! File: 2555C.PROP ! Database: PEPDB ! Date: 17-FEB-1994:07:59:55 coverpage: title_1: CATACLYSMIC VARIABLES AND MILLISECOND PULSARS IN GLOBULAR CLUSTER title_2: CUSPS sci_cat: STELLAR POPULATIONS sci_subcat: GLOBULAR CLUSTERS proposal_for: GO pi_title: PROF. pi_fname: JONATHAN pi_mi: E. pi_lname: GRINDLAY pi_inst: CFA pi_country: USA pi_phone: 617-495-7204 keywords_1: GLOBULAR CLUSTER, CORE COLLAPSE, STELLAR EVOLUTION, keywords_2: CATACLYSMIC VARIABLE, X-RAY BINARY, WHITE DWARF, NEUTRON STAR, MILLISECOND PULSA hours_pri: 2.60 num_pri: 1 wf_pc: X funds_amount: 95027 funds_length: 12 funds_date: JAN-90 pi_position: PROFESSOR off_fname: STEPHEN off_lname: ERICKSON off_title: SR. ASSIST.DIRECTOR off_inst: HARVARD UNIVERSITY off_addr_1: OFFICE OF SPONSORED RESEARCH off_addr_2: HOLYOKE CENTER 448 off_addr_3: 1350 MASSACHUSETTS AVENUE off_city: CAMBRIDGE off_state: MA off_zip: 02138 off_country: USA ! end of coverpage abstract: line_1: We propose to use the PC to obtain H-alpha and comparison wide band red images line_2: of the nearby globular cluster NGC6752 which line_3: appears to be in an advanced stage of dynamical line_4: evolution. We will use these data line_5: for a color map analysis (Bailyn et al. 1988) and DAOPHOT crowded field line_6: photometry, in order to:(1) search for H-alpha emission objects including line_7: cataclysmic variables and nebulae surrounding millisecond pulsars (MSPs) and line_8: planetary nebulae, (2) search for diffuse H-alpha emission from a centrally line_9: concentrated population of the former two types of objects, and (3) study the line_10: radial distribution of H-alpha absorption line objects including faint blue line_11: horizontal branch stars (FBHBs). The central goal of our study is to test line_12: predictions of models for cluster dynamical evolution that predict the line_13: production of a substantial population of compact binaries due to a high rate line_14: of close stellar encounters in dense collapsed cluster cores. Our choice of one line_15: of this cluster that shows evidence of having undergone core collapse line_16: enhances the likelihood that the emission line objects expected from stellar line_17: encounters can be directly detected and resolved. Our search is distinctly line_18: different from, and more sensitive than, compact binary searches being planned line_19: by several GTO investigators. ! ! end of abstract general_form_proposers: lname: COHN fname: HALDAN inst: INDIANA UNIVERSITY country: USA ! lname: LUGGER fname: PHYLLIS inst: INDIANA UNIVERSITY country: USA ! lname: GRINDLAY fname: JONATHAN title: P.I. mi: E. inst: CFA country: USA ! lname: BAILYN fname: CHARLES inst: CFA country: USA ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: We propose to obtain H-alpha (F656N) and comparison red (F675W) line_2: Planetary Camera (PC) frames of the central 1'x1' regions of the line_3: nearby globular cluster NGC6752 (4.1kpc). We plan a single placement line_4: of the PC field on the maximum symmetry center of the cluster, which line_5: we have determined from our ground based CTIO 4 meter PF-CCD data. line_6: Since a single exposure does not provide sufficient dynamic range, line_7: we plan two exposures in each filter: a short exposure to bring line_8: horizontal branch stars just up to the saturation level and a line_9: long exposure to reach a faint limiting magnitude. Our planned line_10: exposure times are detailed in section 5. ! question: 4 section: 1 line_1: The high angular resolution provided by HST is essential for this line_2: project. Our goal is to detect individual emission line objects line_3: in the center of NGC6752, which shows evidence of having undergone line_4: core collapse. The core collapse simulations of Murphy and Cohn line_5: (1988) predict central stellar surface densities > 10**5 pc**-2. line_6: Adopting PSF FWHM vlues of 1.2" for ground-based observations and line_7: 0.09" for the HST PC at 6500A, the predicted number of stars per line_8: resolution element at the cluster center is of order 10-100 for line_9: ground based observations, but only of order 0.1 to 1 for the HST line_10: PC. Thus HST is critical for detecting individual emission line line_11: objects into the cluster center. ! question: 4 section: 2 line_1: We have obtained UBVR and H-alpha frames of this cluster using line_2: the PF-CCD on the CTIO 4 meter in seeing of 1.2"-1.4" (FWHM). line_3: We are currently constructing U/B and H-alpha/R maps which will be line_4: used to extend the HST coverage to more distant regions of the line_5: cluster. However, the spatial resolution of our ground-based line_6: data is clearly insufficient to explore the central 10"x10" line_7: region of NGC6752 which is where a population of CVs is expected line_8: to be concentrated. ! question: 5 section: 1 line_1: We require a dynamic range of 10 magnitudes to cover stars from line_2: the horizontal branch to a limiting magnitude Mv=10 expected line_3: for millisecond pulsars. Since the Planetary Camera only line_4: provides a dynamic range of 7 magnitudes, we plan two exposures line_5: in each filter. The planned exposure times are summarized in the line_6: table below, which gives the corresponding limiting absolute line_7: magnitude for a 5 sigma detection above the read-out noise background. line_8: We adopt a read-out noise of 20e- per pix. The short exposures line_9: will bring horizontal branch stars (Mv=0.6) just up to the point line_10: of saturation. This will saturate the approximately 20 giants line_11: in the field. Assuming that only 2-4 CCD columns are lost per line_12: saturated star, this does not represent a large fraction of the line_13: 1500 column PC field. The long exposure in the red filter will line_14: reach Mv=12, while that in H-alpha will reach Mv=9 for a flat line_15: spectrum source. For an H-alpha emission object, the corresponding line_16: limiting Mv of an object detected in the H-alpha filter will line_17: be about 1 magnitude fainter. ! question: 5 section: 2 line_1: line_2: filter exposure time limiting absolute magnitude line_3: F656N 2700.0 6.5 line_4: F675W 40.0 7.0 line_5: F675W 1100.0 10.6 ! question: 7 section: 1 line_1: We have employed the technique of color mapping in our ground line_2: based observations with considerable success. After matching line_3: the PSF (by filter convolution) and registration, two frames are line_4: divided pixel by pixel, resulting in a map of the cluster by line_5: color rather than intensity. Very faint objects of unusual colors line_6: are then easy to detect, and indeed we have identified only the line_7: second optical counterpart to a cluster LMXB in this way line_8: (Bailyn et al. 1988). ! question: 7 section: 2 line_1: Since these maps measure the area emitting in a given color, line_2: rather than the magnitude of the star emitting it, color line_3: gradients can be examined without the large random fluctuations line_4: due to giants that plague aperture photometry. We have used line_5: color maps to demonstrate that the core of M15 is significantly line_6: bluer than its surroundings (Bailyn et al. 1989). We look line_7: forward to employing this powerful technique on the much higher line_8: resolution data obtainable with HST. ! question: 7 section: 3 line_1: In addition to color map analysis, we also plan to employ DAOPHOT line_2: PSF fitting to obtain photometry for all objects in each PC frame. line_3: Since the expected number of objects per resolution element is line_4: typically of order one or less, this procedure is appropriate for line_5: points sources of H-alpha emission. The Indiana University line_6: VAX 8842 (see section 10) will provide the necessary CPU capacity line_7: for this computationally intensive analysis. ! question: 10 section: 1 line_1: The Harvard-Smithsonian Center for Astrophysics (CfA) has an line_2: extensive variety of computational facilities which will be used line_3: for analysis of the data obtained for this project. In particular, line_4: a fully supported network of SUN computers can be used although line_5: a dedicated node (SUN 3/60) is needed for the extensive analysis line_6: required. The SUN network supports a full implementation of line_7: IRAF, DAOPHOT, and additional processing and spectroscopy line_8: analysis software. The SUN network is connected (via Ethernet) line_9: to a microVAX net as well as a convex machine. There is also line_10: a high speed link between the CfA and the Supercomputer network. ! question: 10 section: 2 line_1: The Indiana University Astronomy Department has developed a line_2: powerful microVAX based image processing system, largely with line_3: University funding. This system runs IRAF and SDAS software, line_4: including DAOPHOT. In addition, Indiana University has recently line_5: acquired a VAX 8842 (equivalent to 24 VAX 780's) which will line_6: provide substantial additional CPU capacity for manipulating line_7: ST images, at no cost to this proposal. Indiana University line_8: funds a high speed link (1.5Mbps) to the National Center for line_9: Supercomputing Applications (NCSA), where we are carrying out line_10: simulations of globular cluster dynamical evolution in line_11: support of this proposed HST program. ! !end of general form text general_form_address: lname: GRINDLAY fname: JONATHAN mi: E. title: PROF. category: PI inst: HARVARD UNIVERSITY addr_1: 60 GARDEN STREET city: CAMBRIDGE state: MA zip: 02138 country: USA ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: NGC6752 descr_1: STAR CLUSTER descr_2: GLOBULAR CLUSTER pos_1: RA = 19H 06M 27.3S +/- 1S, pos_2: DEC = -60D 03' 50.5" +/- 1" equinox: 1950 fluxnum_1: 1 fluxval_1: V= 12 +/- 0.5 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: NGC6752 config: PC opmode: IMAGE aperture: ALL sp_element: F656N num_exp: 3 time_per_exp: 2700S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH = YES req_1: CYCLE 1 /1-3 ! linenum: 2.000 targname: NGC6752 config: PC opmode: IMAGE aperture: ALL sp_element: F675W num_exp: 1 time_per_exp: 40S fluxnum_1: 1 priority: 1 param_1: PRE-FLASH = YES ! linenum: 3.000 targname: NGC6752 config: PC opmode: IMAGE aperture: ALL sp_element: F675W num_exp: 1 time_per_exp: 1100S fluxnum_1: 1 priority: 1 ! ! end of exposure logsheet ! No scan data records found