14111( 2) - 13-Jul-2015 17:06:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14111 Version: 2 Check-in Time: 13-Jul-2015 17:06:37 STScI Edit Number: 0 Title The SN Ia Candidate T Pyxidis: The Mystery of its High Accretion Rate ------------------------------------------------------------------------------------ Type Cycle GO 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Edward M. Sion Villanova University Y CoI: Dr. Sumner G. Starrfield Arizona State University N CoI: Dr. Patrick Godon Villanova University Y CoI: Dr. Mario Livio Space Telescope Science Institute N CoI: Dr. Robert E. Williams Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract T Pyx is a recurrent nova that unexpectedly went into outburst in 2011. It has now declined to its quiescent level but it appears to be accreting at a very high rate, possibly driven by irradiation of the donor star by the hot white dwarf or by the hot inner disk. Our team (Godon et al. 2014) has shown, using the light echo distance of 4.8 kpc (Sokoloski 2013), that the white dwarf in T Pyx is actually growing in mass and might be on its way to exploding as a Type Ia supernova. We propose to continue spectroscopic monitoring of T Pyx with HST COS during Cycle 23, to obtain the first FUV spectrum early in the quiescent period (only four years after its 44 years-delayed outburst). The first FUV spectra of T Pyx following its 1967 outburst were a full 13 years later, in 1980, when IUE was launched. By obtaining FUV spectra with COS at the beginning and at the end of Cycle 23, we will detect any changes in the continuum slope, in the velocity widths and intensities of emission lines. We will use our extensive suite of modeling codes to study the evolution of the accretion disk and also model the stellar photosphere, if detected. Our analysis will yield the accretion rate, WD temperature and elemental abundances. We will compare these data to our values obtained on the decline from outburst and transition into quiescence. Our observations will provide fiducial spectra from 1800A down to 912A for this puzzling and pivotal recurrent nova, and would solidify the identification of recurrent novae as Type Ia Supernova progenitors. ------------------------------------------------------------------------------------ Observations Description ------------------------ T Pyx is the only target. We request that T Pyx be observed at two epochs. The first epoch at the beginning of Cycle 23. The second epoch toward the end of Cycle 23. The observations for the first and second epoch are identical. Each epoch consists of two consecutive observations, each of which lasts only one orbit (so that each epoch lasts only 2 orbits, for a total of 4 orbits). Each epoch consists of two consecutive observations as follows: A first observation/orbit with COS in the FUV spectroscopic configuration G140L central wave 1105A, directly followed by another COS observation/orbit in the 14111( 2) - 13-Jul-2015 17:06:37 - [ 2] FUV spectroscopic configuration G130 at wave 1055A. ------------------------------------------------------------------------------------ 14111( 2) - 13-Jul-2015 17:06:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NOVA-PYX-189 STAR, RECURRENT NOVA RA=09H04M41.5000S +/- 0.1", J2000 V = 17.5 0 DEC=-32D22'47.50" +/- 0.1" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14111( 2) - 13-Jul-2015 17:06:37 - [ 4] Visit: 01 Visit Requirements: BETWEEN 12-OCT-2015:00:00:00 AND 29-OCT-2015:00:00:00 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 NOVA-PYX-18 COS/FUV ACQ/PEA PSA G140L 1105 1 7 S (7 S) 90 KXD Comments: 2 s should be sufficient, but use 7s in case the target has faded ------------------------------------------------------------------------------------------------------------------------------------ 2 NOVA-PYX-18 COS/FUV ACQ/PEA PSA G140L 1105 NUM-POS=5, STEP-SIZE=0.9 1 7 S (7 S) 90 KD Comments: 2 s should be sufficient, but use 7s in case the target has faded ------------------------------------------------------------------------------------------------------------------------------------ 3 NOVA-PYX-18 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=1000 1 197 S (788 90 G S) Comments: ETC BT is 2704, 2/3 of this is 1800, 1000 just to safe (and efficient) ------------------------------------------------------------------------------------------------------------------------------------ 4 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=3 1 736 S (736 90 G S) Comments: ETC BT=8936, 2/3 of which is 6000. Just 800 to match Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 5 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=1 1 910 S (910 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 6 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=2 1 910 S (910 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 7 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=4 1 909 S (909 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 14111( 2) - 13-Jul-2015 17:06:37 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NOVA-PYX-1890 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD NOVA-PYX-1890 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 N/A G NOVA-PYX-1890 4 COS/FUV TIME-TA PSA G130M 1055 none none none none 1 N/A G NOVA-PYX-1890 5 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G NOVA-PYX-1890 6 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G NOVA-PYX-1890 7 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G 14111( 2) - 13-Jul-2015 17:06:37 - [ 6] Visit: 02 Visit Requirements: BETWEEN 01-JUN-2016:00:00:00 AND 25-JUN-2016:00:00:00 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 NOVA-PYX-18 COS/FUV ACQ/PEA PSA G140L 1105 1 7 S (7 S) 90 KXD Comments: 2 s should be sufficient, but use 7s in case the target has faded ------------------------------------------------------------------------------------------------------------------------------------ 2 NOVA-PYX-18 COS/FUV ACQ/PEA PSA G140L 1105 NUM-POS=5, STEP-SIZE=0.9 1 7 S (7 S) 90 KD Comments: 2 s should be sufficient, but use 7s in case the target has faded ------------------------------------------------------------------------------------------------------------------------------------ 3 NOVA-PYX-18 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=1000 1 197 S (788 90 G S) Comments: ETC BT is 2704, 2/3 of this is 1800, 1000 just to safe (and efficient) ------------------------------------------------------------------------------------------------------------------------------------ 4 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=3 1 736 S (736 90 G S) Comments: ETC BT=8936, 2/3 of which is 6000. Just 800 to match Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 5 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=1 1 910 S (910 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 6 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=2 1 910 S (910 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 7 NOVA-PYX-18 COS/FUV TIME-TA PSA G130M 1055 BUFFER-TIME=800, FP-POS=4 1 909 S (909 90 G S) Comments: Use BT=ET-110 for max efficiency. ETC gives BT=6000. (shorter is ok) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ 14111( 2) - 13-Jul-2015 17:06:37 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NOVA-PYX-1890 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD NOVA-PYX-1890 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 N/A G NOVA-PYX-1890 3 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 N/A G NOVA-PYX-1890 4 COS/FUV TIME-TA PSA G130M 1055 none none none none 1 N/A G NOVA-PYX-1890 5 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G NOVA-PYX-1890 6 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G NOVA-PYX-1890 7 COS/FUV TIME-TA PSA G130M 1055 none none none none 2 N/A G 14111( 2) - 13-Jul-2015 17:06:37 - [ 8] Summary Form for Proposal 14111 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1000, BUFFER-TIME=800, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, FP-POS=ALL, NUM-POS=5, STEP-SIZE=0.9 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-JUN-2016:00:00:00 AND 25-JUN-2016:00:00:00, BETWEEN 12-OCT-2015:00:00:00 AND 29-OCT-2015:00:00:00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NOVA-PYX-1890 ------------------------------------------------------------------------------------------------------------------------------------