! File: 4170C.PROP ! Database: PEPDB ! Date: 20-FEB-1994:11:59:00 coverpage: title_1: STRUCTURE AND ENVIRONMENT OF HII REGIONS IN THE title_2: GALAXY AND M33, WFPC AUGMENTATION, CYCLE 3 sci_cat: INTERSTELLAR MEDIUM proposal_for: AUG/WFC cont_id: 3641 pi_title: PROF. pi_fname: JAMES pi_mi: A. pi_lname: WESTPHAL pi_inst: CALTECH pi_country: USA pi_phone: (818) 356-4900 keywords_1: INTERSTELLAR MEDIUM, HII REGIONS, MILKY WAY, M33 hours_pri: 6.56 num_pri: 1 pi_position: PROF. PLANETARY SCI. ! end of coverpage abstract: line_1: Much of the scientific utility of narrow band imaging of nebulae lies in line_2: the study of stratification and structural variations among emission line_3: lines that trace regions of different density, temperature, and line_4: radiation environment. As such, imaging studies of nebulae are not line_5: as seriously affected by HST's optical problems as many programs, line_6: so long as adequate signal to noise is obtained to allow reliable line_7: deconvolution of the structure present. For nearby objects, HST can line_8: resolve physically important scales associated with many gasdynamic and line_9: radiative processes in the ISM. In the present proposal, we: line_10: 1) extend our study of the physical processes in H II regions to two line_11: additional regions (NGC 7635 and M 16), with specific goals to study line_12: the interface between the H II region and the adjoining line_13: photodissociation region, and the interaction between the radiation line_14: field and dense clumps of material, and 2) obtain images of two fields line_15: in M 33 to start the process of applying our understanding of the line_16: structure and physics of Galactic H II regions to the ISM in external line_17: galaxies. ! ! end of abstract general_form_proposers: lname: WESTPHAL fname: JAMES mi: A. inst: CALTECH country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: The WFC will be used to obtain images of NGC 7635 and M 16 in line_2: emission from [O III], H alpha, [S II], and [N II]. This set of line_3: lines is designed to cover a wide range of physical conditions. line_4: [O III] should be formed well away from the H II region / PDR line_5: interface. H alpha traces n(e)**2. [S II] is formed primarily line_6: just at the edge of the PDR where n(S+) is very large but n(e) is line_7: falling. [N II] should be mostly neutral in the PDR, but should line_8: still be largely localized near the H II region / PDR interface line_9: by photoionization of N+ --> N++. A continuum image will be line_10: obtained through F547M (a relatively line-free bandbass) to line_11: distinguish between unresolved emission knots and stars, and to line_12: correct for dust reflection of stellar light. The WFC will be line_13: used to obtain images of two fields in M33. Each field will be line_14: imaged in [O II], [O III], H beta, H alpha, and [S II]. These line_15: lines will allow us to see the effects of reddening, to detect line_16: variations in excitation within the region, to locate ionization line_17: fronts, and to measure the ratio of ([O III] + [O II])/H beta, line_18: which is generally considered to be sensitive to O abundance. line_19: Continuum images will be obtained in F547M to aid in line_20: distinguishing stellar and nebular emission. Broad band U and V line_21: images will be obtained to study the stellar content of the H II line_22: regions to relate emission properties to visible ionizing stellar line_23: content. ! question: 4 section: 1 line_1: We are pursuing observations of Galactic HII regions vigorously line_2: using ground based facilities. We are currently writing up the line_3: results of a ground based narrow band imaging survey of 30 line_4: Galactic H II regions. The results of this survey provided the line_5: basis for selection of fields in NGC 7635 and M 16. Lower line_6: resolution but deeper ground based images of larger fields will line_7: also provide context for interpretation of the HST data. We are line_8: also pursuing a program of ground based imagery of M 33. Very line_9: deep images have been obtained for a number of fields in M 33, line_10: and as above, will provide context for interpretation of the HST line_11: data. In particular, the ground based images (which have better line_12: photometric characteristics than the HST data) will be used to line_13: measure integrated H II region properties, as well as tie WFC line_14: data on the structure of bright H II regions to the local line_15: properties of the ubiquitous Warm Ionized Medium. HST is required line_16: for this project for its ability to obtain very high resolution line_17: images over a moderately large field. In the case of Galactic H line_18: II regions, HST is required to resolve the structure of line_19: photoevaporative flows and other phenomena and physical processes line_20: that occur on scales of 10**15 to 10**16 cm. In the case of H II line_21: regions in M33, HST is required to resolve the regions well line_22: enough to allow meaningful comparisons with the structure of line_23: Galactic H II regions. ! question: 7 section: 1 line_1: Images will be processed to largely remove CCD characteristics line_2: using the best calibration data available at that time. Cosmic line_3: rays will be flagged and removed using CRSPLIT difference images. line_4: Frames will be processed to partially correct for spherical line_5: aberration using a modified version of Lucy deconvolution. We line_6: expect to be able to generate adequate PSFs using stars found in line_7: the program frames themselves. Images taken through different line_8: filters will be aligned with each other and with ground based line_9: data using measured positions of stars. Where quantitive line_10: analysis such as relative fluxes of features is required, we will line_11: estimate the reliability of the deconvolved data by constructing line_12: simple models, convolving them with the PSF with the addition of line_13: appropriate noise, deconvolving in the same way the object data line_14: were deconvolved, and comparing the results with the original. ! !end of general form text general_form_address: lname: HESTER fname: JOHN mi: J. category: CON inst: ARIZONA STATE UNIVERSITY addr_1: DEPT. OF PHYSICS AND ASTRONOMY city: TEMPE state: AZ zip: 85287 country: USA phone: (602) 965-0741 ! lname: WESTPHAL fname: JAMES mi: A. title: PROF. category: PI inst: CALTECH addr_1: M/S 170-25 addr_2: DIVISION OF GEOLOGICAL addr_3: & PLANETARY SCIENCES city: PASADENA state: CA zip: 91125 country: USA phone: (818) 356-4900 ! ! end of general_form_address records fixed_targets: targnum: 2 name_1: M16 descr_1: G, 503, 905, 930 pos_1: RA = 18H 18M 50.0S +/- 0.5", pos_2: DEC=-13D 15' 40" +/- 0.5" equinox: 2000.0 comment_1: HII REGION WITH IONIZATION FRONTS ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 101.000 targname: M16 config: WFC opmode: IMAGE aperture: WFALL sp_element: F502N num_exp: 2 time_per_exp: 2200S priority: 1 param_1: CR-SPLIT=NO,PRE-FLASH=YES req_1: CYCLE 3 / 101-105; req_2: POS TARG -10,10 / 101-105; req_3: GROUP 101-105 WITHIN 3D; comment_1: EQUIV TO CR-SPLIT 2 ORBIT EXPOSURE ! linenum: 102.000 targname: M16 config: WFC opmode: IMAGE aperture: WFALL sp_element: F656N num_exp: 2 time_per_exp: 2200S priority: 1 param_1: CR-SPLIT=NO,PRE-FLASH=YES req_1: SAME POS FOR 102-105 AS 101; req_2: SAME ORIENT FOR 102-105 AS 101; comment_1: EQUIV TO CR-SPLIT 2 ORBIT EXPOSURE ! linenum: 103.000 targname: M16 config: WFC opmode: IMAGE aperture: WFALL sp_element: F673N num_exp: 2 time_per_exp: 2000S priority: 1 param_1: CR-SPLIT=NO,PRE-FLASH=YES comment_1: EQUIV TO CR-SPLIT 2 ORBIT EXPOSURE ! linenum: 104.000 targname: M16 config: WFC opmode: IMAGE aperture: WFALL sp_element: F658N num_exp: 2 time_per_exp: 2000S priority: 1 param_1: CR-SPLIT=NO,PRE-FLASH=YES comment_1: EQUIV TO CR-SPLIT 2 ORBIT EXPOSURE ! linenum: 105.000 targname: M16 config: WFC opmode: IMAGE aperture: WFALL sp_element: F547M num_exp: 2 time_per_exp: 140S priority: 1 param_1: CR-SPLIT=NO,PRE-FLASH=YES ! ! end of exposure logsheet ! No scan data records found