Exoplanetary Detection By Multifractal Spectral Analysis

TL;DR

This paper introduces a novel multifractal spectral analysis method for detecting exoplanets and their orbital characteristics from noisy spectral data without relying on stellar models, demonstrated on real and synthetic spectra.

Contribution

The study presents a new approach based on temporal multifractality for exoplanet detection that is robust against noise and does not require stellar model fitting.

Findings

Successfully detected exoplanetary signals in noisy data with SNR ≥ 75.

Reconstructed planetary orbital and stellar rotation periods from spectral data.

Validated method on real observations of HD 189733b and synthetic spectra.

Abstract

Owing to technological advances, the number of exoplanets discovered has risen dramatically in the last few years. However, when trying to observe Earth analogs, it is often difficult to test the veracity of detection. We have developed a new approach to the analysis of exoplanetary spectral observations based on temporal multifractality, which identifies time scales that characterize planetary orbital motion around the host star, and those that arise from stellar features such as spots. Without fitting stellar models to spectral data, we show how the planetary signal can be robustly detected from noisy data using noise amplitude as a source of information. For observation of transiting planets, combining this method with simple geometry allows us to relate the time scales obtained to primary and secondary eclipse of the exoplanets. Making use of data obtained with ground-based and space-based observations we have tested our approach on HD 189733b. Moreover, we have investigated the use of this technique in measuring planetary orbital motion via Doppler shift detection. Finally, we have analyzed synthetic spectra obtained using the SOAP 2.0 tool, which simulates a stellar spectrum and the influence of the presence of a planet or a spot on that spectrum over one orbital period. We have demonstrated that, so long as the signal-to-noise-ratio $\ge$ 75, our approach reconstructs the planetary orbital period, as well as the rotation period of a spot on the stellar surface.