Examining the Rotation Period Distribution of the 40 Myr Tucana-Horologium Association with TESS

TL;DR

This study measures rotation periods of 313 Tucana-Horologium stars using TESS data, revealing complex rotators, candidate binaries, and rotation distribution insights, demonstrating TESS's effectiveness in confirming young stellar group memberships.

Contribution

First comprehensive TESS-based rotation period analysis of Tuc-Hor, identifying complex rotators, candidate binaries, and providing insights into rotation distributions and youth indicators.

Findings

Measured rotation periods for 255 Tuc-Hor objects

Identified 3 new complex rotators and 11 candidate binaries

Observed significant changes in light curve morphology over TESS cycles

Abstract

The Tucana-Horologium Association (Tuc-Hor) is a 40 Myr old moving group in the southern sky. In this work, we measure the rotation periods of 313 Tuc-Hor objects with TESS light curves derived from TESS full frame images and membership lists driven by Gaia EDR3 kinematics and known youth indicators. We recover a period for 81.4% of the sample and report 255 rotaion periods for Tuc-Hor objects. From these objects we identify 11 candidate binaries based on multiple periodic signals or outlier Gaia DR2 and EDR3 re-normalised unit weight error (RUWE) values. We also identify three new complex rotators (rapidly rotating M dwarf objects with intricate light curve morphology) within our sample. Along with the six previously known complex rotators that belong to Tuc-Hor, we compare their light curve morphology between TESS Cycle 1 and Cycle 3 and find they change substantially. Furthermore, we provide context for the entire Tuc-Hor rotation sample by describing the rotation period distributions alongside other youth indicators such as H{\alpha} and Li equivalent width, as well as near ultra-violet and X ray flux. We find that measuring rotation periods with TESS to be a fast and effective means to confirm members in young moving groups.