-wavelength photometric observations and a large collection of Monte-Carlo simulations of clusters of finite stellar masses. The main priors are the assumed intrinsic distributions of current mass and current age for clusters in a galaxy. Both UBVI and UBVIK data sets are considered, and the study conducted in this paper is restricted to the solar metallicity. Results. We first use the collection of simulations to reassess and explain errors arising from the use of standard analysis methods, which are based on continuous population synthesis models: systematic errors on ages and random errors on masses are large, while systematic errors on masses tend to be smaller. The age-mass distributions obtained after analysis of a synthetic sample are very similar to those found for real galaxies in the literature. The Bayesian approach, on the other hand, is very successful in recovering the input ages and masses over ages ranging between 20 Myr and 1.5 Gyr, with only limited systematics that we explain. Conclusions. Considering stochasticity is important, more important for instance than the choice of adding or removing near-IR data in many cases. We found no immediately obvious reason to reject priors inspired by previous (standard) analyses of cluster populations in galaxies, i.e., cluster distributions that scale with mass as M −2 and are uniform on a logarithmic age scale.

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The distribution of low-mass stars in the Galactic disc

Cited by 1,633 publications

References 0 publications

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

The effects of orbital inclination on the scale size and evolution of tidally filling star clusters

Accounting for stochastic fluctuations when analysing the integrated light of star clusters

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