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# Program information file
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PROGRAM_ID           2024B058
PROGRAM_TITLE        Constraining ultra-cool dwarf formation throughout the history of the Galaxy using the 30pc sample.
PROGRAM_INV1         Richard Smart
PROGRAM_INV2         Celye Reyle
PROGRAM_INV3         Hugh Jones
PROGRAM_INV4         Adam Burgasser
PROGRAM_INV5         Gemma Cheng
PROGRAM_SCICAT       stellar
PROGRAM_ABSTRACT_BEG
We will constrain the formation processes of ultra-cool dwarfs [UCDs] by constructing  a complete, volume limited sample within 30pc of the Sun. We will derive space densities to compare to numerical simulations predicted from an initial mass function and star formation history in the solar neighbourhood and across the stellar-substellar boundary.  The spectra will be used to calibrate correlations of physical characteristics with spectral diagnostics, confirm moving group members, identify common-proper-motion companions to more massive stars, and to search for spectroscopic binaries. This large, statistically significant, spectroscopically classified sample with reliable Gaia astrometry will be a fundamental calibration point for other programs focusing on cooler objects, for example at the L/T boundary to investigate cloud evolution. This proposal is to spectroscopically characterise the remaining northern hemisphere candidates while the southern targets have been observed as part of a large, ongoing, international collaboration. UCD spectra are used to improve the training set of the UCD work-package of the Gaia Data Processing and Analysis Consortium pipeline to generate a complete UCD sample to the Gaia detection limit. This dataset, simply because it will be complete, homogeneous, and local, will be the authoritative sample of ultra-cool dwarfs for the foreseeable future, bridging the stellar to sub-stellar boundary.
 
There are 585 total UCDs within 30pc in Gaia DR3 of which 56 objects [50 visible to IRTF this semester], so 9\%, do not have spectroscopy. This is the closest, most easily characterised, sample to the Sun, and the most promising sample for which we can hope to achieve full completeness. However, there will remain measuring errors and some missing objects due to the Gaia selection function that will leave an uncertainty;  an incomplete spectroscopic followup, however small, is an avoidable, additional, source of uncertainty.
PROGRAM_ABSTRACT_END