6808( 3) - 03/09/96 01:04 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6808 Version: 3 Check-in Date: 08-Mar-1996 17:02:59 1.Proposal Title: Capella: Separating the Giants ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COOL STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Andrea K. Dupree Smithsonian Astrophysical Observatory CoI: Nancy S. Brickhouse Smithsonian Astrophysical Observatory N CoI: Ronald L. Gilliland Space Telescope Science Institute Y ------------------------------------------------------------------------------------ 6. Abstract The bright giants in the Capella system form a test of the evolution of stellar magnetic activity: the primary star is a clump giant in the helium burning phase; the secondary star is a rapidly rotating star in the Hertzsprung Gap. Optical, ultraviolet, and EUV studies give differing and puzzling results as to the assignment of Capella's prodigious radiative output. We propose a unique use of the objective prism on the FOC in order to separate the two components, firmly identify the sources of emission, and answer fundamental questions about the presence and evolution of stellar chromospheres and coronae. ------------------------------------------------------------------------------------ 6808( 3) - 03/09/96 01:04 - [ 2] Observations Description ------------------------ The observations will be made at elongation when the stars are separated by their maximum amount (56.5 mas; Hummel Etal\\ 1994). This occurs approximately every half-period or 52 days. We will select an appropriate time so that the major axis of the apparent orbit is perpendicular to the dispersion of the prisms. The first orbit will be an interactive Bright Target acquisition followed by direct imaging in the near ultraviolet continuum to define the stellar positions and separations. Although we expect the atmospheres to be extended, and hence appear larger in the ultraviolet, they will still have an apparent size less than or comparable to a pixel (14 mas) (If the ultraviolet continuum disk is twice the size of the star in the visible, the disk of the primary is 17.0 mas, and of the secondary 12.8 mas.) We plan to use the Objective Prisms on the FOC in order to obtain spectra of the regions \\gl\\gl1235--1425; \\gl\\gl1525-1675; and the 2800Angstrom\\ region. The setup and exposures amount to one orbit for each of the 3 bands. We will use various crossed filter configurations to acquire our principal lines of interest (see Table 2), and to exclude the red spectral region. The major neutral density filters are located on the same filter wheel as the prisms, and so a mix of crossed wide and medium band filters will need to be set up. We are not concerned about the absolute calibration of the emission line flux since that has been well studied, but we wish to estimate the relative flux in each line from the two stars. A serious consideration is the dynamic range of the detectors, and the unknown relative contribution of the two giants. We will evaluate filter combinations and exposures at the top of the dynamic range for the total flux from the system which is well known; individual fluxes will be less. To isolate the important He II \\gl1640 transition, two filter configurations will likely be needed, although it may be that two prism configurations will also be necessary. The FOC team has obtained prism spectra of standard stars, so those should serve to define the point spread function ( cf. Jakobsen Etal\\ 1993; Paresce Etal\\ 1995). We note that we detected a bug in the prism simulator program for the FOC when applied to line spectra in the far ultraviolet, so that detailed computations of many crossed filter configurations were not possible for this proposal. We have had discussions with the FOC team at the STScI and the computer program could not be modified in time to meet the Cycle 6 deadline for proposals. We are confident however that the spectra can be obtained as proposed in the requested time. =2pc centerline Table 2: Ultraviolet Fluxes from the Capella System def width 16.5 truecm # & # & # & # noalign 2pt noalign 4 pt Emission& Wavelength& multispan2 Observed Flux at Earth noalign\\kern -2pt Feature&(AA)&(10^-12 erg\\ cm^-2 s^- 1)&(photon\\ cm^-2 s^-1) noalign 2pt noalign\\kern 2pt N V& 1240. &8.8&0.55 O I& 1305. &31.4& 2.06 C II& 1335. &23.7&1.59 Si IV& 1400.& 23.9&1.68 C IV& 1549.& 41.0&3.20 He II& 1640.&6.7&0.55 Mg II&2800.&1400.&197. noalign\\kern 2pt noalign 2pt \\medskip ^\\dagger Fluxes from from Linsky Etal\\ 1995 and Ayres and Linsky 1980. Real Time Justification ----------------------- Bright Target Acquisition Procedure for the FOC will be used. A real-time acquisition will be necessary. The brightness of Capella (V=0.08), and our desire to use the 128x128 IMAGE mode force real-time contacts to: 1) verify filter positions before a slew to the target can be made, and 2) perform an interactive acquisition to center the target for the 1.8'' square 128x128 IMAGE field. This program is Time-Critical because an observing date (~ +/- 3 days) must maximize the separation of the stars. We have time awarded on EUVE through 1995 to continue monitoring Capella; we are proposing for additional simultaneous time on ASCA and EUVE in order to better define the emission measure at high temperatures, and to determine the coronal abundances in the system. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6808( 3) - 03/09/96 01:04 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6808( 3) - 03/09/96 01:04 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD34029 STAR, G III-I RA = 05H 16M 41.35S +/- 0.01S, J2000 V = 0.08+/-0.01 DEC = 45D 59' 52.9" +/- 0.1" B-V = 0.80+/-0.01 F-LINE(1335)=21+/-2e-12 F-LINE(1356)=8+/-1e-12 F-LINE(1394)=15+/-1e-12 F-LINE(1486)=18+/-5e-13 F-LINE(1640)=10+/-1e-12 Comments: Coords, PM from Hipparcos INCA (as given in GO-5886) Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 0.0073 -0.425 0.075 6808( 3) - 03/09/96 01:04 - [ 5] Visit: 01 Visit Requirements: PERIOD 52.011D AND ZERO-PHASE JD2447502.44 ORIENT 171D TO 177D SCHED 90% On Hold Comments: Additional Comments: Must be scheduled within +/- 2 days of phase 0.0 or 0.5 for maximum component separation. Period is given as 0.5 of real period, and zero phase is maximum elongation -0.25*period. Orient is calculated to give maximum cross-dispersion separation (max sep in X of FOC). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD34029 FOC/96 ACQ 512X102 F278M,F14 PIXEL=50X25,CHE 1 120S INT ACQ FOR 20-110; PHASE 0.46 TO 0.54 4 0W,F6ND,F CK-FILTER=YES 1ND Comments: Expect center px count rate of 0.8/s. INT ACQ should place target at 48,86 of final 128X128 format, i.e., slightly off-center. ------------------------------------------------------------------------------------------------------------------------------------ 20 HD34029 FOC/96 IMAGE 128X128 F278M,F14 PIXEL=25X25,CHE 1 340S NO SPLIT; 0W,F6ND CK-FILTER=YES Comments: 2.1 cts/s central px. for each star ------------------------------------------------------------------------------------------------------------------------------------ 30 HD34029 FOC/96 IMAGE 128X128 F278M,F14 PIXEL=25X25,CHE 1 320S POS TARG +0.007,+0.000 0W,F6ND CK-FILTER=YES Comments: Provides sub-pixel sampling cross dispersion. ------------------------------------------------------------------------------------------------------------------------------------ 40 HD34029 FOC/96 IMAGE 128X128 F140M,F14 PIXEL=25X25,CHE 1 300S POS TARG +0.007,0.000 0W CK-FILTER=YES Comments: Far UV image, 3.1 cts/s central px. ------------------------------------------------------------------------------------------------------------------------------------ 50 HD34029 FOC/96 IMAGE 128X128 F140M,F14 PIXEL=25X25,CHE 1 300S POS TARG +0.000,0.000 0W CK-FILTER=YES Comments: Far UV image, 3.1 cts/s central px. ------------------------------------------------------------------------------------------------------------------------------------ 60 HD34029 FOC/96 IMAGE 256X256 F140W,F16 PIXEL=25X25,CHE 1 660S NO SPLIT; POS TARG +0.077,-5.900 5W,PRISM2 CK-FILTER=YES Comments: to place 1640A 20 px from y-max, rate at 1640 = 0.15, rate at 1800 = 0.9 Provides spectrum 1630-1830A. ------------------------------------------------------------------------------------------------------------------------------------ 70 HD34029 FOC/96 IMAGE 256X256 F140W,F16 PIXEL=25X25,CHE 1 720S POS TARG +0.070,-5.900 5W,PRISM2 CK-FILTER=YES Comments: to place 1640A 20 px from y-max, rate at 1640 = 0.15, rate at 1800 = 0.9 Provides spectrum 1630-1830A. ------------------------------------------------------------------------------------------------------------------------------------ 80 HD34029 FOC/96 IMAGE 256X256 F140W,F16 PIXEL=25X25,CHE 1 670S POS TARG +0.140,-0.860 5W,PRISM2 CK-FILTER=YES Comments: count rate max of 1.6; at 2800A and below max of 0.8 provides spectrum 2000-3250A ------------------------------------------------------------------------------------------------------------------------------------ 6808( 3) - 03/09/96 01:04 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 90 HD34029 FOC/96 IMAGE 256X256 F140W,F16 PIXEL=25X25,CHE 1 670S NO SPLIT; POS TARG +0.147,-0.860 5W,PRISM2 CK-FILTER=YES Comments: count rate max of 1.6; at 2800A and below max of 0.8 provides spectrum 2000-3250A ------------------------------------------------------------------------------------------------------------------------------------ 100 HD34029 FOC/96 IMAGE 256X256 F140W,F13 PIXEL=25X25,CHE 1 1160S POS TARG +0.270,-5.180 0M,PRISM1 CK-FILTER=YES Comments: max long wave counts about 1/s; 0.01 cts/s at 1640, 0.35 at 1335, 0.16 at 1216 Need 1400A at format center. ------------------------------------------------------------------------------------------------------------------------------------ 110 HD34029 FOC/96 IMAGE 256X256 F140W,F13 PIXEL=25X25,CHE 1 1150S NO SPLIT; POS TARG +0.277,-5.180 0M,PRISM1 CK-FILTER=YES Comments: max long wave counts about 1/s; 0.01 cts/s at 1640, 0.35 at 1335, 0.16 at 1216 Need 1400A at format center. ------------------------------------------------------------------------------------------------------------------------------------ 6808( 3) - 03/09/96 01:04 - [ 7] Summary Form for Proposal 6808 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PIXEL=50X25 CHECK-FILTER=YES PIXEL=25X25 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 52.011D AND ZERO-PHASE JD2447502.44 ORIENT 171D TO 177D SCHED 90% INT ACQ FOR 20-110; PHASE 0.46 TO 0.54 NO SPLIT; POS TARG +0.007,+0.000 POS TARG +0.007,0.000 POS TARG +0.000,0.000 NO SPLIT; POS TARG +0.077,-5.900 POS TARG +0.070,-5.900 POS TARG +0.140,-0.860 NO SPLIT; POS TARG +0.147,-0.860 POS TARG +0.270,-5.180 NO SPLIT; POS TARG +0.277,-5.180 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F278M,F140W,F6ND,F1ND F278M,F140W,F6ND F140M,F140W F140W,F165W,PRISM2 F140W,F130M,PRISM1 ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD34029 ------------------------------------------------------------------------------------------------------------------------------------