6569( 4) - 04/24/97 09:50 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6569 Version: 4 Check-in Date: 24-Apr-1997 09:44:08 1.Proposal Title: The Physics of Nearby Blue Irregular Starbursts ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: JOHN MACKENTY SPACE TELESCOPE SCIENCE INSTITUTE CoI: Colin Norman The Johns Hopkins University N CoI: Richard Burg The Johns Hopkins University N CoI: Richard Griffiths The Johns Hopkins University N CoI: Rosemary Wyse The Johns Hopkins University N ------------------------------------------------------------------------------------ 6. Abstract We propose to exploit the resolution of the WFPC2 to obtain U, V, R, and I and narrow band H Alpha and O III images of an optimally-selected sample of three local dwarf starburst galaxies in order to understand the mechanism of star formation in these systems. These objects have O III equivalent widths greater than 50Angstrom. These dwarf galaxies are close enough that massive stars can be resolved by HST and are extremely important local laboratories for the study of star formation. This type of low luminosity irregular galaxy has been shown to evolve significantly from redshifts of 0.5 - 1 to the current epoch (Glazebrook et al. 1995, Driver et al. 1995, Lilly et al. 1995) in contrast to the more luminous population of early type systems that do not seem to evolve. The understanding of the evolutionary processes in these systems is unclear but interactions, merging, and general starburst activity seem to play a major role. Our detailed study of the sample proposed here may be of significant help in understanding the physics of these objects and there evolution. Many fundamental questions about the essential physical nature of these and larger starburst systems remain unanswered including: (1) is the mass function of a burst restricted to the high mass end; (2) does it depend on metallicity; (3) what physical mechanisms actually trigger the burst. Our HST data will have sufficient spatial resolution to resolve isolated individual high mass main sequence stars and super giants and to distinguish clusters similar to R136A. ------------------------------------------------------------------------------------ 6569( 4) - 04/24/97 09:50 - [ 2] Observations Description ------------------------ We propose to observe three blue dwarf galaxies with WFPC2 and the appropriate wide filter bandpasses for U (F336W), V (F555W), R (F702W), and I (F814W). Images in H Alpha (F656N or F658N) and O III (F502N) will also be obtained. We will request CR-SPLIT images with a ratio of 3:2 to improve the dynamic range of the images and to permit us to reject cosmic rays in the data analysis. Since the star formation is occurring across essentially the entire galaxy for the members of our sample, we request that the PC1 detector be pointed at the centers of these galaxies. Our sample represents the closest galaxies meeting our selection criteria which span a broad range of luminosities as shown below. Name m_B B(0) v_H UGC 685 14.5 -12.88 113 UGC 5456 13.5 -14.31 513 NGC 4214 10.4 -16.6 294 The broad band observations are primarily intended to permit the determination of the magnitudes and colors of the brightest stars which currently (or recently) provide the ionizing flux in the galaxy. These are the B and O main sequence stars and the supergiants. The following exposure times are derived for a distance modulus of 27.6 and are based on the formulae and values given in the WFPC2 Instrument Handbook. A simple calculation indicates that in a total of two orbits we should achieve a S/N of 20 or better for main sequence stars hotter than B0V. These exposures provide similar S/N for supergiants hotter than K0 I except in the U filter where we will only reach F0 I for a signal to noise better than 20. Specifically, for a M_v=-6 star signal levels of 7.3, 16.7, 13.6, and 5.0 e^-/s are expected in F336W, F555W, F702W, and F814W, respectively. The most distant galaxy in our sample (NGC 3432) should have corresponding S/N ratios better than 5. The H Alpha and O III exposure times are more difficult to constrain due to the large range in surface brightnesses in the line emission regions. We propose to obtain a 30 to 40 minutes of integration in each filter (CR-SPLIT) to explore a range of surface brightnesses. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 6569( 4) - 04/24/97 09:50 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4214 GALAXY,MAGELLANIC RA=12H 15M 39.3S +/- 1",DEC=36D J2000 V = 294 V = 10.4+/-0.2 IRREGULAR 19' 38" +/- 1" 2 UGC685 GALAXY,DWARF RA=01H 07M 23S +/- 2",DEC=16D J2000 V = 113 V = 14.5+/-0.2 COMPACT/HII GALAXY 41' 03" +/- 2" 3 UGC5456 GALAXY,DWARF RA=10H 07M 19.7S +/- 2",DEC=10D J2000 V = 513 V = 13.5+/-0.2 COMPACT/HII GALAXY 21' 46" +/- 2" 6569( 4) - 04/24/97 09:50 - [ 4] Visit: 01 Visit Requirements: PCS MODE FINE On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC4214 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 1 260 S IX ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC4214 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 2 900 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC4214 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 1 100 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC4214 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 2 600 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC4214 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 2 500 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC4214 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 1 100 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC4214 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 1 100 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 41 NGC4214 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 2 600 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC4214 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 700 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 51 NGC4214 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 800 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC4214 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 800 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 61 NGC4214 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 800 S SAME POS AS 10 IX ------------------------------------------------------------------------------------------------------------------------------------ 6569( 4) - 04/24/97 09:50 - [ 5] Visit: 02 Visit Requirements: ORIENT 313D TO 343D PCS MODE FINE On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 110 UGC5456 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 1 300 S POS TARG -15,-15 IX ------------------------------------------------------------------------------------------------------------------------------------ 111 UGC5456 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 2 1000 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 120 UGC5456 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 1 100 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 121 UGC5456 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 2 500 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 130 UGC5456 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 2 500 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 131 UGC5456 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 1 100 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 140 UGC5456 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 1 100 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 141 UGC5456 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 2 600 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 150 UGC5456 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 700 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 151 UGC5456 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 800 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 160 UGC5456 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 700 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 161 UGC5456 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 800 S SAME POS AS 110 IX ------------------------------------------------------------------------------------------------------------------------------------ 6569( 4) - 04/24/97 09:50 - [ 6] Visit: 03 Visit Requirements: ORIENT 103D TO 123D PCS MODE FINE On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 210 UGC685 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 1 300 S POS TARG -15,-15 IX ------------------------------------------------------------------------------------------------------------------------------------ 211 UGC685 WFPC2 IMAGE WFALL-F F336W CR-SPLIT=NO 2 1000 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 220 UGC685 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 1 100 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 221 UGC685 WFPC2 IMAGE WFALL-F F555W CR-SPLIT=NO 2 500 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 230 UGC685 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 2 500 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 231 UGC685 WFPC2 IMAGE WFALL-F F702W CR-SPLIT=NO 1 100 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 240 UGC685 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 1 100 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 241 UGC685 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 2 600 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 250 UGC685 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 700 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 251 UGC685 WFPC2 IMAGE WFALL-F F502N CR-SPLIT=NO 1 800 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 260 UGC685 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 700 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 261 UGC685 WFPC2 IMAGE WFALL-F F656N CR-SPLIT=NO 1 800 S SAME POS AS 210 IX ------------------------------------------------------------------------------------------------------------------------------------ 6569( 4) - 04/24/97 09:50 - [ 7] Summary Form for Proposal 6569 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE FINE SAME POS AS 10 ORIENT 313D TO 343D PCS MODE FINE POS TARG -15,-15 SAME POS AS 110 ORIENT 103D TO 123D PCS MODE FINE SAME POS AS 210 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F555W F702W F814W F502N F656N ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4214 UGC5456 UGC685 ------------------------------------------------------------------------------------------------------------------------------------