A case study for JWST: Disentangling auroral and cloud variability in early L dwarfs

0 Assigned ID: 228 ----- Attempting Submission 1 (Thu Apr 04 18:03:34 GMT 2019) ----- HST Phase I Proposal 228 (HST_cycle27.apt) successfully submitted. Receipt: # 228-1 ----- Attempting Submission 2 (Fri Apr 05 23:35:35 GMT 2019) ----- HST Phase I Proposal 228 (HST_cycle27.apt) successfully submitted. Receipt: # 228-2 ----- Attempting Submission 3 (Fri Apr 05 23:38:00 GMT 2019) ----- Updated the orient constraints for visit 2M1906+40 (03) -1059261091 ----- Attempting Submission 1 (Mon Jul 22 18:45:06 GMT 2019) ----- ----- Attempting Submission 2 (Fri Aug 02 01:13:05 GMT 2019) ----- ----- Attempting Submission 3 (Thu Sep 12 18:21:50 GMT 2019) ----- A case study for JWST: Disentangling auroral and cloud variability in early L dwarfs With the James Webb Space Telescope (JWST), spectroscopic studies of atmospheres on directly-imaged exoplanets will be possible for the first time. Such planets include the L3 spectral type super Jupiter Beta Pic b (~1800-2300). To accurately characterize the complex physical processes occurring in exoplanet atmospheres and maximize the impact of these upcoming JWST studies, we will need to distinguish between spectral contributions from clouds, aurorae, and magnetic spots in early L spectral type atmospheres. Our proposed pilot case study will allow us to disentangle the signatures of each process in advance of JWST. We will combine spectral modeling with simultaneous HST/WFC3 grism spectroscopy and VLA radio observations of three early L dwarfs to: (1) characterize and distinguish between auroral, cloudy, and magnetic spot spectral variability, and (2) classify an ambiguous case of spectral variability using our new knowledge of the distinct spectroscopic signatures. This proposal aims to disentangle the effects of cloudy and auroral variability for three, early L spectral type brown dwarfs via simultaneous time-resolved HST/WFC3 G141 spectroscopic and VLA monitoring. To ensure full phase coverage of each object we require 5 orbits of monitoring for 2M0036+18 and 2M1721+33 and 6 orbits for 2M1906+41. Optimal procedures for WFC3 high-precision spectroscopic observations are well-established, the observing procedures set by previous programs [e.g. GO12314, GO14188]. At the beginning of each orbit a direct image will be obtained to accurately determine the position of the source on the detector, which will enable precise wavelength calibration. To preserve photometric stability, the targets will be observed in staring-mode. Dr Johanna Vos (American Museum of Natural History) is an expert in infrared brown dwarf variability monitoring, and has significant experience analysing and publishing brown dwarf variability data from HST, Spitzer and ground-based telescopes (Vos et al. 2018, 2019, Biller, Vos et al. 2015, 2018). She will lead the HST data analysis. Dr. Melodie Kao (Arizona State University) is an expert in L and T dwarf magnetism and brown dwarf radio aurora and has extensive experience using the Very Large Array at the proposed frequencies to characterize brown dwarf radio aurora (Kao et al. 2016, 2018; Pineda, Hallinan & Kao 2017). She will lead the VLA data analysis. Dr. J. Sebastian Pineda (University of Colorado Boulder) has extensive experience in stellar and brown dwarf auroral phenomena (e.g., Pineda, Hallinan & Kao 2017) spanning ultraviolet to radio wavelengths, including the theoretical effects of auroral precipitation in cool atmospheres. He will lead the spectroscopic modeling efforts for comparison to the new HST observations. Dr Vos, Dr Kao and Dr Pineda will contribute to the interpretation and publication of the results. Stellar Physics 0 false false false false true false 27.6 true SUPPORTED EXT-STAR BROWN DWARF NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 J=12.466 EXT-STAR BROWN DWARF NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 J=13.625 EXT-STAR BROWN DWARF NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 J=13.078 WFC3/IR Spectroscopic No No G141 WFC3/IR Spectroscopic No No G141 WFC3/IR Spectroscopic No No G141 1564694406712 The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. This 5-orbit visit should be coordinated with simultaneous VLA observations. 1595766855000 246.10243560296266 (Tic-Visit :proposal-id 15924 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "01-Aug-2019 17:19:56.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1056784 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15924 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15924 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2812 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15924 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2812 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15924 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2812 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15924 :visit-id "01" :orbit-number 4 :pcs-time 302 :si-vis-utilization 2812 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15924 :visit-id "01" :orbit-number 5 :pcs-time 302 :si-vis-utilization 2812 :al-overhead-at-end 0 :internal-dur-at-end 480 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3156 :pcs-gap 0 ) true 5 0 short exposure to determine target position in grism aperture. science exposures for variability monitoring short exposure to determine target position in grism aperture. science exposures for variability monitoring short exposure to determine target position in grism aperture. science exposures for variability monitoring short exposure to determine target position in grism aperture. science exposures for variability monitoring short exposure to determine target position in grism aperture. science exposures for variability monitoring 1564694406712 This 5-orbit visit should be coordinated with simultaneous VLA observations. 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