IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A040 PROGRAM_TITLE Validating a Novel Technique to Find Brown Dwarf Variable Candidates PROGRAM_INV1 Elena Manjavacas PROGRAM_INV2 Daniella Bardalez-Gagliuffi PROGRAM_INV3 Johanna Vos PROGRAM_INV4 Afra Ashraf PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Similar to Jupiter, brown dwarfs experience weather patterns. Patchiness in clouds and varying opacities allow light from deeper layers of the atmosphere to reach the surface of the photosphere. These photospheric inhomogeneities and the rapid rotation of brown dwarfs can be detected as photometric or time-resolved spectroscopic variability. Nonetheless, obtaining light curves and time-resolved spectroscopy are resource-intensive observational techniques, and those surveys have been until now uninformed. In this context, we have developed a technique to identify candidate L7-T2 variable brown dwarfs from a single, low resolution, near-infrared spectrum to inform these searches. To fully validate and develop our novel method, it is crucial to perform near-infrared photometric monitoring of at least a fraction of our candidates, so that we can test the accuracy of our technique, and estimate the potential false-positive rate. We will use the SpeX guider camera with its J-band filter for photometric monitoring of 30% of the variable candidates selected by our spectroscopic index technique to search for brown dwarf variables. We propose to observe following a 5-point dither pattern with 3 exposures at each dither position. We will make sure that the target falls on the same pixel in each position to reduce systematics. We will expose a total of 45 s at each dither position. We will detect our targets [J < 16.8] with a SNR > 100 per exposure. A SNR>100 would allow the detection of a minimum variability amplitude as low 1%. In total, we will need 3 nights to complete the monitoring of the targets proposed. Finally, since the guider has a field of view of 60 arcsec x 60 arcsec, we will use other stars in the field to build a calibration curve, that will eliminate the effects of varying atmospheric conditions during our observations. PROGRAM_ABSTRACT_END