! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 6073,v 8.1 1996/07/05 14:11:20 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: Dustin Manning ! Phone: 410 338-4456 , E-mail: manning@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Date generated: Sun Dec 18 19:08:23 EST 1994 ! Proposal_Information ! Section 4 Title: The Chemical Composition of the Magellanic Bridge Proposal_Category: GO Scientific_Category: Hot Stars Cycle: 5 Investigators PI_name: Philip Dufton PI_Institution: The Queen's University of Belfast ! Contact: Y CoI_Name: Rolf-Peter Kudritzki CoI_Institution: Universitaets-Sternwarte Muenchen Contact: ! Y or N (designate at most one contact) CoI_Name: Danny Lennon CoI_Institution: Universitaets-Sternwarte Muenchen Contact: ! Y or N (designate at most one contact) CoI_Name: Francis Keenan CoI_Institution: Queen's University of Belfast Contact: ! Y or N (designate at most one contact) CoI_Name: Nigel Hambly CoI_Institution: Queen's University of Belfast Contact: ! Y or N (designate at most one contact) CoI_Name: Robert Rolleston CoI_Institution: Armagh Observatory Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Early-type stars are excellent probes of the current chemical composition of our own and external galaxies. Main sequence stars are particularly useful as the physics of their atmospheres are well understood, while their surfaces should be unaffected by the products of interior nuclear reactions. We have used such targets to map the chemical composition of our galaxy and to provide accurate abundances for the SMC and LMC. Our attempts to determine the chemical composition of the Magellanic Bridge have been less successful despite generous allocations of 4m telescope time. This has been principally because of the absence of optical metal absorption lines due to the large metal depletion of the Bridge material and for some elements (e.g. iron) the intrinsic weakness of their optical spectra. Here we propose ultra-violet observations of a B0V Bridge star, DI 1388, which should provide reliable abundances of both the lighter (e.g. carbon and nitrogen) and heavier metals (e.g. silicon and iron). The HST observations will be supplemented by our existing (and possible additional) AAT high resolution echelle spectra. Non-LTE model atmosphere analyses of the optical hydrogen and hydrogen lines will be used to estimate atmospheric parameters, which will then form the basis for non-LTE analyses of the ultra-violet spectra. Using differential methods, abundances accurate to 0.1-0.2 dex should be achievable, which will constrain the origin and evolutionary history of this material. Questions ! Free format text (please update) Observing_Description: We will observe DI 1388 using the GHRS and two gratings, viz. beginenumerate em the low resolution grating G140L (resolution ~ 150kms) in two spectral ranges 1200- 1486Angstrom and 1500-1786Angstrom. These regions contain the resonance lines of N, v 1240Angstrom, C, ii 1335Angstrom, Si, iv 1400Angstrom, C, iv 1540Angstrom and N, iv 1740Angstrom, together with other important features such as the Si, iii triplet multiplet at 1294-1305Angstrom (all wavelengths approximate). em the moderate resolution grating G200M (resolution ~ 14kms) in the spectral region 1890- 1930Angstrom. This region contains the strong Fe III multiplet that we have previously used to estimate iron abundances from IUE spectra of B-type stars (see section 2). endenumerate All these feature should be observable even if the metal depletion in the Bridge material is substantially greater than in the SMC. Our optical spectra indicated that DI 1388 has a moderate rotational velocity (approximately 180kms), which should well match the proposed spectral resolution of the G140L grating. For the higher resolution spectra we will bin together four pixels to improve our single-to-noise ratio without significantly compromising our spectral resolution. Count rates and exposure times have been estimated from a Kurucz low metallicity model atmosphere with the appropriate effective temperature and gravity and assuming an E(B-V) of 0.^m05. Our low resolution IUE observations of the cooler Magellanic Bridge supergiant, DI 1194, implies that reddening in this region is very small and hence our count rates and signal-to-noise ratios may be slightly conservative. In the first orbit, we will undertake both the low resolution observations with exposure times of around 10 and 40 minutes per spectral region resulting in a signal- to-noise ratio of ~50 at 1500Angstrom. In the second orbit, the observations of the iron lines will be made and after binning a signal-to-noise ratio of at least 30 per resolution element should be obtained in approximately 50 minutes. Real_Time_Justification: Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number:1 Target_Name:STAR-025713-725256 Alternate_Names:DI1388 Description:STAR,B0-B2 V-IV Position:RA=2H 57M 11.94S +/- 0.1S, DEC=-72D 52' 54.6" +/- 1", PLATE-ID=00RE Equinox:2000 RV_or_Z:V=150 Flux:V=14.39 TYPE=B0V B-V=-0.26 E(B-V)=0.05 F(1350)=2.32E-13 F(1670)=1.53E-13 F(1910)=1.14E-13 Comments:Fluxes from ATLAS model Teff=32000 logg=4.0 and SMC extinction ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number:1 Visit_Requirements:PCS MODE F Visit_Comments: Exposure_Number:1 Target_Name:STAR-025713-725256 Config:HRS Opmode:ACQ Aperture:2.0 Sp_Element:MIRROR-N2 Wavelength: Optional_Parameters:BRIGHT=RETURN Time_Per_Exposure:9S Number_Of_Iterations:1 Comments:STEP-TIME=1S Special_Requirements:ONBOARD ACQ FOR 2-4 ! Uncomment or copy exposure level special requirements needed Exposure_Number:2 Target_Name:STAR-025713-725256 Config:HRS Opmode:ACCUM Aperture:2.0 Sp_Element:G200M Wavelength:1910 Optional_Parameters:FP-SPLIT=STD Time_Per_Exposure:1414.4S Number_Of_Iterations:1 !Special_Requirements: EXPAND Exposure_Number:3 ! Section 6.5 Target_Name:STAR-025713-725256 Config:HRS Opmode:ACCUM Aperture:2.0 Sp_Element:G140L Wavelength:1343 Optional_Parameters:FP-SPLIT=STD Time_Per_Exposure:761.6S Number_Of_Iterations:1 Exposure_Number:4 ! Section 6.5 Target_Name:STAR-025713-725256 Config:HRS Opmode:ACCUM Aperture:2.0 Sp_Element:G140L Wavelength:1643 Optional_Parameters:FP-SPLIT=STD Time_Per_Exposure:1849.6S Number_Of_Iterations:1 !Special_Requirements: EXPAND 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 ! ! 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