SIMBAD references

We present the results of a photometric study of X-ray-active weak-lined T Tauri (WTT) stars in the η Chamaeleontis star cluster. Multi-epoch V-band photometric monitoring during 1999 and 2000 of the 10 X-ray-active WTT stars found that all were variable in one or both years, with periods ascribed to rotational modulation of starspots. Comparison between the rotational and X-ray properties of these objects indicates the saturation level, {formmu1} observed in other studies of X-ray-active pre-main-sequence stars, persists in the η Cha stars from the slow- to the fast-rotator regimes. Cousins VRI photometry of the WTT stars has enabled us to investigate further the photometric properties of these stars. The stars appear sufficiently coeval to distinguish near-equal-mass binaries within the sample. A new Hertzsprung-Russell diagram for these objects suggests ages of 4-9Myr for M-type RECX primaries using the tracks of D'Antona & Mazzitelli.