I'm
the cosmos holds many different kinds of
stars there are huge giant stars
hundreds of times larger than our Sun
that burn bright and fast for the most
part alive for only a few hundred
million years there are stars like our
Sun relatively smallish stars peppered
throughout the galaxy
they shine at a more moderate
temperature compared to the Giants and
lasts for around ten billion years our
Sun has been around about half that long
and will die some 5 billion years from
now but the vast majority around 85% of
all stars in the sky are cooler dimmer
ones and they are known as red dwarfs as
their name implies a red dwarf is small
no bigger than half the size of the Sun
they are also very dim the brightest
known red dwarf has only 10% of the
luminosity of the Sun and they generate
as little as one ten thousandth of the
energy the smallest among them are
barely able to shine at all these
smaller red dwarf stars those that are
ramier seven and a half percent the size
of the Sun are the smallest objects in
the universe able to shine by the
process of nuclear fusion
but their small size and dim luminosity
has one big advantage red dwarf stars
live the longest relative to all other
stars in the sky they are immortal their
lifetimes extend into the trillions of
years they will live roughly a thousand
times longer than the Sun and 100,000
times longer than most Giants red dwarfs
live so long because they burn their
hydrogen fuel slower than brighter stars
they are of such small size and generate
so little energy they confuse their
hydrogen more efficiently to understand
why we need to look at what's underneath
the surface of a star all stars
regardless of their size have layers
underneath the details of what and how
many layers depends on its mass the Sun
for example has a layer known as the
radiative zone it lies between the core
and another region called the convective
zone when a photon of energy is
generated in the Sun's core once it hits
the radiative zone it hits a kind of
wall energy can only pass through this
zone by collision with another atom and
re-emission giant stars have a much
smaller radiative zone and a larger
convection zone radiation by fusion is a
more efficient process here this process
of collision and re-emission takes a lot
of time it can take a photon passing
through the radiative zone nearly three
million years just to get to the surface
these photons from the Sun had to go
through a lot as well as millions of
years to reach our eyes red dwarf stars
on the other hand do not have this
radiative zone photons emitted from the
core goes straight to the convective
zone where the hydrogen gas is more
efficiently mixed with the core allowing
more of it to be used red dwarf stars
are able to convert virtually all of
their hydrogen fuel to helium to a
degree other stars with large radiative
zones cannot so how will red dwarfs die
long after all other stars have perished
red dwarfs will still be shiny glowing
dimly and feebly these smoldering embers
of creation will be the main source of
radiation in our universe dim reminders
of a once bright and vibrant universe
long after all other stars are gone
after every ounce of their hydrogen has
been spent red dwarfs will slowly fade
into oblivion their embers cooling and
for the first time since the beginning
of the universe the sky will be dark