! File: 2576C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:08:28:29 coverpage: title_1: STAR FORMATION PROCESSES IN THE SPIRAL ARMS OF M51 sci_cat: INTERSTELLAR MEDIUM sci_subcat: H II REGIONS proposal_for: GO pi_title: PROF. pi_fname: STUART pi_lname: VOGEL pi_inst: UNIVERSITY OF MARYLAND, COLLEGE PARK pi_country: USA pi_phone: 301-454-8134 keywords_1: STAR FORMATION, HII REGIONS, STELLAR POPULATIONS, keywords_2: MOLECULAR CLOUDS, SPIRAL STRUCTURE hours_pri: 2.80 num_pri: 1 wf_pc: Y funds_amount: 10000 funds_length: 12 funds_date: JAN-91 pi_position: ASSOC. PROFESSOR off_country: USA ! end of coverpage abstract: line_1: Although density waves are commonly believed to trigger the formation of the O line_2: stars which mark spiral arms, this hypothesis has been recently challenged. line_3: Hubble Space Telescope observations will provide two definitive tests: (1) line_4: dating young clusters in M51 using WFC UBVR and H-ALPHA photometry to determine line_5: if clusters increase in age downstream from the density wave shock; if line_6: they do, we have a unique calibrated clock for the earliest stages of star line_7: formation which can be used to infer timescales for assembling giant molecular line_8: clouds (GMCs) and for triggering star formation; and (2) detemining whether the line_9: molecular dust lanes are complexes of star-producing GMCs or instead inactive line_10: diffuse molecular clouds compressed by an MHD shock; GMCs should be detectable line_11: by HST in R band images as distinct dark clouds against the old stellar line_12: population. Another goal is to test the idea that cloud-cloud collisions are a line_13: general mechanism for triggering massive star formation by looking for the line_14: expected quadratic variation in the relative spatial density of young (i.e., line_15: <1" HII regions and GMCs detected with HST (i.e., a modified Schmidt law). ! ! end of abstract general_form_proposers: lname: WYSE fname: ROSEMARY title: DR. inst: JOHNS HOPKINS UNIVERSITY country: USA ! lname: VOGEL fname: STUART title: P.I. inst: UNIVERSITY OF MARYLAND, COLLEGE PARK country: USA ! lname: NORMAN fname: COLIN title: DR. mi: A. inst: STSCI country: USA ! lname: KULKARNI fname: SHRINIVAS title: DR. mi: R. inst: CALTECH country: USA ! lname: SCOVILLE fname: N. title: DR. mi: Z. inst: CALTECH country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We propose to observe one target field with the WFC in the disk of NGC5194 line_2: (M51). The 0.1" resolution of the WFC camera corresponds to 5 pc at an assumed line_3: distance of 9.6 Mpc, sufficient to resolve and identify young clusters, giant line_4: molecular clouds, and young HII regions. A large (2.6' = 7 kpc) field is line_5: important to insure that we detect sufficient numbers of clusters for age line_6: dating. The proposed field covers most of the NW quadrant of the M51 optical line_7: disk, the region most intensively studied in our ground-based observations. line_8: Our field does NOT include the 1.1' nuclear region; the nuclear region is the line_9: target of GTO proposals, but the GTO fields do not include the spiral arms. line_11: Specifically, we will use the following filters: line_13: F336W U -- U-B will be used to date young clusters. line_14: F439W B -- " " " line_15: F569W V -- Best sensitivity for identifying young clusters. line_16: F675W R -- Detect giant molecular clouds against stellar background. Also line_17: used as continuum to subtract from H-ALPHA line_18: F658N H-ALPHA -- Use the N II z=0 filter to detect H-ALPHA emission and line_19: obtain ionizing fluxes. Note that f658N is actually the line_20: NII filter, but the wavelength coverage is appropriate for line_21: H-ALPHA emission at a redshift of 400 km/sec. ! question: 4 section: 0 line_1: The 0.1" (5 pc) resolution of HST WFC is absolutely essential to this project line_2: to (1) resolve and thereby identify young clusters, which generally have line_3: diameters smaller than 50 pc, especially young clusters; they cannot be line_4: identified from the ground. The clusters are needed to detect the age line_5: gradients needed to verify the density wave model. High resolution is also line_6: required to obtain cluster colors as free as possible from contamination by the line_7: old stellar population; (2) resolve giant molecfular clouds as dark clouds line_8: against the old stellar population; the clouds have dimensions in the range 10- line_9: -100 pc, too small to detected from the ground since a dark cloud cannot be line_10: detected unless it is clearly resolved; (3) resolve young HII regions; we have line_11: extremely deep (emission measure = 10) H-ALPHA CCD frames, but even these are line_12: inadequate -- emission at the relatively low-resolution ground based line_13: observations is dominated by more extended and therefore relatively evolved HII line_14: regions. line_15: The proposed HST data are a key element in a large ongoing project studying the line_16: gaseous components in M51 and their relation to stellar populations and spiral line_17: structure. We have very deep UBVRI and H-ALPHA CCD photometry obtained at line_18: Palomar. We will shortly obtain SIII and near-infrared array obserations. line_19: Our existing 7" CO 1-0 maps will be improved with even higher resolution data. line_20: HI data at the highest feasible resolution are available, as are rdaio line_21: continuum data. Our imaging Fabry-Perot has been used to study the velocity line_22: field of the ionized gas, nicely complementing HI and CO data for unique line_23: complete velcoity coverage of the ISM in a grand design spiral. ! question: 5 section: 0 line_1: Sensitivities and formulas for the WFC listed in the May 1989 Handbook are line_2: used. Our calculations demonstrate that with the adopted exposure times we line_3: achieve the scientific goals with a comfortable margin. line_4: Here are the methods used to calculate S/N for the three parts of the program. line_5: 1) Open cluster identification and colors. From Elson et al. (1987), we line_6: expect in a fairly rich cluster to get V = 24 in a 0.1" pixel at a radius of line_7: 0.5" from the cluster center. Poorer clusters might have V = 24 in the cnetral line_8: pixel. Using colors for a B0 star from Table 5.1.2, the appropriate number of line_9: sky electrons, readout noise, and effective number of pixels, we get S/N ratios line_10: of 28, 36, and 48 for U, B, and V, for integration time sof 2500, 1500, and line_11: 1000 seconds, respectively. With reddening the U fluxes especially may be line_12: lower, but by averaging over a few pixels we should get the necessary 0.1 mag line_13: accuracy. 2) Giant molecular clouds seen as dark clouds against the old stellar line_14: population. Using the Schweizer photometric study of M51, we obtain R =25.0 in line_15: a 0.1" pixel 45" from the nucleus and R=25.6 at 150". Using R=25.6 we obtain line_16: S/N in 0.1" in 2500s. 3) Counts of young HII regions. We wish to detect line_17: as many HII regions as possible. For a ZAMS O9 star Panagia gives log N(LYMAN) line_18: = 48.1. For Case B with all ionizing photons absorbed we expect an integrated line_19: H-ALPHA flux of 4x10**-16 ergs/cm**2/sec. If we take t=2500 seconds, divide line_20: the integrated H-ALPHA flux by the effective frequency width of the filter to line_21: get ergs/cm/s/Hz, we get 550 electrons fodr a S/N of 15. If the HII region is line_22: larger than 0.1" (5 pc), it becomes difficult to detect an O9 star, but line_23: fortunately larger regions are more likely to be ionized by several stars. ! question: 7 section: 0 line_1: We will use the SDAS/IRAF package installed on a Sun workstation for primary line_2: reduction and anlysis of Space Telescope data. We stress that several members line_3: of the team have extensive experience with the Palomar Four-shooter CCD for line_4: UBVRI and H-ALPHA photometry for many programs in addition to the M51 program line_5: (Kulkarni and Scoville). Vogel (along with Kulkarni) built the Imaging Fabry- line_6: Perot, which uses the Palomar CCDs; therefore he also has extensive experience line_7: with CCD reduction and analysis. We have expertise in cluster population line_8: synthesis of colors and spectra (Wyse) and in the theory of star formation and line_9: density waves (Norman). line_11: The data processing and analysis requirements will be large. The HST WFPC line_12: frames have an enormous information content. Our ground-based program, already line_13: well under way, will be expanding. In addition to the spectral line radio line_14: aperture synthesis of CO emission, we will have a nubmer of 800 x 800 x 60 line_15: Fabry-Perot cubes for H-ALPHA and other lines. We will also have additional line_16: Four-shooter frames of numerous bands, and Palomar Double Spectrograph line_17: spectraof 1" regions identified to have young clusters. line_19: Much of the work will be done at STSci, since it is close to home for Norman, line_20: Wyse, and Vogel, and also because so much technical expertise resides there. line_21: Apparently, workstation resources are limited at ST. Therefore, we request line_22: funds for part of a Sun 4/60 workstation to go at ST; roughly half of the line_23: cost will be borne by Norman. ! question: 10 section: 0 line_1: The computer resources at the University of Maryland (Suns, Multiflow, tape line_2: drives, laser printers, etc.) will be available. Norman will supply the disk line_3: drives for the Sun 4/60 at STSci from other sources. The time spent by the line_4: PI's on this project will be funded from other sources. ! !end of general form text general_form_address: lname: VOGEL fname: STUART title: PROF. category: PI inst: UNIVERSITY OF MARYLAND addr_1: ASTRONOMY PROGRAM city: COLLEGE PARK state: MD zip: 20742 country: USA ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC5194 name_2: M51 name_3: WHIRLPOOL descr_1: GALAXY; TYPE=SC; SPIRAL GALAXY; SPIRAL ARM pos_1: RA=13H 27M 44S +/- 15", pos_2: DEC=+47D 28M 40S +/- 15" equinox: 1950 rv_or_z: V = +470 comment_1: POINTING WFC WITHIN 15" WILL comment_2: INCLUDE THE TWO SPIRAL ARMS IN comment_3: 2.6' FIELD OF VIEW. comment_4: FLUXVAL_5 IS H-ALPHA FLUX comment_5: IN 0.1" PIXEL EXPECTED FOR comment_6: WEAKER HII REGIONS comment_7: (REDSHIFTED TO 6568 A). fluxnum_1: 1 fluxval_1: V = 24 +/- 1 fluxnum_2: 2 fluxval_2: B = 23.6 +/- 1 fluxnum_3: 3 fluxval_3: U = 23.3 +/- 1 fluxnum_4: 4 fluxval_4: R = 25 +/- 1 fluxnum_5: 5 fluxval_5: F-LINE(6568)=4 +/- 2 E-16 fluxnum_6: 6 fluxval_6: W-LINE(6568)=1 +/- 0.3 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NGC5194 config: WFC opmode: IMAGE aperture: ALL sp_element: F569W num_exp: 1 time_per_exp: 1200S s_to_n: 10 fluxnum_1: 1 priority: 1 comment_1: ACTUAL FLUXES OF CLUSTERS ARE UNKNOWN comment_2: SO EXPOSURE TIMES GIVE HIGHER S/N THAN comment_3: INDICATED ABOVE TO GIVE SAFETY MARGIN ! linenum: 2.000 targname: ^ config: ^ opmode: ^ aperture: ^ sp_element: F439W num_exp: 1 time_per_exp: 1800S s_to_n: 10 fluxnum_1: 2 priority: 2 ! linenum: 3.000 targname: ^ config: ^ opmode: ^ aperture: ^ sp_element: F336W num_exp: 1 time_per_exp: 3000S s_to_n: 10 fluxnum_1: 3 priority: 3 ! linenum: 4.000 targname: ^ config: ^ opmode: ^ aperture: ^ sp_element: F675W num_exp: 1 time_per_exp: 2800S s_to_n: 20 fluxnum_1: 4 priority: 4 ! linenum: 5.000 targname: ^ config: ^ opmode: ^ aperture: ^ sp_element: F658N num_exp: 1 time_per_exp: 3000S s_to_n: 10 fluxnum_1: 5,6 priority: 5 param_1: PRE-FLASH=YES ! ! end of exposure logsheet ! No scan data records found