9422( 4) - 03/21/03 08:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9422 Version: 4 Check-in Date: 21-Mar-2003 08:12:50 1.Proposal Title: Masses of AGB stars ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Kenneth Hinkle NOAO CoI: Dr. Francis Fekel Jr. Tennessee State University N CoI: Dr. Richard Joyce NOAO N CoI: Dr. Thomas Lebzelter University of Vienna N ------------------------------------------------------------------------------------ 5. Abstract There are few AGB stars with known masses. We have undertaken a program to measure spectroscopic orbits for about 50 binary systems containing M giants and typically white dwarfs. These are all single lined systems so the spectroscopic orbit of the M giant results in a mass function, m_2^3sin^3i / (m_1 + m_2)^2, for the secondary. Under special conditions, it is possible to undertake a simple observation that allows a solution for the masses. By measuring the angular separation at the epoch of greatest elongation of a zero eccentricity, eclipsing system (i.e. a system with a known inclination) m_1+m_2 can be determined, hence allowing the masses to be solved. Parallaxes indicate that there are two systems that can be resolved using HST/ACS. We propose to carry out this observation. ------------------------------------------------------------------------------------ 9422( 4) - 03/21/03 08:14 - [ 2] Observations Description ------------------------ We propose obtaining ACS high resolution images of the two program stars. The images will be in two colors, one (red) which will image the M star and a second (ultraviolet) which will image the white dwarf plus accretion disk. The stars have R band magnitudes of about 5.5. We believe that they can be imaged in a 0.1 second with the F892N filter. CH Cyg (HD 182917) may saturate but since the Airy disk is well resolved at 9000 Angstrom the centroid can be well located. Two exposures are necessary for cosmic ray removal. The ultraviolet magnitudes of the program stars can vary by up to 5 magnitudes depending on the degree of activity. A typical U magnitude is about 11 but can be much brighter. We propose to take two exposures each of 0.1, 1.0 and 10.0 seconds with the F220W filter to obtain a pair of images which can be measured. We will then align the red and ultraviolet images using other stars in the field and measure the offset between the red and ultraviolet image. Assuming a combined mass of 2 M_SUN, the angular offset will be about 8 milliarcseconds for CH Cyg (parallax 3.7 milliarcseconds, orbital period 752 days) and about 2 milliarcseconds for EG And (HD 4174, parallax 1.48 milliarcseconds, period 482 days). While these offsets are small we are confident they can be measured. The offset for CH Cyg is about 1/3 pixel. The total telescope time necessary to observe each star will be about 23 minutes. Real Time Justification ----------------------- The observations are time critical. The program stars should be observed within about 0.1 phase (+/-15 days) of the orbital phase of greatest approach or recession velocity. The dates for EG And (HD 4174) are either Aug 6, 2002 or Apr 5, 2003 and for CH Cyg Aug 16, 2002. These times are based on published orbits (CH Cyg: Hinkle et al. 1993 AJ 105 1074; EG And: Fekel et al. 2000a AJ 120 3225) Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9422( 4) - 03/21/03 08:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD4174 STAR, SYMBIOTIC STAR, RA=00H 44M 37.18S +/- 0.1", J2000 V = 7.23 AGB STAR DEC=40D 40' 45.6" +/- 0.1" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE 2 HD182917 STAR, AGB STAR, RA=19H 24M 33.08S +/- 0.1", J2000 V = 7.5 SYMBIOTIC STAR DEC=50D 14' 29.5" +/- 0.1" Coordinate Source: HIPPARCOS/TYCHO_CATALOGUE 9422( 4) - 03/21/03 08:14 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-HRC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.150 Coordinate_Frame POS-TARG Pattern_Orient 19.89 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 9422( 4) - 03/21/03 08:14 - [ 5] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 22-Nov-2003 AND 12-Dec-2003 On Hold Comments: Additional Comments: Please try to schedule close to December 2, 2003 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD4174 ACS/HR ACCUM HRC F892N CR-SPLIT=NO 1 0.1 S PATTERN 1 10-15 C ------------------------------------------------------------------------------------------------------------------------------------ 15 HD4174 ACS/HR ACCUM HRC F220W CR-SPLIT=NO 1 1 S C ------------------------------------------------------------------------------------------------------------------------------------ 50 HD4174 ACS/HR ACCUM HRC F220W CR-SPLIT=NO 1 245 S PATTERN 1 50-55 C ------------------------------------------------------------------------------------------------------------------------------------ 55 HD4174 ACS/HR ACCUM HRC F892N CR-SPLIT=NO 1 25 S C ------------------------------------------------------------------------------------------------------------------------------------ 9422( 4) - 03/21/03 08:14 - [ 6] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 14-Aug-2003 AND 13-Sep-2003 On Hold Comments: Additional Comments: Please try to schedule close to August 29, 2003 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD182917 ACS/HR ACCUM HRC F892N CR-SPLIT=NO 1 0.1 S PATTERN 1 10-30 C ------------------------------------------------------------------------------------------------------------------------------------ 30 HD182917 ACS/HR ACCUM HRC F220W CR-SPLIT=NO 1 1 S C ------------------------------------------------------------------------------------------------------------------------------------ 50 HD182917 ACS/HR ACCUM HRC F892N CR-SPLIT=NO 1 25 S PATTERN 1 50-60 C ------------------------------------------------------------------------------------------------------------------------------------ 60 HD182917 ACS/HR ACCUM HRC F220W CR-SPLIT=NO 1 250 S C ------------------------------------------------------------------------------------------------------------------------------------ 9422( 4) - 03/21/03 08:14 - [ 7] Summary Form for Proposal 9422 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 22-Nov-2003 AND 12-Dec-2003 PATTERN 1 10-15 PATTERN 1 50-55 BETWEEN 14-Aug-2003 AND 13-Sep-2003 PATTERN 1 10-30 PATTERN 1 50-60 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F892N F220W ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD4174 HD182917 ------------------------------------------------------------------------------------------------------------------------------------