The role of theta Oph in the formation and evolution of the Pipe Nebula - is star formation ever isolated?

Abstract

We propose that the Pipe Nebula is an HII region shell swept up by the B2 IV beta Cephei star theta Ophiuchi. After reviewing the morphological evidence by recent observations, we perform a series of analytical calculations. We use realistic HII region parameters derived with the radiative transfer code Cloudy from observed stellar parameters. We are able to show that the current size, mass and pressure of the region can be explained in this scenario. We investigate the configuration today and come to the conclusion that the Pipe Nebula can be best described by a three phase medium in pressure equilibrium. The pressure support is provided by the ionized gas and mediated by an atomic component to confine the cores at the observed current pressure. In the future, star formation in these cores is likely to be either triggered by feedback of the most massive, gravitationally bound cores as soon as they collapse or by the supernova explosion of theta Ophiuchi itself.

Accepted by ApJ Letters

References in corpus (9)

• The Dynamics of Radiation Pressure-Dominated HII Regions
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• Optical polarimetry toward the Pipe nebula: Revealing the importance of the magnetic field
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Cited by in corpus (8)

• Significance Mode Analysis (SigMA) for hierarchical structures. An application to the Sco-Cen OB association
• The mid-infrared extinction law in the darkest cores of the Pipe Nebula
• Non-linear dense core formation in the dark cloud L1517
• Distortion of Magnetic Fields in a Starless Core III: Polarization--Extinction Relationship in FeSt 1-457
• A correlation between chemistry, polarization and dust properties in the Pipe Nebula starless core FeSt 1-457
• On the Coagulation and Size Distribution of Pressure Confined Cores
• On the IMF in a Triggered Star Formation Context
• Temperature Structure of the Pipe Nebula Studied by the Intensity Anomaly of the OH 18 cm