8395( 9) - 08/10/99 16:12 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8395 Version: 9 Check-in Date: 10-Aug-1999 16:11:42 1.Proposal Title: Sakurai s Novalike Object: Real-Time Monitoring of a Stellar Thermal Pulse-Continued ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Howard Bond Space Telescope Science Institute CoI: Don Pollacco Royal Greenwich Observatory N ------------------------------------------------------------------------------------ 5. Abstract The eruption of Sakurai's novalike variable in Sagittarius presents a "once-in-a- lifetime" opportunity for real-time observations of a star undergoing a final helium thermal pulse. The star rose from obscurity to become an 11th-magnitude, hydrogen- deficient red giant in 1995-96, but it is (possibly) already evolving back to high temperature. During the next few years, it will begin to (re)-ionize its large, faint planetary nebula, and we should be able to witness the reestablishment of a fast stellar wind as the effective temperature increases. We will use STIS to monitor the spectroscopic development of the star in the UV at regular 2-month intervals over the next 3 years. We will also use WFPC2 to check for propagation of a light echo into the surrounding medium by obtaining images twice per year. In combination with ground-based monitoring (optical, IR, and mm), we will produce the first detailed case study of a thermal pulse. As we are essentially seeing a star retracing its evolution across the HR diagram from the AGB to the planetary-nebula phase, these observations will also aid our understanding of the more general case of post-AGB stellar evolution. ------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 2] Observations Description ------------------------ SPECTRA: We will initially obtain STIS CCD UV observations in the range 1650- 3100 A in order to follow development of the Mg II lines at 2800 A and other strong lines. As the star becomes hotter, we will add STIS MAMA spectra at 1150 -1700 A in order to track the evolution of the C IV 1550 A lines and other resonance lines. Including acquisition overheads, we will require two orbits to obtain each observation. In order to suitably sample the warming rate we also require this observation to be repeated every two months. Unfortunately, the HST observing season for this object extends only from February to October (sun angle >50 degrees). Thus our request is 10 spectroscopic orbits per calendar year, or a grand total of 30 over the next 3 years, for the STIS observations. IMAGING: With WFPC2 we will obtain broadband (VI) and narrow-band ([O III]) images over Cycles 7-9. These will enable us to track the dust distribution, light-echo propagation, and ejection of hydrogen-deficient material. We will obtain two images per Cycle, spaced approximately equally in time, for a total of 6 orbits. Detailed WFPC2 goals are as follows: (1) Obtain a set of V, I, and [O III] frames in which the central star reaches about 50% of saturation in its central pixel. Initially we will adopt the 1997 April 18 ground-based magnitude, V=10.86, and will adjust exposure times in the future as the star continues its evolution. These exposures are 0.26, 0.16, and 20 sec, respectively. These are for imaging of the region immediately surrounding the central star. (2) Obtain a second set of V, I, and [O III] frames in which the central pixel from the star reaches about 100, 000 electrons. These exposures are 1.6, 1.0, and 100 sec. These are for deeper imaging of the immediate surroundings. (3) Fill out the single orbit with longer V, I, and [O III] frames. We can accommodate 3 x 40 sec in V, 3 x 40 sec in I, and 2 x 260 sec in [O III]. These are for imaging fainter light echoes and nebular features at somewhat larger radii from the central star, as well as perhaps showing some details of the old planetary nebula surrounding the star. The central star is placed 1/2 way between the center of the PC chip and the apex, in order to cover more area around the central star (including the large surrounding planetary nebula) which still maintaining the high spatial resolution of the PC. Real_Time_Justification The program is time-critical in the sense that the observations must be spaced at roughly equal time intervals. However, these requirements are not exacting and we believe they can be easily met. We will continue to obtain twice-monthly optical spectra of this object from La Palma using primarily the 2.5-m Isaac Newton Telescope and if necessary the 4.2-m William Herschel Telescope. Both instruments are equipped with powerful spectroscopic facilities. During the northern-hemisphere winter months we have access to telescopes at ESO for spectroscopy which will extend the coverage (unfortunately, there will be an interval each winter when the object is hidden by the Sun). We are also involved in campaigns to obtain IR spectroscopy at UKIRT and mm wave photometry at the JCMT. Ground-based photometry is being obtained at SAAO and ESO (optical and IR)Null. While the object remains brighter than about 17th mag amateur astronomers will remain extremely active in following the light curve (for a continuously updated light curve see http://www.kuastro.kyoto- u.ac.jp/vsnet/novae.html). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 3] Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: STSCI Ship Via: Email: bond@stsci.edu ------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI- Star, nova-like, RA=17H 52M 32.73S +/- 1", DEC=- J2000 V=+115 V = 10.86 NOVALIKE-VAR planetary nebula 17D 41' 06.8" +/- 1", PLATE- B-V = 1.62 central star; ISM, ID=060B E(B-V) = 0.6 planetary nebula Comments: Coordinates are taken from measurements of WFPC2 frames taken in August 1996. The target flux level refers to the central star, and was measured on 1997 April 18. Note that the star is slowly variable and its brightness cannot be predicted in advance, but it is monitored regularly from the ground so we will know its brightness in advance of any particular HST observation and can adjust exposure times accordingly. 8395( 9) - 08/10/99 16:12 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENTation 93.05D TO 93.05D BETWEEN 15-AUG-1999 AND 30-SEP-1999 SCHEDulability 40% On Hold Comments: Additional Comments: ORIENT requirement is added to ensure same orientation as images taken in August 1996. This is the first imaging visit for Cycle 7, to be done as close to the beginning of the Cycle as possible in order to maintain our regular monitoring of the star's thermal pulse. Should be done before 1997 Jul 1 if at all possible (use off-nominal roll if necessary...this should be allowable although RPS2 does not seem to realize it). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 1 0.26 S POS TARG -8.5, -8.5 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 1 1.6 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 5 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 1 1.0 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 6 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 1 100 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 7 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F502N CR-SPLIT=NO 2 230 S SAME POS AS 1 EXPAND ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 8 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F814W CR-SPLIT=NO 3 40 S SAME POS AS 1 ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 9 SAKURAI-NOV WFPC2 IMAGE PC1-FIX F555W CR-SPLIT=NO 3 40 S SAME POS AS 1 END ORBIT ALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 6] Visit: 03 Visit Priority: Visit Requirements: SCHEDulability 80% BETWEEN 20-MAY-1999 AND 15-JUL-1999 ON HOLD On Hold Comments: Waiting for target to become active. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV STIS/C ACQ F28X50L MIRROR 1 0.1 S ONBOARD ACQ FOR 3-4 ALIKE-VAR CD P Comments: ETC ID = 05706 ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2200 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2800 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 7] Visit: 04 Visit Priority: Visit Requirements: AFTER 3 BY 50D TO 70D ON HOLD On Hold Comments: Waiting for target to become active. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV STIS/C ACQ F28X50L MIRROR 1 0.1 S ONBOARD ACQ FOR 3-4 ALIKE-VAR CD P Comments: ETC ID = 05706 ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2200 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2800 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 8] Visit: 05 Visit Priority: Visit Requirements: SCHEDulability 40% ON HOLD On Hold Comments: Waiting for target to become active. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV STIS/C ACQ F28X50L MIRROR 1 0.1 S ONBOARD ACQ FOR 3-4 ALIKE-VAR CD P Comments: ETC ID = 05706 ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2200 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2800 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 9] Visit: 06 Visit Priority: Visit Requirements: SCHEDulability 60% ON HOLD On Hold Comments: Waiting for target to become active. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV STIS/C ACQ F28X50L MIRROR 1 0.1 S ONBOARD ACQ FOR 3-4 ALIKE-VAR CD P Comments: ETC ID = 05706 ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2200 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2800 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 10] Visit: 07 Visit Priority: Visit Requirements: SCHEDulability 60% BETWEEN 23-MAR-2000 AND 18-MAY-2000 ON HOLD On Hold Comments: Waiting for target to become active. Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAKURAI-NOV STIS/C ACQ F28X50L MIRROR 1 0.1 S ONBOARD ACQ FOR 3-4 ALIKE-VAR CD P Comments: ETC ID = 05706 ------------------------------------------------------------------------------------------------------------------------------------ 3 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2200 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 4 SAKURAI-NOV STIS/C ACCUM 52X0.2 G230LB 2375 BINAXIS2=4 1 2800 S EXPAND END ORBIT ALIKE-VAR CD Comments: ETC ID = 06279 ------------------------------------------------------------------------------------------------------------------------------------ 8395( 9) - 08/10/99 16:12 - [ 11] Summary Form for Proposal 8395 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX F28X50LP 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO BINAXIS2=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENTation 93.05D TO 93.05D BETWEEN 15-AUG-1999 AND 30-SEP-1999 SCHEDulability 40% POS TARG -8.5, -8.5 SAME POS AS 1 SAME POS AS 1 EXPAND SAME POS AS 1 END ORBIT SCHEDulability 80% BETWEEN 20-MAY-1999 AND 15-JUL-1999 ON HOLD ONBOARD ACQ FOR 3-4 EXPAND END ORBIT AFTER 3 BY 50D TO 70D ON HOLD SCHEDulability 40% ON HOLD SCHEDulability 60% ON HOLD SCHEDulability 60% BETWEEN 23-MAR-2000 AND 18-MAY-2000 ON HOLD ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W F502N MIRROR G230LB ------------------------------------------------------------------------------------------------------------------------------------ Target Names SAKURAI-NOVALIKE-VAR ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2375 ------------------------------------------------------------------------------------------------------------------------------------