vice.mlr

The Mass-Lifetime Relationship (MLR) for Stars: VICE provides several functional forms available for individual calculations as well as for use in chemical evolution models.

Signature: vice.mlr

New in version 1.3.0.

Contents

settingstr

A string denoting which of the following functional forms is to describe the MLR in all chemical evolution models.

recognizedtuple

A tuple of strings denoting the allowed values of the parameter setting. Each string corresponds directly to the name of the function to adopt.

  • “powerlaw”

  • “vincenzo2016”

  • “hpt2000”

  • “ka1997”

  • “pm1993”

  • “mm1989”

  • “larson1974”

powerlaw<function>

The MLR parameterized by a single power-law, a popular exercise in undergraduate astronomy courses.

vincenzo2016<function>

The MLR as characterized by Vincenzo et al. (2016) [1].

hpt2000<function>

The MLR as described in Hurley, Pols & Tout (2000) [2].

ka1997<function>

The MLR as tabulated in Kodama & Arimoto (1997) [3].

pm1993<function>

The MLR as formulated by Padovani & Matteucci (1993) [4].

mm1989<function>

The MLR as characterized by Maeder & Meynet (1989) [5].

larson1974<function>

The MLR as parameterized by Larson (1974) [6].

test<function>

Run unit-tests on VICE’s MLR capabilities.

The following forms of the mass-lifetime relation take into account the metallicity dependence:

  • “vincenzo2016” : Vincenzo et al. (2016)

  • “hpt2000” : Hurley, Pols & Tout (2000)

  • “ka1997” : Kodama & Arimoto (1997)

The following require numerical solutions to the inverse function (i.e. stellar mass as a function of lifetime), and consequently can increase the required integration times in chemical evolution models, particularly for fine timestepping:

  • “hpt2000” : Hurley, Pols & Tout (2000)

  • “ka1997” : Koama & Arimoto (1997)

  • “mm1989” : Maeder & Meynet (1989)

The following quantify the total lifetimes a priori, and any prescription for the post main sequence lifetimes will consequently be neglected in chemical evolution models:

  • “vincenzo2016”: Vincenzo et al. (2016)

  • “ka1997” : Kodama & Arimoto (1997)

Except where measurements of the total lifetimes are available, VICE always implements the simplest assumption of allowing the user to specify the parameter postMS describing the ratio of post main sequence to main sequence lifetimes, and the total lifetime then follows trivially via:

\[\tau_\text{total} = (1 + p_\text{MS}) \tau_\text{MS}\]

where \(p_\text{MS}\) denotes this ratio.

Note

For reasons relating to the implementation, this set of functions is not a module but an object. Consequently, importing them with from vice import mlr will work fine, but for example from vice.mlr import vincenzo2016 will produce a ModuleNotFoundError. If necessary, new variables can always be assigned to map to these functions (e.g. vincenzo2016 = vice.mlr.vincenzo2016).