15316( 5) - 19-Mar-2018 20:01:23 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15316 Version: 5 Check-in Time: 19-Mar-2018 20:01:23 STScI Edit Number: 3 Title Unveiling the mysterious nature of the cataclysmic variable SDSS J153817.35+5123238.0 ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Anna Francesca Pala The University of Warwick Y CoI: Prof. Boris T. Gaensicke The University of Warwick N CoI: Dr. Dean Townsley University of Alabama N CoI: Dr. Matthias R. Schreiber Universidad de Valparaiso N CoI: Dr. Alessandro Ederoclite Centro de Estudios de Fisica del Cosmos de N Aragon CoI: Mr. Javier Abril Centro de Estudios de Fisica del Cosmos de N Aragon ------------------------------------------------------------------------------------ Abstract Evolution of cataclysmic variables (CVs) is driven by angular momentum loss, which keeps mass loss from the donor star continually going, replenishing the disc with new higher-momentum material and maintaining, in this way, the accretion process. The angular momentum loss rate can be accurately constrained by measuring the white dwarf (WD) effective temperature (Teff), and provides one of the best available tests for the present model of the CV evolution. We conducted an HST/COS survey (ID 12870, PI Gaensicke) in which we measured Teff for 31 CV WDs. Our results are in good agreement with the theoretical prediction with one exception: SDSS J153817.35+5123238.0, a short period (93.1 min) CV which contains an anomalously hot WD. We argue that the system is either a very young CV (~20Myr), or has been recently re-heated to ~35000K. While the former hypothesis is statistically unlikely, the latter is most likely related to a nova eruption within the past few 1000 years or to additional mechanisms of angular momentum losses that are not account for by the present theory of CV evolution. To distinguish between these three scenarios, we need higher resolution UV observation to accurately measure the white dwarf mass, its effective temperature and photospheric abundances, along with a search for absorption features due to an ejected shell and their velocity. In this way we will constrain the WD age (from an improved mass measurement), its cooling rate (from this second temperature measurement) and we will also identify possible ashes and the expanding circumstellar gas shell expected in case of a recent nova explosion, shedding light on the mysterious nature of this system. ------------------------------------------------------------------------------------ Observations Description ------------------------ The aim of this program is to obtain high-resolution far-ultraviolet COS G130M spectroscopy of the cataclysmic variable white dwarf SDSS J1538. Our previous observations of this object on Cycle 20 with COS/G140L (dataset LC1V30010) demonstrated that the white dwarf is the dominant source of emission in the ultraviolet, with an effective temperature ~30 000 K. Given the white dwarf temperature, it is quite unlikely that SDSS J1538 can experience a dwarf nova outburst. Nonetheless, in order to insure the safety of the COS detectors, we 15316( 5) - 19-Mar-2018 20:01:23 - [ 2] will carry out an intense ground-based monitoring leading up to the HST observations. We will perform the target acquisition in dispersed light using the G130M grating. The coordinates and proper motions are drawn from the PPMXL catalogue, which has proven to be reliable and accurate to fractions of an arcsec, hence we do not precede the observations with a search pattern. We will make use of the 2 FP-POS positions available for G130M at the central wavelength 1291 A. ------------------------------------------------------------------------------------ 15316( 5) - 19-Mar-2018 20:01:23 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SDSSJ1538+51 STAR, DWARF NOVA RA=15H38M17.3100S +/- 0.1", J2000 V = 18.6 +/- 0.3 23 DEC=+51D23'38.00" +/- 0.1" Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 4.2737580322686097E-4 -0.001 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ1538+51 UNIDENTIFIED, BLANK RA-OFF=-0.74S, DEC-OFF=-5.78", J2000 V = 18.6 +/- 0.3 23-SAFE-TARG FIELD FROM 1 ET Extended: NO Comments: This target is a blank piece of sky which is the bright object safe pointing and is 9.043 arcseconds away at PA (U3) 230.3 degrees from SDSSJ1538+5123. ------------------------------------------------------------------------------------------------------------------------------------ 15316( 5) - 19-Mar-2018 20:01:23 - [ 4] Visit: 01 (SDSS1538+5128 - ACQ/PEAKXD) Visit Requirements: SCHED 100%; ORIENT 81.0D TO 7.0 D; AFTER 02 BY 3 D TO 5 D; BETWEEN 02-APR-2018:00:00:00 AND 09-APR-2018:00:00:00 On Hold Comments: Additional Comments: This visit should be scheduled in the day or evening-local time. Flags need to be cleared during the work day. 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 SDSSJ1538+5 COS/FUV ACQ/PEA PSA G130M 1291 LIFETIME-POS=LP4 1 10.5 S USE OFFSET V01SAF 123 KXD (10.5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ1538+5 COS/FUV ACQ/PEA PSA G130M 1291 STEP-SIZE=0.9, NUM-POS=5, 1 25 S (25 USE OFFSET V01SAF 123 KD CENTER=DEF, LIFETIME-POS=LP4 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1200, FP-POS=3, 1 2140 S USE OFFSET V01SAF 123 G FLASH=YES, SEGMENT=BOTH, (2140 S) LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1459, FP-POS=3, 1 1569 S USE OFFSET V01SAF 123 G FLASH=YES, SEGMENT=BOTH, (1569 S) LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1042, FP-POS=4, 1 1042 S USE OFFSET V01SAF 123 G FLASH=YES, SEGMENT=BOTH, (1042 S) LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 6 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1250, FP-POS=4, 1 2716 S USE OFFSET V01SAF 123 G FLASH=YES, SEGMENT=BOTH, (2716 S) LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1538+5123 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KXD SDSSJ1538+5123 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A KD SDSSJ1538+5123 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G SDSSJ1538+5123 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G SDSSJ1538+5123 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G SDSSJ1538+5123 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A G 15316( 5) - 19-Mar-2018 20:01:23 - [ 5] Visit: 02 (Safe Offset setup) Visit Requirements: ORIENT 81.0D TO 7.0 D On Hold Comments: Additional Comments: This visit allocates and sets up the safe position offset slot for visit 01 which will use that slot. This S/C visit should go earlier in the week while visit 01 will be at least 3 days later. This S/C visit will contain only 1 exposure. Note: weekends are to be avoided since the CS must clear the target within 24 hours of HST execution. 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 SDSSJ1538+5 S/C POINTIN V1 1 5 S (5 S) POS TARG 229.13280, 123 G -241.05750; SAVE OFFSET V01SAF; SPEC COM INSTR ECSLOTSET; QESIPARM ANGLE 230.5; QESIPARM DIST 9.043 Comments: This visit allocates and sets up the safe position offset slot for visit 1531601, which will use that slot. This S/C visit, 1531602, should go earlier in the week while 1531601 will be at least 3 days later. Note: weekends are to be avoided since the CS must clear the target 24 hours before HST execution. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1538+5123 1 S/C POINTIN V1 none none none none 1 N/A G 15316( 5) - 19-Mar-2018 20:01:23 - [ 6] Visit: 03 (SDSS1538+5128 - BOP ONLY) Visit Requirements: SCHED 100%; ORIENT 81.0D TO 7.0 D; BETWEEN 02-APR-2018:00:00:00 AND 09-APR-2018:00:00:00 On Hold Comments: Additional Comments: This visit is for BOP checking the safe target pointing only and should not execute onboard HST. 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 SDSSJ1538+5 COS/FUV ACQ/PEA PSA G130M 1291 LIFETIME-POS=LP4 1 10.5 S 123-SAFE-TA KXD (10.5 S) RGET ------------------------------------------------------------------------------------------------------------------------------------ 2 SDSSJ1538+5 COS/FUV ACQ/PEA PSA G130M 1291 STEP-SIZE=0.9, NUM-POS=5, 1 25 S (25 123-SAFE-TA KD CENTER=DEF, LIFETIME-POS=LP4 S) RGET ------------------------------------------------------------------------------------------------------------------------------------ 3 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1200, FP-POS=3, 1 2140 S 123-SAFE-TA G FLASH=YES, SEGMENT=BOTH, (2140 S) RGET LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 4 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1459, FP-POS=3, 1 1569 S 123-SAFE-TA G FLASH=YES, SEGMENT=BOTH, (1569 S) RGET LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 5 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1042, FP-POS=4, 1 1042 S 123-SAFE-TA G FLASH=YES, SEGMENT=BOTH, (1042 S) RGET LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 6 SDSSJ1538+5 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=1250, FP-POS=4, 1 2716 S 123-SAFE-TA G FLASH=YES, SEGMENT=BOTH, (2716 S) RGET LIFETIME-POS=LP4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1538+5123-SAFE 1 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A -TARGET KXD SDSSJ1538+5123-SAFE 2 COS/FUV ACQ/PEA PSA G130M 1291 none none none none 1 N/A -TARGET KD SDSSJ1538+5123-SAFE 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A -TARGET G SDSSJ1538+5123-SAFE 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A -TARGET G SDSSJ1538+5123-SAFE 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A -TARGET G 15316( 5) - 19-Mar-2018 20:01:23 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SDSSJ1538+5123-SAFE 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A -TARGET G 15316( 5) - 19-Mar-2018 20:01:23 - [ 8] Summary Form for Proposal 15316 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA, V1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, S/C ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, POINTING, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=1042, BUFFER-TIME=1200, BUFFER-TIME=1250, BUFFER-TIME=1459, CENTER=DEF, FLASH=YES, FP-POS=3, FP-POS=4, LIFETIME-POS=LP4, NUM-POS=5, SEGMENT=BOTH, STEP-SIZE=0.9 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 02 BY 3 D TO 5 D, BETWEEN 02-APR-2018:00:00:00 AND 09-APR-2018:00:00:00, ORIENT 81.0D TO 7.0 D, POS TARG 229.13280, -241.05750, QESIPARM ANGLE 230.5, QESIPARM DIST 9.043, SAVE OFFSET V01SAF, SCHED 100%, SPEC COM INSTR ECSLOTSET, USE OFFSET V01SAF ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M ------------------------------------------------------------------------------------------------------------------------------------ Target Names SDSSJ1538+5123, SDSSJ1538+5123-SAFE-TARGET ------------------------------------------------------------------------------------------------------------------------------------