! 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
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! 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
!
!
Ship_Via: UPS ! UPS (2-day) or OVERNIGHT
! Overnight shipping done at PI expense
Recipient_Email: ! Needed if Ship_To: is not PI_Address
! <free-text>
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