7759( 4) - 01/29/99 09:05 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7759 Version: 4 Check-in Date: 29-Jan-1999 09:04:37 1.Proposal Title: Heavy Element Abundances in AV 304, a B0.5 Main Sequence Star in the Small Magellanic Cloud ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Geraldine Peters University of Southern California CoI: James A. Grigsby Wittenberg University N ------------------------------------------------------------------------------------ 5. Abstract We propose HST/GHRS of AV 304, a sharp-lined B0.5 main sequence star in the Small Magellanic Cloud, to determine the abundances of heavy elements, especially those of the iron group. For this exploratory study, we have selected three spectral fields (using the G160M grating) that contain measurable features of Ti III, V III, Cr III, Mn III, and Fe III, as well as prominent lines of C III, Si II, III, and S II. An analysis of ground-based data of this 15th magnitude star by Dufton, et al. (1990) revealed an average underabundance of 0.7 dex for most light elements, but a normal He abundance. This will be the first attempt to measure the abundances of Fe group elements in the photosphere of an early B, main sequence star in an external galaxy. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, the above- mentioned study did not yield this information because measurable lines from these species are found only in the UV spectral region. Abundances and abundance ratios of both heavy & light elements will be compared with results from H II regions, supernova remnants, and evolved massive stars in the SMC and theoretical calculations of nucleosynthesis. ------------------------------------------------------------------------------------ 7759( 4) - 01/29/99 09:05 - [ 2] Observations Description ------------------------ For this project we are targeting four spectral fields that contain a large number of relatively strong lines from the Fe group elements. We will use the STIS FUV-MAMA & NUV-MAMA detectors with gratings G140M and G230M and the narrowest slit, 52X0.1 arcsec. Further details, including exposure times to achieve a S/N of 10-25 & important ions contained in the bandpass, are provided in Table 1. TABLE 1 Ion Species Contained in Proposed Spectral Fields Sp. Interval Exposure Time Some Species Contained in Field 1194-1249 42 min. Cr III (UV 21), SI II (UV 5), Si III (UV ) 1245-1299 44 min. Si II (UV 4), S II (UV 1), Ti III (UV 2), V III (UV 5 & 7), Mn III (UV 9), 1294-1348 43 min. C II (UV 1), Si III(UV 4), Ti III(UV 1), Mn III(UV 9) 1344-1398 43 min. Si II (UV 7), Cr III(UV 36), Mn III (UV 8), P III (UV 7), Si IV (UV 1) 1724-1814 38 min. Ni III (UV 15 & 16), Co III (UV 21) 1888-1978 94 min. Fe III (UV 34, 51, 52, 53, 83, 95, 96, 108) Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: Media: ELECTRONIC Blocking Factor: 10 Ship To: STSCI Ship Via: Email: gjpeters@mucen.usc.edu ------------------------------------------------------------------------------------ 7759( 4) - 01/29/99 09:05 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AV304 EXT-STAR, B0-B2 V-IV RA=1H 2M 21.4S +/- 0.1S, DEC=- J2000 V = 14.98 72D 39' 14.6" +/- 0.50" B-V = -0.20 U-B = -0.98 E(B-V) = 0.08 F-CONT(1300)=1.9e-13 7759( 4) - 01/29/99 09:05 - [ 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 AV304 STIS/C ACQ F28X50L MIRROR 1 1 S ONBOARD ACQ FOR 10, 20, CD P 30, 40, 50 ------------------------------------------------------------------------------------------------------------------------------------ 10 AV304 STIS/C ACQ/PEA 52X0.1 MIRROR 1 1 S ONBOARD ACQ FOR 20, 30, CD K 40, 50 ------------------------------------------------------------------------------------------------------------------------------------ 20 AV304 STIS/F ACCUM 52X0.1 G140M 1222 1 42 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 AV304 STIS/F ACCUM 52X0.1 G140M 1272 1 44 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 AV304 STIS/F ACCUM 52X0.1 G140M 1321 1 43 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 AV304 STIS/F ACCUM 52X0.1 G140M 1371 1 36 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7759( 4) - 01/29/99 09:05 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 AV304 STIS/C ACQ F28X50L MIRROR 1 1 S ONBOARD ACQ FOR 20, 30, CD P 40, 50 ------------------------------------------------------------------------------------------------------------------------------------ 20 AV304 STIS/C ACQ/PEA 52X0.1 MIRROR 1 1 S ONBOARD ACQ FOR 30, 40, CD K 50 ------------------------------------------------------------------------------------------------------------------------------------ 30 AV304 STIS/N ACCUM 52X0.1 G230M 1769 1 38 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 AV304 STIS/N ACCUM 52X0.1 G230M 1933 1 46 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 50 AV304 STIS/N ACCUM 52X0.1 G230M 1933 1 42 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7759( 4) - 01/29/99 09:05 - [ 6] Summary Form for Proposal 7759 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 10, 20, 30, 40, 50 ONBOARD ACQ FOR 20, 30, 40, 50 ONBOARD ACQ FOR 30, 40, 50 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140M G230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names AV304 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1222 1272 1321 1371 1769 1933 ------------------------------------------------------------------------------------------------------------------------------------