The spectroscopic characteristics of intermediate-aged pre-main-sequence stars: the  η  Chamaeleontis cluster     

A-Ran Lyo  Warrick A. Lawson  M. S. Bessell 《Monthly notices of the Royal Astronomical Society》2004,355(2):363-373

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Long-lived disc accretion in the η Chamaeleontis pre-main sequence star cluster     

Warrick A. Lawson  A-Ran Lyo  James Muzerolle 《Monthly notices of the Royal Astronomical Society》2004,351(2):L39-L43

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Population and dynamical state of the η Chamaeleontis sparse young open cluster     

A-Ran Lyo  Warrick A. Lawson  Eric D. Feigelson  Lisa A. Crause 《Monthly notices of the Royal Astronomical Society》2004,347(1):246-254

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A deep photometric survey of the η Chamaeleontis cluster down to the brown dwarf – planet boundary     

A-Ran Lyo  Inseok Song  Warrick A. Lawson  M. S. Bessell  B. Zuckerman 《Monthly notices of the Royal Astronomical Society》2006,368(3):1451-1455

We report the outcome of the deep optical/infrared photometric survey of the central region (33 × 33 arcmin² or 0.9 pc²) of the η Chamaeleontis (η Cha) pre-main sequence star cluster. The completeness limits of the photometry are I = 19.1, J = 18.2 and H = 17.6, faint enough to reveal low-mass members down to the brown dwarf and planet boundary of ≈13 M_Jup. We found no such low-mass members in this region. Our result combined with a previous shallower ( I = 17) but larger area survey indicates that low-mass objects  (0.013 < M /M_⊙ < 0.075)  were either not created in the η Cha cluster or lost due to the early dynamical history of the cluster and ejected to outside the surveyed areas.  相似文献