Stellar flare study of nearby young moving group members with TESS Data

Abstract

We analyze TESS data to explore stellar flares and rotational characteristics in members of Nearby Young Moving Groups (NYMGs). Our study focuses on 417 members of NYMGs aged 10-150 Myr. Using detrended light curves from the TESS Science Office Quick-Look Pipeline, coupled with our own additional detrending scheme for fast rotators, we systematically detect and characterize 6,288 stellar flares from 27,416 flare candidates. We analyzed light curves from Cycles 1-4 of the TESS mission, finding that for each NYMG member analyzed, at least one stellar flare was present. Flare candidates are initially detected using the AltaiPony flare package, followed by a recovery flare amplitudes, durations, and local continuum background levels. We examine the relationship between flare energy, age, and mass, finding a reduced flaring rate for late-type stars with age for high energy flares, as well as 5.5 times more flares detected in the 10-minute cadence TESS data compared to 30-minute cadence data. Additionally, flare events with extreme energies (E >= 10^{34} erg) on M-dwarf and solar-type stars, providing implications for further exploration into exoplanet habitability.

Figures (15)

• Figure 1: Distribution of the selected NYMG sample in the sky that had QLP data available for download, color coded by age of the associated moving group.
• Figure 2: The contamination plot for the TESS data in this study. Data points lying above the orange line are potential contaminants, as they have additional stars in the TESS aperture so that for a given G-band magnitude, we see higher flux values. Data points marked with a red 'X' potentially contain interference from non-astrophysical sources.
• Figure 3: Top: KSPSAP detrended flux of 2MASS J00273330-6157169. A strong rotational modulation of around $0.55$ days (calculated using Lomb-Scargle) is still present even after detrending. Bottom: the KSPSAP Flux with the Hampel filter applied. In both plots, the red shaded regions indicate data gaps.
• Figure 4: Example of a flare fitted using the "aflare" method, where 'tstop' is defined as 'tstart'+ 'dur' from Davenport_2016, and the flare shape function takes the form of the aflare function added to a quadratic background term: $\text{aflare(time,tstart,tdur,amplitude)} + A*\text{time}**2 + B*\text{time} + C$
• Figure 5: Recovery efficiency of fake flares as a function of flare energy ratio ($E_{\text{flare}}/E_{\text{0}}$) for both 10-minute (top) and 30-minute (bottom) cadence data. The blue bars represent the percentage of fake flares recovered at each energy level, with the total number of recovered flares $N_{\text{rec}}$ and total number of injected flares $N_{\text{tot}}$ indicated for each cadence set. The red dashed line marks the energy level at which the recovery efficiency reaches 90%. For both cadences, the recovery efficiency increases with flare energy, achieving over 90% recovery for flares with $E_{\text{flare}}/E_{\text{0}}$ greater than approximately $10^{-2.8}$. The higher cadence (10-minute) data shows a slightly lower energy threshold for achieving 90% recovery, highlighting the enhanced sensitivity of the 10-minute cadence data in detecting fainter flares.