A major asymmetric ice trap in a planet-forming disk: II. prominent SO and SO2 pointing to C/O < 1

Abstract

Gas-phase sulphur bearing volatiles appear to be severely depleted in protoplanetary disks. The detection of CS and non-detections of SO and SO2 in many disks have shown that the gas in the warm molecular layer, where giant planets accrete their atmospheres, has a high C/O ratio. In this letter, we report the detection of SO and SO2 in the Oph-IRS 48 disk using ALMA. This is the first case of prominent SO2 emission detected from a protoplanetary disk. The molecular emissions of both molecules is spatially correlated with the asymmetric dust trap. We propose that this is due to the sublimation of ices at the edge of the dust cavity and that the bulk of the ice reservoir is coincident with the millimetre dust grains. Depending on the partition of elemental sulphur between refractory and volatile materials the observed molecules can account for 15-100% of the total sulphur budget in the disk. In strong contrast to previous results, we constrain the C/O ratio from the CS/SO ratio to be < 1 and potentially solar. This has important implications for the elemental composition of planets forming within the cavities of warm transition disks.

arXiv commentAccepted to A&A Letters 7th June 2021

References in corpus (32)

• Gaia Data Release 2. Summary of the contents and survey properties
• Observations of the Icy Universe
• A Major Asymmetric Dust Trap in a Transition Disk
• Chemical enrichment of giant planets and discs due to pebble drift
• Resolved gas cavities in transitional disks inferred from CO isotopologues with ALMA
• First detection of gas-phase methanol in a protoplanetary disk
• Meridional flows in the disk around a young star
• Dust depleted inner disks in a large sample of transition disks through long-baseline ALMA observations
• Molecular abundances and C/O ratios in chemically evolving planet-forming disk midplanes
• Meridional circulation of gas into gaps opened by giant planets in three-dimensional low-viscosity disks
• Gas structure inside dust cavities of transition disks: Oph IRS 48 observed by ALMA
• Herschel observations of EXtra-Ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey Toward Orion KL I. Methods
• Abundant refractory sulfur in protoplanetary disks
• The ALMA-PILS survey: The sulphur connection between protostars and comets: IRAS 16293-2422 B and 67P/Churyumov-Gerasimenko
• DIGIT survey of far-infrared lines from protoplanetary disks I
• On the diversity of asymmetries in gapped protoplanetary disks
• Sulfur chemistry in protoplanetary disks: CS and H2CS
• A new study of an old sink of sulfur in hot molecular cores: the sulfur residue
• Chemistry in Disks X: The Molecular Content of Proto-planetary Disks in Taurus
• Spatial separation of small and large grains in the transitional disk around the young star IRS 48
• CID: Chemistry in disks VI.sulfur-bearing molecules in the protoplanetary disks surrounding LkCa15, MWC480, DM Tau, and GO Tau
• First detection of gas-phase ammonia in a planet-forming disk
• A major asymmetric ice trap in a planet-forming disk: I. Formaldehyde and methanol
• A 30 AU radius CO gas hole in the disk around the Herbig Ae star Oph IRS 48
• Sulfur-driven Haze Formation in Warm CO2-rich Exoplanet Atmospheres
• Sulphur monoxide exposes a potential molecular disk wind from the planet-hosting disk around HD100546
• ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT) V: Sample, overview, and demography of disk molecular emission
• AB Aur, a Rosetta stone for studies of planet formation (I): chemical study of a planet-forming disk
• Spatially resolved HCN J=4--3 and CS J=7--6 emission from the disk around HD 142527
• Solving grain size inconsistency between ALMA polarization and VLA continuum in the Ophiuchus IRS 48 protoplanetary disk
• Molecular content of the circumstellar disk in AB Aur: First detection of SO in a circumstellar disk
• ALMA chemical survey of disk-outflow sources in Taurus (ALMA-DOT). IV. Thioformaldehyde (H${}_2$CS) in protoplanetary disks: spatial distributions and binding energies