5826( 5) - 11/22/95 12:01 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5826 Version: 5 Check-in Date: ********** 1.Proposal Title: Investigating Dwarf Galaxy Formation and Evolution Searching for Diffuse Ionized Gas Around Leo I ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Galaxies & Clusters GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: David V. Bowen Space Telescope Science Institute CoI: Eline Tolstoy Kapteyn Astronomical Institute N CoI: J. Chris Blades Space Telescope Science Institute N CoI: Elias Brinks NRAO N ------------------------------------------------------------------------------------ 6. Abstract We propose searching for the remnants of dwarf galaxy formation and evolution by looking for tenuous amounts of metal enriched gas in the outer regions of the dwarf galaxy Leo I. We have found 3 QSOs and AGNs 2.1, 3.7 & 8.1 kpc from the center of the galaxy, and wish to search for C IV, Si IV & Si II absorption lines from gas around the galaxy. We have observed one QSO previously with HST and found no Mg II at the redshift of Leo I, which suggests that any gas which lies outside the galaxy is highly ionized, either by the UV background or by the physical processes which placed the gas there initially. If so, C IV & Si IV are ideal transitions with which to search for such gas. We wish to search for these lines to determine the existence of gas around the galaxy, gauge the total extent of the gas and its covering factor, detect variations in line strength and ionization (as measured from the Si II/Si IV ratio) with radius, and search for large scale kinematic variations in the absorbing gas which may be indicative of gas outflows or expanding shells. Many models of dwarf galaxy formation and evolution implicitly assume that gas either escapes or falls into the galaxy; this proposal explicitly tests that assumption. ------------------------------------------------------------------------------------ 5826( 5) - 11/22/95 12:01 - [ 2] Observations Description ------------------------ The observations of 3 sightlines with the G140L will cover a wavelength range which includes Si IV, C IV, and Si II absorption lines, as well as C II and Ni II lines. The AGN are compact and at low redshift, which has the advantage that no higher redshift Lyman limit system will cut off the UV flux. Exposure times are estimated either from known UV fluxes, or from V magnitudes extrapolated to 1400 Angstrom\ assuming the object has a power law of the form F_Nu \propto\ nu^-1. Exposure times are calculated to give a S/N of 18 per pixel for half-stepped data. Assuming a background count rate of 36 counts/diode/hr, the S/N gives a 3Sigma equivalent width limit of 0.1 Angstrom\ for a resolving power of 2150 at Si IV and 0.15 Angstrom\ at C IV These limits are sufficient to detect absorption lines from our own Galactic halo, W(Si IVLambda1393)= 0.2 Angstrom , W(C IVLambda1548)= 0.3 Angstrom . The high S/N ensures that absorption from Leo I will be clearly resolved from local Milky Way absorption lines, which will allow accurate line centers, equivalent widths etc. to be determined. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: stsci Ship Via: Internal mail Email: , ------------------------------------------------------------------------------------ 5826( 5) - 11/22/95 12:01 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 1004+1303 GALAXY,QSO;EXT- RA=10H 07M 26.10S +/- 0.6S, J2000.0 z=0.240 V=15.15 MEDIUM,absorption line DEC=12D 48' 56.0" +/- 0.6", F(1400)=0.8e-14 system PLATE-ID=028W 2 1008+1319 GALAXY,QSO;EXT- RA=10H 11M 10.84S +/- 1.0S, J2000.0 z=1.287 V=16.29 MEDIUM,absorption line DEC=13D 04' 11.7" +/- 1.0", system PLATE-ID=028W 3 0957+1317 GALAXY,seyfert;EXT- RA=09H 59M 55.86S +/- 0.6S, J2000.0 z=0.035 V=15.15 MEDIUM,absorption line DEC=13D 02' 37.2" +/- 0.6", system PLATE-ID=028W Comments: UV excess galaxy 5826( 5) - 11/22/95 12:01 - [ 4] Visit: 01 Visit Requirements: 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 1004+1303 HRS ACQ 2.0 MIRROR-N1 bright=return,s 1 90S ONBOARD ACQUISITION FOR 20 earch-size=3 Comments: step-time=10s ------------------------------------------------------------------------------------------------------------------------------------ 20 1004+1303 HRS ACCUM 2.0 G140L 1421 fp-split=two 27 217.6S ------------------------------------------------------------------------------------------------------------------------------------ 5826( 5) - 11/22/95 12:01 - [ 5] Visit: 02 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 1008+1319 HRS ACQ 2.0 MIRROR-N1 bright=return,s 1 90S ONBOARD ACQUISITION FOR 40 earch-size=3 Comments: step-time=10s ------------------------------------------------------------------------------------------------------------------------------------ 40 1008+1319 HRS ACCUM 2.0 G140L 1421 fp-split=two 27 217.6S ------------------------------------------------------------------------------------------------------------------------------------ 5826( 5) - 11/22/95 12:01 - [ 6] Visit: 03 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 0957+1317 HRS ACQ 2.0 MIRROR-N1 bright=return,s 1 90S ONBOARD ACQUISITION FOR 60 earch-size=3 Comments: step-time=10s ------------------------------------------------------------------------------------------------------------------------------------ 60 0957+1317 HRS ACCUM 2.0 G140L 1421 fp-split=two 27 217.6S ------------------------------------------------------------------------------------------------------------------------------------ 5826( 5) - 11/22/95 12:01 - [ 7] Summary Form for Proposal 5826 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters bright=return search-size=3 fp-split=two ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Galaxies & Clusters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQUISITION FOR 20 ONBOARD ACQUISITION FOR 40 ONBOARD ACQUISITION FOR 60 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1004+1303 1008+1319 0957+1317 ------------------------------------------------------------------------------------------------------------------------------------