6680( 5) - 03/28/96 14:56 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6680 Version: 5 Check-in Date: 28-Mar-1996 14:53:21 1.Proposal Title: The post mass-transfer binary S1040 in M67 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle BINARIES AND STAR FOR GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Wayne Landsman Hughes STX CoI: Theodore Stecher NASA/Goddard Space Flight Center N CoI: Allen Sweigart NASA/Goddard Space Flight Center N CoI: Ben Dorman NASA/Goddard Space Flight Center N ------------------------------------------------------------------------------------ 6. Abstract The yellow giant S1040 (V=11.52, \bv = 0.88) in M67 is a single-lined spectroscopic binary that shows the following two anomalies. First, S1040 occupies a ``red straggler'' position in the M67 color-magnitude diagram, 0.2 mag blueward of the red giant branch. Second, S1040 was detected at 1520 Angstrom\ on an image of M67 obtained with the Ultraviolet Imaging Telescope (UIT), with an ultraviolet flux far above that expected from its optical colors. The most likely explanation for these two anomalies is that the secondary of S1040 is a hot white dwarf, and that the peculiar position of S1040 in the color-magnitude diagram is due to previous mass transfer from the white dwarf progenitor. If this scenario is correct, then S1040 is an evolutionary descendant of a M67 blue straggler. We propose to obtain a GHRS G140L spectrum of S1040 centered at 1320 Angstrom, in order to confirm the white dwarf identification, and to derive the white dwarf temperature and gravity from the Ly alpha profile. The white dwarf cooling age and mass can then be derived using evolutionary models. Used in conjunction with the known age and metallicity of M67, these parameters will allow us to constrain models of the binary stellar evolution of S1040, and evaluate its possible origin as a blue straggler. ------------------------------------------------------------------------------------ 6680( 5) - 03/28/96 14:56 - [ 2] Observations Description ------------------------ We propose to obtain a 120 minute large-aperture G140L exposure of S1040 centered at 1320 Angstrom. Using the white dwarf model which matches the observed UIT flux at 1520 Angstrom\\ (Figure 2), and the procedure PREDICT\\_GHRS available at Goddard Space Flight Center, we estimate that a 120 minute exposure will give S/N ~ 12 near Ly-alpha. Due to the large width of the white dwarf Ly-alpha\\ profile, it will be possible to improve the S/N by smoothing the spectra to ~ 8 Angstrom\\ resolution without losing senstivity to T(eff)\\ and \\logg. The UV flux of S1040 is too faint to allow an acquisition with side 1 on GHRS, so we are asking for an FOS/BL assisted acquisition. Note that an ACQ/BIN acquisition with FOS should suffice, since S1040 is an HST Guide Star Catalog source, and relatively bright at wavelengths longer that 2500 Angstrom. After the FOS/BL acquisition, we will obtain a 5 minute FOS low- dispersion spectrum using the G270H blue side to cover the 2400 -- 3300 Angstrom\\ spectral region where the flux from the K star is predicted to drop by more than a factor of 100. This short exposure will provide a sensitive diagnostic of the K star effective temperature. Real Time Justification ----------------------- None. None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6680( 5) - 03/28/96 14:56 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC2682- STAR,COMPOSITE SPECTRAL RA = 08H 51M 23.85S +/- 0.01S, J2000 V = 11.52+/-0.02 S1040 TYPE,K III-I,DA DEC = 11D 49' 49.3" +/- 0.2", B-V = 0.88+/-0.03 PLATE-ID=028I E(B-V) = 0.03+/-0.02 F(1520)=2.3+/-0.5e-15 6680( 5) - 03/28/96 14:56 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC2682- FOS/BL ACQ/BIN 4.3 MIRROR 1 2.1S ONBOARD ACQ FOR 20-40 S1040 ARY Comments: ACQ FOLLOWED BY BOTH FOS AND GHRS EXPOSURES ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC2682- FOS/BL ACCUM 4.3 G270H 1 5M S1040 ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC2682- HRS ACCUM 2.0 G140L 1320 STEP-PATT=5 11 598.4S S1040 ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC2682- HRS ACCUM 2.0 G140L 1320 STEP-PATT=5 1 27.2S S1040 ------------------------------------------------------------------------------------------------------------------------------------ 6680( 5) - 03/28/96 14:56 - [ 5] Summary Form for Proposal 6680 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters STEP-PATT=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category BINARIES AND STAR FORMATION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20-40 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC2682-S1040 ------------------------------------------------------------------------------------------------------------------------------------