11601( 5) - 13-Apr-2010 20:04:13 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11601 Version: 5 Check-in Time: 13-Apr-2010 20:04:13 STScI Edit Number: 3 Title UV spectroscopy of the hot bare stellar core H1504+65 ------------------------------------------------------------------------------------ Type Cycle GO 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Klaus Werner Universitat Tubingen, Institut fur Astronomie & Astrophysik CoI: Dr. Thomas Rauch Universitat Tubingen, Institut fur N Astronomie & Astrophysik ------------------------------------------------------------------------------------ Abstract H1504+65 is the hottest known white dwarf (Teff=200, 000 K). It has an extraordinary surface composition. The surface is devoid of hydrogen and helium. It is mainly composed of carbon and oxygen (by equal amounts) and neon (2%). We obviously see the exposed core of a former red giant. The evolutionary history of this unique object is unknown. We have identified magnesium absorption lines in the soft X-ray photospheric Chandra spectrum, which suggests that H1504+65 may be an O-Ne-Mg white dwarf. We will test this hypothesis by abundance determinations of Mg and Na. If confirmed, then H1504+65 would be the most compelling case for the existence of single O-Ne-Mg white dwarfs. ------------------------------------------------------------------------------------ Observations Description ------------------------ We want to use COS gratings G130M and G160M, covering the range 1132-1775A. This provides the spectral resolution needed for a quantitative analysis of the narrow metal lines. Besides prominent C and O lines this range contains many Mg VII and Na VI suitable for spectroscopic analyses. We used the COS Exposure Time Calculator to determine the exposure times necessary to achieve S/N of about 30. From our experience with previous HST data analyses this S/N is necessary to determine abundances as accurate as 0.3 dex, which is required to answer our scientific questions. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11601( 5) - 13-Apr-2010 20:04:13 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 H1504+65 STAR, PG1159 STAR RA=15H02M9.6200S +/- 0.1", J2000 V = 16.24 +/- 0.1 DEC=+66D12'18.64" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 11601( 5) - 13-Apr-2010 20:04:13 - [ 3] Visit: 01 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 H1504+65 COS/FUV ACQ/SEA PSA G130M 1291 STEP-SIZE=1.767, 1 0.2 S RCH CENTER=FLUX-WT, SCAN-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 H1504+65 COS/NUV ACQ/IMA BOA MIRRORA 1 83 S GE ------------------------------------------------------------------------------------------------------------------------------------ 3 H1504+65 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=130, FP-POS=AUTO, 1 1592 S G FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ 4 H1504+65 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=240, FP-POS=AUTO, 1 2792 S G FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ H1504+65 1 COS/FUV ACQ/SEA PSA G130M 1291 none none none none 1 N/A RCH H1504+65 2 COS/NUV ACQ/IMA BOA MIRRORA none none none none 1 N/A GE H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 1 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 2 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 3 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 4 1 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 1 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 2 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 3 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 4 2 N/A G 11601( 5) - 13-Apr-2010 20:04:13 - [ 4] Visit: 51 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 H1504+65 COS/FUV ACQ/SEA PSA G130M 1291 STEP-SIZE=1.767, 1 0.2 S RCH CENTER=FLUX-WT, SCAN-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ 2 H1504+65 COS/NUV ACQ/IMA BOA MIRRORA 1 83 S GE ------------------------------------------------------------------------------------------------------------------------------------ 3 H1504+65 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=130, FP-POS=AUTO, 1 1560 S G FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ 4 H1504+65 COS/FUV TIME-TA PSA G160M 1600 BUFFER-TIME=240, FP-POS=AUTO, 1 2772 S G FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ H1504+65 1 COS/FUV ACQ/SEA PSA G130M 1291 none none none none 1 N/A RCH H1504+65 2 COS/NUV ACQ/IMA BOA MIRRORA none none none none 1 N/A GE H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 1 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 2 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 3 1 N/A G H1504+65 3 COS/FUV TIME-TA PSA G130M 1291 none none none 4 1 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 1 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 2 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 3 2 N/A G H1504+65 4 COS/FUV TIME-TA PSA G160M 1600 none none none 4 2 N/A G 11601( 5) - 13-Apr-2010 20:04:13 - [ 5] Summary Form for Proposal 11601 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures BOA, PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, ACQ/SEARCH, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=130, BUFFER-TIME=240, CENTER=FLUX-WT, FLASH=YES, FP-POS=AUTO, SCAN-SIZE=3, STEP-SIZE=1.767 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, G160M, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names H1504+65 ------------------------------------------------------------------------------------------------------------------------------------