15870( 8) - 25-Feb-2020 14:47:51 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15870 Version: 8 Check-in Time: 25-Feb-2020 14:47:51 STScI Edit Number: 2 Title Search for UV aurora from the Brown Dwarf 2MASS J1237+6526 ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Joachim Saur Universitat zu Koeln Y CoI: Dr. Alexandre Wennmacher Universitat zu Koeln N CoI: Christian Fischer Universitat zu Koeln N CoI: Dr. Lorenz Roth Royal Institute of Technology N CoI: Dr. Ansgar Reiners Georg-August-Universitat N CoI: Dr. Darrell F. Strobel The Johns Hopkins University N CoI: Alexander Marzok Universitat zu Koeln N CoI: Clarissa Willmes Universitat zu Koeln N ------------------------------------------------------------------------------------ Abstract 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. ------------------------------------------------------------------------------------ Observations Description ------------------------ 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 15870( 8) - 25-Feb-2020 14:47:51 - [ 2] 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. ------------------------------------------------------------------------------------ 15870( 8) - 25-Feb-2020 14:47:51 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J12373 STAR, BROWN DWARF RA=12H37M39.1963S +/- 0.19", J2000 V = 25.0 Spectral Type: T6.5; J (V): 919+6526148 DEC=+65D26'14.81" +/- 0.19" 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) Reference Frame: ICRS Comments: 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, ... Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1999.1973 -0.1606980464132567 -0.525 0.09607 ------------------------------------------------------------------------------------------------------------------------------------ 15870( 8) - 25-Feb-2020 14:47:51 - [ 4] Visit: 01 (2-Orbit Visit) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J1237 STIS/CCD ACQ 50CCD MIRROR 1 150 S (150 3919+652614 S) 8 Comments: For the acquisition we used wavelength dependent flux measurements for lambda >6000 A obtained by Burgasser et al. 2002 and Liebert & Burgasser 2007. ------------------------------------------------------------------------------------------------------------------------------------ 2 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 BUFFER-TIME=1000 1 814 S (814 SHADOW 3919+652614 -MAMA G S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 3 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 BUFFER-TIME=1000 1 807 S (807 SHADOW 3919+652614 -MAMA G S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 4 2MASS-J1237 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1475 S 3919+652614 -MAMA G (1475 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 15870( 8) - 25-Feb-2020 14:47:51 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 5 2MASS-J1237 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=1000 1 1475 S 3919+652614 -MAMA G (1475 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J12373919+652 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A 6148 2MASS-J12373919+652 2 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 none none none none 1 N/A 6148 -MAMA G 2MASS-J12373919+652 3 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 none none none none 1 N/A 6148 -MAMA G 2MASS-J12373919+652 4 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 2 N/A 6148 -MAMA G 2MASS-J12373919+652 5 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 2 N/A 6148 -MAMA G 15870( 8) - 25-Feb-2020 14:47:51 - [ 6] Visit: 02 (3-Orbit Visit) Visit Requirements: AFTER 01 BY 0 D TO 120 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 2MASS-J1237 STIS/CCD ACQ 50CCD MIRROR 1 150 S (150 3919+652614 S) 8 Comments: For the acquisition we used wavelength dependent flux measurements for lambda >6000 A obtained by Burgasser et al. 2002 and Liebert & Burgasser 2007. ------------------------------------------------------------------------------------------------------------------------------------ 2 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=1000 1 872 S (872 3919+652614 -MAMA G S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 3 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=1000 1 871 S (871 3919+652614 -MAMA G S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 4 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=750 1 1404 S 3919+652614 -MAMA G (1404 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 15870( 8) - 25-Feb-2020 14:47:51 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 5 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 BUFFER-TIME=1000 1 1055 S SHADOW 3919+652614 -MAMA G (1055 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 6 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 BUFFER-TIME=750 1 1404 S 3919+652614 -MAMA G (1404 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ 7 2MASS-J1237 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 BUFFER-TIME=1000 1 1159 S SHADOW 3919+652614 -MAMA G (1159 S) 8 Comments: 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. ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J12373919+652 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A 6148 2MASS-J12373919+652 2 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 1 N/A 6148 -MAMA G 2MASS-J12373919+652 3 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 1 N/A 6148 -MAMA G 2MASS-J12373919+652 4 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 2 N/A 6148 -MAMA G 2MASS-J12373919+652 5 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 none none none none 2 N/A 6148 -MAMA G 15870( 8) - 25-Feb-2020 14:47:51 - [ 8] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 2MASS-J12373919+652 6 STIS/FUV TIME-TA 52X0.2D1 G140L 1425 none none none none 3 N/A 6148 -MAMA G 2MASS-J12373919+652 7 STIS/FUV TIME-TA 52X0.2D1 G140M 1218 none none none none 3 N/A 6148 -MAMA G 15870( 8) - 25-Feb-2020 14:47:51 - [ 9] Summary Form for Proposal 15870 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD, 52X0.2, 52X0.2D1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1000, BUFFER-TIME=750 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 0 D TO 120 D, SHADOW ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G140M, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names 2MASS-J12373919+6526148 ------------------------------------------------------------------------------------------------------------------------------------