Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4481c Report Date: 09-May-96:19:38 Version: ********** Check-in Date: ********** 1.Proposal Title: THE NATURE OF THE INTERSTELLAR MEDIUM AROUND SN 1987A ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM GO Sub Category ABSORPTION LINES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Frederick C. Bruhweiler THE CATHOLIC UNIVERSITY OF A ------------------------------------------------------------------------------------ 7. Abstract The extreme initial brightness of SN 1987A allowed the IUE and ground-based observatories to obtain an unsurpassed dataset for interstellar (IS) absorption lines for the LMC; it provided a unique opportunity to probe the IS environment of supernova. However, several unanswered questions remain. First, were the unusually strong C IV and Si IV features seen in the IUE spectrum formed in a UV flash of the supernova or did they pre-exist the explosion as the diffuse \[O III\] emission and 800 O stars in the vicinity suggest\? Second, what is the origin of the strong optical \[Fe X\] absorption seen toward SN 1987A\? In an effort to answer these questions, we will use the GHRS, in the G160M, G200M, and echelle-B modes to probe the directions toward two LMC stars, Sk -69 203 and Sk -69 209a, that lie within 50 pc of SN 1987A in the plane of the sky. These stars are uncontaminated by the UV flash or circumstellar nebula and likely share the same interstellar environment as SN 1987A. We will search for strong C IV (1548,1550A) in these stars to assess if the strong C IV predated SN 1987A. We will also observe high ionization N V (1238,1242A), which cannot be produced by normal stellar photoionization, to place constraints on the formation of \[Fe X\] and the distribution of hot coronal gas near SN 1987A. We will observe Zn II and Fe II to determine the depletion patterns in the 10-24 expected discrete components along the line-of-sight. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 7.75 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4481c PI: Frederick C. Bruhweiler Proposal Title: THE NATURE OF THE INTERSTELLAR MEDIUM AROUND SN 1987A ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Frederick C. Bruhweiler THE CATHOLIC UNIVERSITY OF USA AMERICA Michelle A. Fitzurka THE CATHOLIC UNIVERSITY OF USA AMERICA Andrew M. Smith NASA/GODDARD SPACE FLIGHT CENTER USA Stephen P. Maran NASA/GODDARD SPACE FLIGHT CENTER USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We have selected two UV bright stars nearest to SN 1987A in the LMC accessible at moderate dispersion with the GHRS( Sk -69 209a HD269828; WN3-5 M_v=10.9 and Sk -69 203 (B0.5 I; M_v=12.2). The projected lines-of-sight toward Sk -69 203 and Sk -69 209a pass within 35 and 50 pc of SN 1987A, assuming (d_LMC=50 kpc). observations would sample lines-of-sight free of any effects of a UV-flash or CS- envelope and probe the ambient interstellar environment of SN 1987A. The GHRS observations of the two LMC stars 1987A will provide data at S/N ~ 20 through the large science aperture (LSA). The data will be obtained using G160M, G200M, and ECH-B gratings. The echelle-B will be centered at 2379A to obtain data for two Fe II lines (2382.76 and 2373.74A) for expected vel. range, spanning a factor of 10 in f-value. The G200M at 2045A will sample Zn II doublet at 2026.14 and 2062.66A. As a bonus, we will also sample Cr II, Mg I, and Co II at the same grating settings. Blending of high velocity Zn II and Cr II can be acounted for in the data analysis. We will sample C IV doublet at 1550A and C I lines near 1560A with a single G160M setting. We will use the deduced absorption from the low-lying J-levels in C I to obtain pressures in intervening diffuse clouds (Smith et al. 1991). A G160M exposure, centered at 1250A, will sample absorption from the N V, Mg II, S II, and Si II from 1238 to 1260. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Observations of these two targets with the IUE in 1987 showed that neither bright enough to give useful high dispersion spectra with IUE. Therefore, the GHRS on HST is required for this research. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. N/A ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. We will only require wavelength calibrations at the specified wavelength settings as presented in exposure logsheet. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. All data will be reduced and analyzed using software at either NASA/GSFC or CUA that has developed by the P-I or members of the GHRS Support Group at GSFC. The procedure for data reduction and analysis is as follows: After the individual FP- SPLITS have been co-added, the accompanying wavelength calibrations will be used to place all the data on an accurate wavelength (velocity) scale. We will use profile fitting in the velocity frame to determine the number of absorption components along the line-of-sight. In addition to curve-of-growth techniques, we will adopt the formulation of Savage and Sembach (1991) to present column density versus velocity (see Savage et al. 1991 for application to GHRS data). Presented in this way, the data quickly and easily show how elemental depletion varies along the line-of-sight from component to component. The two lines-of- sight toward Sk -69 203 and Sk -69 209a will be compared with those obtained from IUE data for SN 1987A. This direct comparison will determine which, if any, velocity components of C IV seen in the IUE actually were produced via a UV-flash of the supernova. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Seven refereed publications, none directly related to this program. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The PI and graduate students at CUA are working with members of the GHRS/IDT at NASA with access to NASA computing facilities. Also, CUA has same software installed on comparable, but faster machines at CUA. Moreover, the PI, along with several capable graduate students, has developed the necessary software for the complete analysis of data requested in this proposal. ------------------------------------------------------------------------------------ 11. Address Information Name: Frederick C. Bruhweiler Category: PI Institution: The Catholic University of Americ Address: Physics Department - 200 Hannan Hall 620 Michigan Avenue N. E. City: Washington D. C. State: Zip Code: 20064 Country: USA Telephone: (202)319-5315 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4481c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 SK-69D203 B,105 RA = 05H 35M 27.31S +/- 2000 1 V=12.2 GSC09162.006 0.1S, 2 F-CONT(1240)=1.9 E-13 29 DEC = -69D 13' 52.2" +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ 2 SK-69D209A B,105 RA = 05H 35M 59.69S +/- 2000 1 V=10.9 GSC09162.001 0.1S, 2 F-CONT(1240)=4.8 E-13 37 DEC = -69D 11' 52.2" +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4481c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SK-69D203 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 1 1 CYCLE 3 /1.0-7.1 ONBOARD ACQ FOR 1.1 Comments: STEP-TIME=0.2 S ------------------------------------------------------------------------------------------------------------------------------------ 1.1 SK-69D203 HRS ACQ/ 2.0 MIRROR-N2 1 20.4S 1 1 ONBOARD ACQ FOR PEAKUP 2.1-7.1 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2.1 SK-69D203 HRS ACCUM 2.0 G160M 1247 STEP-PATT=4 5 345.6S 10 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 3.1 SK-69D203 HRS ACCUM 2.0 G160M 1550 STEP-PATT=4 9 345.6S 20 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 4.1 WAVE HRS ACCUM SC2 G160M 1550 STEP-PATT=4 1 60S 20 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 5.1 SK-69D203 HRS ACCUM 2.0 G200M 2045 STEP-PATT=4 5 345.6S 20 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 6.1 SK-69D203 HRS ACCUM 2.0 ECH-B24 2379.29 STEP-PATT=7 7 217.6S 20 1 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 7.1 WAVE HRS ACCUM SC2 ECH-B24 2379.29 STEP-PATT=7 1 60S 20 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4481c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN STEP-PATT=4 STEP-PATT=7 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 7.75 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ABSORPTION LINES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 3 /1.0-7.1; ONBOARD ACQ FOR 1.1; ONBOARD ACQ FOR 2.1-7.1; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M G200M ECH-B24 ------------------------------------------------------------------------------------------------------------------------------------ Target Names SK-69D203 GSC09162.00629 SK-69D209A GSC09162.00137 ------------------------------------------------------------------------------------------------------------------------------------