5884( 0) - 07/18/95 18:27 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 5884 Version: ********** Check-in Date: ********** 1.Proposal Title: A White Dwarf Probe of Interstellar Deuterium ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Interstellar Medium GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Wayne Landsman Hughes STX CoI: Pierre Bergeron Universite de Montreal N CoI: Ulysses Sofia NRC/NASA/GSFC N ------------------------------------------------------------------------------------ 6. Abstract We propose to obtain GHRS echelle observations of interstellar hydrogen and deuterium toward the hot (Teff ~ 50,000 K) white dwarf HZ 43. EUV observations of HZ 43 (d = 65 pc) show it to be located in an unusually low column density direction (N(HI) ~ 6.5 * 10^17 cm^-2). Previous GHRS observations toward late-type stars have demonstrated the capability to study interstellar deuterium Ly-alpha\ in directions where the total column density is less than ~ 3 * 10^18 cm^-2. However, the derived D/H abundances toward late-type stars includes a systematic uncertainty due to the complex and poorly understood line profile of the chromospheric Ly-alpha\ emission. In contrast, the spectrum of HZ 43 has been successfully fit with a pure hydrogen model atmosphere at all wavelengths at which it has been observed. A second advantage of HZ 43 over late-type stars as a probe of the D/H abundance is its strong EUV and FUV continuum. In particular, the 504-912 Angstrom\ EUV continuum provides an independent check on the HI column density derived from Ly-alpha, and we will use the FUV continuum to observe interstellar species of small Doppler width, such as Mg II and Fe II, to resolve the velocity structure along the line of sight. Our simulations show that HZ 43 is sufficiently bright to yield a good S/N echelle spectrum at Ly-alpha, and likely provide the most unbiased estimate of D/H in the local interstellar medium. ------------------------------------------------------------------------------------ 5884( 0) - 07/18/95 18:27 - [ 2] Observations Description ------------------------ Six of our nine orbits will be dedicated to observing the Ly- alpha\ profile of HZ 43 with the echelle. We will use the large aperture to maximize the S/N. Geocoronal emission will be present but this emission is sufficiently narrow (< 0.1 Angstrom) that it can be placed entirely within the saturated interstellar core by observing at times of the year when the Earth's velocity toward HZ 43 matches the bulk velocity of the ISM toward HZ43 (~ -12 kms). To characterize the velocity and component structure we will use Ech-B to observe the Mg II Lambda2800 doublet and Fe II Lambda2382. The lines have been selected on the basis of their moderate strength (\log NfLambda (cm^-1) ~ 6.8-7.9) for the expected column density toward HZ 43. There are other moderate strength lines such as Si II Lambda1260, OI Lambda1302, Fe Lambda1608 that would be useful for studying depletions, but we defer their observations for future observing cycles. We will also obtain a medium resolution G160 spectrum at 1210 Angstrom\ to cover the entire broad (~ 30 Angstrom) white dwarf Ly-alpha\ absorption, in order to confirm the accuracy of the adopted model profile. begincenter begintabularrrrrrrrr Line & Wave & Orbit & Grating & Aper & Exp Time & S/N , NI, Ly-alpha & 1210 & 1 & G160M & SSA & 23m & 25 , Ly-alpha & 1215.7 & 2-7 & Ech- A & LSA & 275m & 22 , Mg II & 2795, 2803 & 8 & Ech-B & LSA & 40m & 25 , Fe II & 2382 & 9 & Ech-B & LSA & 43m & 25 , endtabular endcenter Real Time Justification ----------------------- We request observations during certain times of the year (within a 4 month period) when the Earth velocity matches the bulk interstellar velocity toward HZ 43. Calibration Justification ------------------------- None. Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 5884( 0) - 07/18/95 18:27 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HZ43 STAR, DA RA = 13H 16M 21.99S +/- 0.02S, J2000 V = 12.89 DEC = 29D 05' 57.0" +/- 0.2", B-V = -0.10 PLATE-ID = 002K F(1215) = 5 +/- 1 E-13 F(2382) = 4 +/- 0.5 E-13 F(2800) = 2.7 +/- 0.5 E-13 Comments: Coordinates are from GSC Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1982.387 -0.0116 -0.0813 0.0155 5884( 0) - 07/18/95 18:27 - [ 4] Visit: 01 Visit Requirements: BETWEEN 30-JUL-1995 AND 5-OCT-1995 On Hold Comments: Additional Comments: ALSO BETWEEN 18-MAR-1996 AND 23-MAY-1996 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 HZ43 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 9S ONBOARD ACQ FOR 12-14 Comments: STEP-TIME=1S; EXPECT 3700 COUNTS IN STEP-TIME ------------------------------------------------------------------------------------------------------------------------------------ 12 HZ43 HRS ACCUM 2.0 ECH-A 1215.6 FP-SPLIT=STD 12 652.8S ------------------------------------------------------------------------------------------------------------------------------------ 13 WAVE HRS ACCUM SC2 ECH-A 1215.6 SPYBAL=YES 1 DEF Comments: WAVECAL for exposure 14, Do NOT move carrousel ------------------------------------------------------------------------------------------------------------------------------------ 14 HZ43 HRS ACCUM 2.0 ECH-A 1215.6 FP-SPLIT=STD, 11 652.8S SPYBAL=NO ------------------------------------------------------------------------------------------------------------------------------------ 5884( 0) - 07/18/95 18:27 - [ 5] Visit: 02 Visit Requirements: BETWEEN 30-JUL-1995 AND 5-OCT-1995 On Hold Comments: Additional Comments: ALSO BETWEEN 18-MAR-1996 AND 23-MAY-1996 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 21 HZ43 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S ONBOARD ACQ FOR 22-23 Comments: STEP-TIME=0.2S; EXPECT 11860 COUNTS IN STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 22 HZ43 HRS ACCUM 2.0 ECH-B 2382 FP-SPLIT=STD 4 544S Comments: Fe II ------------------------------------------------------------------------------------------------------------------------------------ 23 HZ43 HRS ACCUM 2.0 ECH-B 2800 FP-SPLIT=STD 4 544S Comments: Mg II ------------------------------------------------------------------------------------------------------------------------------------ 24 HZ43 HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 25 KUP Comments: STEP-TIME=0.2, EXPECT 5900 COUNTS IN STEP- TIME ------------------------------------------------------------------------------------------------------------------------------------ 25 HZ43 HRS ACCUM 0.25 G160M 1210 13 108.8S Comments: Ly Alpha ------------------------------------------------------------------------------------------------------------------------------------ 5884( 0) - 07/18/95 18:27 - [ 6] Summary Form for Proposal 5884 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ACQ/PEAKUP ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN FP-SPLIT=STD SPYBAL=YES SPYBAL=NO SEARCH-SIZE = 5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Interstellar Medium ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 30-JUL-1995 AND 5-OCT-1995 ONBOARD ACQ FOR 12-14 ONBOARD ACQ FOR 22-23 ONBOARD ACQ FOR 25 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 ECH-A MIRROR-N2 ECH-B G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HZ43 WAVE ------------------------------------------------------------------------------------------------------------------------------------