Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1215c Report Date: 09-May-96:16:19 Version: ********** Check-in Date: ********** 1.Proposal Title: ULTRAVIOLET SPECTRAL ATLAS OF O STARS IN THE MILKY WAY AND MAGELLANIC CLOUDS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GTO/HRS Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Sara R. Heap NASA, GODDARD SPACE FLIGHT C USA 301-286-5359 ------------------------------------------------------------------------------------ 7. Abstract We will obtain high S/N far-ultraviolet spectra of O giants and supergiants in the Milky Way and the Large and Small Magellanic Clouds. We will derive the properties of the star/wind systems from the photospheric and wind spectra, and we will investigate the effect of chemical composition on the properties of the wind. ------------------------------------------------------------------------------------ 8. Scientific Key Words: STELLAR WINDS, EXTENDED ATMOSPHERES ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 8.80 par: 0 10. Num targs pri: 8 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1215c PI: Sara R. Heap Proposal Title: ULTRAVIOLET SPECTRAL ATLAS OF O STARS IN THE MILKY WAY AND MAGELLANIC CLOUDS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Sara R. Heap NASA, GODDARD SPACE FLIGHT USA CENTER ------------------------------------------------------------------------------------ 2. Scientific Justification. Recent observations (e.g. Hutchings 1982, Ap.J. 38, 309) have shown that O stars in the Magellanic clouds have winds with lower terminal velocities than do O stars of the same spectral type in the Milky Way. Models of radiatively driven winds (e.g. Kudtitzki, Pauldrach, Puls, 1987) are now able to explain this effect. Chemical abundance is the key factor: it plays a role in determining the structure and intensity of the wind. Hence, stars in the Magellanic Clouds should have smaller mass-loss rates and terminal velocities than their spectral counterparts in the Milky Way, due to their lower metallicities. In this program, we will investigate the effects of chemical composition in greater detail. From ground-based and HRS spectra, we will estimate the basic parameters of each star: temperature, gravity, and chemical composition of the atmosphere. From HRS spectra, we will also estimate the intensity, kinematic and ioniztion structure, and terminal velocity of the wind. We will then seek to explain these data in terms of radiatively driven winds. ------------------------------------------------------------------------------------ 3. Description of proposed observations. Cycle 0: PC images of the 30 Doradus field. Line 13.5. Cycles 1 & 2: the remainder of the targets. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The ST/HRS is necessary to obtain a high-dispersion ultraviolet spectrum at high S/N. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. No special requirements. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. none ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. We will need to make astrometric reductions of the WFPC images to ensure the proper target acquisition by the HRS. At the HRS Data Analysis Facility, we will integrate the spectral segments obtained at different grating settings to form a single, high- quality spectrum of each star in the program. We will publish the set of spectra as an atlas, with appropriate commentary. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. High dispersion ground-based spectra will also be needed to help determine basic stellar parameters. However, these observations will be obtained well in advance of the HRS observations. ------------------------------------------------------------------------------------ 13. The HRS team will construct an ultraviolet spectral atlas (1100-1750 A) of O stars in the Milky Way and Magellanic Clouds. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: SARA R. HEAP Category: PI Institution: GODDARD SPACE FLIGHT CENTER Address: CODE 681 City: GREENBELT State: MD Zip Code: 20771 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 1215c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 2 MK42 STAR; O3 I/WN6-A RA=05H38M42.10S+/-0.5", 2000 COMP 1 V=12.67+/-0.1, E(B-V)=0.30 IN 30 DORADUS (LMC) DEC=-69D05'54.76"+/-0.5" ------------------------------------------------------------------------------------------------------------------------------------ 8 30DOR-STARS STAR; O STARS NEAR R = 12.5", 1950 1 V=10.2+/-0.1 R136A PA = 0D, IN 30 DORADUS (LMC) FROM 2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1215c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 13.5 30DOR-STARS PC IMAGE ALL F284W PRE-FLASH=YES 5 450S 1 DO FOR TARG 8 UNPROTECTED CYCLE 0 Comments: ALL 30 DOR O-STARS (TARGETS 1- 3) ARE IN THIS FIELD OF VIEW. STELLAR AND SCATTERING CONTINUM FILTER. REVISED IN LIGHT OF POST-LAUNCH CAPABILITIES FOR CYCLE 0. EARLY ACQ FOR 100-250 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1215c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HRS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 8.80 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements DO FOR TARG 8; UNPROTECTED; CYCLE 0 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F284W ------------------------------------------------------------------------------------------------------------------------------------ Target Names MK42 30DOR-STARS ------------------------------------------------------------------------------------------------------------------------------------