A novel water-band technique to identify brown dwarfs and planetary mass objects in the Solar neighbourhood
Creators: name: Damian, Belinda
name: Jose, Jessy
name: Biller, Beth
name: Albert, Loïc
name: Allers, Katelyn
name: Zhang, Zhoujian
name: Liu, Michael C.
name: Dubber, Sophie
name: Paul, KT
name: Chen, Wen-Ping
name: Lalchand, Bhavana
name: Sharma, Tanvi
Publisher: name: Zenodo
Year: 2023
Subjects: Brown dwarfs
Low mass stars
Initial mass function
Star forming regions

description: In star-forming regions, the low-mass brown dwarfs and free-floating planets are vital tracers of the low mass end of star formation and are key analogues to exoplanets around stars. The complete census of a star-forming cloud, to masses well below the deuterium-burning limit, will also constrain the very low-mass end of the IMF. Our team surveys various nearby young star-forming regions in the solar neighborhood like Taurus, Serpens, IC348 etc. in search of brown dwarfs and planetary mass objects using a novel and robust technique which photometrically identifies these ultra cool objects. Here we present the study of one such nearby young star-forming region, Sigma Orionis located at a distance of ~400pc with very low extinction (Av&lt;1mag). We use the near-IR WIRCam data from the 3.6m Canada-France Hawaii Telescope (CFHT) in the custom W-band filter (centred at 1.45µm water absorption feature) combined with the data from the J and H broadband filters to classify brown dwarfs based on a reddening insensitive index (Q). The Q-index distinguishes the sub-stellar objects below the hydrogen burning limit (i.e. M6 spectral type) and the sub-stellar objects thus identified were then spectroscopically followed-up using the SpeX spectrograph on the 3.2m NASA Infrared Telescope Facility (IRTF). All our candidate brown dwarfs are found to have spectral types M5-M8.5 and along with data from previous studies we have the complete census of spectroscopically confirmed members of the region up to ~15M<sub>Jup</sub>. This shows that with our novel approach we can efficiently identify low-mass objects. Studying these brown dwarfs enables us to probe the IMF down to the sub-stellar regime and aid in understanding their formation mechanism in one of the well-known young clusters in the solar neighborhood for the first time. Our study explores the potential environmental influence on the brown dwarf formation scenario by performing a comparative analysis with the nearby well-studied star-forming regions.
description: {"references": ["Caballero, J. A., (2018), Geosciences, 8, 362", "Offner, S. S. R. et al. (2014), Protostars and Planets VI. Univ. Arizona Press, Tucson, AZ, p. 53", "Salpeter, E. E. (1955), ApJ, 121, 161", "Bastian, N. et al. (2010), ARA&amp;A, 48, 339", "Allers, K. N., &amp; Liu, M. C. (2013), ApJ, 772, 79", "Allers K. N., Liu M. C. (2020), arXiv e-prints, p. ArXiv:2008.00010", "Jose, J. et al. (2020), ApJ, 892, 122", "Dubber, S et al. (2021), MNRAS, 505, 4215", "Lalchand, B. et al. (2022), AJ, 164, 125", "Dubber, S et al. (2023), MNRAS", "Hern \u0301andez, J. (2007), ApJ, 662, 1067", "Su\u00e1rez, G. (2019), MNRAS, 486, 1718", "Mu\u017ei\u0107, K. et al. (2019), ApJ, 881, 79"]}