Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4239c Report Date: 09-May-96:19:28 Version: ********** Check-in Date: ********** 1.Proposal Title: ABUNDANCE ENHANCEMENTS IN HALO GAS -- RPT FOR HOPR#64 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID INTERSTELLAR MEDIUM RPT/GO 2348 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Edward B. Jenkins PRINCETON UNIVERSITY USA 609-258-3826 SR. RES. ASTRONOMER ------------------------------------------------------------------------------------ 7. Abstract We propose to use HRS in its moderate resolution mode to examine interstellar absorption lines in the spectra of stars situated ~1 kpc or more from the galactic plane. We will compare Fe II, S II, Si II and Al II to see if their relative abundances differ from ordinary interstellar gas, as indicated by a conservative interpretation of some IUE data. We will equate possible abundance enhancements in halo gas, if they are indeed real, with element replenishments found in shocked gases in the plane (associated with the Vela SNR) to see if the pattern from element to element differs from that resulting from the destruction of grains. This differentiation will indicate whether the principal enhancements are from grain evaporation as the gas is ejected from the plane, or whether element injection from Type I supernovae plays an important role. ------------------------------------------------------------------------------------ 8. Scientific Key Words: HALO, SUPERNOVA REMNANT, ABUNDANCES, GAS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 12.00 par: 0 10. Num targs pri: 7 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4239c PI: Dr. Edward B. Jenkins Proposal Title: ABUNDANCE ENHANCEMENTS IN HALO GAS -- RPT FOR HOPR#64 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ P.I. Edward B. Jenkins PRINCETON UNIVERSITY USA George Wallerstein WASHINGTON, UNIVERSITY OF USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. A SHORT DESCRIPTION OF THE PROPOSED OBSERVATIONS For all of the 7 stars covered by this proposal, we intend to observe the following lines using the GHRS G160M grating. Our goal is to achieve a signal-to-noise ratio of approximately 50 for any diode which is exposed to a full continuum level. ION WAVELENGTH(A) LOG (F LAMBDA) COMMENTS S II 1250.586 0.83 these two lines can be Fe II 1608.456 2.55 Al II 1670.784 3.50 Al III 1854.720 2.70 these two lines can be P II 1301.878 1.35 Bonus line O I 1302.169 1.80 Bonus line Si II 1304.369 2.28 Strong line to match Al II Si II 1808.003 0.83 Weak line to match S II The two lines of S II can be observed simultaneously. The Fe II line may be observed at the same carrousel setting as the S II lines. The singly ionized species are the dominant ionization stages and represent the primary information on abundances. In addition, we'll observe doubly ionized Al to check that these elements are not appreciably ionized more than once by an extragalactic radiation flux below the Lyman limit. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. THE NEED FOR CAPABILITIES OF HST Lines from the ground states of the ions discussed in this proposal are found only in the ultraviolet. An extensive investigation of high-resolution spectra in the IUE archives revealed tantalizing but rather crude indications that indeed there is element enrichment in the halo gas. Unfortunately, interstellar absorption lines which are strong enough to measure reliably with IUE almost always are badly saturated. Correcting for the saturation using curve-of-growth techniques is of dubious value. If one has good signal-to-noise recordings at a high enough resolution to completely resolve the velocity structure of a line, column densities may be derived by integrating the optical depth over velocity intervals where the line is not heavily saturated. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. All of our stars except HD120086 (target 6) have published fluxes at 1565A available from the TD-1 survey. To obtain fluxes at wavelengths that will be covered by this program, relative to the flux at 1565A, we used spectra in the IUE spectral atlas for stars of similar spectral type. There are no large reddening corrections to apply to our stars, since all values of E(B-V) are of order or less than 0.1. To observe wavelength intervals centered at 1252.5, 1318.5, 1619.0, 1667.0, 1817.5, and 1857.0 A at a signal-to-noise ratio of 50:1 per diode, we expect that an observing time given by t_(-10) = sum{2.50e13 / [(S(lambda) F / F_1560) 0.94]} = 29715 seconds will be required to cover the 6 wavelength intervals for a star with F(1560) = 10^{-10} erg cm^{-2} s^{-1} A^{- 1}. We used values of S(lambda) tabulated in an update on instrument performance dated 6 May 1991 (p. 8 of GHRS memo). These numbers, in turn, were multiplied by the SSA loss factor of 0.25. The factor 0.94 results from our planning to use Substep pattern #5. For the 7 stars in our program our total observing time T = t(-10) sum{[F(1565)X10^10]^-1} = 533 minutes. Since we need to observe each star only once, the additional spacecraft time is only 7 stars X (15 min acquisision + 6 min set-up) = 147 min. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. PLANS FOR DATA REDUCTION AND ANALYSIS We think that it is very likely that the capabilities of the SDAS/IRAF analysis system will satisfy our reduction requirements. We intend to familiarize ourselves with this system during one or more visits to the STScI in the early phases of the program. If it is not too difficult, we may try to install this software on our own computer systems and continue to work on our data at our home institutions. If this is not feasible, we will complete our reductions during subsequent visits to the STScI. Present systems at our home institutions are a VAX/8350, Sun and Convex at Princeton, and a VAX/780 and MicroVAX cluster at the University of Washington. IRAF is currently up and running at the University of Washington. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). VAX/8350, Sun-4 and Convex computers at Princeton VAX/780, and MicroVAX cluster at the University of Washington ------------------------------------------------------------------------------------ 11. Address Information Name: EDWARD B. JENKINS Category: PI Institution: PRINCETON UNIVERSITY Address: DEPT. OF ASTROPHYSICAL SCI. PEYTON HALL; IVY LANE City: PRINCETON State: NJ Zip Code: 08544 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4239c [ 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 HD177566 STAR; TYPE=B1 III RA = 19H 03M 36.8S +/- 1." , 1950 V=-131 1 V = 10.2, TYPE=B1 III DEC = -41D 47' 57" +/- 1" 2 F-CONT(1565)=1.2+/-.1E-11 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4239c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1.01 DEFINE # HRS ACCUM 0.25 G160M 1252.5 STEP-PATT=4 1 110S # 2 1 SC1 FP-SPLIT=STD Comments: COVERAGE: S II 1250.586 ------------------------------------------------------------------------------------------------------------------------------------ 1.02 ^ # ^ ^ ^ G160M 1318.5 ^ 1 110S # 1 ^ Comments: COVERAGE: SI II 1304.369 ------------------------------------------------------------------------------------------------------------------------------------ 1.03 ^ # ^ ^ ^ G160M 1619.0 ^ 2 110S # 2 ^ 220S Comments: COVERAGE: FE II 1608.456 ------------------------------------------------------------------------------------------------------------------------------------ 1.04 ^ # ^ ^ ^ G160M 1667.0 ^ 2 110S # 2 ^ 220S Comments: COVERAGE: AL II 1670.784 ------------------------------------------------------------------------------------------------------------------------------------ 1.05 ^ # ^ ^ ^ G160M 1817.5 ^ 2 110S # 2 ^ 220S Comments: COVERAGE: SI II 1808.003 ------------------------------------------------------------------------------------------------------------------------------------ 1.06 ^ # ^ ^ ^ G160M 1857.0 ^ 2 110S # 2 ^ 220S Comments: COVERAGE: AL III 1854.720 1862.795 ------------------------------------------------------------------------------------------------------------------------------------ 5 HD177566 HRS ACQ 2.0 MIRROR-N2 FAINT=5000 1 5S 1 1 ONBOARD ACQ FOR SEARCH-SIZE=5 5.01 BRIGHT=65535 CYCLE 1 / 5.00- 5.02 Comments: COMPUTED RATE = 104K C/S. ------------------------------------------------------------------------------------------------------------------------------------ 5.01 HD177566 HRS ACQ/ 2.0 MIRROR-N2 1 9.2S 1 1 ONBOARD ACQ FOR PEAKUP 5.02 ------------------------------------------------------------------------------------------------------------------------------------ 5.02 USE SC1 HD177566 X4.0 33.3 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4239c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ^ ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ^ ACQ ACQ/PEAKUP ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters STEP-PATT=4 FP-SPLIT=STD FAINT=5000 SEARCH-SIZE=5 BRIGHT=65535 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for RPT/GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 12.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category INTERSTELLAR MEDIUM ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 5.01; CYCLE 1 / 5.00-5.02; ONBOARD ACQ FOR 5.02 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160M MIRROR-N2 ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD177566 ------------------------------------------------------------------------------------------------------------------------------------