[NCTS Astrophysics Lunch Seminar] The W Band Survey: Water-bearing Brown dwarfs in the Rho Ophiuchi Complex
Title：The W Band Survey: Water-bearing Brown dwarfs in the Rho Ophiuchi Complex
Time：2023/03/31 (Fri.) 12:10
4F Lecture Hall, Cosmology Hall, NTU
Webex online (Meeting number：2559 898 7530 / Password：TG23 (8423 from phones and video systems))
Brown dwarfs, with spectral types later than about M6, have cool atmospheres (< 2800K) that allow formation of molecules such as water or methane. Here we report identification of brown dwarf candidates in the Rho Ophiuchi complex with the W-band method, i.e., by imaging photometry on and off the water absorption band near 1.45 microns, using a custom-made spectral (W) filter adapted to the CFHT/WIRCam. Combining with the broad-band photometry at J and H bands, we are able to distinguish water-bearing brown dwarfs from reddened field stars. We diagnosed proper-motion membership of faint candidates with multi-epoch (spanning 6 years) CFHT/WIRCam images bootstrapped with astrometry of bright sources retrieved from Gaia DR3. We present the methodology, the confirmed and highly probable substellar sample, and constrain the age of the sample by comparison with model isochrones.