7757( 6) - 02/23/99 15:23 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7757 Version: 6 Check-in Date: 23-Feb-1999 15:22:43 1.Proposal Title: Time-Resolved Spectrophotometry of the Smallest Mass Function Binary Star ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO/CAR 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Bruce Margon University of Washington CoI: Stefanie Wachter University of Washington N CoI: Scott Anderson University of Washington Y ------------------------------------------------------------------------------------ 5. Abstract The 7 s X-ray pulsar X1626-67 is one of the rare cases in which an X-ray pulsar is a member of a low mass X-ray binary (LMXB) system. The optical counterpart (KZ TrA) exhibits optical pulsations with the same period as the X-ray pulsations. No Dopppler variations due to orbital motion in the X-ray pulse arrival times have been detected, but an additional lower frequency optical sideband pulsation indicates a probable orbital period of about 40 min. The system has the smallest known mass function of any binary system mbox(f(M)<=sssim 10^-6 M_\odot) and its evolutionary history is still a puzzle. We propose to use the HST to obtain time resolved spectra over the 40 min orbit. The optical spectrum of KZ TrA is almost featureless and provides few model constraints. In the UV, however, the spectra of LMXBs are usually characterized by numerous strong emission lines due to the ionizing flux of the incident X-rays. The line fluxes and ratios constrain the size, density, and degree of ionization in the emission region and are an invaluable tool in determining the physical conditions in the system. Monitoring of the line flux variations over the orbital cycle will constrain the location of the emission region in the system. We will also search for UV pulsations with the 7 s period in the continuum and the lines, which could be very strong. ------------------------------------------------------------------------------------ 7757( 6) - 02/23/99 15:23 - [ 2] Observations Description ------------------------ Time-resolved spectroscopy in the UV is undertaken to sample spectral changes over both 7s pulsation and 42 minute binary periods. STIS TIME-TAG G140L and G230L spectra are to be taken (to provide similar wavelength coverage as in the original GO/FOS observations), but with an emphasis on G140L as it includes most of the strongest UV lines commonly found in X-ray binaries. KZ TrA is on the edge of the HST Continuous Viewing Zone. We do not assume or request here that this will be executed as a CVZ proposal, but merely point out that there is a substantial probability that CVZ observing will prove to be possible, significantly enhancing observing efficiency. We select a small slit for G140L to minimize geocoronal LyAlpha contamination for this relatively faint object, and thus maximize the possibility of the detection of stellar LyAlpha emission. The observations have to be broken up into three visits to avoid the SAA/MAMA restrictions. In order to limit the impact of long-term variability of the target, we would like the three visits as close in time as possible (e.g., within 70 days). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7757( 6) - 02/23/99 15:23 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 KZ-TRA STAR, LMXB RA=16H 32M 16.67S +/- 0.04S, 2000 V = 18.5+/-0.8 DEC=-67D 27' 39.4" +/- 1", PLATE F(1400)=2.0e-15 -ID=00JI Comments: TA exposure time estimates based on V=19.3 and B- V=+0.1 7757( 6) - 02/23/99 15:23 - [ 4] Visit: 01 Visit Priority: Visit Requirements: SEQ 1-3 WITHIN 70D On Hold Comments: Additional Comments: Target is sometimes in CVZ, so efficiency can be markedly improved if schedulable in CVZ (although this is not required). Please contact GO if CVZ scheduling deemed feasible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 KZ-TRA STIS/C ACQ 50CCD MIRROR ACQTYPE=POINT 1 12 S ONBOARD ACQ FOR 102 CD ------------------------------------------------------------------------------------------------------------------------------------ 102 KZ-TRA STIS/C ACQ/PEA 52X0.1 MIRROR 1 25 S ONBOARD ACQ FOR 103-106 CD K ------------------------------------------------------------------------------------------------------------------------------------ 103 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 1950 S UV-MAM G A Comments: Buffer-time based on extremely conservative assumption of flat continuum with flambda 5e-15 ------------------------------------------------------------------------------------------------------------------------------------ 104 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 105 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 106 KZ-TRA STIS/N TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=4300 1 2550 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 7757( 6) - 02/23/99 15:23 - [ 5] Visit: 02 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Target is sometimes in CVZ, so efficiency can be markedly improved if schedulable in CVZ (although this is not required). Please contact GO if CVZ scheduling deemed feasible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 201 KZ-TRA STIS/C ACQ 50CCD MIRROR ACQTYPE=POINT 1 12 S ONBOARD ACQ FOR 202 CD ------------------------------------------------------------------------------------------------------------------------------------ 202 KZ-TRA STIS/C ACQ/PEA 52X0.1 MIRROR 1 25 S ONBOARD ACQ FOR 203-206 CD K ------------------------------------------------------------------------------------------------------------------------------------ 203 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 1950 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 204 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 205 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 206 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 7757( 6) - 02/23/99 15:23 - [ 6] Visit: 03 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Target is sometimes in CVZ, so efficiency can be markedly improved if schedulable in CVZ (although this is not required). Please contact GO if CVZ scheduling deemed feasible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 301 KZ-TRA STIS/C ACQ 50CCD MIRROR ACQTYPE=POINT 1 12 S ONBOARD ACQ FOR 302 CD ------------------------------------------------------------------------------------------------------------------------------------ 302 KZ-TRA STIS/C ACQ/PEA 52X0.1 MIRROR 1 25 S ONBOARD ACQ FOR 303-307 CD K ------------------------------------------------------------------------------------------------------------------------------------ 303 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 1950 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 304 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 305 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 306 KZ-TRA STIS/F TIME-TA 52X0.1 G140L 1425 BUFFER-TIME=4100 1 2850 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 307 KZ-TRA STIS/N TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=4300 1 2550 S UV-MAM G A ------------------------------------------------------------------------------------------------------------------------------------ 7757( 6) - 02/23/99 15:23 - [ 7] Summary Form for Proposal 7757 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD 52X0.1 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT BUFFER-TIME=4100 BUFFER-TIME=4300 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-3 WITHIN 70D ONBOARD ACQ FOR 102 ONBOARD ACQ FOR 103-106 ONBOARD ACQ FOR 202 ONBOARD ACQ FOR 203-206 ONBOARD ACQ FOR 302 ONBOARD ACQ FOR 303-307 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L G230L ------------------------------------------------------------------------------------------------------------------------------------ Target Names KZ-TRA ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2376 ------------------------------------------------------------------------------------------------------------------------------------