7749( 2) - 10/13/98 17:22 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7749 Version: 2 Check-in Date: 29-Jul-1997 10:08:15 1.Proposal Title: The wind momentum-luminosity relationship for LMC A- and B-supergiants ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Daniel Lennon Isaac Newton Group 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 ------------------------------------------------------------------------------------ 5. 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. In Cycle 6 we observed a sample of late B- and early A-type supergiants in the LMC, however this program (6530) was incomplete and we have two carry-over orbits for Cycle 7 (this program) to observe one additional A-type supergiant. ------------------------------------------------------------------------------------ 7749( 2) - 10/13/98 17:22 - [ 2] Observations Description ------------------------ Using STIS, we will observe HDE269781 with the E230M medium resolution echelle grating and the NUV-MAMA detector. We will use the two prime central wavelength settings to obtain complete wavelength coverage from 1575 to 3100 Angstroems. The star should have a terminal velocity 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) as well the MgII resonance lines, all of which lie between 2400 and 2900 A. Additional important diagnostic lines at shorter wavelengths (additional FeII lines, AlIII resonance lines) will also be obtained thanks to the excellent wavelength coverage of the E230M. In fact we will obtain data of unprecented quality and information content for an A-type hypergiant in the LMC. The two 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 effective binned resolution element. Estimates of UV fluxes for the target star was obtained from IUE low resolution observations and the exposure times were estimted to give a S/N of approximately 30 (before binning), well matched to the MAMA capabilities. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7749( 2) - 10/13/98 17:22 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HDE269781 EXT-STAR, A0-A3 III-I RA=5H 34M 22.56S +/-0.3", DEC=- J2000 V = 9.90 67D 01' 23.6" +/-0.3", PLATE- B-V = 0.07 ID=06B0 E(B-V) = 0.1 F-CONT(2600)=5.e-13 7749( 2) - 10/13/98 17:22 - [ 4] Visit: 01 Visit Priority: Visit Requirements: 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 HDE269781 STIS/C ACQ F28X50O MIRROR 1 1.0 S ONBOARD ACQ FOR 2-4 CD II ------------------------------------------------------------------------------------------------------------------------------------ 2 HDE269781 STIS/N ACCUM 0.2X0.2 E230M 2707 1 20 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 3 HDE269781 STIS/N ACCUM 0.2X0.2 E230M 1978 1 15 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 4 HDE269781 STIS/N ACCUM 0.2X0.2 E230M 1978 1 50 M UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7749( 2) - 10/13/98 17:22 - [ 5] Summary Form for Proposal 7749 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50OII 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2-4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HDE269781 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 2707 1978 ------------------------------------------------------------------------------------------------------------------------------------