8678( 5) - 05/23/01 16:45 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8678 Version: 5 Check-in Date: 23-May-2001 16:44:29 1.Proposal Title: Galaxy Mass and the Fate of the ISM in Candidate Proto-Spheroidals at z~0.2-0.4 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Rafael Guzman University of Florida CoI: Prof. David Koo Lick Observatory, UCSC N CoI: Prof. Matthew Bershady University of Wisconsin-Madison N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain STIS long-slit spectra for a sample of 5 faint blue compact galaxies (BCGs) at z ~ 0.2 to 0.4. Despite being very luminous (M_B~-20), BCGs have velocity widths Sigma <~ 60 kms, and half-light radii r_e <~ 0.5'' (or R_e <~ 3Kpc). The small sizes and velocity widths suggest that BCGs are low-mass stellar systems (Mla10^10M_\odot), while their very blue colors, strong emission lines and low M/L- ratios indicate that they are undergoing a major starburst. If the star-forming process halts after the current burst, galaxy evolution models predict that BCGs will fade by ~3-4 magnitudes after a few Gyrs to reach the low luminosities and surface brightnesses characteristic of spheroidal galaxies. Thus we may be witnessing, in-situ, the last major episode of star formation in today's dwarf, low surface brightness galaxies such as NGC 205. Spatially-resolved spectroscopy will allow us to perform unique tests of this evolutionary scenario by providing: i) measurements of rotational velocities --rather than Sigma-- to determine whether BCGs are indeed low-mass stellar systems; and ii) evidence for any substructure in the line emitting region associated to SN- driven galactic winds. This information will shed light on the ultimate fate of the ISM in BCGs, and thus on whether it is reasonable to expect that no further star formation episodes will occur after the current burst. ------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 2] Observations Description ------------------------ We propose to obtain long-slit spectra of 5 faint (B~21) very blue compact galaxies (BCGs) at z~0.2-0.4. These galaxies were chosen to have the highest OIII5007 fluxes in our BCG sample (i.e., I_Lambda = 1--5times10^-15 erg s^-1 cm^-2 AA^-1 arcsec^-2). We emphasise that, although fainter than most objects typically observed by STIS, our BCGs have very high average surface brightness (SB_e ~ 20 mag arcsec^-2). In fact, typical SB_e values for our sample are very similar to those of the most compact nearby elliptical galaxies, even considering the (1+z)^4 cosmological dimming. We have two main scientific goals: to measure rotation curves using HAlpha, and to measure emission-line ratios in the spectral region that spans from HBeta to SII6717+6731. For kinematics studies, spectra will be obtained around the HAlpha region using the 52''* 0.2'' slit and the G750M grating, which yield a spectral resolution of FWHM=2.2Angstrom\ (or Sigma~45 km s^-1). This resolution matches adequately the typical velocity widths measured for this BCG sample (i.e., Sigma ~40-70 km s^- 1). The slit will be positioned either along the galaxy major axis --if it is well-defined-- or along the various high surface brightness knots seen in some of the WFPC2 images. The central wavelength for each setup will be chosen depending on the redshift of each object. For line-ratio studies, we will obtain spectra in the range 5250-11490 Angstroms using the 52''* 0.5'' slit and the G750L grating. We have used the STIS Exposure Time Calculator (ETC) to estimate the adequate exposure time and S/N for the proposed observations. A flux-calibrated spectrum of a typical BCG was used as input for the ETC program. The typical intensity of HAlpha in BCGs is sim5*10^-15 erg s^-1 cm^-2 AA^-1 arcsec^-2. Relative to HAlpha, the intensities of OIII, HBeta and SII, are 0.3, 0.15, and 0.2, approximately. Considering that BCGs have a typical half-light diameter of ~0.7'', and using default values for the remaining ETC parameters, we derive a S/N of ~35 per resolution element in HAlpha for a total exposure time t=4800s. From our simulations, we estimate that S/N~30 per resolution element in the core provides adequate S/N to reliably determine the rotation curve out to ~2* r_e. The expected S/N for fainter emission lines, such as HBeta and SII is ~11 per resolution element, which is adequate for measuring intensities and deriving the OIII/HBeta and SII/HAlpha line ratios with the ~30\ shock-excited and star- forming regions. The total exposure time per orbit for the declination of our sample is typically ~3300s. Allowing ~900s for overheads (general, acquisition, and CCD fringes flat), we intend to observe our objects for t=2400s (CR-SPLIT) per orbit. Thus 2 orbits per object per setup, or 4 orbits per object including both setups, are needed to achieve the required S/N required in the various emission lines of interest for our analysis. Since we have 5 objects in our sample, the completion of our program requires a grand total of 20 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SA68-6134 GALAXY, DWARF COMPACT, RA=0H 15M 36.187S +/- 0.1", DEC= B1950.0 Z=0.2852 V = +21.0 STARBURST 15D 31' 13.53" +/- 0.1" B-V = 0.2 R-I = 0.55 Coordinate Source: OTHER_SOURCE 2 HER1-13385 GALAXY, DWARF COMPACT, RA=17H 20M 0.505S +/- 0.1", DEC= B1950.0 Z=0.0954 V = +20.4 STARBURST 50D 04' 29.15" +/- 0.1" B-V = 0.3 U-B = -0.2 Coordinate Source: OTHER_SOURCE 3 SA57-10601 GALAXY, DWARF COMPACT, RA=13H 6M 25.031S +/- 0.1", DEC= B1950.0 Z=0.4384 V = +21.2 STARBURST 29D 39' 39.69" +/- 0.1" B-V = 0.3 R-I = 0.62 Coordinate Source: OTHER_SOURCE 4 HER1-13088 GALAXY, DWARF COMPACT, RA=17H 19M 04.375S +/- 0.1", B1950.0 Z=0.4357 V = +20.7 STARBURST DEC= 50D 03' 59.93" +/- 0.1" B-V = 0.3 R-I = 0.62 Coordinate Source: OTHER_SOURCE 5 HER1-14739 GALAXY, DWARF COMPACT, RA=17H 19M 26.556S +/- 0.1", B1950.0 Z=0.2350 V = +20.3 STARBURST DEC= 50D 07' 30.76" +/- 0.1" B-V = 0.3 U-B = -0.2 Coordinate Source: OTHER_SOURCE 8678( 5) - 05/23/01 16:45 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 109D TO 139D On Hold Comments: Additional Comments: ORIENT was calculated to have the slit within 15D of PA=259D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SA57-10601 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 M CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SA57-10601 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 28 M CD ------------------------------------------------------------------------------------------------------------------------------------ 3 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 4 SA57-10601 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 6 SA57-10601 STIS/C ACCUM 52X0.2 G750M 9336 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750M 9336 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8 SA57-10601 STIS/C ACCUM 52X0.2 G750M 9336 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 9 CCDFLAT STIS/C ACCUM 52X0.2 G750M 9336 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 5] Visit: 02 Visit Priority: Visit Requirements: ORIENT 116D TO 146D On Hold Comments: Additional Comments: ORIENT was calculated to have the slit within 15D of PA=266D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SA68-6134 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 M CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 SA68-6134 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 28 M CD ------------------------------------------------------------------------------------------------------------------------------------ 3 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 4 SA68-6134 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 6 SA68-6134 STIS/C ACCUM 52X0.2 G750M 8311 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750M 8311 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8 SA68-6134 STIS/C ACCUM 52X0.2 G750M 8311 CR-SPLIT=2 1 40 M CD ------------------------------------------------------------------------------------------------------------------------------------ 9 CCDFLAT STIS/C ACCUM 52X0.2 G750M 8311 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 6] Visit: 03 Visit Priority: Visit Requirements: ORIENT 112D TO 142D On Hold Comments: Additional Comments: ORIENT was calculated to have the slit within 15D of PA=262D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HER1-13385 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 M CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HER1-13385 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 30 M CD ------------------------------------------------------------------------------------------------------------------------------------ 3 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 4 HER1-13385 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 6 HER1-13385 STIS/C ACCUM 52X0.2 G750M 7283 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750M 7283 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8 HER1-13385 STIS/C ACCUM 52X0.2 G750M 7283 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 9 CCDFLAT STIS/C ACCUM 52X0.2 G750M 7283 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 7] Visit: 04 Visit Priority: Visit Requirements: ORIENT 5D TO 35D On Hold Comments: Additional Comments: ORIENT was calculated to have the slit within 15D of PA=335D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HER1-14739 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 M CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HER1-14739 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 30 M CD ------------------------------------------------------------------------------------------------------------------------------------ 3 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 4 HER1-14739 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 6 HER1-14739 STIS/C ACCUM 52X0.2 G750M 8311 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750M 8311 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8 HER1-14739 STIS/C ACCUM 52X0.2 G750M 8311 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 9 CCDFLAT STIS/C ACCUM 52X0.2 G750M 8311 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 8] Visit: 05 Visit Priority: Visit Requirements: ORIENT 34D TO 64D On Hold Comments: Additional Comments: ORIENT was calculated to have the slit within 15D of PA=4D Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HER1-13088 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 M CD P ------------------------------------------------------------------------------------------------------------------------------------ 2 HER1-13088 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 30 M CD ------------------------------------------------------------------------------------------------------------------------------------ 3 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 4 HER1-13088 STIS/C ACCUM 52X0.5 G750L 7751 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/C ACCUM 52X0.5 G750L 7751 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 6 HER1-13088 STIS/C ACCUM 52X0.2 G750M 9336 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/C ACCUM 52X0.2 G750M 9336 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8 HER1-13088 STIS/C ACCUM 52X0.2 G750M 9336 CR-SPLIT=2 1 42 M CD ------------------------------------------------------------------------------------------------------------------------------------ 9 CCDFLAT STIS/C ACCUM 52X0.2 G750M 9336 2 DEF CD ------------------------------------------------------------------------------------------------------------------------------------ 8678( 5) - 05/23/01 16:45 - [ 9] Summary Form for Proposal 8678 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.5 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 109D TO 139D ORIENT 116D TO 146D ORIENT 112D TO 142D ORIENT 5D TO 35D ORIENT 34D TO 64D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750L G750M ------------------------------------------------------------------------------------------------------------------------------------ Target Names SA57-10601 CCDFLAT SA68-6134 HER1-13385 HER1-14739 HER1-13088 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 7751 9336 8311 7283 ------------------------------------------------------------------------------------------------------------------------------------