15884( 7) - 11-Oct-2021 22:10:16 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15884 Version: 7 Check-in Time: 11-Oct-2021 22:10:16 STScI Edit Number: 4 Title Confirmation of an Astrometrically Detected Exoplanet Candidate Orbiting the closest Brown Dwarfs ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Luigi R. Bedin Osservatorio Astronomico di Padova Y CoI: Prof. Daniel Apai University of Arizona N CoI: Prof. Adam J. Burgasser University of California - San Diego N CoI: Dr. Mattia Libralato Space Telescope Science Institute - ESA - N JWST ------------------------------------------------------------------------------------ Abstract At a distance of slightly less than 2 pc WISE 1049-5319 (or Luhman 16 AB) is the closest system to Earth after those of alpha Centauri and Barnard's Star. The analysis of astrometric measurements collected in 12 HST epochs (between 2014.64 and 2016.76) revealed a weak astrometric signature indicating the presence of an exoplanet in the Luh16AB system. This candidate was reported in 2017. A single additional epoch ---collected in August 2018--- and re-analysis of the data with more advanced methods increased the significance level of the planet candidate. Here we propose to use HST in the same observing mode to collect data at two new epochs to confirm or disprove the astrometric signature that suggest the presence of a sub-Neptune-mass exoplanet orbiting one component of the closest known brown dwarf system. If confirmed, it would be the first astrometrically detected exoplanet around a brown dwarf and the third closest known exoplanet; a major discovery which only requires a relatively modest investment of two additional HST orbits. The proposed epochs will extend the temporal coverage of the astrometric monitoring to two planet orbital periods (based on the current orbit fits). Coverage over two periods is required to: (a) confirm that our model of the planetary system is predictive, and (b) verify and refine uncertainty estimates. Furthermore, should the orbit be non-circular, these additional measurements will determine this and significantly improve the orbital semi-major axis measurement. ------------------------------------------------------------------------------------ Observations Description ------------------------ Each epoch contains three images in point source imaging mode, and four in spatial-scanning mode with WFC3/UVIS. In addition to the images taken in spatial scan mode and to the short two point-source images at the beginning and at the end of the single orbit-visits --- as requested at the phase I stage --- it turned out possible to fit in the orbit one extra point source images of 348s in F606W. The color information will be a precious to discriminate the nature (and so the distance) of the reference sources in the field 15884( 7) - 11-Oct-2021 22:10:16 - [ 2] (for example to separate slow close by red dwarf from far away giants) ------------------------------------------------------------------------------------ 15884( 7) - 11-Oct-2021 22:10:16 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LUHMAN-16-SF STAR, BROWN DWARF RA=10H49M12.1430S, J2000 V = 16.2 T DEC=-53D19'34.59" Reference Frame: Other: SIMBAD Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. This a binary with the two component at ~ 1 arcsec separation Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 -0.3079031198719211 0.354 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 LUHMAN16AB-S STAR, BROWN DWARF RA=10H49M15.5000S, J2000 V = 24 +/- 1 Sloan-i = 15 +/- .5 FT DEC=-53D19'20.60" Reference Frame: ICRS Comments: We have mapped the relative path of Luhman 16AB between 2014 and 2016 ------------------------------------------------------------------------------------------------------------------------------------ 15884( 7) - 11-Oct-2021 22:10:16 - [ 4] Visit: 01 (2019 OCT) Visit Requirements: ORIENT 225D TO 260 D; BETWEEN 19-OCT-2019 AND 25-OCT-2019 On Hold Comments: Additional Comments: Epoch 2019 OCT. This is the epoch is taken at the ricciolo of the cycloid apparent motion. The epoch must be around 2019-10-20 +/- 15 days 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 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 60 S (60 POS TARG -4, 4 FT S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 378 S (378 POS TARG -4, 4; SPATIAL FT S S) SCAN 0.012, 270.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 378 S (378 POS TARG -4, -4; SPATIAL FT S S) SCAN 0.012, 0.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F606W FLASH=12 1 348 S (348 POS TARG 0, 0 FT S S) ------------------------------------------------------------------------------------------------------------------------------------ 5 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 378 S (378 POS TARG 4, 4; SPATIAL FT S S) SCAN 0.012, 180.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 6 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 378 S (378 POS TARG 4, -4; SPATIAL FT S S) SCAN 0.012, 90.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 7 LUHMAN-16-S WFC3/UVI ACCUM UVIS1 F814W FLASH=12 1 60 S (60 POS TARG 4, -4 FT S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LUHMAN-16-SFT 1 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S LUHMAN-16-SFT 2 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S LUHMAN-16-SFT 3 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S 15884( 7) - 11-Oct-2021 22:10:16 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LUHMAN-16-SFT 4 WFC3/UVI ACCUM UVIS1 F606W none none none none 1 N/A S LUHMAN-16-SFT 5 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S LUHMAN-16-SFT 6 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S LUHMAN-16-SFT 7 WFC3/UVI ACCUM UVIS1 F814W none none none none 1 N/A S 15884( 7) - 11-Oct-2021 22:10:16 - [ 6] Visit: 02 (2021 NOV) Visit Requirements: ORIENT 345D TO 35 D; AFTER 01-NOV-2021:00:00:00 On Hold Comments: Additional Comments: Epoch 2021 NOV This is the epoch is taken at the ricciolo of the cycloid apparent motion. The epoch must be after 2021-11-01 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 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=18 1 59 S (59 POS TARG -4, 4 SFT S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=12 1 378 S (378 POS TARG -4, 4; SPATIAL SFT S S) SCAN 0.012, 270.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 3 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=12 1 378 S (378 POS TARG -4, -4; SPATIAL SFT S S) SCAN 0.012, 0.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 4 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F606W FLASH=12 1 348 S (348 POS TARG 0, 0 SFT S S) ------------------------------------------------------------------------------------------------------------------------------------ 5 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=12 1 378 S (378 POS TARG 4, 4; SPATIAL SFT S S) SCAN 0.012, 180.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 6 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=12 1 378 S (378 POS TARG 4, -4; SPATIAL SFT S S) SCAN 0.012, 90.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ 7 LUHMAN16AB- WFC3/UVI ACCUM UVIS2 F814W FLASH=18 1 58 S (58 POS TARG 4, -4 SFT S S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LUHMAN16AB-SFT 1 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S LUHMAN16AB-SFT 2 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S LUHMAN16AB-SFT 3 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S 15884( 7) - 11-Oct-2021 22:10:16 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LUHMAN16AB-SFT 4 WFC3/UVI ACCUM UVIS2 F606W none none none none 1 N/A S LUHMAN16AB-SFT 5 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S LUHMAN16AB-SFT 6 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S LUHMAN16AB-SFT 7 WFC3/UVI ACCUM UVIS2 F814W none none none none 1 N/A S 15884( 7) - 11-Oct-2021 22:10:16 - [ 8] Summary Form for Proposal 15884 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=12, FLASH=18 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01-NOV-2021:00:00:00, BETWEEN 19-OCT-2019 AND 25-OCT-2019, ORIENT 225D TO 260 D, ORIENT 345D TO 35 D, POS TARG -4, -4, POS TARG -4, 4, POS TARG 0, 0, POS TARG 4, -4, POS TARG 4, 4, SPATIAL SCAN 0.012, 0.0 Degrees, Forward, 0.45 Arcsec, 6, SPATIAL SCAN 0.012, 180.0 Degrees, Forward, 0.45 Arcsec, 6, SPATIAL SCAN 0.012, 270.0 Degrees, Forward, 0.45 Arcsec, 6, SPATIAL SCAN 0.012, 90.0 Degrees, Forward, 0.45 Arcsec, 6 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names LUHMAN-16-SFT, LUHMAN16AB-SFT ------------------------------------------------------------------------------------------------------------------------------------