! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! Id: 6092 ! ! For help call your Program Coordinator: Max Mutchler ! Phone: 410 338-1321 , E-mail: mutchler@stsci.edu Proposal_Information Title: Disk Globular Clusters in Edge-On Spiral Galaxies Proposal_Category: GO Scientific_Category: Galaxies & Clusters Cycle: 5 Investigators PI_name: Keith Ashman PI_Institution: University of Kansas CoI_Name: Stephen Zepf CoI_Institution: University of California, Berkeley Contact: N ! Y or N (designate at most one contact) CoI_Name: Kenneth Freeman CoI_Institution: Mount Stromlo & Siding Springs Observatory Contact: N Abstract: ! Free format text (please update) The role of interactions and mergers in the formation and evolution of galaxies is controversial. However, evidence is growing that galaxy morphology is determined to some extent by mergers. In this proposal we address the specific question of the origin of the thick disk component of spiral galaxies. By searching two nearby edge-on spirals for the presence of disk globular clusters we will be able to constrain formation models for thick disks. With only modest exposure times we will test the hypothesis that the thick disks of spiral galaxies are formed by the accretion of one or more satellite galaxies. This hypothesis is directly related to critical questions concerning galaxy formation, including the frequency of galaxy mergers, the role mergers play in determining the morphology of galaxies, the observed thinness of spiral disks and the conflict it raises with predicted merger rates in cosmological models, and the relation between the thick disk stars and globular clusters in the Milky Way. The discovery of disk globular clusters in our target objects would represent the first detection of such objects outside the Local Group. Questions ! Free format text (please update) Observing_Description: We propose to use the WFPC2 to obtain images in the B (F450W) and I (F814W) filters of the edge-on spiral galaxies NGC 4565 and NGC 5907 in order to search for globular clusters analogous to the thick disk clusters in the Milky Way. We aim to obtain photometry with a signal-to-noise of 10 for objects as faint as M_V = -5.5, which is 1.5Sigma past the expected turnover of the luminosity function. The primary source of noise in the images will be the bright galaxy background, which is about V=21.5 mag/arcsec^2 over most of the image. At the distance of our target galaxies (15 Mpc for NGC 4565 and 11 Mpc for NGC 5907), globular clusters will be just at the resolution limit of the WFC CCDs. Therefore, we consider photometry within a radius of two pixels and use the colors appropriate for spiral galaxies and globular clusters to find that for globular clusters of M_V=-5.5, exposure times of 32 minutes in I and 45 minutes in B are necessary for a S/N of 10 at the distance of NGC 4565, and the corresponding exposure times required for the more nearby NGC 5907 are 10 minutes in I and 15 minutes in B. For NGC 4565, one WFPC2 image with two of the WFC CCDs aligned along the axis of the disk provides sufficient spatial coverage to include almost all expected thick disk clusters. Therefore, we propose to image this galaxy in two orbits, the first for the I image, and the second for the B image. NGC 5907 is nearer, so the exposure times are shorter, but the areal coverage of an individual WFPC2 frame is not as good. Therefore we propose to observe at two positions in this galaxy, with one orbit dedicated to obtaining both B and I exposures at one position, and a second orbit for the other position. Real_Time_Justification: None. Study of thick disk clusters in these galaxies is not feasible except with the spatial resolution of HST. The photometry which provides the basis for the detection of the stellar thick disk in NGC 4565 and the upper limit on such a component in NGC 5907 has been published. Fixed_Targets Target_Number: 1 Target_Name: NGC5907 Alternate_Names: UGC09801 Description: GALAXY, SPIRAL Position: RA=15H 15M 54.00S +/- 5", DEC=56D 19' 45.5" +/- 5", PLATE-ID=01RT Equinox: 2000 RV_or_Z: V = +667 Epoch: Flux: B=25.7, B-I=2.0 +/- 0.2, SURF-BKG(B)=22.0, SURF-BKG(I)=20.5 Comments: Flux values for (faintest) globular clusters in target galaxies Background flux is for galaxy Target_Number: 3 Target_Name: NGC4565 Alternate_Names: Description: GALAXY, SPIRAL Position: RA=12H 36M 20.69S +/- 3.4", DEC=25D 59' 16.7" +/- 2.5", PLATE-ID=038A Equinox: B2000 RV_or_Z: V = +1227 Epoch: Flux: B=26.4, B-I=2.0 +/- 0.2, SURF-BKG(B)=22.0, SURF-BKG(I)=20.5 Comments: Flux values for (faintest) globular clusters in target galaxies Background flux is for galaxy Visits Visit_Number: 1 Visit_Requirements: PCS MODE Fine ORIENT 268D TO 274D Visit_Comments: Align disk of galaxy along Y-axis of WFC Exposure_Number: 1 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 0.0,19.0 Exposure_Number: 2 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 0.5,18.5 Exposure_Number: 3 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG -0.5,19.5 Exposure_Number: 4 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.0,19.0 Exposure_Number: 5 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.5,18.5 Exposure_Number: 6 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF2-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG -0.5,19.5 Exposure_Number: 7 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 0.0,-19.0 Exposure_Number: 8 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 0.5,-18.5 Exposure_Number: 9 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG -0.5,-19.5 Exposure_Number: 10 ! Section 6.5 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.0,-19.0 Exposure_Number: 11 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 0.5,-18.5 Exposure_Number: 12 Target_Name: NGC4565 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 230S Special_Requirements: POS TARG -0.5,-19.5 Visit_Number: 2 Visit_Requirements: PCS MODE Fine ORIENT 197D TO 203D Visit_Comments: Align disk of galaxy along X-axis of WFC Exposure_Number: 1 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 20.0,0.0 Exposure_Number: 2 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 20.5,-0.5 Exposure_Number: 3 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 200S Special_Requirements: POS TARG 19.5,0.5 Exposure_Number: 4 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 20.0,0.0 Exposure_Number: 5 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 20.5,-0.5 Exposure_Number: 6 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF4-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG 19.5,0.5 Exposure_Number: 7 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 260S Special_Requirements: POS TARG -20.0,0.0 Exposure_Number: 8 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 260S Special_Requirements: POS TARG -20.5,0.5 Exposure_Number: 9 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F450W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 260S Special_Requirements: POS TARG -19.5,-0.5 Exposure_Number: 10 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG -20.0,0.0 Exposure_Number: 11 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG -20.5,0.5 Exposure_Number: 12 ! Section 6.5 Target_Name: NGC5907 Config: WFPC2 Opmode: IMAGE Aperture: WF3-FIX Sp_Element: F814W Wavelength: Optional_Parameters: CR-SPLIT=NO Number_of_Iterations: 1 Time_Per_Exposure: 160S Special_Requirements: POS TARG -19.5,-0.5 Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! Dept.\ of Physics & Astronomy, ! 1082 Malott Hall, Lawrence, ! KS 66045-2151 ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address !