Structure and Energetics of Massive Outflows from ALMA

• Grant number: 23/03573-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2023
• End date: March 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Astrophysics of the Interstellar Medium
• Principal Investigator: Ciriaco Goddi
• Grantee: Gabriel Menezes Sousa
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/01183-8 - Astrophysical jets at the highest-angular resolution with very long baseline interferometry, AP.JP

Abstract

Outflows from massive young stellar objects (HMYSOs) play an important role in high-mass star formation (HMSF), but their driving mechanism is poorly understood. Various driving mechanisms have been proposed, including magneto-centrifugal processes, ionization pressure, and stellar radiation. The latter result in different morphologies (e.g. wide vs. narrow base, single vs. multiple distinct flows), different degrees and length-scales of collimation, and different spatial variation of momentum and energy. In order to get constraints on these models and progress in this field, in the main proposal we introduce a programme to be carried out with ALMA, whose main goals are to derive the morphology of individual outflows and their velocity field, and to examine how their physical properties (velocity, mass, momentum, energy) vary with distance from the central protostar and its mass/luminosity. In this project, the master student will test the methodology to be adopted in theALMA study of the POETS sample. To that end, the student will analyse together ALMA observations, carried out during cycles 2-4, towards one of the most luminous and fertile stellar nurseries in the Galaxy, W51 (5.4 Kpc). In particular, our ALMA Cycle 2 survey (0.2''; Ginsburg et al. 2017) has identified dozens of collimated outflows stemming from HMYSOs, making it a compelling target for outflow studies in HMSF. ALMA imaging will uniquely provide the velocity field and the physical conditions of the outflowing material as a function of both the distance from the central protostar(at R< 103 104 au) and its mass/luminosity. The ultimate goal of the project (once extended to the full sample) is to address some of the open questions in HMSF: Do outflow physical properties change with mass or over time? Can accretion continue after the onset of an HII region or all the HII regions expand? What's the driving mechanism of outflows from HMYSOs?