Performing asteroseismology in the time domain

[christinahedges]

Asteroseismology can unlock stellar properties such as mass and radius independently from other methods. Until recently, asteroseismic analyses were only carried out in the frequency domain, by using Fourier Transforms on time series photometry. Recent research into the use of Gaussian Process models (Ambikasaran et al. 2015; Foreman-Mackey et al. 2017) and Gaussian Process-based Continuous Auto-Regressive Moving Average models (CARMA; Farr et al. 2018) have been able to reveal asteroseismic information by fitting simple harmonic oscillator models in the time domain. These techniques offer the potential to unlock oscillations at very low signal to noise level, but their use on Kepler data is yet to be explored thoroughly. Validating these methods on Kepler data, where verification of results using the frequency domain is possible, will help establish whether these methods can be used to detect solar-like oscillations in TESS data.

[kstassun]

One of the major advances enabled by Kepler was the development of methods for extracting asteroseismically related information from direct (non-Fourier) analysis of time-domain light curves. For example, Bastien et al. (2013, 2016) have shown that from the Kepler long-cadence light curves it is possible to extract the granulation "flicker" that correlates very strongly with stellar surface gravity and thus provides a means for measuring stellar surface gravity with a precision of ~0.1 dex, for stars with logg > 2.5. More recent work demonstrates that the addition of metallicity as a term in the fit enables the surface gravity precision to be improved to ~0.05 dex (Corsaro et al. 2017, Tayar et al. 2018). Application of these methods to the full Kepler + K2 data set holds the promise of enabling the determination of precise stellar properties for stars far beyond the original Kepler footprint. Finally, overlap of the Kepler/K2 sample with upcoming TESS observations should enable calibration and extension of the granulation "flicker" methodology to TESS stars across the entire sky (see, e.g., Stassun et al. 2018).

[christinahedges]

@kstassun thanks so much for these insights and great reading material. I 100% agree, flicker noise is another excellent way to learn more about stellar properties.

Can I clarify;

Application of these methods to the full Kepler + K2 data set holds the promise of enabling the determination of precise stellar properties for stars far beyond the original Kepler footprint.

Here do you mean by building scaling relations using the original Kepler/K2 sets and then applying them to other surveys?

I'd really like to open another issue discussing this further, with a new project title. I'm thinking "Investigating Flicker noise across the Kepler/K2 sample"? The project that we've described here is more about fitting models in the time domain to measure the acoustic oscillations of stars. I think this discussion deserves its own project!

[kstassun]

OK, sounds fine to me!