Project C

Not going out quietly: variability in dying stars

Nicola Gentile Fusillo, Anna Pala & Tommaso Marchetti

(email advisors)

White dwarfs represent the final stage in the evolution of most stars in the Galaxy. Join us in discovering and deciphering the mysterious variability these stars can show at the end of their lifetime.

Over 95% of all stars will end their lives as white dwarfs and a large fraction of them are already at this stage. Despite being just cooling stellar embers, these stars do not simply and quietly fade away into darkness. Many of them show a surprisingly degree of variability in their light, ranging from subtle pulsations to explosive behavior. The causes of this variability can be extremely diverse: e.g. cataclysmic interaction with a companion star, extreme magnetic fields, or even the presence of ancient planets.

Identifying the origin of this variability and characterizing the related properties requires repeated monitoring, potentially over timescales of years. Many surveys observe the sky nightly and have obtained lightcurves for millions of stars, sometimes spanning time periods longer than a decade. In the past we did not know enough white dwarfs to make full use of these large datasets, but thanks to the Gaia satellite we now have over 150,000 previously unknown white dwarfs to explore!

This project will focus on large scale data mining and combining different datasets to identify variable white dwarfs. We will then explore in detail the most promising candidates and attempt to uncover the origin of the observed variability though simple modelling, comparison with known objects, and a number of numerical analysis tools.

In this project  the students will learn how to handle large datasets and will utilize photometric observations from a vast array of surveys. They will familiarize themselves with the principle of time-resolved observations as well as the basic  physics of white dwarfs both isolated and in binaries. The skill set acquired will certainly prove very useful beyond the projects itself.

#Lightcurves #Gaia #Python #Topcat #photometry #whitedwarf #exoplanet

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