Understanding Stellar Rotation in Young Clusters with Large Surveys

Stellar rotation significantly affects the observed properties of stars, altering their luminosity, colour, and evolutionary paths. This project investigates how stellar rotation influences the appearance of stars in colour–magnitude diagrams of young star clusters using large spectroscopic surveys such as Gaia, LAMOST, and GALAH. The goal is to map rotational velocities to photometric changes, identify the most sensitive photometric filters, and use state-of-the-art stellar evolution models to refine cluster parameter estimates including ages, masses, and evolutionary states.

school Student intake

This project is open for Honours and PhD students

Observatory

Mount Stromlo Observatory

label Research theme

Galactic archaeology

Stellar and planetary astronomy

traffic Project status

Potential

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About

Stellar rotation is a fundamental physical property that affects the internal structure, evolution, and observable characteristics of stars. Rapid rotation modifies stellar temperature distributions through gravity darkening, alters evolutionary timescales, and changes stellar luminosities and colours. These effects introduce systematic biases in the interpretation of colour–magnitude diagrams (CMDs), particularly in young star clusters where rotation velocities can be as high as 300 km/s.

This project aims to quantify the impact of stellar rotation on CMD morphology and cluster properties. Using rotational velocity measurements from large spectroscopic surveys such as Gaia, LAMOST, and GALAH, the student will construct rotational distributions for stars in selected young clusters. These distributions will be analysed as a function of stellar mass, age, and evolutionary stage to identify correlations and trends.

A key component of the project involves mapping rotational velocity to shifts in colour and magnitude. This will require combining high-quality photometric data with spectroscopic rotational velocity measurements to empirically quantify rotational effects across multiple photometric systems. The student will also investigate which photometric filters are most sensitive to rotational effects, helping optimise observational strategies for future surveys.

The project will make use of state-of-the-art stellar evolution models that include rotation, such as MESA and PARSEC. By comparing observed CMDs with rotating and non-rotating models, the student will assess how rotation affects cluster age and mass determinations. This may lead to revised cluster parameters and improved understanding of stellar evolution in young populations.

This project combines observational data analysis, stellar evolution modelling, and statistical inference, and contributes directly to improving the accuracy of stellar population studies. Possible extensions include carrying out targeted observations of specific star clusters with the Hermes spectrograph at the Anglo-Australian Telescope.