Discovery of molecular gas around HD 131835 in an APEX molecular line survey of bright debris disks

Resolved Gas Interior to the Dust Rings of the HD 141569 Disk

“…Conversely, Pascucci et al (2006), using mid-infrared spectroscopy and single disk mm CO spectroscopy, put upper limits on the gas in the outer radii of debris disks of a few earth masses, below what we derive in the HD 141569 system. Our gas mass is similar to that derived using CO emission from cold gas in the disks around 49 Ceti, with M gas =3.9 ± 0.9 × 10 −5 M ⊙ , HD 21997, with M gas =8-20×10 −5 M ⊙ (Kóspál et al 2013), and HD 131835 with M gas =1.3±0.6×10 −5 M ⊙ (Moór et al 2015), all examples of massive CO disks. Our dust mass, estimated from the 870µm continuum, is 1.8×10 −4 M ⊙ =0.6 M ⊕ similar to the ∼ 0.1 M ⊕ dust masses seen in debris disks at ages of ∼10-100 Myr (Wyatt 2008) and implies an average gas/dust mass ratio of ∼10.…”

“…Their flux ratio of 10±1 implies an excitation temperature of 17±2 K, assuming both are optically thin, which indicates that the gas is very cold. The CO(1-0) flux implies a CO mass of M CO = 1.05±0.06 × 10 −8 M ⊙ , assuming a temperature derived from the line ratio, which is similar to 49 Ceti, HD 21997 and HD 131835 Kóspál et al 2013;Moór et al 2015). This corresponds to M gas =1.05±0.06 × 10 −4 M ⊙ =0.11±0.01 M jup , assuming CO/H 2 =10 −4 , which is not enough to create a Jupiter-sized gas giant, but is larger than typically found among debris disks (Pascucci et al 2006).…”

“…ALMA observations of β Pic find CO gas confined to a belt, with clear asymmetries, and a mass of only 2 × 10 −5 M ⊕ (Dent et al 2014). Recently HD 131835 was discovered to have CO emission consistent with M CO ∼ 4×10 −4 M ⊕ (Moór et al 2015). In addition to these radio observations, optical surveys have revealed gas in the the debris disk systems HR 10 (Lagrange-Henri et al.…”