Star formation and Stellar Evolution

Jan Forbrich, Philip Lucas

We are conducting a novel survey of protostellar radio emission in the famous Orion Nebula Cluster with three major radio observatories: the NRAO Very Large Array (VLA), the NRAO Very Long Baseline Array (VLBA), and the Atacama Large Millimeter/submm Array (ALMA). In particular, we are continuing a multi-year monitoring effort to observe nonthermal flares toward hundreds of young stellar objects with the VLBA, which will produce unprecedented and novel constraints on such high-energy emission of protoplanetary disks. Additionally, precision astrometry will allow us to measure proper motions of embedded young stellar objects, complementing Gaia. While previous such observations were limited to very few objects per observation, the use of software correlation allows us to observe hundreds of objects simultaneously in this area of data-intensive radio astronomy. You will learn these methods, and we will place the results in a rich multi-wavelength context in this famous star-forming region.

Philip Lucas, Jan Forbrich, Yi Sun

The VISTA Variables in the Via Lactea survey (VVV) is the first serious exploration of variable stars in the Milky Way at infrared wavelengths. The survey has run for 10 years, led by Prof Lucas at Hertfordshire and Prof Minniti in Chile, but we are only beginning to explore the science potential of the full dataset, which contains about 1 billion stars. Many of these stars are hidden from view in visible light by Interstellar dust. This PhD project will be open for the student to pick one of several topics to work on, using VVV data and likely doing follow up with other telescopes. Many of the topics are in star formation but we are also working on: (i) machine learning classification of the dataset to find new kinds of infrared variable source;

(ii) explorations of unusual types of star using classical methods.

Example projects are:

• Eruptive variability in newborn stars (There are several options within this one, including studies based more on the mid-infrared NASA WISE satellite than VVV)
• Machine learning-based searches for new types of variable star (This is to builds on an existing PhD project, either extending it or exploring new directions)
• Extinction events in newborn stars
• ALMA follow up of eruptive variable newborn stars
• Variability in high mass newborn stars.