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THE WIDE INFRARED SURVEY EXPLORER CATALOGUED ALMOST A BILLION INFRARED SOURCES AND HAS SEVERAL THOUSAND CITATIONS TO DATE BUT ITS TEMPORAL DIMENSION REMAINS RELATIVELY UNEXPLORED. THE COMBINATION OF THE ALLWISE DATA RELEASE AND THE NEOWISE DATA PROVIDES LIGHT CURVES FOR EVERY OBJECT WITH ~70-200 DATA POINTS PROBING A VARIETY OF TIME SCALES FROM A FRACTION OF A DAY TO WEEKS. WE PROPOSE TO DEVELOP TOOLS FOR THE ANALYSIS OF THE VARIABILITY DATA FROM WISE TO MINE THE TEMPORAL DIMENSION OF THE ALLWISE AND NEOWISE RELEASES AND IN PARTICULAR TO USE THESE DATA TO CHARACTERIZE THE VARIABILITY OF YOUNG STELLAR OBJECTS AND THEIR CIRCUMSTELLAR DISKS. YOUNG STARS ARE SURROUNDED BY DISKS -- FROM WHICH THE PLANETS PRESUMABLY FORM -- WHICH ARE NOW KNOWN TO BE VIOLENT STRONGLY VARYING ENVIRONMENTS. THE PHYSICAL PROCESSES GOVERNING THE TIME EVOLUTION OF DISKS REMAIN POORLY UNDERSTOOD. (1) WE WILL PRODUCE THE FIRST SYSTEMATIC STUDY OF THE UTILITY OF THE WISE LIGHT CURVES FOR EVALUATING VARIABILITY OF ANY TYPE OF ASTROPHYSICAL SOURCE. FOR EVERY LIGHT CURVE WE WILL DEVELOP AND REPORT A SET OF KEY METRICS THAT CHARACTERIZE THE AMPLITUDE AND THE TIMESCALE OF VARIABILITY AND THE LIKELIHOOD OF PERIODICITY. (2) FOR STELLAR POPULATIONS ACCESSIBLE AT OPTICAL WAVELENGTHS WE WILL USE DISTANCES FROM GAIA TO CHARACTERIZE INFRARED VARIABILITY OF STARS OF ALL TYPES FROM MAIN SEQUENCE TO EVOLVING GIANTS TO WHITE DWARFS AND WE WILL SEARCH FOR NEW AND UNUSUAL KINDS OF VARIABILITY IN THE MULTI-DIMENSIONAL SPACE OF STELLAR COLORS AND VARIABILITY METRICS. (3) FURTHERMORE WE WILL STUDY INFRARED VARIABILITY OF STRONGLY OBSCURED POPULATIONS INACCESSIBLE TO GAIA. FOR>20 000 VARIABLE YOUNG STELLAR OBJECTS AVAILABLE IN WISE -- MORE THAN AN ORDER OF MAGNITUDE INCREASE IN SAMPLE SIZE OVER EXISTING DATA -- WE WILL MEASURE THE POWER SPECTRA OF VARIABILITY DEVELOP QUANTITATIVE TOOLS FOR CLASSIFYING DIFFERENT TYPES OF VARIABILITY EVALUATE THESE PROPERTIES AS A FUNCTION OF THESE OBJECTS' AGES AND ENVIRONMENTS AND SEARCH FOR PERIODIC AND QUASI-PERIODIC MOTIONS WITHIN THE INNER CIRCUMSTELLAR DISKS. THESE MEASUREMENTS WILL BE ESSENTIAL FOR DISENTANGLING THE CONTRIBUTIONS OF MAGNETIC FIELDS SUNSPOTS DISK TWISTS AND DISK WARPS AND INNERMOST PLANETS AS SOURCES OF DISK VARIABILITY. (4) ADDITIONALLY WE WILL SEARCH FOR CIRCUMPLANETARY DISKS AT LARGE DISTANCES FROM THE STAR (~1AU) THAT REMAIN AFTER THE MAIN CIRCUMSTELLAR DISK HAS DISSIPATED. THESE DISKS ARE PREDICTED TO OCCUR REGULARLY IN SYSTEMS YOUNGER THAN 100 MYR BUT THERE ARE ONLY A COUPLE OF POSSIBLE CANDIDATES WITH OBSERVATIONS AND THEREFORE THE PROPERTIES OF THIS POPULATION ARE COMPLETELY UNCONSTRAINED. OUR ANALYSIS WILL PROVIDE THE TOOLS NECESSARY FOR EXPLORING THE TIME DOMAIN OF THE WISE SURVEY AND WE WILL USE THESE TOOLS TO ADDRESS PRESSING ISSUES IN PLANET FORMATION. HOWEVER THE TOOLS WE ARE DEVELOPING HAVE BROADER APPLICABILITY IN TIME-DOMAIN ASTRONOMY AND IN DATA MINING. THIS PROPOSAL DIRECTLY ADDRESSES THE GOAL OF NASA ASTROPHYSICS DATA ANALYSIS PROGRAM TO ENHANCE THE VALUE OF THE ARCHIVAL DATA FROM NASA SPACE ASTROPHYSICS MISSIONS AND THE NASA ASTROPHYSICS GOAL OF UNDERSTANDING PLANET FORMATION.

$367,079FY2020National Aeronautics and Space AdministrationNASA

The Johns Hopkins University

Investigators

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