! File: 3987C.PROP ! Database: PEPDB ! Date: 20-FEB-1994:02:47:42 coverpage: title_1: PC IMAGING FOR ULTRAVIOLET SPECTRAL ATLAS OF O STARS IN THE title_2: MILKY WAY AND MAGELLANIC CLOUDS sci_cat: STELLAR ASTROPHYSICS proposal_for: GTO/HRS cont_id: 1215 pi_fname: SARA pi_mi: R. pi_lname: HEAP pi_inst: NASA, GODDARD SPACE FLIGHT CENTER pi_country: USA pi_phone: 301-286-9545 keywords_1: STELLAR WINDS, EXTENDED ATMOSPHERES wf_pc: Y ! end of coverpage abstract: line_1: We will obtain B-band pictures of the 30 Dor region in the line_2: Large Magellanic Cloud, which we will combine with existing U line_3: and V-band pictures in order to construct a color-magnitude diagram line_4: for the region. In later cycles, we will obtain G160M spectra of line_5: O stars in the Milky Way in order to carry out a quantitative, line_6: non-LTE photospheric analysis. ! ! end of abstract general_form_proposers: lname: HEAP fname: SARA mi: R. inst: NASA, GODDARD SPACE FLIGHT CENTER country: USA ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: Recent observations line_2: have shown that O stars in the Magellanic clouds have winds with line_3: lower terminal velocities than do O stars of the same spectral line_4: type in the Milky Way. Models of radiatively driven winds line_5: (e.g. Kudtitzki, Pauldrach, Puls, 1987) are now able to line_6: explain this effect. Chemical abundance is the key factor: line_7: it plays a role in determining the structure and intensity of the line_8: wind. Hence, stars in the Magellanic Clouds should have smaller line_9: mass-loss rates and terminal velocities than their spectral line_10: counterparts in the Milky Way, due to their lower metallicities. line_11: In this program, we will investigate the effects of chemical line_12: composition in greater detail. From ground-based and HRS line_13: spectra, we will estimate the basic parameters of each star: line_14: temperature, gravity, and chemical composition of the atmosphere. line_15: From HRS spectra, we will also estimate the intensity, kinematic line_16: and ioniztion structure, and terminal velocity of the wind. We line_17: will then seek to explain these data in terms of radiatively line_18: driven winds. ! question: 3 section: 1 line_1: PC images in F439W are obtained of 30 Doradus to provide line_2: B passband pictures to supplement the U and V pictures taken line_4: of the region in August 1990. Only with a 3rd passband is it line_5: possible to construct a color-color diagram, evaluate line_6: differential extinction, construct an HR diagram for the line_7: cluster, etc. line_8: Additional GHRS data are requested in later cycles. ! question: 4 section: 1 line_1: The HST/GHRS is necessary to obtain a high-dispersion ultraviolet spectrum at line_2: high S/N. The HST/WFPC is needed to obtain pictures of a very crowded line_3: stellar cluster with sufficient angular resolution to resolve line_4: individual stars in the cluster, especially R136a. ! question: 5 section: 1 line_1: No special requirements. ! question: 6 section: 1 line_1: none ! question: 7 section: 1 line_1: We will need to make astrometric reductions of the WFPC images line_2: to ensure the proper target acquisition by the HRS. At the HRS line_3: Data Analysis Facility, we will integrate the spectral segments line_4: obtained at different grating settings to form a single, high- line_5: quality spectrum of each star in the program. We will publish line_6: the set of spectra as an atlas, with appropriate commentary. ! question: 8 section: 1 line_1: High dispersion ground-based spectra will also be needed to help line_2: determine basic stellar parameters. However, these observations line_3: will be obtained well in advance of the HRS observations. ! question: 13 section: 1 line_1: The HRS team will construct an ultraviolet spectral atlas line_2: (1100-1750 A) of O stars in the Milky Way and Magellanic line_3: Clouds. ! !end of general form text general_form_address: lname: HEAP fname: SARA mi: R. category: PI inst: NASA, GODDARD SPACE FLIGHT CENTER addr_1: CODE 681 city: GREENBELT state: MD zip: 20771 country: USA ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: 30DOR-STARS descr_1: STAR; O STARS NEAR R136A descr_2: IN 30 DORADUS (LMC) pos_1: RA = 5H 38M 42.5S +/- 0.1S, pos_2: DEC = -69D 06' 02.80" +/- 0.1", equinox: 2000 pm_or_par: NO fluxnum_1: 1 fluxval_1: V=10.2+/-0.1 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: 30DOR-STARS config: PC opmode: IMAGE aperture: P6 sp_element: F439W num_exp: 1 time_per_exp: 30S priority: 1 param_1: PRE-FLASH=YES, req_1: CYCLE 1; ! linenum: 2.000 targname: 30DOR-STARS config: PC opmode: IMAGE aperture: P6 sp_element: F439W num_exp: 5 time_per_exp: 180S priority: 1 param_1: PRE-FLASH=YES, req_1: CYCLE 1; ! ! end of exposure logsheet ! No scan data records found