Lifetime of star on main sequence
=================================

The main sequence is a stage of stellar evolution following the protostar stage. At the beginning
of the main sequence stage, the age of the star is considered to be zero. The lifetime of a star
can be approximated from the mass of the star.

**Notation:**

#. :math:`M_\odot` (:code:`M_Sun`) is :attr:`~symplyphysics.quantities.solar_mass`.

**Notes:**

#. The indicator has the value of :math:`4.75` for stars with mass of :math:`0.7` to
   :math:`2` solar masses, and :math:`4.75 m + 2.125` for stars with mass of :math:`0.1`
   to :math:`0.7` solar masses. Here :math:`m` refers to the mass of the star.

**Links:**

#. `Wikipedia <https://en.wikipedia.org/wiki/Main_sequence#Lifetime>`__. Corresponds to the
   current law with a fixed indicator value.

.. py:currentmodule:: symplyphysics.astronomy.stellar_evolution.lifetime_of_star_on_main_sequence

.. py:data:: lifetime

    The lifetime (:attr:`~symplyphysics.symbols.basic.time`) of the star.

Symbol:
    :code:`t`

Latex:
    :math:`t`

Dimension:
    :code:`time`


.. py:data:: mass

    :attr:`~symplyphysics.symbols.basic.mass` of the star.

Symbol:
    :code:`m`

Latex:
    :math:`m`

Dimension:
    :code:`mass`


.. py:data:: indicator

    A dimensionless parameter whose value depends on the mass of the star.

Symbol:
    :code:`n`

Latex:
    :math:`n`

Dimension:
    :code:`dimensionless`


.. py:data:: ten_billion_years

    A quantity equal to ten billion years.

Symbol:
    :code:`10 Gyr`

Latex:
    :math:`10 \, \text{Gyr}`

Dimension:
    :code:`time`


.. py:data:: law

    :code:`t = 10 Gyr * (m / M_Sun)^(1 - n)`


    Latex:
        .. math::
            t = 10 \, \text{Gyr} \left(\frac{m}{M_\odot}\right)^{1 - n}