Among young main sequence stars surrounded by debris disks, a handful of remarkable objects exhibit a substantial amount of primordial gas, making them hybrid disks between proto-planetary and debris disks: 49 Ceti (40 Myr, Zuckerman et al. 1995; Moór et al. 2011), HD 21997 (30 Myr, Kóspál et al. 2013), HD 141569 (5 Myr, Dent et al. 2005), and HD 131835 (16 Myr, Moór et al. 2015).
Online Language Learning Tool SkELL allows users to search for phrases in sentences, collocates and similar words. These examples have been automatically selected and may contain errors.
