6427( 10) - 04/22/96 13:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6427 Version: 10 Check-in Date: 22-Apr-1996 13:33:56 1.Proposal Title: Direct measurement of the BE Ursae Majoris sdO primary star mass-a critical test case for common envelope evolution ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle BINARIES AND STAR FOR GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Donald H. Ferguson Ferguson Enterprises CoI: James Liebert Steward Observatory, University of Arizona N CoI: Thomas James Chaffey High School N ------------------------------------------------------------------------------------ 6. Abstract BE UMa is a post-common envelope, pre-cataclysmic binary system with nearly unique properties. The primary is a very hot ~100,000 K sdO, about to become a white dwarf, separated by 8 solar radii from a G9V-K5V secondary. With most of its energy distribution emitted in the extreme ultraviolet, it produces a spectacular reprocessing spectrum on the facing side of the cool main sequence companion. This spectrum includes strong optical continuum and emission lines, which have been used to determine the radial velocity of the secondary star. It is also one of the few evolved systems which eclipses, so that tight constaints on the orbital inclination are available, as is the spectrum of the cool secondary star. It is one of the few to have an associated planetary nebula. Most importantly, the parameters derived for the primary star suggest that the binary has been ``uncloaked'' from the common envelope for only 1E6 years. But has the primary star evolved as a normal post-AGB objects, as the atmospheric parameters and mass (0.6 solar) inferred from analyzing its spectrum suggest? Our model of the reprocessed envelope suggests instead that the primary has a substantially higher mass. We propose here to obtain GHRS spectra to measure the velocity of the He II 1640A absorption line in the helium-rich primary especially at orbital quadratures in order to measure directly the mass, from the orbital solution and well as from any detectable gravitational redshift. The orbital separation, another key parameter of the modeling, is also determined. If the result validates the reflection effect models of Ferguson and James (1994), this would allow masses and separations for a broader selection of stars in a similar evolutionary phase (including non-eclipsers or those with less energetic reflection effects); e.g. certain planetary nebulae central stars. ------------------------------------------------------------------------------------ 6427( 10) - 04/22/96 13:37 - [ 2] Observations Description ------------------------ Three sets of exposures at binary phases 0.0, 0.25, and 0.75 required. Each exposure set requires 56 min. Hence, 3 full orbits are required. The first observation MUST be at phase=0 with the offset saved to ensure the exposures at quadrature have the longest integrations. Each exposure set consists of placing the star in the SSA and collecting several exposures with a wavelength calibration on either end. Real Time Justification ----------------------- The observations must be timed to the binary ephemeris for optimum value. The current best ephemeris for BE UMa is that of Wood et al. 1995: minimum light corresponding to eclipse of the hot sdO by the secondary star occurs at HJD 2444998.2810 + 2.2911658(7) days. We require one observation each at minimum phase and opposite quadratures, all within a delta-phase of 0.08, in order to obtain spectra near maximum radial velocity shifts. These observations need not be obtained during hte same binary orbit cycle, however. Calibration Justification ------------------------- Additional Comments ------------------- (Answer to the TAC question of how we'll remove the emission peak) The 1640A feature consists of a broad absorption line from the high-gravity sdO and a narrow emission line from a reflection effect on the side of the main sequence- like secondary facing the sdO. Note first that the emission feature is in near- eclipse around phase =0 and so has greatly reduced intensity. With the spectrum at phase 0, we will fit the outer wings of the absorption line using the models of Liebert et al 1994 as far toward the central wavelength as possible until a deviation in slope of the profile upward is detected using least-squares fitting. Now at quadrature, the emission line will be displaced from zero due to orbit-induced Doppler shifting by +- 102 km/s and the sdO lines will of course be Doppler shifted in the opposite direction, increasing the magnitude of the emission peak movement away from the central wavlength of the absorption line. We will fit the entire absorption line profile (including the uncontaminated half opposite the emission peak) with the results from the zero phase absorption line profile, allowing removal of the central peak. ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6427( 10) - 04/22/96 13:37 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 BE-UMA STAR, SDO RA = 11H 57M 44.78S +/- 0.05S, J2000 V = -67 V = 14.7+/-1.5 DEC = 48D 56' 18.7" +/- 0.5", B-V = 0.13+/-0.13 PLATE-ID = 024C F-CONT(1640)=5+/-11e-14 Comments: Coordinates are from an inventory GASP measurement by Karla 6427( 10) - 04/22/96 13:37 - [ 4] Visit: 01 Visit Requirements: PERIOD 54.98798H AND ZERO-PHASE JD2449980.2810 On Hold Comments: Additional Comments: This visit is at phase 0. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 BE-UMA HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 7.2S ONBOARD ACQ FOR 20 SEQ 10-50 NON-INT EARCH-SIZE=3 Comments: assuming 500 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 20 BE-UMA HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 20S ONBOARD ACQ FOR 30-50 KUP ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S PHASE 0.96 TO 0.04 1657 ------------------------------------------------------------------------------------------------------------------------------------ 40 BE-UMA HRS ACCUM 0.25 G160M 1623- DOPPLER=DEF,CEN 3 326.4S 1657 SOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S 1657 ------------------------------------------------------------------------------------------------------------------------------------ 6427( 10) - 04/22/96 13:37 - [ 5] Visit: 02 Visit Requirements: PERIOD 54.98798H AND ZERO-PHASE JD2449980.2810 On Hold Comments: Additional Comments: This visit is at phase .25. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 BE-UMA HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 7.2S ONBOARD ACQ FOR 20 SEQ 10-50 NON-INT EARCH-SIZE=3 Comments: assuming 500 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 20 BE-UMA HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 20S ONBOARD ACQ FOR 30-80 KUP ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S PHASE 0.21 TO 0.29 1657 ------------------------------------------------------------------------------------------------------------------------------------ 40 BE-UMA HRS ACCUM 0.25 G160M 1623- DOPPLER=DEF,CEN 3 326.4S 1657 SOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S 1657 ------------------------------------------------------------------------------------------------------------------------------------ 60 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S SEQ 60-80 NON-INT 1657 ------------------------------------------------------------------------------------------------------------------------------------ 70 BE-UMA HRS ACCUM 0.25 G160M 1623- DOPPLER=DEF,CEN 7 326.4S 1657 SOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 80 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S 1657 ------------------------------------------------------------------------------------------------------------------------------------ 6427( 10) - 04/22/96 13:37 - [ 6] Visit: 03 Visit Requirements: PERIOD 54.98798H AND ZERO-PHASE JD2449980.2810 On Hold Comments: Additional Comments: This visit is at phase .75. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 BE-UMA HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 7.2S ONBOARD ACQ FOR 20 SEQ 10-50 NON-INT EARCH-SIZE=3 Comments: assuming 500 counts/s ------------------------------------------------------------------------------------------------------------------------------------ 20 BE-UMA HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 20S ONBOARD ACQ FOR 30-80 KUP ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S PHASE 0.71 TO 0.79 1657 ------------------------------------------------------------------------------------------------------------------------------------ 40 BE-UMA HRS ACCUM 0.25 G160M 1623- DOPPLER=DEF,CEN 3 326.4S 1657 SOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S 1657 ------------------------------------------------------------------------------------------------------------------------------------ 60 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S SEQ 60-80 NON-INT 1657 ------------------------------------------------------------------------------------------------------------------------------------ 70 BE-UMA HRS ACCUM 0.25 G160M 1623- DOPPLER=DEF,CEN 7 326.4S 1657 SOR=YES ------------------------------------------------------------------------------------------------------------------------------------ 80 WAVE HRS ACCUM SC2 G160M 1623- 1 54.4S 1657 ------------------------------------------------------------------------------------------------------------------------------------ 6427( 10) - 04/22/96 13:37 - [ 7] Summary Form for Proposal 6427 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 SEARCH-SIZE=5 CENSOR=YES DOPPLER=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category BINARIES AND STAR FORMATION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 54.98798H AND ZERO-PHASE JD2449980.2810 ONBOARD ACQ FOR 20 SEQ 10-50 NON-INT ONBOARD ACQ FOR 30-50 PHASE 0.96 TO 0.04 ONBOARD ACQ FOR 30-80 PHASE 0.21 TO 0.29 SEQ 60-80 NON-INT PHASE 0.71 TO 0.79 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names BE-UMA WAVE ------------------------------------------------------------------------------------------------------------------------------------