Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2623c Report Date: 09-May-96:17:15 Version: ********** Check-in Date: ********** 1.Proposal Title: A MEASUREMENT OF THE PRIMORDIAL HELIUM ABUNDANCE OF MU-CASSIOPEIAE ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR POPULATIONS GO 3 Long Term yrs Sub Category ASTROMETRY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Prof. Dennis J. Hegyi MICHIGAN, UNIVERSITY OF USA (313)-764-5448 PROFESSOR OF PHYSICS ------------------------------------------------------------------------------------ 7. Abstract At the present time, the primordial helium abundance is the single most important observable which can be used to test the standard model of the big bang. The most precise measurements of the primordial helium abundace have been obtained from extragalactic HII regions. However, many correction are involved in reducing measured line intensities to helium abundances. Because the primordial helium abundance plays such an essential role in both cosmology and astrophysics, it is important to accurately measure it using more than one method. By applying the stellar mass-luminosity law, we propose to determine the helium abundance of the astrometric binary Mu-Cas using ST to obtain an orbit to determine the masses of the stars. Based on simulations, three years of ST observations would yield a mass uncertainty of the primary star corresponding to an uncertainty in the helium abundace by mass of 0.006. This uncertainty could be even further reduced if observations were extended over a longer interval of time. ST is necessary to achieve the desired measuring accuracy because astrometric observations of the faint, close secondary with respect to a background field of stars can only be obtained with ST; since the secondary has a motion almost five times larger than that of the primary, its orbit is much less sensitive to unknown systematic effects for the same measuring precision. ------------------------------------------------------------------------------------ 8. Scientific Key Words: POPULATION II, SUBDWARF, BINARY, ASTROMETRY ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.74 par: 0 10. Num targs pri: 10 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FGS WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2623c PI: Prof. Dennis J. Hegyi Proposal Title: A MEASUREMENT OF THE PRIMORDIAL HELIUM ABUNDANCE OF MU-CASSIOPEIAE ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pierre Demarque YALE UNIVERSITY USA P.I. Dennis J. Hegyi MICHIGAN, UNIVERSITY OF USA Philippe Crane EUROPEAN SOUTHERN OBSERVATORY FRG X James W. Haywood MICHIGAN, UNIVERSITY OF USA Robert L. Kurucz CFA USA Christopher Sneden TEXAS, UNIVERSITY OF USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to use the FGS to measure the position of HD6582 with respect to 9 reference field stars twice a year for three years. Each observation consists of the following sequence. First, using the F5ND neutral density filter, HD6582 is observed. Then that filter is removed, the F583W Astrometry Clear Filter is inserted, and four of the field stars are observed. Next, HD6582 is again observed, the 5 remaining field stars are observed, and HD6582 is observed for the last time. The neutral density filter is required for each observation of HD6582. The separation between Mu-Cas-A and Mu-Cas-B is measured by placing Mu- Cas-A on the the Baum spot since there is a large magnitude difference between the stars. Three exposures are obtained twice each year for three years. The three exposures are shifted by a small amount relative to one another to minimize the consequences of one of the stars falling on a bad pixel. Because the observations are separated by 6 months, it will be necessary to use different guide stars for each of these observations. Therefore, HD6582 (Mu-Cas) must be acquired interactively once for each set of guide stars so that two interactive acquisitions will be required. ------------------------------------------------------------------------------------ 11. Address Information Name: DENNIS J. HEGYI Category: PI Institution: UNIVERSITY OF MICHGAN Address: 500 E. UNIVERSITY City: ANN ARBOR State: MI Zip Code: 48109 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2623c [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD6582 STAR; BINARY; TYPE=G5 RA = 1H 4M 55.72S +/- 0.5", 1950 1 V =5.16 +/- 0.1, TYPE = G5 V (MU_CAS) V;SUBDWARF DEC = +54D 40' 32.8" +/- 0.5" Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 0.2291 +/- 0.0000 -1.5787 +/- 0.0002 0.1368 +/- 0.0033 ------------------------------------------------------------------------------------------------------------------------------------ 2 AST1-REF STAR; ASTROMETRIC XI-OFF = 161" +/- 3", 1950 1 V =9 +/- 2 REFERENCE ETA-OFF = -48" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 AST2-REF STAR; ASTROMETRIC XI-OFF = 159" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = -108" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 4 AST3-REF STAR; ASTROMETRIC XI-OFF = +104" +/- 3", 1950 1 V =16 +/- 3 REFERENCE ETA-OFF = -150" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 5 AST4-REF STAR; ASTROMETRIC XI-OFF = +59" +/- 3", 1950 1 V =13 +/- 3 REFERENCE ETA-OFF = -56" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 6 AST5-REF STAR; ASTROMETRIC XI-OFF = +37" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = -51" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 7 AST7-REF STAR; ASTROMETRIC XI-OFF = +96" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = +15" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 8 AST8-REF STAR; ASTROMETRIC XI-OFF = +134" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = -15" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 9 AST9-REF STAR; ASTROMETRIC XI-OFF = +88" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = -26" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 10 AST10-REF STAR; ASTROMETRIC XI-OFF = +104" +/- 3", 1950 1 V =15 +/- 3 REFERENCE ETA-OFF = -44" +/- 3", FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2623c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE HD6582 PC IMAGE P8 F8ND PRE-FLASH=YES 1 0.7S 170 1 1 INTMU ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE HD6582 PC IMAGE ALL-ND F439W PRE-FLASH=YES 1 0.7S 170 1 1 SEQ 2-4 NON-INT PCMU POS TARG 16.8, - 16.8 ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE HD6582 PC IMAGE ALL-ND F439W PRE-FLASH=YES 1 0.7S 170 1 1 POS TARG 17.1, - PCMU 16.8 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE HD6582 PC IMAGE ALL-ND F439W PRE-FLASH=YES 1 0.7S 170 1 1 POS TARG 16.8, - PCMU 17.1 ------------------------------------------------------------------------------------------------------------------------------------ 5 USE INT ACQ FOR 6 INTMU POS TARG 10,-10 ------------------------------------------------------------------------------------------------------------------------------------ 6 USE GROUP 6, 21 WITHIN PCMU 3D AT 1-FEB-91 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 7 USE INT ACQ FOR 8 INTMU ------------------------------------------------------------------------------------------------------------------------------------ 8 USE GROUP 8, 22 WITHIN PCMU 3D AT 3-AUG-91 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 9 DEFINE HD6582 FGS POS PRIME F5ND DATA-RATE=32 1 5.2S 100 1 1 SEQ 9-20 NON-INT ASTROM FES-TIME=0.1 ------------------------------------------------------------------------------------------------------------------------------------ 10 DEFINE AST1-REF FGS POS PRIME F583W DATA-RATE=32 1 5.2S 100 1 1 ASTROM FES-TIME=0.1 ------------------------------------------------------------------------------------------------------------------------------------ 11 DEFINE AST2-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ 12 DEFINE AST3-REF FGS POS PRIME F583W DATA-RATE=32 1 104.4S 50 1 2 ASTROM FES-TIME=3.2 ------------------------------------------------------------------------------------------------------------------------------------ 13 DEFINE AST4-REF FGS POS PRIME F583W DATA-RATE=32 1 14.8S 50 1 1 ASTROM FES-TIME=0.4 ------------------------------------------------------------------------------------------------------------------------------------ 14 DEFINE HD6582 FGS POS PRIME F5ND DATA-RATE=32 1 5.2S 100 1 1 ASTROM FES-TIME=0.1 ------------------------------------------------------------------------------------------------------------------------------------ 15 DEFINE AST5-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ 16 DEFINE AST7-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2623c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 17 DEFINE AST8-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ 18 DEFINE AST9-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ 19 DEFINE AST10-REF FGS POS PRIME F583W DATA-RATE=32 1 53.2S 50 1 2 ASTROM FES-TIME=1.6 ------------------------------------------------------------------------------------------------------------------------------------ 20 DEFINE HD6582 FGS POS PRIME F5ND DATA-RATE=32 1 5.2S 100 1 1 ASTROM FES-TIME=0.1 ------------------------------------------------------------------------------------------------------------------------------------ 21 USE AT 1-FEB-91 +/- 5D ASTROM ------------------------------------------------------------------------------------------------------------------------------------ 22 USE AT 3-AUG-91 +/- 5D ASTROM CYCLE 1 / 6, 8, 21 , 22 ------------------------------------------------------------------------------------------------------------------------------------ 23 USE GROUP 23, 25 PCMU WITHIN 3D AT 1-FEB-92 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 24 USE GROUP 24, 26 PCMU WITHIN 3D AT 2-AUG-92 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 25 USE AT 1-FEB-92 +/- 5D ASTROM ------------------------------------------------------------------------------------------------------------------------------------ 26 USE AT 2-AUG-92 +/- 5D ASTROM CYCLE 2 / 23, 24, 25, 26 ------------------------------------------------------------------------------------------------------------------------------------ 27 USE GROUP 27, 29 PCMU WITHIN 3D AT 1-FEB-93 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 28 USE GROUP 28, 30 PCMU WITHIN 3D AT 3-AUG-93 +/- 5D ------------------------------------------------------------------------------------------------------------------------------------ 29 USE AT 1-FEB-93 +/- 5D ASTROM ------------------------------------------------------------------------------------------------------------------------------------ 30 USE AT 3-AUG-93 +/- 5D ASTROM CYCLE 3 / 27, 28, 29, 30 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2623c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE POS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=YES DATA-RATE=32 FES-TIME=0.1 FES-TIME=1.6 FES-TIME=3.2 FES-TIME=0.4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.74 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ASTROMETRY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 2-4 NON-INT; POS TARG 16.8, -16.8 POS TARG 17.1, -16.8 POS TARG 16.8, -17.1 INT ACQ FOR 6; POS TARG 10,-10 GROUP 6, 21 WITHIN 3D; AT 1-FEB-91 +/- 5D INT ACQ FOR 8 GROUP 8, 22 WITHIN 3D; AT 3-AUG-91 +/- 5D; SEQ 9-20 NON-INT AT 1-FEB-91 +/- 5D; CYCLE 1 / 6, 8, 21, 22 GROUP 23, 25 WITHIN 3D; AT 1-FEB-92 +/- 5D GROUP 24, 26 WITHIN 3D; AT 2-AUG-92 +/- 5D; AT 1-FEB-92 +/- 5D; CYCLE 2 / 23, 24, 25, 26 GROUP 27, 29 WITHIN 3D; AT 1-FEB-93 +/- 5D GROUP 28, 30 WITHIN 3D; AT 3-AUG-93 +/- 5D; AT 1-FEB-93 +/- 5D; CYCLE 3 / 27, 28, 29, 30 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F8ND F439W F5ND F583W ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD6582 (MU_CAS) AST1-REF AST2-REF AST3-REF AST4-REF AST5-REF AST7-REF AST8-REF AST9-REF AST10-REF ------------------------------------------------------------------------------------------------------------------------------------