Gaia: Orion's Integral Shaped Filament is a Standing Wave

Abstract

The Integral Shaped Filament (ISF) is the nearest molecular cloud with rapid star formation, including massive stars, and it is therefore a star-formation laboratory. We use Gaia parallaxes, to show that the distances to young Class II stars ('disks') projected along the spine of this filament are related to the gas radial velocity by $$v=-\frac{D}{\tau }+K;\tau =4\mathrm{Myr},$$ where $K$ is a constant. This implies that the ISF is a standing wave, which is consistent with the Stutz & Gould (2016) 'Slingshot' prediction. The $\tau =4\mathrm{Myr}$ timescale is consistent with the 'Slingshot' picture that the Orion Nebula Cluster (ONC) is the third cluster to be violently split off from the Orion A cloud (following NGC 1981 and NGC 1987) at few-Myr intervals due to gravito-magnetic oscillations. We also present preliminary evidence that the truncation of the ISF is now taking place $16^{\prime }$ south of the ONC and is mediated by a torsional wave that is propagating south with a characteristic timescale ${\tau }_{\mathrm{torsion}}=0.5\mathrm{Myr}$, i.e. eight times shorter. The relation between these two wave phenomena is not presently understood.

5 pages, 5 figures, submitted to MNRAS Letters

References in corpus (3)

• Kinematics in Young Star Clusters and Associations with Gaia DR2
• The APOGEE-2 Survey of the Orion Star Forming Complex II: Six-dimensional structure
• Magnetic fields in star forming systems (I): Idealized synthetic signatures of dust polarization and Zeeman splitting in filaments

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• Gas velocity structure of the Orion A Integral Shaped Filament
• Filament rotation in the California L1482 cloud
• Sheets, filaments and clumps - high resolution simulations of how the thermal instability can form molecular clouds
• Benchmarking the IRDC G351.77-0.53: Gaia DR3 distance, mass distribution, and star formation content
• Interactions of a shock with a molecular cloud at various stages of its evolution due to thermal instability and gravity
• The CARMA-NRO Orion Survey: Core Emergence and Kinematics in the Orion A Cloud
• Striations, integrals, hourglasses and collapse -- thermal instability driven magnetic simulations of molecular clouds