! File: 4541C.PROP ! Database: PEPDB ! Date: 22-FEB-1994:16:54:27 coverpage: title_1: CEPHEID MASSES -CYC3-HIGH sci_cat: COOL STARS sci_subcat: PULSATING STARS proposal_for: GO longterm: 3 pi_fname: ERIKA pi_mi: HR pi_lname: BOHM-VITENSE pi_inst: 3760 pi_country: USA hours_pri: 11.99 num_pri: 7 hrs: Y time_crit: Y funds_length: 36 off_fname: DONALD off_mi: W off_lname: ALLEN off_title: DIRECTOR off_inst: 3760 off_addr_1: 3935 UNIVERSITY WAY NE off_addr_2: JM-24 off_city: SEATTLE off_state: WA off_zip: 98195 off_country: U.S.A. off_phone: 206 543 4043 ! end of coverpage abstract: line_1: For 2 decades the "Cepheid mass problem" has persisted: Mass line_2: determinations from standard evolutionary tracks and those from line_3: pulsation theory gave conflicting values. The luminosity of a Cepheid line_4: of given mass depends sensitively on the amount of convective overshoot line_5: above the core of the main sequence progenitor. Hence a good mass line_6: determination for the Cepheid with known luminosity will measure the line_7: amount of convective core overshoot. This knowledge is important for line_8: interpretation of HR diagrams of populous clusters in the LMC and line_9: especially for age determinations. It is also necessary for the line_10: understanding of the mixing processes in stars. line_11: IUE observations have revealed a number of Cepheid binaries with line_12: blue companions, whose orbits have now been determined by groundbased line_13: observations. We propose to measure the orbital radial velocities of 5 line_14: blue Cepheid companions on GHRS spectra for wavelengths shorter than line_15: 2000 A. The ratios of the orbital velocities for the binaries provide line_16: the mass ratios for the stars. The effective temperature of the line_17: companion can be determined from its energy distribution. For main line_18: sequence stars this also determines its mass. With GHRS spectra the line_19: orbital velocity ratio and thereby the mass ratio can be determined line_20: with an accuracLy of +/- 10 %. ! ! end of abstract general_form_proposers: lname: BOHM-VITENSE fname: ERIKA title: PI mi: HR inst: 3760 country: U.S.A. ! lname: EVANS fname: NANCY mi: R inst: INST. SPACE & TERRESTRIAL SCIENCE, NORTH YORK country: CANADA ! lname: CARPENTER fname: KENNETH mi: G inst: 2856 country: U.S.A. ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The purpose of this proposal is to measure the orbital velocities line_2: of the main sequence companions of 5 classical Cepheids. We would line_3: like to observe each target twice. The observations are spread out line_4: over several observing cycles in order to observe most targets both line_5: at maximum and at minimum orbital velocity. The highest accuracy will line_6: be achieved if the observations can be done close to the middle of line_7: the observing windows given. line_8: We plan to use the GHRS with the 2" aperture and the Echelle B line_9: at 1722 A for the observations for S Mus B which has the brightest line_10: companion. For the comparison star HD 66591 the same instrument line_11: configuration has to be used. We want to use the G200M grating at line_12: 1860 A for the other stars. The stars HD 65456 and HD 139129 are line_13: standard stars for comparison with the other Cepheid companions. The line_14: G200M grating at 1860 A has to be used for those. These stars line_15: should also be observed twice to be sure that we measure the same line_16: velocity. We would like the standard stars to be observed once line_17: during cycle 3 and the second time during cycle 4. line_18: We would like a wavelength calibration before and after each line_19: stellar observation. line_20: We need to break up the exposures into subexposures of not more line_21: than 5 minutes duration each in order to avoid geomagnetic smearing line_22: They will then be aligned by cross-correlation and co-added. ! question: 4 section: 1 line_1: We need the UV capabilities and the large collection area of HST. line_2: The Cepheid companions can only be seen in the ultraviolet because line_3: in the optical their light is drowned by the light of the luminous line_4: Cepheid. Because of the temperature difference between the components line_5: ,the hotter main sequence companions dominate, however, for line_6: wavelengths shorter than 2000 A. Companion velocities can therefore line_7: be measured only on UV spactra. The companions (except for S Mus B) line_8: are too faint to be observed with IUE at high resolution, needed line_9: for radial velocity measurements. line_10: Orbits for all program stars have been determined from the ground. line_11: In some cases we are working with collaborators to obtain additional line_12: velocity data to improve the orbits. line_13: We have also observed all the program stars in low resolution line_14: with IUE to determine the spectral types and the UV absolute fluxes line_15: for the companions. For S Mus, V636 Sco, and U Aql we have also line_16: attempted to measure the companion velocities. For S Mus and SU Cyg line_17: we have demonstrated that the cross-correlation technique works well line_18: to measure velocity differences between the Cepheid and the line_19: companion. The velocity differences are uncertain by about +/- 2.5 line_20: km/sec. The companion velocity becomes more uncertain because the line_21: somewhat uncertain Cepheid velocity (pulsation+orbit) has to be line_22: subtracted. With IUE we have been able to measure absolute line_23: velocities with an accuracy of about +/- 5 km/sec. ! question: 4 section: 2 line_1: We have estimated the exposure times from the fluxes on the IUE line_2: spectra, which are available for all the target stars. Count rates line_3: have been computed by Carpenter based on grating sensitivities and line_4: experience with observations. line_5: A signal to noise ratio of 15 is adequate for a reliable radial line_6: velocity measured by cross-correlation techniques. In addition we line_7: will be able to examine the companion spectra, which have not been line_8: observed at high resolution before. line_9: As discussed above, we plan to observe at least two standard line_10: stars to be used as primary velocity comparisons. To obtain the line_11: necessary wavelength accuracy wavelength calibration exposures line_12: will have to be taken before and after the stellar observations. ! question: 5 section: 1 line_1: In order to achieve the highest possible accuracy for the orbital line_2: velocity ratio, we need to observe the companions at phases near line_3: orbital radial velocity extrema. The orbits are typically a few line_4: years. Specific scheduling requests are detailed in Table 3. line_5: Generally a window of several months is available, which should line_6: assure that spacekraft constraints will not preclude our orbital line_7: requirements. Highest accuracy will be achieved in the middle of the line_8: windows. We stress that the selected intervals are set by orbital line_9: mechanics. If the length of a HST cycle should change, we require line_10: the requested times of observation even if they shift to a different line_11: cycle. line_12: In order to obtain an accuracy in the mass determination of 10% line_13: (which we consider necessary for a significant result), we require line_14: a velocity accuracy of 2 km/sec. In order to obtain this accuracy, line_15: a wavelength calibration is required before and after each stellar line_16: exposure. In addition, we intend to break the long exposures up into line_17: a series of short exposures to avoid geomagnetic smearing. These line_18: will then be aligned by cross-correlation and co-added. By the line_19: combination of the spectra, wavelength calibrations, and an line_20: aperture map the 0.2 diode wavelength accuracy should be possible line_21: within the large science aperture, on which the exposure times line_22: are based. ! question: 6 section: 1 line_1: In order to obtain an accuracy in the mass determination of line_2: +/-10% (which we consider necessary for a significant result), we line_3: require a velocity accuracy of 2 km/sec. This corresponds to a line_4: wvalength accuracy of 0.2 diode or better with the G200M grating. line_5: We believe that this can be obtained because of the results of line_6: Carpenter et al. (May 1991,HST Workshop) on the emission line line_7: spectrum of alpha Tau. In order to obtain this accuracy a wavelength line_8: calibration is required before and after each stellar exposure. line_9: In addition we intend to break the long exposures up into a series line_10: of short exposures to avoid geomagnetic smearing. These will then be line_11: aligned by cross-correlation and co-added. By the combination of the line_12: spectra, wavelength calibrations, and an aperture map the 0.2 diode line_13: wavelength accuracy should be possible within the large science line_14: aperture, on which the exposure times are based. ! question: 7 section: 1 line_1: The first step in reducing the HST spectra is to cross-correlate line_2: them. The absolute wavelength scale can then be determined from the line_3: wavelength calibrations. The velocities will be determined in three line_4: ways as described above. The primary determination will be to cross- line_5: correlate the program spectra with the spectra of the standard stars line_6: with known velocities to determine the velocity difference between line_7: them. In addition we will cross-correlate the two spectra of the line_8: companions taken at minimum and maximum orbital radial velocity to line_9: measure the velocity amplitude. Since we then measure velocity line_10: differences any systematic errors will cancel.The methods should line_11: agree. Any difference will alert us to an incomplete understanding line_12: of a spectral region which has not previously been used for high line_13: precision velocity measurements. line_14: The measured companion velocity will then be ratioed with the line_15: Cepheid orbital velocity at the same phase to give the inverse mass line_16: ratio. Since the effective temperature of the main sequence line_17: companion is known from the IUE measured energy distribution the line_18: mass of the companion can be determined very accurately,( +/- 2% line_19: according to Anderson 1991). (Small evolutionary corrections line_20: for the main sequence companion, which has a much smaller mass than line_21: the Cepheid, can be applied, knowing the age of the Cepheid). The line_22: orbital velocity ratio gives the inverse mass ratio of the binary line_23: components. The mass of the Cepheid can thus be derived. ! !end of general form text general_form_address: lname: BOHM-VITENSE fname: ERIKA mi: HR category: PI inst: 3760 addr_1: ASTRONOMY DEPARTMENT FM-20 addr_2: UNIVERSITY OF WASHINGTON city: SEATTLE state: WA zip: 98195 country: U.S.A. phone: (206) 543 4858 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: HD106111 name_2: HR4645 name_3: S-MUS-B descr_1: A;147;175;178; descr_2: 134;111 pos_1: RA= 12H 12M 47.23S +/- 0.5", pos_2: DEC= -70D 09' 6.0" +/- 1.0", pos_3: PLATE-ID=05ZX equinox: 2000 pm_or_par: Y pos_epoch_bj: J pos_epoch_yr: 1950.00 ra_pm_val: -0.002003 ra_pm_unct: 0.000079 dec_pm_val: -0.0200 dec_pm_unct: 0.0100 an_prlx_val: 0.0200 an_prlx_unct: 0.0030 rv_or_z: V=11.0 comment_1: WE OBSERVE THE B5V COMPANION comment_2: OF THE F8II CEPHEID S-MUS comment_3: THE CEPHEID MAGNITUDE IS 6.7+/-1 comment_4: FOR THE CEPHEID B-V=0.5+/0.1 fluxnum_1: 1 fluxval_1: V=8.9+/-1, TYPE=B5V fluxnum_2: 1 fluxval_2: B-V=0.07+/-0.1 fluxnum_3: 2 fluxval_3: E(B-V)=0.24+/-0.04 fluxnum_4: 3 fluxval_4: F-CONT(1722)=3.2+/-0.2E-12 ! targnum: 2 name_1: HD66591 name_2: HR3159 descr_1: A;111 pos_1: RA= 08H 00M 20.00S +/- 1.0", pos_2: DEC= -63D 34' 03.2" +/- 1.0" equinox: 2000 pm_or_par: Y pos_epoch_bj: J pos_epoch_yr: 1950.00 ra_pm_val: 0.001003 ra_pm_unct: 0.000030 dec_pm_val: 0.0200 dec_pm_unct: 0.0100 an_prlx_val: 0.0040 an_prlx_unct: 0.0010 rv_or_z: V=22.0 comment_1: THIS IS A VELOCITY CALIBRATION STAR comment_2: FOR THE OBSERVATIONS OF S-MUS fluxnum_1: 1 fluxval_1: V=4.82+/-0.02, TYPE=B3V fluxnum_2: 1 fluxval_2: B-V=-0.17+/-0.02 fluxnum_3: 2 fluxval_3: E(B-V)=0.0 fluxnum_4: 3 fluxval_4: F-CONT(1722)=5.0E-10 ! targnum: 3 name_1: HD91595 name_2: Y-CAR-B descr_1: A;147;175;178;134; descr_2: 112 pos_1: RA= 10H 33M 10.90S +/- 1.0", pos_2: DEC= -58D 29' 55.7" +/- 1.0", equinox: 2000 pm_or_par: Y pos_epoch_bj: J pos_epoch_yr: 1950.00 ra_pm_val: 0.000077 rv_or_z: V=-14.1 comment_1: WE WANT TO OBSERVE THE B9V comment_2: COMPANION OF THE CEPHEID Y CAR comment_3: THE CEPHEID HAS V=7.5+/-1 fluxnum_1: 1 fluxval_1: V=11.9+/-1 fluxnum_2: 1 fluxval_2: B-V=0.09+/-0.05 fluxnum_3: 2 fluxval_3: E(B-V)=0.08+/-0.05 fluxnum_4: 3 fluxval_4: F-CONT(1860)=1.0E-13 ! targnum: 4 name_1: HD172167 name_2: HR7001 name_3: ALPHA-LYRAE descr_1: A,123 pos_1: RA=18H36M56.3S+/-0.1S, pos_2: DEC=+38D47'01"+/-1" equinox: 2000.00 pm_or_par: Y pos_epoch_bj: J pos_epoch_yr: 1950.00 ra_pm_val: 0.017096 ra_pm_unct: 0.000599 dec_pm_val: 0.2900 dec_pm_unct: 0.0300 an_prlx_val: 0.1200 an_prlx_unct: 0.0100 rv_or_z: V=-14.0 comment_1: THIS IS A CALIBRATION STAR comment_2: TO MEASURE THE RADIAL comment_3: VELOCITY OF Y-CAR-B fluxnum_1: 1 fluxval_1: V=0.02+/-0.02, TYPE=A0V fluxnum_2: 1 fluxval_2: B-V=0.01 fluxnum_3: 2 fluxval_3: E(B-V)=0.0 fluxnum_4: 3 fluxval_4: F-CONT(1860)=5.5E-9 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: HD106111 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 1.8S fluxnum_1: 1 priority: 1 param_1: LOCATE=YES, param_2: BRIGHT=RETURN, param_3: SEARCH-SIZE=3 req_1: ONBOARD ACQ FOR 2.000; req_2: SEQ 1 - 5; req_3: CYCLE 3/1-45; req_4: AT 22-NOV-93+/-50D comment_1: USE STEP-TIME = 0.2 SEC. comment_2: EXPECT ROUGHLY 50000.CTS/0.2S ! linenum: 2.000 targname: HD106111 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 1 priority: 1 comment_1: STEP-TIME = 0.2 SEC ! linenum: 3.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: ECH-B wavelength: 1722.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 4 NO SLEW; req_2: SEQ 2-5 NON-INT; ! linenum: 4.000 targname: HD106111 config: HRS opmode: ACCUM aperture: 2.0 sp_element: ECH-B wavelength: 1722.0 num_exp: 5 time_per_exp: 5.0M s_to_n: 15 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=7, param_2: FP-SPLIT=NO comment_1: S/N IS FOR SUM OF 5 EXP'S. ! linenum: 5.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: ECH-B wavelength: 1722.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 4 NO SLEW ! linenum: 11.000 targname: HD91595 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 1.8S fluxnum_1: 1 priority: 1 param_1: LOCATE=YES, param_2: BRIGHT=RETURN, param_3: SEARCH-SIZE=3 req_1: ONBOARD ACQ FOR 12.000; req_2: SEQ 11-15; req_3: AT 14-JUL-93+/-20D; comment_1: USE STEP-TIME = 200 MSEC. comment_2: EXPECT ROUGHLY 2938 CTS/200MS ! linenum: 12.000 targname: HD91595 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 1 priority: 1 comment_1: STEP-TIME = 200 MSEC ! linenum: 13.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 14 NO SLEW; req_2: SEQ 12-15 NON-INT; ! linenum: 14.000 targname: HD91595 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G200M wavelength: 1860.0 num_exp: 5 time_per_exp: 5.0M s_to_n: 15 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=5, param_2: FP-SPLIT=NO comment_1: S/N IS FOR SUM OF 5 EXP'S. ! linenum: 15.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 14 NO SLEW ! linenum: 15.200 targname: HD91595 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-N2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 1 priority: 1 comment_1: STEP-TIME = 200 MSEC ! linenum: 15.500 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 15.6 NO SLEW; req_2: SEQ 15.2-15.7 NON-INT; ! linenum: 15.600 targname: HD91595 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G200M wavelength: 1860.0 num_exp: 5 time_per_exp: 5.0M s_to_n: 15 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=5, param_2: FP-SPLIT=NO comment_1: S/N IS FOR SUM OF 5 EXP'S. ! linenum: 15.700 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 15.6 NO SLEW ! linenum: 31.000 targname: HD66591 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-A2 num_exp: 1 time_per_exp: 1.8S fluxnum_1: 1 priority: 1 param_1: LOCATE=YES, param_2: BRIGHT=RETURN, param_3: SEARCH-SIZE=3 req_1: ONBOARD ACQ FOR 32.000; req_2: SEQ 31 - 35 comment_1: USE STEP-TIME = 200 MSEC. comment_2: EXPECT 12000 CTS/200MS ! linenum: 32.000 targname: HD66591 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-A2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 1 priority: 1 comment_1: STEP-TIME = 200 MSEC ! linenum: 33.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: ECH-B wavelength: 1722.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 34 NO SLEW; req_2: SEQ 32-35 NON-INT; ! linenum: 34.000 targname: HD66591 config: HRS opmode: ACCUM aperture: 2.0 sp_element: ECH-B wavelength: 1722.0 num_exp: 2 time_per_exp: 27.2S s_to_n: 15 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=7, param_2: FP-SPLIT=NO comment_1: S/N IS FOR SUM OF 2 EXP'S. ! linenum: 35.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: ECH-B wavelength: 1722.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 34 NO SLEW ! linenum: 41.000 targname: HD172167 config: HRS opmode: ACQ aperture: 2.0 sp_element: MIRROR-A2 num_exp: 1 time_per_exp: 1.8S fluxnum_1: 1 priority: 1 param_1: LOCATE=YES, param_2: BRIGHT=RETURN, param_3: SEARCH-SIZE=3 req_1: ONBOARD ACQ FOR 42.000; req_2: SEQ 41-45; comment_1: USE STEP-TIME = 200 MSEC. comment_2: EXPECT >>>> CTS/200MS ! linenum: 42.000 targname: HD172167 config: HRS opmode: ACQ/PEAKUP aperture: 2.0 sp_element: MIRROR-A2 num_exp: 1 time_per_exp: 20.4S fluxnum_1: 1 priority: 1 comment_1: STEP-TIME = 200 MSEC ! linenum: 43.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 44 NO SLEW; req_2: SEQ 42-45 NON-INT; ! linenum: 44.000 targname: HD172167 config: HRS opmode: ACCUM aperture: 2.0 sp_element: G200M wavelength: 1860.0 num_exp: 2 time_per_exp: 3.2S s_to_n: 15 fluxnum_1: 2 priority: 1 param_1: STEP-PATT=3, param_2: FP-SPLIT=NO comment_1: S/N IS FOR SUM OF 5 EXP'S. ! linenum: 45.000 targname: WAVE config: HRS opmode: ACCUM aperture: SC2 sp_element: G200M wavelength: 1860.0 num_exp: 1 time_per_exp: 30.0S priority: 1 param_1: STEP-PATT=3 req_1: CALIB FOR 44 NO SLEW ! ! end of exposure logsheet ! No scan data records found