8651( 4) - 06/18/01 09:13 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8651 Version: 4 Check-in Date: 18-Jun-2001 09:13:17 1.Proposal Title: STIS UV Spectroscopy in the Magellanic Bridge: A Typical QSO Absorption Line System? ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Henry Kobulnicky University of Wisconsin - Madison CoI: Dr. James Lowenthal University of Massechusetts N CoI: Marla Geha UC Santa Cruz N CoI: Dr. Dennis Zaritsky University of Arizona N CoI: Dr. David Bowen Princeton N ------------------------------------------------------------------------------------ 5. Abstract We are proposing STIS echelle UV absorption line spectroscopy through the Magellanic Bridge (near the SMC) to probe the temperature, ionization, and kinematic structure in a metal- poor environment like those observed in the early universe. The sightline toward the QSO B0312-770 is especially interesting because of the proximity of the absorber (~ 60 kpc) and the radio loud background source. Using 21- cm absorption and emission spectroscopy we have measured H I column densities of 10^20 cm^-2 which approach those in damped LyAlpha systems. Most importantly, we measure well- constrained spin temperatures for the absorbing neutral hydrogen components, T_S=30-200 K. By comparing the velocity structure and optical depths of common UV lines like Mg I, Mg II, Si II, Si IV, C IV, with the 21-cm diagnostics, we will identify the mixture of physical phases (hot and cold) and kinematic structure that comprise a nearby metal-poor environment for comparison to the high-z universe. If this sightline resembles the high-z UV absorbers, then the existence of ongoing star formation in the Magellanic Bridge implies that QSOs absorption line systems may be active sites of star formation as well. ------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 2] Observations Description ------------------------ sectionObservational Requirements We will use the E140M and E230M modes to measure the UV spectrum from 1150Angstrom\ - 1700Angstrom\ and to 2300Angstrom\ - 3100Angstrom\ at 6-10 kms\ velocity resolution. We require a minimum signal- to- noise of >10:1 in the continuum at the wavelength of the primary absorption lines of interest as listed in Table 1. For target magnitudes of 16.2, the STIS instrument manual and the STIS online Exposure Time Calculator indicate exposure times of 12 orbits for the Far-UV and 2 orbits for the Mg II region of the near UV. With a S/N of >=10 and spectral resolution of 0.05Angstrom\ (~8 kms), we will be sensitive to absorption features with 37 mAngstrom\ at the 3Sigma level. Based on the absorption line ratios observed in damped LyAlpha systems with similar HI column densities (sim1- 2*10^21 \cmmb), we list in Table 1 the strong absorption species which we will measure in the observed spectral range. The most important of these, are the strong C IV (Lambda1548, 1550), Si II (Lambda1526), Si IV (Lambda1394, 1402), and Mg II (Lambda2796, 2803) lines which are most commonly seen in high redshift systems. The E140M and E230M gratings will cover this wavelength interval. The expected velocity range for SMC absorption from low-ionization species is 150-250 km/s based on 21-cm neutral hydrogen velocities. With a velocity resolution of ~10 km/s, we will easily be able to distinguish between SMC/Bridge and Galactic gas. \medskip centerline Targets & Integration Time Estimates centerline(for 10:1 or better at the crucial lines) centerline begintabularlllrrrrrrr ID & Object & z & N(HI) & Mag (V) & Primary Lines & Orbits & tilt & Exp (s) B0312-770 &0.22 & 1.0E21 & 16.2 & Si II Lambda1526 & 12 & E140M & 42000 Mg II Lambda2803 & 2 & E230M/2 & 7000 plotonekobulnickyF1.ps 0.0cm Fig 1---HI 21cm contours of the Magellanic Clouds (Mathewson & Ford 1984). The location of the target background QSO is marked. It falls in the region with HI columns densities of 1times10^20 cm^-2. Absorption experiments through the SMC enable us to sample well-studied, low-metallicity environments that are ~1/10 solar respectively, for comparison to high-z absorbers. 21-cm HI absorption and emission observations at 0.5 kms resolution provide measurements of the column densities and spin temperatures along each sightline (Kobulnicky & Dickey 1998). plotonekobulnickyF2.ps -0.7cm Fig 2---21-cm emission and absorption spectra toward B0312-770 behind the Magellanic Bridge. The top panel shows the \HI\ emission spectrum from the Parkes 64 m antenna toward the background radio source. The 21-cm absorption spectrum against the background radio sources obtained with the Australia Telescope Compact Array appears in the central panel. Three absorption components are seen with spin temperatures, T_S, that vary between 30 K and 200 K. sectionSupporting Ground- Based Observations and Chemical Modeling We will acquire ground-based echelle spectroscopy of the optical Ca II and Na I absorption lines along direction. These additional low- ionization species will have high spectral resolution (few km/s) intermediate between the radio 21-cm data and the STIS UV data. The line profiles and optical depths will be used to constrain CLOUDY models of the cold absorbing medium in the Magellanic Bridge and derive chemical abundances and ionization conditions. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 B0312-770 GALAXY, QUASAR RA=03H 11M 55.38S +/- 0S, DEC=- 2000 z=0.22 V = 16.2 76D 51' 50.8" +/- 0", PLATE- B-V = 0 ID=00RE Coordinate Source: GSC_SURVEY_PLATE Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0 0 0 8651( 4) - 06/18/01 09:13 - [ 4] Visit: 01 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 3 B0312-770 STIS/F ACCUM 0.2X0.2 E140M 1425 4 40 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 5] Visit: 02 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 23 B0312-770 STIS/F ACCUM 0.2X0.2 E140M 1425 4 40 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 6] Visit: 03 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 31 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 33 B0312-770 STIS/F ACCUM 0.2X0.2 E140M 1425 4 40 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 7] Visit: 04 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 41 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 43 B0312-770 STIS/N ACCUM 0.2X0.2 E230M 2561 2 30 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 8] Visit: 13 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 31 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 33 B0312-770 STIS/F ACCUM 0.2X0.2 E140M 1425 4 40 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 9] Visit: 14 Visit Priority: 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 ------------------------------------------------------------------------------------------------------------------------------------ 41 B0312-770 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 3.0 S CD P ------------------------------------------------------------------------------------------------------------------------------------ 43 B0312-770 STIS/N ACCUM 0.2X0.2 E230M 2561 2 30 M EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 8651( 4) - 06/18/01 09:13 - [ 10] Summary Form for Proposal 8651 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements EXPAND ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names B0312-770 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 2561 ------------------------------------------------------------------------------------------------------------------------------------