5822( 10) - 11/07/95 15:52 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5822 Version: 10 Check-in Date: ********** 1.Proposal Title: Wind Accretion in the Mira AB System ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Hot Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Margarita Karovska Smithsonian Institution Astrophysical Observatory CoI: John Raymond Smithsonian Institution Astrophysical N Observatory CoI: Warren Hack Space Telescope Science Institute N CoI: Edward Guinan Villanova University N ------------------------------------------------------------------------------------ 6. Abstract Mira AB system belongs to a class of detached binaries where a compact object, possibly a white dwarf, accretes mass from the wind of a cool giant or supergiant. This system is an ideal case for detailed study of accretion processes in binaries because it is the only case of a wind accreting object that can be easily resolved using the HST. We propose to carry out multiwavelength observations of the components of the Mira AB system using the HST FOC camera to study the accretion processes in this system and explore, for the first time, the extended atmosphere of Mira A (the prototype of Mira-type variables) at UV wavelengths. HST observations are essential for successful accomplishment of this project because important spectral diagnostics of Mira A and Mira B occur in the UV. In addition, HST presents a unique opportunity of observing Mira B at UV and optical wavelengths uncontaminated by the red giant. The principal goals of this project are: (1) to determine the the accretion luminosity of Mira B at UV and optical wavelengths, (2) to test the viability of wind accretion models, (3) to determine the nature of the accreting star, and (4) to measure the apparent diameter of Mira A as a function of wavelength and to image the asymmetries in its atmosphere. ------------------------------------------------------------------------------------ 5822( 10) - 11/07/95 15:52 - [ 2] Observations Description ------------------------ FOC imaging of the Mira system will provide a unique perspective of an accreting system. The FWHM of the FOC f/96 COSTAR-corrected PSF at 4860 Angstrom is 42 mas (FOC Instrument Handbook V5.0, 1994), increasing up to about 50 mas in the UV (FOC SMOV Final Report, R. Jedrzjewski, 1994). In addition to the system itself, Mira A can also be resolved with the HST and diameter measurements can be obtained. The direct images taken in the near- and far-UV with the FOC would provide the highest accuracy positional data for the secondary ever. This set of images would also provide detailed information on the continuum and line emission from the secondary separated from the primary's emission for the first time ever. HST observations carried around the minimum light of Mira A (V ~ 9.5) will result in a direct measurement of the brightness of Mira B at UV and optical wavelengths. This will allow us to derive the total accretion luminosity. The observations in the UV would detect the red- giant in a spectral region where it is comparable in magnitude to the secondary, allowing for easier measurement of both stars. This technique was used successfully in the imaging of R Aqr using the FOC in previous cycles (Paresce and Hack, 1994), proving its viability for the Mira system. Furthermore, it will be possible to use the PSF from the point-source secondary to deconvolve the image of Mira A and then measure the diameter by precise fitting of model profiles to the power spectra. Power spectral analysis has proven to be a powerful tool for high spatial resolution diameter measurements (or axes of asymmetries) from ground based interferometry(Papaliolios et al. 1989; Karovska et al. 1991) and has been recently successfully applied to HST observations (Nisenson and Falco 1994). IUE spectra of the Mira system, taken when the primary (Mira A) was near a minimum, show strong MgII emission line at 2800 Angstrom mainly due to Mira B, along with a host of other lines in the far-UV. For a simulation of the spectrum of Mira B we used an IUE spectrum of the Mira system recorded near Mira A minimum and extrapolated it linearly into the visible assuming V=11.15 for Mira B. For Mira A, we used an observed M7III spectrum from the STSDAS BPGS catalog normalized to V=8 (as an upper limit), which is about 1 magnitude brighter than Mira A near the minimum when we anticipate observing with the FOC. These spectra were then used in FOCSIM by Hack to simulate what the HST images would be like. These simulations have determined a peak count rate of 4.1 count/sec/pixel for a F278M+F275W+F4ND+F1ND image assuming that all the light seen in the IUE spectra comes from the secondary as a point source. Additional images taken with the F152M, F190M, F307M, and F346M filters (with from 4ND to 7ND, as needed) would result in images whose peak count rates are always less than 3 counts/sec/pixel. Images taken in the visible with the F410M (with 7ND), F470M (with 7ND), and the F550M (with 6ND) would also have peak count rates for an unresolved primary with M7III spectra of V=8 of about 7 counts/sec/pixel. These images would allow for comparisons with contemporaneous ground-based Stromgren photometry and with spectroscopy of the system. Furthermore, the F501N image will be used to search for shock (HII) regions at the interface of the winds from each component. The count rates expected for the images can be accommodated using the small 256*256 format, which can maintain linearity for point sources with peak count rates up about 4 counts/sec/pixel, as long as the observations are scheduled near or during the variable's minimum. At most of the wavelengths longer than 3000 Angstrom, we expect to obtain sufficient S/N for both components with 270 s exposures. The 270 second long exposures also provide good S/N for Mira B at wavelengths shorter than 2800 Angstrom. For sufficient S/N in the images of both components recorded using F278M and F307M filters we need longer exposures due to the lower count rates we will be obtaining from the stars. The use of the 256*256 format will require an interactive acquisition in order to insure that the target fell inside the 3.5"*3.5" field of view. Objective prism images, taken with PRISM1+F140W+F165W and PRISM2+F175W, would also provide low resolution spectroscopy of both components, again separated from each other for the first time ever. Simulations done using the 'focprism' package in STSDAS show that the 270 second exposures would provide a S/N ~ 5-30 for most of the wavelengths shorter than 3000 Angstroms. For wavelengths longer than 3000 Angstrom, the light from the primary might be non-linear, but only with a peak count rate of 3 counts/sec/pixel for the PRISM2 image and a count rate of about 7 counts/sec/pixel for the PRISM1 image. Although the count rates are high in the visible end of the objective prism images, they pose no danger to the FOC and represent an upper limit to the count rate if these images are taken near or at the photometric minimum. The direct images, especially the F307M image, would be useful in the final calibrations of the objective prism spectra. Thus, the program is envisioned as follows: Orbit 1: INT ACQ image (F190M+F6ND), F550M+F6ND Orbit 2: F152M+F175W, F346M+F6ND+F1ND, F278M+F275W+F4ND+F1ND, F307M+F275W+F4ND+F1ND Orbit 3: F501N+F4ND+F1ND, F410M+F6ND+F1ND, F470M+F6ND, PRISM2+F175W, PRISM1+F140W+F165W Most exposures are 270 seconds long and include the necessary neutral density filters (from 4 - 7ND) to provide the proper count rates in the small format. Additional filters have been added to reduce the 'redleak' of the UV filters and to further reduce the count rates. REFERENCES Bonneau, D., Foy, R., Blazit, A., and Labeyrie, A. 1982, Astr. Ap, 106, 235. Jenkins, L.F. 1952, General Catalogue of Stellar Parallaxes, (Yale University). Jura, M. and Helfand, D. J. 1984, Ap. J., 287, 785. Karovska M., Nisenson, P., Papaliolios, C., and Boyle 1991 Ap. J., 374, L51. Karovska, M. Nisenson, P., and Beletic, J. 1993, Ap. J., 402, 311. Livio, M. 1988, in Symbiotic Phenomenon, Proccedings of IAU Coll. No. 103. Livio, M., and Warner, B. 1984, Observatory, 104, 152. Paresce, F. and Hack, W. 1994, Astr. Ap, 287, 154 Papaliolios, C., et al. 1989, Nature, 338, 565. Reimers, D., and Cassatella, A.. 1985, Ap. J., 297, 275. Rowan- Robinson, M., Lock,T. D., Walker, D. W., Harris, S. 1986, M.N.R.S., 222, 273. Nisenson, P. and Falco, E. 1994 Second HST Restoration Workshop, in press Willson, L. A 1988, in Polarized Radiation of Circumstellar Origin, (Ed. G. Coyne). Real Time Justification ----------------------- The use of the 256x256 format requires an INT ACQ in order to be assured that the target ends up in the 3.5x3.5 arcsecond field of view. The secondary's position as determined from ground-based speckle observations is at a P.A. of about 113 degrees and a separation of about 0.5 arcseconds. In order to separate the two sources objective prism spectra, they need to be separated by at least 0.25" in the image, providing a loose constraint on the orientation of 57 +/- 30 degrees or 237 +/- 30 degrees, whichever occurs near or during the primary's minimum (expected around mid-November 1995, J. Mattei priv. comm.). In support of the HST observations we plan to carry out coordinated ground- based photometric and spectroscopic observations. Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- Ground based observations will be made in order to track the photometry of the system. This will be used to insure that the count rates expected from simulations used for the exposures will be correct. The primary will reach minimum in late November with V=9.5. By the beginning of January, the primary will reach V=8. The simulations assumed an upper limit of V=8 for the exposures in this proposal. ------------------------------------------------------------------------------------ 5822( 10) - 11/07/95 15:52 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5822( 10) - 11/07/95 15:52 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD14386 Star RA=02H 19M 20.71S +/- 1S, DEC=- J2000 V=8.0 02D 58' 39.400" +/- 1" Comments: This star is variable and needs to be observed near minimum to insure the safety of the FOC and to obtain photometric images. Coordinates have been derived from Hipparchos plates, as this object very bright. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000.0 -0.0008 -0.233 0.0 5822( 10) - 11/07/95 15:52 - [ 5] Visit: 01 Visit Requirements: ORIENTation 52D TO 62D BETWEEN 4-DEC-1995 and 25-DEC-1995 On Hold Comments: Additional Comments: This visit should be scheduled in the earliest possible alignment (in late November or during December 1995, but before 1 January 1996) in order to view the variable when it is near minimum. This is critical to obtaining properly exposed images. If this is not the case modifications to the exposures will be required in order to maintain properly exposed images. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HD14386 FOC/96 IMAGE 512x102 F190M,F6N PIXEL=50x25,CHE 1 240S INT ACQ for 2 - 11 4 D CK-FILTER=YES Comments: We request as short as decision time as possible in order to accomodate an extra exposure during this orbit. Shorter decision time is possible due to the simplicity of the centering procedure for this target. ------------------------------------------------------------------------------------------------------------------------------------ 2 HD14386 FOC/96 IMAGE 256x256 F550M,F6N CHECK- 1 270S D FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 3 HD14386 FOC/96 IMAGE 256x256 F152M,F17 CHECK- 1 270S 5W FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 4 HD14386 FOC/96 IMAGE 256x256 F346M,F6N CHECK- 1 270S D,F1ND FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 5 HD14386 FOC/96 IMAGE 256x256 F278M,F27 CHECK- 1 540S 5W,F4ND,F FILTER=YES 1ND ------------------------------------------------------------------------------------------------------------------------------------ 6 HD14386 FOC/96 IMAGE 256x256 F307M,F27 CHECK- 1 360S MAX DUR 110% 5W,F4ND,F FILTER=YES 1ND ------------------------------------------------------------------------------------------------------------------------------------ 7 HD14386 FOC/96 IMAGE 256x256 F501N,F4N CHECK- 1 270S D,F1ND FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 8 HD14386 FOC/96 IMAGE 256x256 F410M,F6N CHECK- 1 270S D,F1ND FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 9 HD14386 FOC/96 IMAGE 256x256 F470M,F6N CHECK- 1 180S D FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 10 HD14386 FOC/96 IMAGE 256x102 PRISM2,F1 CHECK- 1 270S 4 75W FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ 5822( 10) - 11/07/95 15:52 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 HD14386 FOC/96 IMAGE 256x102 F140W,PRI CHECK- 1 270S POS TARG 0,-4.3 4 SM1,F165W FILTER=YES Comments: Expected count rates for primary and secondary are expected to be below 4 c/s/pixel in the peak for all but the PRISM 1 image(7 c/s/pixel) and F410M image (7.5 c/s/pixel for the secondary). These count rates are all upper limits for these variable stars. ------------------------------------------------------------------------------------------------------------------------------------ 5822( 10) - 11/07/95 15:52 - [ 7] Summary Form for Proposal 5822 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOC/96 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PIXEL=50x25 CHECK-FILTER=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Hot Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENTation 52D TO 62D BETWEEN 4-DEC-1995 and 25-DEC-1995 INT ACQ for 2 - 11 MAX DUR 110% POS TARG 0,-4.3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F190M,F6ND F550M,F6ND F152M,F175W F346M,F6ND,F1ND F278M,F275W,F4ND,F1ND F307M,F275W,F4ND,F1ND F501N,F4ND,F1ND F410M,F6ND,F1ND F470M,F6ND PRISM2,F175W F140W,PRISM1,F165W ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD14386 ------------------------------------------------------------------------------------------------------------------------------------