0 Assigned ID: 495 ----- Attempting Submission 1 (Fri Apr 05 16:01:58 GMT 2019) ----- HST Phase I Proposal 495 (APT_BD_2019.apt) successfully submitted. Receipt: # 495-1 ----- Attempting Submission 2 (Fri Apr 05 18:31:18 GMT 2019) ----- 0 The T6.5 brown dwarf 2MASS J1237+6526, in the following abbreviated as 2M-1237, displays exceptionally bright H-alpha emission among late L- and T-dwarfs. It also exhibits circularly polarised radio emission indicating that 2M-1237 possesses a very strong surface magnetic field of at least 2.9 kG. Here we propose to observe the spectrum of 2M-1237 through the UV to test whether the radio and H-alpha emission is due to auroral processes similar to those known from the massive magnetized planets of the solar system or if the cool T6.5 dwarf has UV properties similar to those of low mass stars. Based on observed UV spectra of Jupiter and a very late M-dwarf, both scenarios are detectable with sufficient signal to noise. First observations of UV aurora outside of the solar system would be highly exciting. Detection of auroral emission would provide a new means to detect or provide constraints on a close-in planet or gas torus around the dwarf 2M-1237. The proposed observations also serve as a benchmark study whether UV emission from other brown dwarfs with less intense H-alpha and radio emission can be detected in the future. We will use STIS with three different gratings to explore the UV emission of the brown dwarf 2M-1237 over a broad spectral range and to search for auroral emission. We propose 2 visits. Visit 1 constains one orbit for the Ly-wings and one orbit at NUV wavlengths. Visit 2 contains three consecutive orbits in the FUV (without Ly-alpha) to resolve possible time-variability NUV-Range We will use STIS and first order grating G230L (1570-3180 A) to investigate and confirm the emission from 2M-1237 in the NUV range. The grating has a dispersion of 1.58 A/pixel and an average throughput of approximately 0.01. Because geocoronal light is not an issue at the wavelengths of interest, we will use the 52'' x 0.2'' slit. We expect to detect the Mg II doublet near 2800 A with a S/N = 6 within one HST orbit of approx. 40 min (Fig. 2b). We will additionally search for other lines typical of chromospheric emission known from M-dwarfs in this band pass, e.g., Fe II. FUV-Range without Ly-ALPHA We will use STIS and first order grating G140L (1150-1730 A) in order to investigate the auroral FUV emission, its spectral structure and time-variability. The grating has a dispersion of 0.6 A/pixel and an average throughput of approximately 0.015. Similarly to the NUV-range, we will use the 52'' x 0.2'' slit. Depending on the physics driving the emission within the FUV-range we expect an S/N up to 9. To resolve possible time-variability we ask the three orbits in the FUV to be consecutive. Ly-ALPHA wings We will use STIS and first order grating G140M (1190-1245 A) at central wavelength = 1218 A to observe the Ly-ALPHA wings. STIS with this grating provides a good compromise between spectral resolution and sensitivity. The dispersion of the grating is 0.04 A/pixel. The throughput at Ly-ALPHA wavelengths Lambda_Ly-ALPHA =1215.67 A is ~0.015. We use the 52 arcsec x 0.2 arcsec slit to minimize the geocoronal background. We expect to detect the Ly-ALPHA wings with an S/N of approx. 5. We need to observe in Earth shadow and ask for a maximum angular separation between the sun and 2M-1237 to minimize geocoronal effects. Dr. Joachim Saur has expertise in HST data reduction for STIS, the instrument used in the proposed observation. Dr. Saur has led 4 HST campaigns as PI, with the latest one on STIS observations of the ultracool dwarf LSR J1835+3259 similar to the proposed observations (Saur et al. 2018, ApJ). Dr. Saur is an expert in auroral and plasma physics with, e.g., about 50 publications on the Jupiter system. He is a team member on the NASA JUNO spacecraft with one of the prime aims to explore Jupiter's aurora. Dr. Saur also modeled and studied the plasma environment around stars and exoplanets with two recent publications and one chapter in the handbook of exoplanets. Dr. Ansgar Reiners is an expert on ultracool dwarfs and led large surveys of low mass stars and brown dwarfs (e.g., characterization of H-alpha and lithium). He will provide interpretation and context for the results. Dr. Lorenz Roth has experience in data reduction and analysis of HST data including STIS. He was PI of several HST programs. Dr. Darrell Strobel is an expert in planetary atmospheres/astrophysics, radiative transfer and aeronomic processes necessary to interpret and model the emissions. Dr. Alexandre Wennmacher is an astronomer with background in the physics of the interstellar medium. He has experience in the data analysis of radioastronomical, optical, and satellite-based observations. Christian Fischer, Alexander Marzok and Clarissa Willmes are students working with the PI Saur. They will help analyze and model the results. Stellar Physics 6 false false true false false false false SUPPORTED STAR BROWN DWARF This object was generated by the targetselector and retrieved from the SIMBAD database. The V-magnitude is not been determined to the proposer's knowledge. It is at least V=25, but might be 26, 27, ... J2000 J2000 Spectral Type: T6.5; J (V): 16.053 [0.087], H (V): 15.739 [0.145], K (V): 16.40 [0.10], u (AB): 25.06 [0.97], g (AB): 24.96 [0.61], r (AB): 24.55 [0.65], i (AB): 23.54 [0.62], z (AB): 19.57 [0.08] (Flux values in order of: filter-name (system): flux-value [error]; reference: SIMBAD) STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/FUV-MAMA Spectroscopic No No G140L 1425 STIS/FUV-MAMA Spectroscopic No No G140M 1218 1582641752966 Timing link suitability includes constraints ([02 After 01 by at most 120.0 days]) The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. /private/var/folders/6l/d2vtb4894bs5t3xhhq13gv3h00023n/T/OPVisit747527797084496253.xml 1579200987000 266.6 (Tic-Visit :proposal-id 15870 :visit-id "01" :proposal-version -1 :trans-version "20191203" :date "25-Feb-2020 09:42:32.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 609168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15870 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15870 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 3093 :al-overhead-at-end 0 :internal-dur-at-end 1901 :dark-offset 1234 :dark-utilization 1859 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3486 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15870 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 3184 :al-overhead-at-end 0 :internal-dur-at-end 582 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3486 :pcs-gap 0 ) true 2 0 For the acquisition we used wavelength dependent flux measurements for lambda >6000 A obtained by Burgasser et al. 2002 and Liebert & Burgasser 2007. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. 1582641690867 Timing link suitability includes constraints ([02 After 01 by at most 120.0 days]) The scheduling data was generated by CASM 28.0. CASM was run in Phase II mode. /private/var/folders/6l/d2vtb4894bs5t3xhhq13gv3h00023n/T/OPVisit6565455313933041948.xml (Tic-Visit :proposal-id 15870 :visit-id "02" :proposal-version -1 :trans-version "20191203" :date "25-Feb-2020 09:41:30.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 922240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15870 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15870 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 3093 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3486 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15870 :visit-id "02" :orbit-number 2 :pcs-time 302 :si-vis-utilization 3184 :al-overhead-at-end 0 :internal-dur-at-end 1929 :dark-offset 2099 :dark-utilization 1085 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3486 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15870 :visit-id "02" :orbit-number 3 :pcs-time 302 :si-vis-utilization 3184 :al-overhead-at-end 0 :internal-dur-at-end 440 :dark-offset 1995 :dark-utilization 1189 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3486 :pcs-gap 0 ) true 3 0 For the acquisition we used wavelength dependent flux measurements for lambda >6000 A obtained by Burgasser et al. 2002 and Liebert & Burgasser 2007. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal. Exposure time calculator generates unrelatistic long exposure times as it calculates S/N for each resolution element. We will integrate flux over all wavenlengths or target certain lines within the spectrum, see feasibility discussion in proposal.