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Estimating TESS Stellar Rotation Periods with CNNs

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Mission Overview

Estimating TESS stellar rotation periods with CNNs

The NASA TESS mission conducts an all-sky survey searching for exoplanets that transit their host stars. To do so, it collects time series photometry called “light curves” for millions of stars across the sky. These light curves have many science uses besides exoplanets, including stellar rotation. As a star rotates, cool magnetic spots come into and out of view, causing periodic wiggles in the brighness measurements through time. We can therefore use light curves from TESS to infer stellar rotation periods, which are useful for studying stellar magnetism, structure, and ages.

In this tutorial we use a convolutional neural network (CNN) to estimate stellar rotation periods from frequency transforms of TESS light curves. For our training set, we will use the simulations from the MAST High Level Science Product SMARTS. SMARTS combines physically realistic simulations of rotational light curves with real noise and systematics from TESS. This combination allows CNNs to learn the difference between rotation signals and systematics and estimate stellar rotation periods.

Data:The SMARTS HLSP

Notebook: Estimating TESS stellar rotation periods with CNNs

Released: 2025年09月02日

Updated: 2025年09月02日

Tags: neural networks, 2d data, supervised, regression, convolutional neural networks

[画像:This image represents the wavelet power spectrum of a stellar light curve. It has a black field with a wispy, horizontal white band spanning the full width. There is also a red, horizontal, dotted line, which also spans the image width, just above the white band.]
Image of a wavelet transform of a TESS rotating star light curve, which is the chosen representation for the training data in this exercise. The wavelet transform acts as a time-varying Fourier transform, with time on the x-axis, frequency on the y-axis, and "brightness" indicating the power spectral density at that time and frequency. Rotating stars with magnetic star spots have sinusoidal-like light curves, which maintain power at a specific frequency for a long period of time. The red dotted line is at the equatorial rotation period of this star, which is slightly faster than the observed period of maximum power. This is due to latitudinal differential rotation, where spots emerge at more slowly rotating latitudes away from the star's equator.

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