Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 2581c Report Date: 09-May-96:17:13 Version: ********** Check-in Date: ********** 1.Proposal Title: STELLAR WINDS OF MASSIVE STARS IN NEARBY GALAXIES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Luciana Bianchi ASTRONOMICAL OBSERVATORY TOR ITALY ITALY-11-84204 ASTRONOMER ------------------------------------------------------------------------------------ 7. Abstract We propose to study the stellar wind characteristics of hot massive stars in M31 and M33 by observing with the HST-FOS the profiles of UV resonance lines which are the main wind indicators. The immediate aim is to understand how mass loss rates, and other characteristics of the stellar winds, such as the velocity-laws (i.e. the acceleration) and the ionization, depend on metallicity. The final goal is to understand the evolution of massive stars in galaxies of different chemical composition. The dependence of hot star winds on metallicity is in fact predicted by the theory of radiation-pressure driven winds, but it could be observed so far only in the MCs stars (Hutchings, 1982; Garmany and Conti 1985; Kudritzski et al, 1987). In the past years we have pushed IUE to its limits to observe far UV spectra of the brightest/hottest stars in M31 and M33. In spite of the very low resolution (insufficent for quantitative line analysis) we observed for all the stars of our sample significantly lower terminal velocities and weaker P Cygni profiles than for galactic stars of similar type. The results of this pioneer study (that involved also an extensive ground based observing program) on one hand, and the recent significant improvements of the radiation driven wind theory and treatment of ionization equilibrium in the stellar atmospheres and envelopes on the other hand, show that a higher resolution study of the UV lines will be very interesting. ------------------------------------------------------------------------------------ 8. Scientific Key Words: EXTRAGALACTIC STARS, STELLAR WINDS, MASS LOSS, UV, SPECTROSCOPY. ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 8.00 par: 0 10. Num targs pri: 5 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 2581c PI: Dr. Luciana Bianchi Proposal Title: STELLAR WINDS OF MASSIVE STARS IN NEARBY GALAXIES ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Henny Lamers UTRECHT LABORATORY FOR SPACE NETHERLANDS X RESEARCH Phillip Massey KPNO, NOAO USA John B. Hutchings DOMINION ASTROPHYSICAL CANADA OBSERVATORY Rolf-Peter Kudritzki MUNICH UNIVERSITY FRG X P.I. Luciana Bianchi TURIN ASTRONOMICAL OBSERVATORY ITALY X ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to observe some of the stars for which we have IUE spectra (and therefore we know UV fluxes and can assess line presence) at a resolution sufficient for quantitative analysis of the broad wind profiles - to determine mass loss rates- and accurate measurements of wind terminal velocities, by covering the whole range where the lines of interest are contained. The resolution is sufficient to analyze the broad wind lines but also to detect other weaker lines -that cannot be measured or even detected in IUE spectra. A S-to-N ratio higher than 20 is required for a good analysis of the broad profiles. We plan to cover with two spectra the range from the strong wind line of NV at 1240A to the photospheric NIII at 1750A. In the original proposal we asked to use GHRS, but the long exposure times would have forced us to rebin most spectra by a factor two, to achieve a S-to-N higher or equal 20 at the wavelenghts of the most important features. Using the most updated information on FOS sensitivity, we find that in the time granted to us we can achieve the S-to-N adequate for our purpose without rebinning, and the slight degradation of resolution for the change of instrument is therefore acceptable. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Given the magnitude of the targets (around 17-18th) and the need of high resolution UV line profiles for the proposed scientific goals, it is evident that these observations can only be performed with the HST spectrographs. P.M. has obtained extensive optical observations of selected regions in M33 and M31, first to identify the most luminous/hottest stars that could be observed with IUE (grens plates at CFHT, UBV-CCD frames at KPNO 4m tel). Then spectra of several selected stars were secured at MMTO and low resolution (6A) spectra with IUE of the hottest ones, allowing line identification and determination of extinction, eff.Temp., Sp.type, Lbol. These results -described in Section 2- provided the basis for the proposed research. The study with low resolution spectra is continuing with IUE and ground-based telescopes, to extend the object sample, and fainter stars not accessible with IUE will be observed with the HST-FOS by J.H. (GTO). At high resolution we ask to observe only the brightest objects, for which we have analyzed already sufficient low dispersion data (see our references). High resolution H and He photospheric lines is planned from the ground (at MMTO or CFHT) though wery difficult, to determine Teff and Gravity with the improved model atmospheres of R.K. (see Mendez et al.1988), i.e. in a way independent from our previous results (comparison of UV continuum with model atmopsheres). This will be a complementary study to the wind analysis proposed with the HST, as it provides stellar parameters useful for the unified model. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Most of the stars proposed for HST have already been observed by us with IUE. Therefore we know the flux level, in the range of interest, with an accuracy of 10%. From these UV fluxes (quoted in the Target list), the sensitivity tables in the handbooks and subsequent updates, we estimated the exposure times listed in the Exposure forms, for the needed resolution and S-to-N ratio as described in Section 3a. ( S-to-N better than 20). By switching to FOS (from the originally approved GHRS) the exposure times are longer at the shorter wls, and shorter at the longer wls, but we gain time and efficiency with the acquisitions. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The preliminary data reduction will be done at the ST-ECF and at the ST ScI. Part of these data reduction packages is already available and more will be - also at our home institutes. The scientific analysis will be performed - besides the obvious steps of line identification, measurements of velocities and equivalent widths- as described in Section 2. A fit of the line profiles will be done with codes existing at the Observatory of Torino and SRL Hutrecht that compute theoretical P Cygni profiles with the SEI method. The ionization equilibrium will be computed with a detailed model developed at the Munich Astronomical Institute. A "unified model" fit will also be done to compute mass loss rate, wind dynamics, abundances and global stellar parameters for each star consistently (combining also the optical data). ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We have tried - for the Phase II proposal - to measure coordinates of the targets on GASP frames but most of them are rather faint so the results are not very accurate, or the gaussian centering fails. We obtained more precise results by measuring a good KPNO-4m tel. plate for M31, and a recent CCD frame for M33. The measurements were reduced using GSS stars as reference stars, and for these we quote the corresponding Plate-id. in the target list. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). We think that we have already available at our home Institutes the necessary S/W for data reduction, computing facilities and theoretical codes (on Vaxes and Cray) for the analysis described in this proposal. Computing capabilities and supporting man-power are planned to keep expanding in the future years. Students will also be available to collaborate to this project if needed. Travel funds, publication costs etc. are already granted to this project, by home Institutions and Research Foundations of each author's Country. ------------------------------------------------------------------------------------ 11. Address Information Name: LUCIANA BIANCHI Category: PI Institution: ASTRONOMICAL OBSERVATORY OF TORIN Address: OSSERVATORIO ASTRONOMICO I-10025 PINO TORINESE (TO) City: State: Zip Code: Country: ITALY Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 2581c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-NGC206- EXT-STAR; WN OF STAR PLATE-ID=2801, 1950.0 1 V = 18.6 , B-V = -0.03 231 RA = 0H 37M 46.25S +/- 2 F-CONT(1300) = 0.6 E-14 0.05S, 3 F-CONT(1550) = 0.4 E-14 DEC = +40D 28' 2.6" +/- 0.3" 4 TYPE = WN7 5 F-CONT(1240) = 0.7 E-14 Comments: TARGET COORDINATES MEASURED ON GOOD 4M- TEL PLATE USING GSS REFERENCE STARS FROM QUOTED GSS-FRAMES (PLATE-ID) TARGET TOO FAINT ON GASP FRAME CNTRTS=230 CALC'D W OLD TBLE 4.2 AND OLD FORMULA (THE ONLY AVAIL) ------------------------------------------------------------------------------------------------------------------------------------ 2 M31-OB78-277 EXT-STAR; TYPE = B1 PLATE-ID =2801, 1950.0 1 V = 17.4 , B-V = -0.06 RA = 0H 37M 46.83S +/- 2 F-CONT(1300) = 1.3 E-14 0.05S, 3 F-CONT(1550) = 1.0 E-14 DEC = +40D 26' 5.7" +/- 0.3" 4 TYPE = B1 5 F-CONT(1240) = 2.0 E-14 Comments: TARGET COORDINATES MEASURED ON GOOD 4M- TEL PLATE USING GSS REFERENCE STARS FROM PLATE QUOTED TARGET TOO WEAK ON GASP FRAME CNTRTS=614 CALC'D W OLD TBLE 4.2 AND OLD FORMULA (THE ONLY AVAIL) ------------------------------------------------------------------------------------------------------------------------------------ 3 M31-OB48-444 EXT-STAR; TYPE = O8 PLATE-ID=2805, 1950.0 1 V = 19.1 , B-V = -0.02 RA = 0H 42M 30.32S +/- 2 TYPE = O8 0.05S, 3 F-CONT(1300) = 0.4 E-14 DEC = +41D 21' 23.9" +/- 0.3" Comments: TARGET COORDINATES MEASURED ON GOOD 4M- TEL PLATE USING GSS REFERENCE STARS FROM PLATE QUOTED TARGET TOO WEAK ON GASP FRAME CNTRTS=77 CALC'D W OLD TBLE 4.2 AND OLD FORMULA (THE ONLY AVAIL) ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 2581c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-NGC206- FOS/BL ACCUM 1.0 G130H 1150- 1 89.08M 25 2 1 CYCLE1/1-12 231 1608 ------------------------------------------------------------------------------------------------------------------------------------ 2 M31-NGC206- FOS/BL ACCUM 1.0 G190H 1595- 1 23M 22 3 1 CYCLE1/1-12 231 2282 ------------------------------------------------------------------------------------------------------------------------------------ 3 M31-NGC206- FOS/BL ACCUM 1.0 G270H 2227- 1 7M 25 1 CYCLE1/1-12 231 3306 ------------------------------------------------------------------------------------------------------------------------------------ 4 M31-OB78- FOS/BL ACCUM 1.0 G130H 1150- 1 101M 25 2 1 CYCLE1/1-12 277 1608 ------------------------------------------------------------------------------------------------------------------------------------ 5 M31-OB78- FOS/BL ACCUM 1.0 G190H 1595- 1 13M 24 3 1 CYCLE1/1-12 277 2282 ------------------------------------------------------------------------------------------------------------------------------------ 6 M31-OB78- FOS/BL ACCUM 1.0 G270H 2227- 1 7M 24 1 CYCLE1/1-12 277 3306 ------------------------------------------------------------------------------------------------------------------------------------ 7 M31-OB48- FOS/BL ACCUM 1.0 G130H 1150- 1 123M 25 1 1 CYCLE1/1-12 444 1608 ------------------------------------------------------------------------------------------------------------------------------------ 8 M31-OB48- FOS/BL ACCUM 1.0 G190H 1595- 1 22M 24 1 1 CYCLE1/1-12 444 2282 ------------------------------------------------------------------------------------------------------------------------------------ 9 M31-OB48- FOS/BL ACCUM 1.0 G270H 2227- 1 7M 25 1 CYCLE1/1-12 444 3306 ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-NGC206- FOS/BL ACQ/ 4.3 MIRROR 1 60.0S 1 1 ONBOARD ACQ FOR 1- 231 BINARY 3 CYCLE1/1-12 Comments: TEN TIMES THE EXP TIME FROM TABLE 2 PAGE 10 OF HANDBOOK; ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-OB78- FOS/BL ACQ/ 4.3 MIRROR 1 20.0S 1 1 ONBOARD ACQ FOR 4- 277 BINARY 6 CYCLE1/1-12 Comments: TEN TIMES THE EXP TIME FROM TABLE 2 PAGE 10 OF HANDBOOK; ------------------------------------------------------------------------------------------------------------------------------------ 12 M31-OB48- FOS/BL ACQ/ 4.3 MIRROR 1 96.0S 1 1 ONBOARD ACQ FOR 7- 444 BINARY 9 CYCLE1/1-12 Comments: TEN TIMES THE EXP TIME FROM TABLE 2 PAGE 10 OF HANDBOOK; ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 2581c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ACQ/BINARY ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 8.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE1/1-12 ONBOARD ACQ FOR 1-3; ONBOARD ACQ FOR 4-6; ONBOARD ACQ FOR 7-9; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130H G190H G270H MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names M31-NGC206-231 M31-OB78-277 M31-OB48-444 ------------------------------------------------------------------------------------------------------------------------------------