HD 139614b: a Gas Giant Exoplanet Embedded in a Herbig Ae Host Star's Protoplanetary Disk?

A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614: Further evidence for a giant planet inside the disk?

Authors:

Carmona et al

Abstract:

Context: 

Quantifying the gas content inside the dust gaps of transition disks is important to establish their origin. Aims: We seek to constrain the surface density of warm gas in the disk of HD 139614, a Herbig Ae star with a transition disk exhibiting a dust gap from 2.3 to 6 AU. 

Methods: 

We have obtained ESO/VLT CRIRES high-resolution spectra of CO ro-vibrational emission. We derive disk structure constraints by modeling the line profiles, the spectroastrometric signal, and the rotational diagrams using flat Keplerian disk models. 

Results: 

We detected v=1-0 12CO, 2-1 12CO, 1-0 13CO, 1-0 C18O, and 1-0 C17O ro-vibrational lines. 12CO v=1-0 lines have an average width of 14 km/s, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km/s narrower, and are dominated by emission at R>6 AU. The 12CO v=1-0 line profile indicates that if there is a gap in the gas it must be narrower than 2 AU. We find that a drop in the gas surface density (delta_gas) at R=5-6 AU is required to reproduce the line profiles and rotational diagrams of the three CO isotopologues simultaneously. Delta_gas can range from 10^-2 to 10^-4 depending on the outer disk's gas-to-dust ratio. We find that at 1

Conclusions: 

The dust gap in the disk of HD 139614 has gas. The gas surface density in the disk at R<6 139614="" 6="" a="" absence="" accretion="" alpha-disk="" and="" assuming="" au="" density="" drop="" expected="" from="" gas="" gradient="" hd="" inside="" is="" lower="" model.="" non-negative="" of="" rate="" s="" significantly="" surface="" than="" the="" viscous="" wide="">2 AU) gas gap suggest the presence of an embedded <2 4="" around="" at="" au.="" mj="" p="" planet="">