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E. D. Araya
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JOURNEY: Jets and Outflows Revealing the Nature and Evolution of massive YSOs


Project goal: improve our understanding of mass outflows during the formation of high-mass stars using observational probes on a variety of spatial length scales. Project JOURNEY.


Star Formation from Galactic Molecular Clouds to Starburst Galaxies


Our group focuses on the study of star formation, in particular the formation of stars eight times or more massive than the Sun – commonly called massive stars. We conduct observations at radio frequencies with the most powerful radio telescopes available, including the Very Large Array (VLA) in New Mexico.

Observations at radio frequencies are necessary because stars form in very opaque clouds, and thus the very early phases of star formation can be only studied at low frequencies and not at, for example, optical wavelengths. Astrophysical research conducted at radio (meter to sub-mm) wavelengths is in the process of a revolution. The arrival of new and upgraded facilities will improve current capabilities by orders of magnitude in almost all desired characteristics, e.g., from sensitivity, such as the Jansky Very Large Array (VLA), to wavelength coverage, from the Long Wavelength Array (LWA) to the Atacama Large Millimeter/Submillimeter Array (ALMA). Research in astronomy, in particular in radio astronomy, is also experiencing a fundamental change due to the internet: observations using the most powerful radio telescopes can be done in remote mode without the need of traveling.

The research of our group may be divided in four broad areas:

Identification and High Angular Resolution Observations

– Identification of very early sites of Massive Star Formation: Given the short time-scale for the formation of massive stars, the identification of the youngest objects is fundamental. We use a number of molecular probes, radio continuum observations, and infrared data to identify very young regions of massive star formation.

– High Angular Resolution Studies: We are conducting several radio continuum and molecular line studies at sub-arcsecond angular resolution with the final goal of understanding the process of massive star formation.

Large Scale Environment and the Milky Way

– Molecular Clumps and Envelopes: Massive stars form in large molecular clouds. We explore the use of different molecular transitions to study the kinematics of molecular clumps and envelopes associated with star formation.

– Kinematic Distances to Star Forming Regions: Together with a number of collaborators, we have conducted several surveys using molecular and radio recombination lines to derive kinematic distances to massive star forming regions. Our efforts on this front continue, in particular evaluating the reliability of the methods used to resolve distance ambiguities and to explore the spiral structure of the Milky Way.

Non-thermal Phenomena associated with Star Formation

– Formaldehyde Masers: Our goal is to understand the physics of H2CO 6 cm maser emission. We have conducted several surveys that have more than doubled the number of known H2CO 6 cm maser regions in the Galaxy. Recent data are showing that H2CO masers trace very young massive stellar objects, prior to the formation of ultra-compact H II regions.

– Other Molecular Masers: Other more abundant maser species such as H2O and CH3OH masers are also used to explore the conditions where massive stars are forming, in particular as outflow tracers.

– Variability: We are particularly interested in two types of transients: 1. radio continuum outburst from low mass protostars (as a tool to explore the population of low mass protostars in massive star forming regions), and 2. variability of astrophysical masers, specifically correlated variability of different maser species and the astrophysics of periodic maser flares.


Extragalactic Environments

– Megamasers and Molecular Absorption in Starburst Galaxies:  We have conducted observations of H2CO absorption and megamaser emission toward a number of galaxies including starbursts. The goal of the project is to study the molecular environment where the most profuse star formation takes place.


VLA
ALMA
GBT
NASA-ADS
SIMBAD
NED
IRSA
NVSS
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