17881( 3) - 25-Oct-2024 21:09:05 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17881 Version: 3 Check-in Time: 25-Oct-2024 21:09:05 STScI Edit Number: 1 Title Far-UV detection of the low-mass companion responsible for Betelgeuse's long secondary period ------------------------------------------------------------------------------------ Type Cycle GO/DD 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Meridith Paige Joyce University of Wyoming Y CoI: Dr. Jared Austin Goldberg Flatiron Institute N CoI: Dr. Christian Johnson Space Telescope Science Institute N CoI: Dr. Laszlo Molnar Konkoly Observatory N CoI: Dr. Katelyn Breivik Carnegie Mellon University N CoI: Dr. Annalisa Calamida Space Telescope Science Institute N CoI: Dr. Anna O'Grady Carnegie Mellon University N CoI: Brendan O'Connor Carnegie Mellon University N CoI: Maria Drout University of Toronto N CoI: Dr. Maxwell Moe University of Wyoming N ------------------------------------------------------------------------------------ Abstract The approximately 2100-day cycle of variability exhibited by the nearby red supergiant Alpha Orionis, popularly known as Betelgeuse, has become the subject of scrutiny after Betelgeuse's sudden, 1.6 V-mag brightness drop in late 2019. The nature of this 2100-day periodicity is closely tied to Betelgeuse's time-until-explosion: if it is the fundamental mode (FM), the star might be close to becoming a supernova. Recent studies, however, have converged instead on the conclusion that the 2100-day variability cycle is actually a Long Secondary Period, or LSP. The origins of the LSP phenomenon are unknown, but consensus is building that LSPs are caused by low-mass companions around the star. Since late August of 2024, two independent studies have proposed such an orbital companion, alpha Ori B, as the cause of Betelgeuse's LSP. The combination of photometric, radial velocity, and astrometric observations indicates a minimum mass of either 0.6 or 1.2 solar mass, and a separation of 2.4 stellar radii from Betelgeuse, which makes direct detection of the companion challenging due to an expected luminosity contrast of >10^4. However, by exploiting the strategic timing of maximum orbital separation occurring on Dec 6, 2024, this observational campaign proposes to find alpha Ori B via far-UV excess, using STIS with the E140M grating. This campaign will yield either the direct discovery of the hidden companion or provide an important constraint on the mass of alpha Ori B, shedding light on the nature of the LSP phenomenon and massive star multiplicity. An additional outcome will be the benchmarking of the chromospheric properties of our nearest RSG. ------------------------------------------------------------------------------------ Observations Description ------------------------ The target will be suitable for observation during the time frame of November 6, 2024 to January 6, 2025, when alpha Orionis B is most likely to be detected. The optimal date of observation, corresponding to maximum orbital separation between Betelgeuse and the companion from our vantage point, is December 6th. We divide four orbits across four visits, one orbit per visit. We do not 17881( 3) - 25-Oct-2024 21:09:05 - [ 2] require the visits to be consecutive, but it is helpful if they take place close in time. Into a single orbit, we fit one imaging acquisition on Betelgeuse (alpha Ori) and two 1000-second science exposures. From each acquisition, we pivot 0.084 (-0.084) arcsec in x and 0.084 (-0.084) arcsec in y. Each visit has one pointing, tiling Betelgeuse in a 2x2 square with the 0.2x0.2 slit. No special orientation is required. No background requirements. This campaign does not require coordination with any other observations, but it will supplement observations from Chandra scheduled around December 9th, 2024. ------------------------------------------------------------------------------------ 17881( 3) - 25-Oct-2024 21:09:05 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 -ALF-ORI STAR, SUPERGIANT O RA=05H55M10.3054S, J2000 V = 0.42 DEC=+07D24'25.43" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0018514498381218894 0.011300000000000001 0.006549999999999999 ------------------------------------------------------------------------------------------------------------------------------------ 17881( 3) - 25-Oct-2024 21:09:05 - [ 4] Visit: 01 (quadrant1) Visit Requirements: BETWEEN 06-NOV-2024:00:00:00 AND 06-JAN-2025:00:00:00 On Hold Comments: Additional Comments: first of four visits, one pointing per visit 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 -ALF-ORI STIS/CCD ACQ F25ND5 MIRROR 1 1 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG 0.084, 0.084 -MAMA (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG 0.084, 0.084 -MAMA (1000 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-ORI 1 STIS/CCD ACQ F25ND5 MIRROR none none none none 1 N/A -ALF-ORI 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA -ALF-ORI 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 17881( 3) - 25-Oct-2024 21:09:05 - [ 5] Visit: 02 (quadrant2) Visit Requirements: BETWEEN 06-NOV-2024:00:00:00 AND 06-JAN-2025:00:00:00 On Hold Comments: Additional Comments: first of four visits, one pointing per visit 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 -ALF-ORI STIS/CCD ACQ F25ND5 MIRROR 1 1 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG -0.084, 0.084 -MAMA (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG -0.084, 0.084 -MAMA (1000 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-ORI 1 STIS/CCD ACQ F25ND5 MIRROR none none none none 1 N/A -ALF-ORI 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA -ALF-ORI 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 17881( 3) - 25-Oct-2024 21:09:05 - [ 6] Visit: 03 (quadrant3) Visit Requirements: BETWEEN 06-NOV-2024:00:00:00 AND 06-JAN-2025:00:00:00 On Hold Comments: Additional Comments: first of four visits, one pointing per visit 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 -ALF-ORI STIS/CCD ACQ F25ND5 MIRROR 1 1 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG -0.084, -0.084 -MAMA (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG -0.084, -0.084 -MAMA (1000 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-ORI 1 STIS/CCD ACQ F25ND5 MIRROR none none none none 1 N/A -ALF-ORI 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA -ALF-ORI 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 17881( 3) - 25-Oct-2024 21:09:05 - [ 7] Visit: 04 (quadrant4) Visit Requirements: BETWEEN 06-NOV-2024:00:00:00 AND 06-JAN-2025:00:00:00 On Hold Comments: Additional Comments: first of four visits, one pointing per visit 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 -ALF-ORI STIS/CCD ACQ F25ND5 MIRROR 1 1 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG 0.084, -0.084 -MAMA (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 -ALF-ORI STIS/FUV ACCUM 0.2X0.2 E140M 1425 1 1000 S POS TARG 0.084, -0.084 -MAMA (1000 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 | ------------------------------------------------------------------------------------------------------------------------------------ -ALF-ORI 1 STIS/CCD ACQ F25ND5 MIRROR none none none none 1 N/A -ALF-ORI 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA -ALF-ORI 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA 17881( 3) - 25-Oct-2024 21:09:05 - [ 8] Summary Form for Proposal 17881 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.2, F25ND5 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 06-NOV-2024:00:00:00 AND 06-JAN-2025:00:00:00, POS TARG -0.084, -0.084, POS TARG -0.084, 0.084, POS TARG 0.084, -0.084, POS TARG 0.084, 0.084 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E140M, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names -ALF-ORI ------------------------------------------------------------------------------------------------------------------------------------