16881( 3) - 23-Dec-2021 22:01:22 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16881 Version: 3 Check-in Time: 23-Dec-2021 22:01:22 STScI Edit Number: 0 Title The Origin of The Fastest Spinning White Dwarf in a CV Binary ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Peter M. Garnavich University of Notre Dame Y CoI: Prof. Paula Szkody University of Washington N CoI: Mr. Colin Littlefield University of Notre Dame N CoI: Dr. R. Mark Wagner The Ohio State University N CoI: Dr. John Thorstensen Dartmouth College N ------------------------------------------------------------------------------------ Abstract Recently, LAMOST-J0240 was identified as a likely second propeller in a cataclysmic variable (CV) system with optical properties that are very similar to the original propeller: AE Aqr. Only after the Cycle 29 proposal deadline was the white dwarf (WD) rotation in LAMOST-J0240 detected with a period of just 25s, making it the fastest spinning WD in a CV binary. We propose ultraviolet spectroscopy of this newly confirmed propeller to tests two theories of magnetic CV evolution. First, we will use the CIV and NV emission line ratio, observable only in the FUV, to test the thermal time-scale mass transfer model as the way to spin-up WDs. Peculiar CNO abundance ratios are a signature of unstable mass transfer that can reach down to the companion star's core. Inverted NV/CIV ratios are seen in CV systems with WD spin periods between 30s and 40s. Second, we will test the crystallization theory for generating magnetic fields in WDs by precisely measuring the WD surface temperature. In an analogy with convective planetary magnetic field generation, only fast-spinning WDs that have cooled to the point of core crystallization form significant fields. Being a propeller, LAMOST-J0240 clearly has a fast rotating, magnetic WD, and the model predicts that its surface temperature should be half of the ground-based limit of 25000K. Further, the data will establish a baseline for estimating the spin-down age of the WD to constrain the time since the unstable mass transfer event. ------------------------------------------------------------------------------------ Observations Description ------------------------ LAMOST-J0240 is an intermediate polar (IP) that has a rapidly spinning, magnetic white dwarf (WD). Gas donated from the secondary gets accelerated by the rotating magnetosphere and is ejected from the system. The scenario is thought to be similar to AE Aquarii, except in J0240 we view the system nearly edge-on, so that eclipses and the ejected gas is visible in optical spectra. Here, we plan to observed J0240 in the FUV with COS using the G140L grating and Time-tag mode. We plan to cover an entire binary orbit of 7.3 hours. This period is nearly identical to 5 Hubble orbits, so observing over 5 consecutive orbits is ideal. If this is not schedulable, we can divide the observations up into two visits (3+2) with a constraint to allow the second visit to complete the binary orbital phase coverage. COS ETC calculations are based on the brightest FOS spectrum of AE Aqr scaled to the distance of J0240 (36 times 16881( 3) - 23-Dec-2021 22:01:22 - [ 2] fainter). ------------------------------------------------------------------------------------ 16881( 3) - 23-Dec-2021 22:01:22 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LAMOST-J0240 STAR, EJECTA, EMISSION RA=02H40M48.5357S +/- 0.00006", J2000 V = 17.0 +/- 0.5 Between 1e-16 and LINE STAR, INTERMEDIATE DEC=+19D52'27.05" +/- 0.00006" 12e-16 erg/cm2/s/Ang at 2200 Ang from POLAR Swift Reference Frame: ICRS Extended: NO Comments: Variable in the optical with an amplitude of 1 magnitude Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -2.878081094871937E-4 -0.005969 0.0016 ------------------------------------------------------------------------------------------------------------------------------------ 16881( 3) - 23-Dec-2021 22:01:22 - [ 4] Visit: 01 (visit01) 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 LAMOST-J024 COS/NUV ACQ/IMA PSA MIRRORA 1 30 S (30 0 GE S) Comments: Swift UVOT provide a flux of 1e-16 erg/cm2/s/A at 2200 Ang. The imaging acquire ETC shows a S/N=20 in a 20s exposure of NUV, Mirror A, and the PSA. To be safe, we have increased the exposure to 30s. ------------------------------------------------------------------------------------------------------------------------------------ 2 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=1 1 2376 S 0 G (2376 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=2 1 2700 S 0 G (2700 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=3 1 2700 S 0 G (2700 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=3 1 1285 S 0 G (1285 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=4 1 1300 S 0 G (1300 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 LAMOST-J024 COS/FUV TIME-TA PSA G140L 1105 BUFFER-TIME=8000, FP-POS=4 1 2700 S 0 G (2700 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 | ------------------------------------------------------------------------------------------------------------------------------------ LAMOST-J0240 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE LAMOST-J0240 2 COS/FUV TIME-TA PSA G140L 1105 none none none none 1 N/A G LAMOST-J0240 3 COS/FUV TIME-TA PSA G140L 1105 none none none none 2 N/A G LAMOST-J0240 4 COS/FUV TIME-TA PSA G140L 1105 none none none none 3 N/A G LAMOST-J0240 5 COS/FUV TIME-TA PSA G140L 1105 none none none none 4 N/A G 16881( 3) - 23-Dec-2021 22:01:22 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LAMOST-J0240 6 COS/FUV TIME-TA PSA G140L 1105 none none none none 4 N/A G LAMOST-J0240 7 COS/FUV TIME-TA PSA G140L 1105 none none none none 5 N/A G 16881( 3) - 23-Dec-2021 22:01:22 - [ 6] Summary Form for Proposal 16881 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=8000, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names LAMOST-J0240 ------------------------------------------------------------------------------------------------------------------------------------