Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3987c Report Date: 09-May-96:19:01 Version: ********** Check-in Date: ********** 1.Proposal Title: PC IMAGING FOR 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 1215 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Sara R. Heap NASA, GODDARD SPACE FLIGHT C USA 301-286-9545 ------------------------------------------------------------------------------------ 7. Abstract We will obtain B-band pictures of the 30 Dor region in the Large Magellanic Cloud, which we will combine with existing U and V-band pictures in order to construct a color-magnitude diagram for the region. In later cycles, we will obtain G160M spectra of O stars in the Milky Way in order to carry out a quantitative, non-LTE photospheric analysis. ------------------------------------------------------------------------------------ 8. Scientific Key Words: STELLAR WINDS, EXTENDED ATMOSPHERES ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0 par: 0 10. Num targs pri: 0 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3987c PI: Sara R. Heap Proposal Title: PC IMAGING FOR 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 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. PC images in F439W are obtained of 30 Doradus to provide B passband pictures to supplement the U and V pictures taken of the region in August 1990. Only with a 3rd passband is it possible to construct a color-color diagram, evaluate differential extinction, construct an HR diagram for the cluster, etc. Additional GHRS data are requested in later cycles. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST/GHRS is necessary to obtain a high-dispersion ultraviolet spectrum at high S/N. The HST/WFPC is needed to obtain pictures of a very crowded stellar cluster with sufficient angular resolution to resolve individual stars in the cluster, especially R136a. ------------------------------------------------------------------------------------ 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. Page 3 ------------------------------------------------------------------------------------ 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 Name: SARA R. HEAP Category: PI Institution: NASA, 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 = 3987c [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 30DOR-STARS STAR; O STARS NEAR RA = 5H 38M 42.5S +/- 0.1S, 2000 1 V=10.2+/-0.1 R136A DEC = -69D 06' 02.80" +/- IN 30 DORADUS (LMC) 0.1", ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3987c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 30DOR-STARS PC IMAGE P6 F439W PRE-FLASH=YES 1 30S 1 CYCLE 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 30DOR-STARS PC IMAGE P6 F439W PRE-FLASH=YES 5 180S 1 CYCLE 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3987c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/HRS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 1; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 30DOR-STARS ------------------------------------------------------------------------------------------------------------------------------------