Non-linear Time Series Analysis: NTSA

Context

Photometric light curves measure the total brightness variation of a star over time. In order to extract information on these periodic brightness variations (i.e., the variability of a variable star) from this data product, various software suites can be used (which typically employ harmonic analysis). One such suite is the computational framework described on this page, NTSA, which I started developing during my PhD.

Purpose

Originally, the main purpose of this framework was to detect resonances (i.e., resonant combination frequencies) among the frequencies of stellar oscillations. Variable stars whose light curves display such resonances were considered (high) priority targets for the theoretical modeling of (non-linear) mode energy exchange.

Applications

Use of NTSA for the detection of resonant combination frequencies is highlighted in Van Beeck et al. (2021), where we specifically searched for three-mode resonances in light curves of variable stars of spectral type B¹ that fuse hydrogen isotopes in their cores (i.e., stars on the main sequence), which are the so-called slowly pulsating B (SPB) stars.

Citations/using this code

An article describing the generic computational framework is to be made. When using (part of) this code, you should therefore cite the application article, Van Beeck et al. (2021).²