NDLI: Survival of molecular gas in cavities of transition disks

Content Provider	EDP Sciences
Author	Simon Bruderer
Abstract	Context. Planet formation is closely related to the structure and dispersal of protoplanetary disks. A certain class of disks, called transition disks, exhibit cavities in dust images at scales of up to a few 10s of AU. The formation mechanism of the cavities is still unclear. The gas content of such cavities can be spatially resolved for the first time using the Atacama Large Millimeter/submillimeter Array (ALMA).Aims. We develop a new series of models to simulate the physical conditions and chemical abundances of the gas in cavities to address the question whether the gas is primarily atomic or molecular inside the dust free cavities exposed to intense UV radiation. Molecular/atomic line emission by carbon monoxide (CO), its isotopologues (^{13^{CO, C^{18^{O, C^{17^{O, and ^{13^{C^{18^{O) and related species ([C i], [C ii], and [O i]) is predicted for comparison with ALMA and the Herschel Space Observatory.Methods. We use a thermo-chemical model, which calculates the radiative transfer both in lines and the continuum, and solves for the chemical abundances and gas temperature. The model is based on our previous work, but includes several improvements. We study the dependence of CO abundances and lines on several parameters such as gas mass in the cavity, disk mass and luminosity of the star.Results. The gas can remain in molecular form down to very low amounts of gas in the cavity (~1% of M_{Earth_{). Shielding of the stellar radiation by a dusty inner disk (“pre-transition disk”) allows CO to survive down to lower gas masses in the cavity. The column densities of H_{2_{and CO in the cavity scale almost linearly with the amount of gas in the cavity down to the mass where photodissociation becomes important. The main parameter for the CO emission from cavity is the gas mass. Other parameters such as the outer disk mass, bolometric luminosity, shape of the stellar spectrum or PAH abundance are less important. Since the CO pure rotational lines readily become optically thick, the CO isotopologues need to be observed in order to quantitatively determine the amount of gas in the cavity. Determining gas masses in the cavity from atomic lines ([C i], [C ii], and [O i]) is challenging.Conclusions. A wide range of gas masses in the cavity of transition disks (~4 orders of magnitude) can be probed using combined observations of CO isotopologue lines with ALMA. Measuring the gas mass in the cavity will ultimately help to distinguish between different cavity formation theories.}}}}}}}}}}}}}}
Page Count	26
File Format	HTM / HTML PDF
ISSN	00046361
Alternate Webpage(s)	https://www.aanda.org/articles/aa/abs/2013/11/aa21171-13/aa21171-13.html
e-ISSN	14320746
Journal	Astronomy & Astrophysics
Volume Number	559
DOI	10.1051/0004-6361/201321171
Language	English
Publisher	EDP Sciences
Publisher Date	2013-11-01
Access Restriction	Open
Rights Holder	© ESO, 2013
Subject Keyword	protoplanetary disks stars: formation astrochemistry methods: numerical radiative transfer protoplanetary disks / stars: formation / astrochemistry / methods: numerical / radiative transfer
Content Type	Text
Resource Type	Article
Subject	Astronomy and Astrophysics Space and Planetary Science

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Modelling mid-infrared molecular emission lines from T Tauri stars

Uncertainties in water chemistry in disks: An application to TW Hydrae

Protoplanetary disk masses from CO isotopologue line emission

Nitrogen isotope fractionation in protoplanetary disks

CN rings in full protoplanetary disks around young stars as probes of disk structure

Radiation thermo-chemical models of protoplanetary disks — I. Hydrostatic disk structure and inner rim

Consistent dust and gas models for protoplanetary disks — I. Disk shape, dust settling, opacities, and PAHs

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA

Survival of molecular gas in cavities of transition disks — I. CO

Similar Documents

Modelling mid-infrared molecular emission lines from T Tauri stars

Uncertainties in water chemistry in disks: An application to TW Hydrae

Protoplanetary disk masses from CO isotopologue line emission

Nitrogen isotope fractionation in protoplanetary disks

CN rings in full protoplanetary disks around young stars as probes of disk structure

Radiation thermo-chemical models of protoplanetary disks — I. Hydrostatic disk structure and inner rim

Consistent dust and gas models for protoplanetary disks — I. Disk shape, dust settling, opacities, and PAHs

Gas structure inside dust cavities of transition disks: Ophiuchus IRS 48 observed by ALMA

Resolved gas cavities in transitional disks inferred from CO isotopologs with ALMA

Survival of molecular gas in cavities of transition disks — I. CO