! Proposal 6542, submission 1 ! PI: Jason A. Cardelli ! Received Thu Feb 15 15:06:01 EST 1996 ! From: jason@hrssun.gsfc.nasa.gov ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6542,v 5.1 1996/07/31 20:40:07 pepsa Exp $ ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6542,v 5.1 1996/07/31 20:40:07 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Manning ! Phone: 410-338-4456 , E-mail: manning@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-0394.cardelli.prop ! Date generated: Fri Dec 22 16:51:00 EST 1995 ! Proposal_Information ! Section 4 Title: Interstellar Carbon Abundance in Low Density Gas Proposal_Category: GO Scientific_Category: INTERSTELLAR MEDIUM Cycle: 6 Investigators PI_name: Ulysses J. Sofia PI_Institution: Villanova University CoI_Name: David M. Meyer CoI_Institution: Northwestern University Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) We propose to obtain high signal-to-noise data (~1300) with the GHRS of the weak intersystem line of C II (Lambda2325 Angstrom) toward Kappa Ori and Lambda Ori to determine the limits on the gas-phase abundance of carbon, C/H, in environments where other elements show measurable return from dust to the gas-phase in comparison to moderately dense sight lines like Zeta Oph. In a recent study with the GHRS, we found that the abundance of carbon is remarkably constant in sight lines where the fraction of H in H_2, f(H_2), ranges between 10^-1 and 1. At the same time however, other elements exhibiting a similar bulk depletion (from solar) show a modest increase in their gas-phase abundance from high-to-low f(H_2). This increase is observed to continue to significantly lower values of f(H_2) of the order of 10^-5. Since we interpret this increase as the return of matter to the gas from the dust, the lack of variability in the observed C/H would seem to suggest that the carbon-based grains (and/or PAHs) are not easily disrupted. However, the existing C/H data in the moderate-to-low f(H_2) sight lines are not definitive. Determining the gas-phase C/H toward Kappa Ori and Lambda Ori f(H_2) ~eq 3times10^-5 and 3times10^-2, respectively will set practical limits on the variability of gas-phase C/H in low density gas and the resiliency of the carriers of carbon in non-atomic form. Given the high S/N requirements for this project, this is the last opportunity to achieve these results since such precision weak line work will not be possible with STIS. Questions ! Free format text (please update) Observing_Description: We propose to obtain Ech-B data in the LSA (2 samples/diode) on the C II line at Lambda2325.403 Angstrom\ toward Kappa and Lambda Ori, stars sampling moderate-to-low f(H_2) values (see Fig. 1). We use the LSA to maximize the throughput (the 20\% reduction in resolution over the SSA will have no impact on the science goals). Basic target information is shown in the table below. Since the C II line will be weak toward these two stars (see Fig. 2), accurate measures require very high S/N values at each diode substep. Accounting for guide star acquistion, target ACQ, ACQ/PEAKUP, and exposure overhead times, these values can be obtained in the time remaining in a single orbit (these estimates are based on the post-COSTAR LSA throughput data given in the GHRS Cycle 6 Handbook) for each star. The required S/N values will be achieved through analysis of multiple grating position subexposures, each obtained with the FP-SPLIT command. We are well versed in both the development and use of the techniques for obtaining high S/N GHRS data -- Cardelli & Ebbets 1994, ``Attaining High Signal-to-Noise Data with the Goddard High Resolution Spectrograph", in Calibrating the Hubble Space Telescope, (STScI: Baltimore) and Cardelli 1995, ``High S/N Spectroscopy with the GHRS: Methods and Applications", in Calibrating HST in the Post-Costar Era (STScI: Baltimore), in press. begintableh begintabularccccccccc Name & & Spectral Type & & V & & Log H_total^a & & Log f(H_2)^b , Kappa Ori (HD 38771) & & B0.5 Ia & & 2.09 & & 20.52 & & - 4.54 , Lambda Ori (HD 36861) & & O8 V & & 3.66 & & 20.83 & & -1.41 , endtabular beginraggedright, ^alog of the total column density of hydrogen nuclei, H_total = 2H_2 + H I, ^blog of the fractional abundance of hydrogen nuclei in H_2, f(H_2) = 2H_2/H_total, endraggedright endtable The targets proposed here have been previously observed with the GHRS (see Fig. 2). We plan on combining the higher S/N data obtained in this program with the existing data. This should yield a cumulative S/N ~ 1300 for each star (at each diode substep). We have already shown that such high S/N values are possible with the GHRS (Cardelli & Ebbets 1994; Meyer et al. 1994). Given that STIS will be unable to obtain such precise measures of weak lines, this represents the last foreseeable opportunity to do this type of science. Real_Time_Justification: NONE NONE Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 !tau CMa------------------------------- Target_Number: 1 Target_Name: HD57061 Alternate_Names: tau-cma Description: STAR, SUPERGIANT O Position: RA=07H 18M 42.4S +/- 0.03S, DEC=-24D 57' 15.2" +/- 0.5" Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V=4.40, B-V=-0.15 Comments: target previously observed with ghrs-these coordinates come from the hst observing log ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed !------------------------------------------------------- !HD57061 !------------------------------------------------------- Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 On_Hold_Comments: Visit_Comments: Exposure_Number: 1 ! Section 6.5 Target_Name: HD57061 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-A2 Wavelength: Optional_Parameters: BRIGHT=RETURN, SEARCH-SIZE=3 Number_of_Iterations: 1 Time_Per_Exposure: 1.8S Special_Requirements: ONBOARD ACQ FOR 2-4 ! Section 7.2 Comments: STEP-TIME = 0.2s !------------------------------------------------------- Exposure_Number: 2 ! Section 6.5 Target_Name: HD57061 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-B24 Wavelength: 2324 Optional_Parameters: FP-SPLIT=STD,STEP-PATT=6 Number_of_Iterations: 3 Time_Per_Exposure: 6.72M !11.52M Special_Requirements: ! Section 7.2 Comments: !------------------------------------------------------- Exposure_Number: 3 ! Section 6.5 Target_Name: HD57061 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-B24 Wavelength: 2325 Optional_Parameters: FP-SPLIT=STD,STEP-PATT=6 Number_of_Iterations: 3 Time_Per_Exposure: 6.72M !11.52M Special_Requirements: ! Section 7.2 Comments: !------------------------------------------------------- Exposure_Number: 4 ! Section 6.5 Target_Name: HD57061 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-B24 Wavelength: 2326 Optional_Parameters: FP-SPLIT=STD,STEP-PATT=6 Number_of_Iterations: 3 Time_Per_Exposure: 6.72M !11.52M Special_Requirements: ! Section 7.2 Comments: !------------------------------------------------------- Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! 800 Lancaster Ave ! Villanova ! 19085 ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address ! ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator