NGTS V. Star and cluster ages, masses and periods

From 5749 light curves of Orion members, we report periodic signatures for 2268 objects and analyse rotation period distributions as a function of colour for 1789 stars with spectral types F0-M5. We select candidate members of Orion using Gaia data and assign our targets to kinematic sub-groups.

We correct for interstellar extinction on a star-by-star basis and determine stellar and cluster ages using magnetic and non-magnetic stellar evolutionary models. Rotation periods generally lie in the range 1-10 d, with only 1.5 per cent of classical T Tauri stars or Class I/II young stellar objects rotating with periods shorter than 1.8 d, compared with 14 per cent of weak-line T Tauri stars or Class III objects. In period-colour space, the rotation period distribution moves towards shorter periods among low-mass (>M2) stars of age 3-6 Myr, compared with those at 1-3 Myr, with no periods longer than 10 d for stars later than M3.5.