6530( 3) - 02/12/96 08:18 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6530 Version: 3 Check-in Date: 12-Feb-1996 08:14:21 1.Proposal Title: The wind momentum-luminosity relationship for LMC A- and B-supergiants ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Daniel Lennon Universitaets-Sternwarte Muenchen CoI: Kim Venn Universitaets-Sternwarte Muenchen N CoI: Stephan Haser 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 ------------------------------------------------------------------------------------ 6. Abstract The wind momentum-luminosity relationship (WLR) for supergiant stars provides the means to determine the distances of these objects in other galaxies more accurately than traditional methods. The late B- and early A-type supergiants are particulary important since these stars are the brightest at visual wavelengths where the critical wind diagnostic feature, the HAlpha line, is observed. However, as has been demonstrated using O-stars in the Magellanic Clouds, the WLR is dependent on metallicity. In order to calibrate this method we have undertaken a systematic investigation of these objects in our galaxy and in the Magellanic Clouds. However, in contrast to the O-stars, the dynamics of the winds of late B- and early A-type supergiants as a function of metallicity are poorly understood. This information, in particular the velocity fields and terminal velocities, is most reliably derived for these stars from the shifts of wind lines in the ultra-violet; the required spectra for galactic objects is forthcoming from IUE observations while observations for stars in the SMC will be carried out with HST during Cycle 5. Here we propose observing a sample of late B- and early A-type supergiants in the LMC, to extend our sample to metallicities intermediate between the SMC and the Milky Way. This calibration is essential if we are to extend this method to supergiants in even more distant resolved galaxies beyond the Local Group using very large ground-based telescopes (Keck, VLT, HET). ------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 2] Observations Description ------------------------ Using the GHRS, we will observe 6 of the most luminous supergiants in the LMC (one target from the Phase I proposal being dropped due to TAC constraints on total orbit allocation). The spectral types of our targets range from B8 to A5 which, together with a high resolution IUE spectrum of the A3 supergiant HD33579 (the brightest {\\em normal} star in the LMC), will give us continuous coverage of the effective temperature range of greatest interest. These stars are expected to have terminal velocities of the order 200km/s and it has been shown that the wind outflow velocities are best determined by investigating the velocity shifts of the stong FeII multiplets 1 and 62,63 in the ultaviolet (Stahl et al, 1991, A&A, 252, 693). These multiplets will therefore be observed using the G270M medium resolution grating (resolution approximately 10km/s) to cover the spectral ranges 2580-2630A and 2710-2760A with two exposures per star. These exposures will be binned by a factor of two lower resolution (adequate for our purposes) which will also improve the s/n, our requirement here being that we obtain a minimum s/n of 50 per resolution element. Estimates of UV fluxes for the target stars were obtained using Kurucz model atmosphere fluxes (with appropriate stellar parameters) and scaling visible to UV flux ratios corrected for extinction. Exposure times for each of the spectral regions given above were then estimated using the sensitivities of the G270M grating (Table 8-2 of the GHRS Instrument Handbook) of approximately 4.8E-12 (counts/sec/diode) per incident (erg/cm/cm/sec/A). For example the star HDE269781 has a continuum flux of 4.8E-13 erg/cm/cm/sec/A at 2700A implying a count rate of 2.30 counts/sec/diode and an exposure time of 540 seconds for a s/n of 50 per two-pixel resolution element (see above) for each of the two grating settings. Thus in this example only one orbit is required in this visit. The actual exposure times for each grating setting are adjusted to fill the orbit efficiently, or in the cases where more than one orbit are required, to fill the last orbit. Therefore the actual s/n obtained will be somewhat greater than the minimum required (see above). Use of the LSA is justified since inspection of digitized sky survey data confirms that all the targets are in uncrowded fields (at this level of spatial resolution). Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HDE269832 EXT-STAR, B6-B9.5 III-I RA=5H 36M 04.62S +/-0.3", DEC=- 2000 V = 10.36 69D 24' 08.1" +/-0.3", PLATE- B-V = 0.09 ID=06B0 2 HD32034 EXT-STAR, B6-B9.5 III-I RA=4H 55M 11.15S +/-0.3", DEC=- 2000 V = 9.70 67D 10' 10.6" +/-0.3", PLATE- B-V = 0.10 ID=06AF 3 HDE269781 EXT-STAR, A0-A3 III-I RA=5H 34M 22.56S +/-0.3", DEC=- 2000 V = 9.90 67D 01' 23.6" +/-0.3", PLATE- B-V = 0.07 ID=06B0 4 HDE270086 EXT-STAR, A0-A3 III-I RA=5H 45M 16.68S +/-0.3", DEC=- 2000 V = 10.24 68D 59' 51.8" +/-0.3", PLATE- B-V = 0.23 ID=06B0 5 HDE269905 EXT-STAR, A0-A3 III-I RA=5H 38M 26.94S +/-0.3", DEC=- 2000 V = 10.96 69D 45' 50.9" +/-0.3", PLATE- B-V = 0.18 ID=06B0 6 HDE269651 EXT-STAR, A4-A9 III-I RA=5H 30M 32.50S +/-0.3", DEC=- 2000 V = 10.73 69D 09' 11.6" +/-0.3", PLATE- B-V = 0.19 ID=06B0 6530( 3) - 02/12/96 08:18 - [ 4] Visit: 01 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 HDE269832 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 2.25S ONBOARD ACQ FOR 2-3 EARCH-SIZE=3 Comments: STEP-TIME=0.25S ------------------------------------------------------------------------------------------------------------------------------------ 2 HDE269832 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 870.4S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 3 HDE269832 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 870.4S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 5] Visit: 02 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 HD32034 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 2.25S ONBOARD ACQ FOR 5-6 EARCH-SIZE=3 Comments: STEP-TIME=0.25S ------------------------------------------------------------------------------------------------------------------------------------ 5 HD32034 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 870.4S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 6 HD32034 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 870.4S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 6] Visit: 03 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 HDE269781 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 2.25S ONBOARD ACQ FOR 8-9 EARCH-SIZE=3 Comments: STEP-TIME=0.25S ------------------------------------------------------------------------------------------------------------------------------------ 8 HDE269781 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 870.4S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 9 HDE269781 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 870.4S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 7] Visit: 04 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HDE270086 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 4.5S ONBOARD ACQ FOR 11-12 EARCH-SIZE=3 Comments: STEP-TIME=0.25S ------------------------------------------------------------------------------------------------------------------------------------ 11 HDE270086 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 2393.6S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 12 HDE270086 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 2393.6S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 8] Visit: 05 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 13 HDE269905 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 9S ONBOARD ACQ FOR 14-15 EARCH-SIZE=3 Comments: STEP-TIME=1S ------------------------------------------------------------------------------------------------------------------------------------ 14 HDE269905 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 3916.8S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 15 HDE269905 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 3916.8S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 9] Visit: 06 Visit Requirements: PCS MODE F On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 16 HDE269651 HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,S 1 9S ONBOARD ACQ FOR 17-18 EARCH-SIZE=3 Comments: STEP-TIME=1S ------------------------------------------------------------------------------------------------------------------------------------ 17 HDE269651 HRS ACCUM 2.0 G270M 2580- FP-SPLIT=STD 1 3916.8S 2630 ------------------------------------------------------------------------------------------------------------------------------------ 18 HDE269651 HRS ACCUM 2.0 G270M 2710- FP-SPLIT=STD 1 3916.8S 2760 ------------------------------------------------------------------------------------------------------------------------------------ 6530( 3) - 02/12/96 08:18 - [ 10] Summary Form for Proposal 6530 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE F ONBOARD ACQ FOR 2-3 ONBOARD ACQ FOR 5-6 ONBOARD ACQ FOR 8-9 ONBOARD ACQ FOR 11-12 ONBOARD ACQ FOR 14-15 ONBOARD ACQ FOR 17-18 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HDE269832 HD32034 HDE269781 HDE270086 HDE269905 HDE269651 ------------------------------------------------------------------------------------------------------------------------------------