The Multiple Pre-main-sequence System PR Ori and the Associated HH 305 Flow

• Published in: The Astronomical journal Vol. 156; no. 1; pp. 25 - 39
• Main Authors: Reipurth, Bo, Herbig, G. H., Bally, J., Geballe, T. R., Bowler, B. P., Raga, A. C., Chiang, H.-F., Connelley, M. S., Aspin, C.
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.07.2018; IOP Publishing
• Subjects: Astronomy; Binary stars; Collimation; Flow; H alpha line; ISM: jets and outflows; Knots; Luminosity; Morphology; Pre-main sequence stars; Spectroscopic analysis; stars: formation; stars: individual (PR Ori); stars: low-mass; stars: pre-main sequence; Stellar winds; T Tauri stars; Wavelengths
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/aac020

A detailed imaging and spectroscopic analysis is presented of the little-studied T Tauri star PR Ori and its associated Herbig-Haro flow HH 305, located on the outskirts of the L1641-N cluster in Orion. PR Ori is shown to be a multiple system, where the A component is a close 0 077 binary, and the B component, at a distance of 3 50, is the driver of the large Herbig-Haro flow. A low-luminosity source, here called C, is located 9 3 to the southeast and is shown spectroscopically to be straddling the stellar/brown dwarf boundary. The corresponding separations in projection are 32, 1450, and 3900 au, respectively. Although PR Ori A is a weak-line T Tauri star, high-resolution optical spectra reveal high-velocity outflowing winds and, at the same time, material infalling with speeds up to 200 km s−1. PR Ori B shows a similar combination of outflow and infall but is a strong H emission star, with a major near-infrared excess that dominates the luminosity of the system at wavelengths longer than ∼5 m. HH 305 displays three pairs of knots symmetrically on either side of PR Ori, with higher velocities near the source and gradually decreasing velocities with increasing distance from the source. The innermost knots show bubble-like morphologies, very different from a collimated jet, with the northern lobe redshifted and the southern lobe blueshifted. The origin and nature of this unusual Herbig-Haro flow is discussed.