Year: 2020
Type: article
Abstract: All-sky photometric time-series missions have allowed for the monitoring of thousands of young ( t age < 800 Myr) stars in order to understand the evolution of stellar activity. Here, we developed a convolutional neural network (CNN), stella , specifically trained to find flares in Transiting Exoplanet Survey Satellite (TESS) short-cadence data. We applied the network to 3200 young stars in order to evaluate flare rates as a function of age and spectral type. The CNN takes a few seconds to identify flares on a single light curve. We also measured rotation periods for 1500 of our targets and find that flares of all amplitudes are present across all spot phases, suggesting high spot coverage across the entire surface. Additionally, flare rates and amplitudes decrease for stars t age > 50 Myr across all temperatures T eff ≥ 4000 K, while stars from 2300 ≤ T eff < 4000 K show no evolution across 800 Myr. Stars of T eff ≤ 4000 K also show higher flare rates and amplitudes across all ages. We investigate the effects of high flare rates on photoevaporative atmospheric mass loss for young planets. In the presence of flares, planets lose 4%–7% more atmosphere over the first 1 Gyr. stella is an open-source Python toolkit hosted on GitHub and PyPI.
Source: The Astronomical Journal
Authors: Adina D. Feinstein, Benjamin T. Montet, Megan Ansdell, Brian Nord, Jacob L. Bean, Maximilian N. Günther, Michael A. Gully-Santiago, Joshua E. Schlieder
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: G4404904460, G498139845, G5616713406, G585908603, G6267553773, G716412294, Graduate Research Fellowship Program (GRFP), THE OBJECTIVES OF THIS PROPOSAL ARE TO PROVIDE DIAGNOSTIC TOOLS TO SEARCH FOR THE PRESENCE OF CARBON MATERIALS IN SPACE AND STUDY THEIR EVOLUTION. TO THIS END WE INTEND TO MEASURE IN THE LABORATORY THE SPECTRAL PROPERTIES AND CHARACTERISTICS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) AND CARBON-BEARING MOLECULES CLUSTERS AND NANOPARTICLES IN EMISSION USING TWO COMPLEMENTARY HIGHLY-SENSITIVE LASER BASED TECHNIQUES LASER INDUCED FLUORESCENCE (LIF) AND LASER INDUCED INCANDESCENCE (LII). THESE LABORATORY MEASUREMENTS PERFORMED UNDER ASTROPHYSICALLY RELEVANT CONDITIONS WILL HELP DETECT AND CHARACTERIZE THE GAS PHASE MOLECULES AND CLUSTERS AS WELL AS THE SOLID GRAINS (DUST PARTICLES). THE COSMIC SIMULATION FACILITY (COSMIC) DEVELOPED AT NASA AMES WILL BE USED TO STUDY NEUTRAL AND IONIZED MOLECULES AND CLUSTERS IN A PULSED SUPERSONIC JET-COOLED PLASMA EXPANSION I.E. ISOLATED IN A COLLISION-FREE ENVIRONMENT AND AT LOW TEMPERATURE (50-100K) REPRESENTATIVE OF THE INTERSTELLAR ENVIRONMENT. WE INTEND TO BUILD AN EXTENSIVE GAS-PHASE EMISSION DATABASE FOR INTERSTELLAR ANALOGS OF NEUTRAL AND IONIC PAHS PAHCLUSTERS AND LARGE CARBON MOLECULES THAT CAN BE DIRECTLY COMPARED TO SPACE DATA FOR THE UNAMBIGUOUS DETECTION OF SPECIFIC SPECIES IN SPACE. IN PARTICULAR PAH-RELATED PHOTOPRODUCTS SUCH AS HYDROGENATED PAHS (HN-PAHS) NITROGENATED PAHS (PANHS) AND POLYYNYL-SUBSTITUTED PAHS WILL BE CONSIDERED IN THIS PROJECT SINCE THEY ARE PROBABLY PRESENT IN THE ISM AND MAY CONTRIBUTE TO THE OBSERVED AROMATIC EMISSION BANDS., G86560745, G8816780348, G969889393
OpenAlex ID: W3024332222