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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 rotation periods for Tuc-Hor objects. From these objects we identify 11 candidate binaries based on multiple periodic signals or outlier Gaia DR2 and EDR3 renormalized unit weight error 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 that 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 Hα and Li equivalent width, as well as near-ultraviolet and X-ray flux. We find that measuring rotation periods with TESS is a fast and effective means to confirm members in young moving groups.
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Exploration of a Dissolving Association Made Up of IC 2602, Tucana–Horologium, and Other Young Comoving Groups
Abstract Recently Gagné et al. suggested that young moving groups with similar kinematic properties could be part of larger dissolving structures. One example was IC 2602 as the core of a group of associations, including its corona (CIC 2602), Tucana-Horologium (THA), and parts of Theia 92. We explore this hypothesis by measuring the rotation periods of 953 objects selected using Gaia DR3 kinematics from IC 2602, CIC 2602, Theia 92, and a newly identified group of stars that bridge IC 2602 and THA. We use Transiting Exoplanet Survey Satellite (TESS) full frame images to measure new rotation periods and combine these with the rotation periods for THA from Popinchalk et al. to compare their rotation period distributions and other youth indicators where available to examine if the groups could be coeval. We find strong agreement between the rotation distributions of IC 2602, CIC 2602, and THA, suggesting a shared age of ∼40 Myr, and which in combination could serve as an example of a typical distribution at this age. Theia 92 does not agree at the same level, and we explore the potential kinematic reasons it does not match the rotation period distribution of the larger groups. Additionally, in our light curve analysis we identify ∼50 potential binaries, as well as four new M dwarf complex rotators that show major morphological changes between TESS cycles. Finally, using the amplitudes of the rotation periods we measured, we find strong agreement with the amplitude–age relation presented in Morris for our 40 Myr groups.
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- Award ID(s):
- 2238468
- PAR ID:
- 10540124
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 972
- Issue:
- 2
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 178
- Size(s):
- Article No. 178
- Sponsoring Org:
- National Science Foundation
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