Proposal_Information Title: Nearby young dwarf galaxies and their Lyman Alpha emission Proposal_Category: GO Scientific_Category: COSMOLOGY Cycle: 6 Investigators PI_Name: Trinh X. Thuan PI_Institution: University of Virginia CoI_Name: Yuri Izotov CoI_Institution: Main Astronomical Observatory Contact: N CoI_Name: Valentin Lipovetsky CoI_Institution: Special Astrophysical Observatory Contact: N Abstract: We wish to obtain GHRS UV spectra of 3 and WFPC2 V and I images of 2 of the most metal-deficient ( Zsun/41 <=sssim Z <=sssim Zsun/21) blue compact galaxies (BCGs) known. These BCGs are the best candidates for nearby young primeval galaxies where massive star formation can be studied and constraints put on theories of gas collapse and fragmentation in a nearly pristine environment. Color-magnitude diagrams will constrain ages. The high resolution imaging will allow to determine the sizes, luminosities and colors of the ionizing star clusters. The absence or presence of an underlying low-surface-brightness old stellar population will tell us whether the BCG is genuinely young or not. The UV spectra will allow to examine the Ly-alpha/H Beta--O/H correlation. For galaxies with Z >~ 0.1 Zsun, there appears to be a correlation of increasing Ly-alpha emission with decreasing metallicity. HST has found the surprising result that the most metal-deficient BCG known, IZw18, does not have Ly-alpha emission. Is the latter suppressed in nearly primordial objects? If this is the case, Ly-alpha searches for high-redshift primeval galaxies will have to be rethought entirely. Questions Observing_Description: We wish to carry out an imaging program with the WFPC2 and a spectroscopic program with the GHRS. 1. Imaging. The WFPC2 will be used to obtain V(F555W) and I(F814W) images of the 2 BCGs T1214-277 and Tol 65. We shall use 2 orbits for each object. We shall split each orbit into two, spending 13 mn for the V exposure and 25 mn for the I exposure. Thus 2x13 mn will be spent with F555W and 2x25 mn will be spent with F814W. The same position and orientation angle are to be maintained for the 2 orbits, so it is desirable that they are consecutive. 2. Spectra. The GHRS will be used to obtain UV spectra of 3 BCGs: SBS0335-052, T1214-277 and Tol65. We shall use the grating G140L with the LSA (1.75" diameter) to obtain spectra in the wavelength range 1150 to 1450 A. We shall spend 3 orbits on SBS0335-052 with 1 orbit used for acquisition and 2 orbits for collecting data, and 2 orbits each for T1214-277 and Tol65, with 1 orbit for acquisition and 1 orbit for collecting data. Real_Time_Justification: None Calibration_Justification: Additional_Comments: Fixed_Targets Target_Number: 1 Target_Name: SBS0335-052 Alternate_Names: Description: GALAXY,DWARF COMPACT, Position: RA=03H 37M 43.99S +/- 0.02S,DEC=-05D 02' 39.0" +/- 0.3",PLATE-ID=044L Equinox: J2000 RV_or_Z: Z = 0.0137 RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 16.30+/-0.31 F-CONT(1300)=7.5+/-1.0e-15 Comments: Target_Number: 2 Target_Name: T1214-277 Alternate_Names: Description: GALAXY,DWARF COMPACT, Position: RA=12H 17M 17.08S +/- 0.03S,DEC=-28D 02' 32.4" +/- 0.5",PLATE-ID=01C8 Equinox: J2000 RV_or_Z: Z = 0.026 RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 17.50+/-0.50 F-CONT(1300)=2.5+/-1.0e-15 Comments: Target_Number: 3 Target_Name: TOL65 Alternate_Names: Description: GALAXY,DWARF COMPACT, Position: RA=12H 25M 46.47S +/- 0.03S,DEC=-36D 14' 02.3" +/- 0.5",PLATE-ID=04HG Equinox: J2000 RV_or_Z: Z = 0.0094 RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 17.70+/-0.50 F-CONT(1300)=2.0+/-1.0e-15 Comments: Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 01 Visit_Requirements: On_Hold_Comments: Visit_Comments: HRS Spectrum of SBS0335-052 at Ly-alpha Exposure_Number: 1 Target_Name: SBS0335-052 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-Y=1.23,SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 10.0S Special_Requirements: ONBOARD ACQ FOR 2 Comments: Exposure_Number: 2 Target_Name: SBS0335-052 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 1.0 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2 Number_of_Iterations: 1 Time_Per_Exposure: 11.0S Special_Requirements: ONBOARD ACQ FOR 3 Comments: Exposure_Number: 3 Target_Name: SBS0335-052 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 12.0S Special_Requirements: ONBOARD ACQ FOR 4-6 Comments: Three stage ACQ followed by GHRS exposures Exposure_Number: 4 Target_Name: SBS0335-052 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1162-1448 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 326.4S Special_Requirements: Comments: Exposure_Number: 5 Target_Name: SBS0335-052 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1162-1448 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2720.0S Special_Requirements: Comments: Exposure_Number: 6 Target_Name: SBS0335-052 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1162-1448 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2692.8S Special_Requirements: Comments: Visit_Number: 02 Visit_Requirements: On_Hold_Comments: Visit_Comments: HRS Spectrum of T1214-277 at Ly-alpha Exposure_Number: 7 Target_Name: T1214-277 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-Y=1.23,SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 10.0S Special_Requirements: ONBOARD ACQ FOR 8 Comments: Exposure_Number: 8 Target_Name: T1214-277 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 1.0 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2 Number_of_Iterations: 1 Time_Per_Exposure: 11.0S Special_Requirements: ONBOARD ACQ FOR 9 Comments: Exposure_Number: 9 Target_Name: T1214-277 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 12.0S Special_Requirements: ONBOARD ACQ FOR 10-11 Comments: Three stage ACQ followed by GHRS exposures Exposure_Number: 10 Target_Name: T1214-277 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1177-1463 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 353.6S Special_Requirements: Comments: Exposure_Number: 11 Target_Name: T1214-277 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1177-1463 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2720.0S Special_Requirements: Comments: Visit_Number: 03 Visit_Requirements: On_Hold_Comments: Visit_Comments: HRS Spectrum of TOL65 at Ly-alpha Exposure_Number: 12 Target_Name: TOL65 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 4.3 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-Y=1.23,SEARCH-SIZE-X=1,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 10.0S Special_Requirements: ONBOARD ACQ FOR 13 Comments: Exposure_Number: 13 Target_Name: TOL65 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 1.0 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.61,SCAN-STEP-Y=0.61,SEARCH-SIZE-X=6,SEARCH-SIZE-Y=2 Number_of_Iterations: 1 Time_Per_Exposure: 11.0S Special_Requirements: ONBOARD ACQ FOR 14 Comments: Exposure_Number: 14 Target_Name: TOL65 Config: FOS/BL Opmode: ACQ/PEAK Aperture: 0.5 Sp_Element: MIRROR Wavelength: Optional_Parameters: SCAN-STEP-X=0.29,SCAN-STEP-Y=0.29,SEARCH-SIZE-X=3,SEARCH-SIZE-Y=3 Number_of_Iterations: 1 Time_Per_Exposure: 12.0S Special_Requirements: ONBOARD ACQ FOR 15-16 Comments: Three stage ACQ followed by GHRS exposures Exposure_Number: 15 Target_Name: TOL65 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1157-1443 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 408.0S Special_Requirements: Comments: Exposure_Number: 16 Target_Name: TOL65 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G140L Wavelength: 1157-1443 Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2774.4S Special_Requirements: Comments: Visit_Number: 04 Visit_Requirements: On_Hold_Comments: Visit_Comments: WFC Images in V and I of T1214-277 Exposure_Number: 17 Target_Name: T1214-277 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F555W Wavelength: 5398 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 800S Special_Requirements: Comments: Exposure_Number: 18 Target_Name: T1214-277 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F814W Wavelength: 7921 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1600S Special_Requirements: SAME POS AS 17 Comments: Exposure_Number: 19 Target_Name: T1214-277 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F555W Wavelength: 5398 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 800S Special_Requirements: SAME POS AS 17 Comments: Exposure_Number: 20 Target_Name: T1214-277 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F814W Wavelength: 7921 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1600S Special_Requirements: SAME POS AS 17 Comments: Visit_Number: 05 Visit_Requirements: On_Hold_Comments: Visit_Comments: WFC Images in V and I of TOL65 Exposure_Number: 21 Target_Name: TOL65 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F555W Wavelength: 5398 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 800S Special_Requirements: Comments: Exposure_Number: 22 Target_Name: TOL65 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F814W Wavelength: 7921 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1700S Special_Requirements: SAME POS AS 21 Comments: Exposure_Number: 23 Target_Name: TOL65 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F555W Wavelength: 5398 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 800S Special_Requirements: SAME POS AS 21 Comments: Exposure_Number: 24 Target_Name: TOL65 Config: WFPC2 Opmode: IMAGE Aperture: WF3 Sp_Element: F814W Wavelength: 7921 Optional_Parameters: CR-SPLIT=NO,CR-TOLERANCE=0.0 Number_of_Iterations: 1 Time_Per_Exposure: 1700S Special_Requirements: SAME POS AS 21 Comments: Data_Distribution ! 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