A tell-tale tracer for externally irradiated protoplanetary disks: comparing the [CI] 8727 A line and ALMA observations in proplyds

Abstract

The evolution of protoplanetary disks in regions with massive OB stars is influenced by externally driven winds that deplete the outer parts of disks. These winds have previously been studied via forbidden oxygen emission lines, which also arise in isolated disks in low-mass star forming-regions (SFRs) with weak external UV fields in photoevaporative or magnetic (internal) disk winds. It is crucial to determine how to disentangle external winds from internal ones. Here, we report a proxy for unambiguously identifying externally driven winds with a forbidden line of neutral atomic carbon, [C i] 8727 A. We compare for the first time the spatial location of the emission in the [O i] 5577 A, [O i] 6300 A, and [C i] 8727 A lines traced by VLT/MUSE-NFM, with the ALMA Band 7 continuum disk emission in a sample of 12 proplyds in the Orion Nebula Cluster (ONC). We confirm that the [O i] 5577 A emission is co-spatial with the disk emission, whereas the [O i] 6300 A is emitted both on the disk surface and on the ionization front of the proplyds. We show for the first time that the [C i] 8727 A line is also co-spatial with the disk surface in proplyds, as seen in the MUSE and ALMA data comparison. To verify whether the [C i] 8727 A line is detected in regions where external photoevaporation is not expected, we examine VLT/X-Shooter spectra for young stars in low-mass SFRs. Although the [O i] lines are well detected in all these targets, there is <<10% detection rate in the case of the [C i] 8727 A line. This number increases substantially to a ~40% detection rate in sigma-Orionis, a region with intermediate UV radiation. The spatial location of the [C i] 8727 A line emission and the lack of its detection in isolated disks in low-mass SFRs strongly suggest that this line is a tell-tale tracer of externally driven photoevaporative winds, which agrees with recent excitation models.

Accepted to A&A on October 25, 2024

References in corpus (14)

• ALMA Observations of the Orion Proplyds
• Tracing Slow Winds from T Tauri Stars via Low Velocity Forbidden Line Emission
• Connection between jets, winds and accretion in T Tauri stars: the X-shooter view
• X-Shooter spectroscopy of young stellar objects: V - Slow winds in T Tauri stars
• PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar
• Formation of the Methyl Cation by Photochemistry in a Protoplanetary Disk
• PENELLOPE: the ESO data legacy program to complement the Hubble UV Legacy Library of Young Stars (ULLYSES) I. Survey presentation and accretion properties of Orion OB1 and $\sigma$-Orionis
• Carbon depletion observed inside T Tauri inner rims: Formation of icy, kilometer size planetesimals by 1 Myr
• PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula
• Kaleidoscope of irradiated disks: MUSE observations of proplyds in the Orion Nebula Cluster. I. Sample presentation and ionization front sizes
• [OI] 6300Å emission as a probe of external photoevaporation of protoplanetary discs
• PDRs4All. X. ALMA and JWST detection of neutral carbon in the externally irradiated disk d203-506: Undepleted gas-phase carbon
• PENELLOPE IV. A comparison between optical forbidden lines and ${\mathrm{H}}_2$ UV lines in the Orion OB1b and $\sigma$-Ori associations
• A spectacular jet from the bright 244-440 Orion proplyd: the MUSE NFM view

Cited by in corpus (4)

• XUE. JWST spectroscopy of externally irradiated disks around young intermediate-mass stars
• Observation of an Accreting Planetary-Mass Companion with Signs of Disk-Disk Interaction in Orion
• Line ratio identification of external photoevaporation
• H3+ in irradiated protoplanetary disks: Linking far-ultraviolet radiation and water vapor