A New Look at Disk Winds and External Photoevaporation in the $\sigma$-Orionis Cluster

Abstract

Disk winds play a crucial role in the evolution of protoplanetary disks. Typical conditions for star and planet formation are in regions with intermediate or strong UV radiation fields produced by massive stars. The $\sigma$-Orionis cluster is the ideal site to study disk winds under these conditions; its outer parts can be used to study disk evolution, while its innermost regions to study the effect of external irradiation. For this, we analyze the $[\mathrm{OI}]\lambda$6300, $[\mathrm{NII}]\lambda$6583, and $[\mathrm{SII}]\lambda$6731,$\lambda$6716 lines using high-resolution MIKE spectra of 27 classical T Tauri stars and complemented by intermediate-resolution X-shooter data. We decompose the line profiles into multiple Gaussian components. We calculated luminosities, line ratios, and kinematic properties of these components. We found that the $[\mathrm{OI}]\lambda$6300 line luminosity and kinematic properties are similar to those found in low-mass star-forming regions (SFRs). The frequency of single-component $[\mathrm{OI}]\lambda$6300 line profiles reflects the expected evolutionary stage given the intermediate age of $\sigma$-Orionis. This points to internal processes contributing to the line emission. However, the highly irradiated disks do not follow the accretion - [OI] luminosity relation found in low-mass SFRs, and all exhibit single-component line profiles. Line ratios of highly ionized species of [NII] and [SII] show higher ratios than typical values found in low-mass SFRs. The innermost regions of $\sigma$-Orionis are clearly affected by external irradiation, evidenced by the lack of correlation in the accretion - [OI] luminosity relation. The broad line widths of close-in sources, however, indicate a contribution from internal processes, such as magnetohydrodynamical winds and/or internal photoevaporation. This suggests a coevolution of internal and external winds in $\sigma$-Orionis.

Accepted for publication on Astronomy & Astrophysics. 14 pages, 11 figures + appendix. Abstract abridged to meet arXiv requirements

References in corpus (23)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• Molecfit: A general tool for telluric absorption correction. I. Method and application to ESO instruments
• The Photoevaporation of Discs Around Young Stars in Massive Clusters
• ALMA Observations of the Orion Proplyds
• Tracing Slow Winds from T Tauri Stars via Low Velocity Forbidden Line Emission
• UV Radiation Fields Produced by Young Embedded Star Clusters
• 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
• Disks around Brown Dwarfs in the Sigma Orionis Cluster
• Proplyds around a B1 star - 42 Orionis in NGC 1977
• Orbital and physical properties of the $\sigma$ Ori Aa,Ab,B triple system
• GIARPS High-resolution Observations of T Tauri stars (GHOsT). IV. Accretion properties of the Taurus-Auriga young association
• The interpretation of protoplanetary disc wind diagnostic lines from X-ray photoevaporation and analytical MHD models
• The impact of pre-supernova feedback and its dependence on environment
• A spectroscopic census in young stellar regions: the Sigma Orionis cluster
• Survey of Orion Disks with ALMA (SODA) II: UV-driven disk mass loss in L1641 and L1647
• A High-resolution Optical Survey of Upper Sco: Evidence for Coevolution of Accretion and Disk Winds
• Photochemical-dynamical models of externally FUV irradiated protoplanetary discs
• A Herschel view of protoplanetary disks in the $\sigma$ Ori cluster
• Testing external photoevaporation in the $\sigma$-Orionis cluster with spectroscopy and disk mass measurements
• Testing viscous disc theory using the balance between stellar accretion and external photoevaporation of protoplanetary discs
• [OI] 6300Å emission as a probe of external photoevaporation of protoplanetary discs
• The STAR-MELT Python package for emission line analysis of YSOs