6078( 7) - 02/12/96 17:36 - [ 1]
PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only
ID: 6078
Version: 7
Check-in Date: 12-Feb-1996
15:57:19
1.Proposal Title:
The wind momentum--luminosity relationship for SMC A- and B-supergiants
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2. Scientific Category 3. Proposal For 4. Cycle
Hot Stars GO 5
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5. Investigators
Contact?
PI: Daniel Lennon Universitaets-Sternwarte Muenchen
CoI: Stephan Haser Universitaets-Sternwarte Muenchen N
CoI: Kim Venn Universitaets-Sternwarte Muenchen N
CoI: Rolf-Peter Kudritzki Universitaets-Sternwarte Muenchen N
CoI: Otmar Stahl Landessternwarte Koenigstuhl Heidelberg N
CoI: Bernhard Wolf Landessternwarte Koenigstuhl Heidelberg N
CoI: Joachim Puls Universitaets-Sternwarte Muenchen N
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6. Abstract
Very recently a tight empirical relation between the wind momentum and luminosity
has been found for galactic supergiants of spectral type O,B and A. This wind
momentum-luminosity relationship provides the means of determining the distances of
blue supergiants in other galaxies much more accurately than traditional methods.
However using HST observations of O-stars in the Magellanic Clouds it has been
demonstrated that this method is dependent on metallicity with large departures from
the Milky Way results occurring for the SMC. We propose observing a sample of A- and
B-supergiants in the SMC to derive wind terminal velocities which will be used
together with visual data, including HAlpha profiles, to derive stellar parameters
and mass-loss rates. These results for the low metallicity environment of the SMC,
and analogous results for Milky Way and LMC, will be used to calibrate and verify
this technique for blue supergiants such that it can be applied to stars in even
more distant galaxies. An important corollary to this work is that the calibration
of mass-loss rates as a function of metallicity is important for many other aspects
of astronomy involving massive stars; stellar evolution, starburst regions/galaxies,
dynamics/energetics of HII regions and chemical evolution of galaxies.
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6078( 7) - 02/12/96 17:36 - [ 2]
Observations Description
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We plan to observe a selection of luminosity class Ia supergiants in the SMC
covering spectral types B1 to A2 in the SMC using the GHRS. The early to middle
B-type supergiants are expected to have terminal velocities as low as 500kms
and these will be observed using the low resolution grating (G140L - resolution
~ 150kms) covering the spectral range 1300-1586Angstrom\\ in one exposure per
star. This region contains important P-Cygni features due to resonance lines of
C, ii 1335Angstrom , Si, iv 1400Angstrom\\ and C, iv 1540Angstrom\\
(wavelengths approximate) and many lines of iron group elements for spectral
types as late as B5 Ia (Walborn & Nichols-Bohlin, 1987, PASP, 99, 40). The late
B- type and early A-supergiants on the other hand can have terminal velocities
as low as 200kms and these stars we propose to observe with the G270M medium
resolution grating (resolution approximately 10kms) covering the spectral
regions 2580-2630Angstrom\\ and 2710-2760Angstrom\\ in two esposures per star.
These regions contain the important Fe, ii multiplets 1 and 62,63 respectively
which can be used to estimate stellar terminal velocities (Stahl et al, 1991,
A&A, 252, 693) but also iron abundances in conjunction with optical data. These
latter set of observations will be binned to a factor two lower resolution
which will also improve s/n per resolution element. For many of our targets low
resolution IUE observations are available with which to estimate count rates,
for other objects we scaled flux distributions from similar spectral types
(corrected for extinction but which in all cases is not more than 0.1 mag) or
were estimated using appropriate Kurucz low metallicity, low gravity model
atmospheres. Typical exposure times (excluding overheads) range from 8 minutes
for AV264 to 41 minutes for AV268 for a s/n of 50. Thus for each of 9 B-
supergiants we require a single orbit to complete the observation, for the
brighter stars this will result in a s/n significantly better than 50,
important for spectrum synthesis of metal lines. Exposure times for the A-
supergiants are longer due to the reduced uv flux and the higher resolution,
for each of 4 A-supergiants we require 2 orbits to obtain a s/n of 50 (in two
wavelength regions) except that the faintest A-supergiant, AV478, requires 3
orbits.
Real Time Justification
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Calibration Justification
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Additional Comments
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Data Distribution
Media: 8MM
Blocking Factor: 10
Ship To: PI_Address
Ship Via: UPS
Email: ,
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6078( 7) - 02/12/96 17:36 - [ 3]
TARGET LIST a) Fixed Targets
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Tar| Target | Target | Target |Coord | Radial | Flux data
No | Name | Description | Position |Eqnx | Vel. |
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1 AV483 STAR, B0-B2 III-I RA=01H 15M 28.82S +/-1", DEC=- 2000 V = 11.85
73D 19' 49.8" +/-1", PLATE- B-V = -0.08
ID=06B1
2 AV393 STAR, B0-B2 III-I RA=01H 05M 56.30S +/-1", DEC=- 2000 V = 11.43
72D 19' 44.8" +/-1", PLATE- B-V = -0.02
ID=06B1
3 AV242 STAR, B0-B2 III-I RA=01H 00M 06.84S +/-1", DEC=- 2000 V = 12.11
72D 13' 57.0" +/-1", PLATE- B-V = -0.13
ID=06B1
4 AV264 STAR, B0-B2 III-I RA=01H 01M 07.72S +/-1", DEC=- 2000 V = 12.36
71D 59' 58.6" +/-1", PLATE- B-V = -0.15
ID=06B1
9 AV340 STAR, B0-B2 III-I RA=01H 03M 49.50S +/-1", DEC=- 2000 V = 12.71
72D 07' 30.0" +/-1", PLATE- B-V = -0.06
ID=06B1
10 AV315 STAR, B6-B9.5 III-I RA=01H 02M 49.60S +/-1", DEC=- 2000 V = 10.90
72D 10' 14.2" +/-1", PLATE- B-V = 0.06
ID=06B1
11 AV415 STAR, B6-B9.5 III-I RA=01H 07M 18.20S +/-1", DEC=- 2000 V = 10.52
72D 28' 03.5" +/-1", PLATE- B-V = 0.10
ID=06B1
12 AV136 STAR, A0-A3 III-I RA=00H 52M 51.30S +/-1", DEC=- 2000 V = 10.97
73D 06' 53.2" +/-1", PLATE- B-V = 0.13
ID=06B1
13 AV478 STAR, A0-A3 III-I RA=01H 14M 21.60S +/-1", DEC=- 2000 V = 11.56
73D 12' 45.0" +/-1", PLATE- B-V = 0.10
ID=06B1
6078( 7) - 02/12/96 17:36 - [ 4]
Visit: 01
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: <none>
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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1 AV483 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 4.5S ONBOARD ACQ FOR 2
Comments: STEP-TIME=0.5S
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2 AV483 HRS ACCUM 2.0 G140L 1200- FP-SPLIT=STD 1 544S
1486
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3 AV483 HRS ACCUM 2.0 G140L 1480- FP-SPLIT=STD 1 979.2S
1766
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6078( 7) - 02/12/96 17:36 - [ 5]
Visit: 02
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: <none>
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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1 AV393 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 9S ONBOARD ACQ FOR 2
Comments: STEP-TIME=1S
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2 AV393 HRS ACCUM 2.0 G140L 1200- FP-SPLIT=STD 1 544S
1486
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3 AV393 HRS ACCUM 2.0 G140L 1480- FP-SPLIT=STD 1 979.2S
1766
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6078( 7) - 02/12/96 17:36 - [ 6]
Visit: 03
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: <none>
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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1 AV242 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 9S ONBOARD ACQ FOR 2
Comments: STEP-TIME=1S
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2 AV242 HRS ACCUM 2.0 G140L 1200- FP-SPLIT=STD 1 544S
1486
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3 AV242 HRS ACCUM 2.0 G140L 1480- FP-SPLIT=STD 1 979.2S
1766
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6078( 7) - 02/12/96 17:36 - [ 7]
Visit: 04
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: GS ACQ FOR 10 TO BEGIN ON 1ST ORBIT:TOTAL = 2 ORBITS FOR VISIT
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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7 AV264 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 18S ONBOARD ACQ FOR 8
Comments: STEP-TIME=2S
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8 AV264 HRS ACCUM 2.0 G140L 1290- FP-SPLIT=STD 1 652.8S
1576
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9 AV340 HRS ACQ 2.0 MIRROR-N1 BRIGHT=RETURN 1 18S ONBOARD ACQ FOR 10
Comments: STEP-TIME=2S, SAME ORBIT AS EXP 8
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10 AV340 HRS ACCUM 2.0 G140L 1290- FP-SPLIT=STD 1 1958.4S
1576
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6078( 7) - 02/12/96 17:36 - [ 8]
Visit: 06
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: GS ACQ FOR 15 TO BEGIN IN 2ND ORBIT: TOTAL = 3 ORBITS FOR VISIT
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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11 AV315 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S ONBOARD ACQ FOR 12-13
Comments: STEP-TIME=0.5S
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12 AV315 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 1196.8S
2630
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13 AV315 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 1305.6S
2760
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14 AV415 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S ONBOARD ACQ FOR 15-16
Comments: STEP-TIME=0.5S
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15 AV415 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 1088S
2630
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16 AV415 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 1088S
2760
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6078( 7) - 02/12/96 17:36 - [ 9]
Visit: 08
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: <none>
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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17 AV136 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 4.5S ONBOARD ACQ FOR 18-19
Comments: STEP-TIME=0.5S
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18 AV136 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 2284.8S
2630
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19 AV136 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 2393.6S
2760
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6078( 7) - 02/12/96 17:36 - [ 10]
Visit: 09
Visit Requirements: PCS MODE F
On Hold Comments: <none>
Additional Comments: <none>
Exposures
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Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special
Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements
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20 AV478 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 9S ONBOARD ACQ FOR 21-22
Comments: STEP-TIME=1S
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21 AV478 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 3699.2S
2630
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22 AV478 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 4134.4S
2760
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6078( 7) - 02/12/96 17:36 - [ 11]
Summary Form for Proposal 6078
Item Used in this proposal
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Configurations HRS
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Opmodes ACQ ACCUM
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Optional Parameters BRIGHT=RETURN FP-SPLIT=STD
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Proposal Category GO
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Scientific Category Hot Stars
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Special Requirements PCS MODE F ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 8 ONBOARD ACQ FOR 10 ONBOARD ACQ FOR 12-13 ONBOARD ACQ
FOR 15-16 ONBOARD ACQ FOR 18-19 ONBOARD ACQ FOR 21-22
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Spectral Elements MIRROR-N1 G140L MIRROR-N2 G270M
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Target Names AV483 AV393 AV242 AV264 AV340 AV315 AV415 AV136 AV478
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