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# Program information file
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PROGRAM_ID           2023A005
PROGRAM_TITLE        Coordinated IRTF/SpeX and VLTI MATISSE observations of Pre-Main Sequence Disks with known Variability
PROGRAM_INV1         Michael Sitko
PROGRAM_INV2         Ray Russell
PROGRAM_INV3         William Danchi
PROGRAM_INV4         Bruno Lopez
PROGRAM_INV5         Jozsef Varga
PROGRAM_SCICAT       stellar
PROGRAM_ABSTRACT_BEG
Recent observations of HD 163296 with the Very Large Telescope Interferometer indicate structural changes in the disk near the inner edge of its disk, about 0.3 AU from the star. These might signal perturbations due to turbulence or a pressure bump from an embedded or slightly external exo-protoplanet. Both Guaranteed Telescope Observations and Guest Observations of HD 163296 are planned for this object using the MATISSE 4-telescope  instrument on the VLTI at L, M, and N bands. Spectroscopic and photometric observations overlapping the MATISSE observations with SpeX on the IRTF are needed to aid in the interpretation of the interferometry. SAO 206462 is also on the GTO planning list for MATISSE. While both objects are known IR variable stars, cadences of the time scale of ~1 week are rare, and hourly cadences do not exist. However, such observations are needed to rule out the possibility that some of the variability is due to illumination by accretion-generated hot spots on the stars, as their rotational periods are on the time scale of a few days for HD 163296 and hours for SAO 206462.
PROGRAM_ABSTRACT_END