  Age is a fundamental stellar property, yet for many stars it is difficult to
reliably determine. For M dwarfs it has been notoriously so. Due to their lower
masses, core hydrogen fusion proceeds at a much slower rate in M dwarfs than it
does in more massive stars like the Sun. As a consequence, more customary age
determination methods (e.g. isochrones and asteroseismology) are unreliable for
M dwarfs. As these methods are unavailable, many have searched for reliable
alternatives. M dwarfs comprise the overwhelming majority of the nearby stellar
inventory, which makes the determination of their fundamental parameters even
more important. Further, an ever-increasing number of exoplanets are being
found to orbit M dwarfs and recent studies have suggested they may relatively
higher number of low-mass planets than other spectral types. Determining the
ages of M dwarfs then allows us to better study any hosted exoplanets, as well.
Fortunately, M dwarfs possess magnetic activity and stellar winds like other
cool dwarf stars. This causes them to undergo the spindown effect (rotate with
longer periods) as they age. For this reason, stellar rotation rate has been
considered a potentially powerful age determination parameter for over 50
years. Calibrating reliable age-rotation relationships for M dwarfs has been a
lengthy process, but here we present the age-rotation relationships for ~M0-6.5
dwarfs, determined as part of the Living with a Red Dwarf program. These
relationships should prove invaluable for a wide range of stellar astrophysics
and exoplanetary science applications.
