Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5688 Report Date: 18-Jul-95:17:51 Version: ********** Check-in Date: ********** 1.Proposal Title: UV OBSERVATIONS OF THE HUBBLE-SANDAGE VARIABLES IN M33 - Cycle 4 Carryover ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/CAR 3815 Sub Category MASSIVE STARS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Roberta M. Humphreys UNIVERSITY OF MINNESOTA USA 612-624-6530 ------------------------------------------------------------------------------------ 7. Abstract The Hubble-Sandage variables in M33 are luminous blue variables (LBVs) -- very luminous, eruptively unstable stars in the same general class as S Dor, Eta Car, and P Cyg. UV observations of H-S variables will significantly enhance the limited information available to us concerning the evolution and structure of the most massive stars. ---- LBVs are important in several major astrophysical connections and are only beginning to be understood. Since the LBV stage of evolution is brief, only a few examples are available in our Galaxy and in the Magellanic Clouds, close enough for UV observations with IUE. Therefore our coverage of the wide parameter space embraced by LBVs has been so sparse that theoretical development has been hindered. ---- With the ST, we can significantly increase this coverage by adding the H-S variables in M33 to the set of "useful" LBVs. UV spectroscopy is needed to determine their temperatures, luminosities, and mass-loss rates. These parameters are required to clarify their relations to other LBVs and very massive stars in general, and to provide more information on evolutionary origin of LBVs, physical causes of the violent eruptions, and other problems. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 1.96 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5688 PI: Roberta M. Humphreys Proposal Title: UV OBSERVATIONS OF THE HUBBLE-SANDAGE VARIABLES IN M33 - Cycle 4 Carryover ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Roberta M. Humphreys UNIVERSITY OF MINNESOTA USA Kris Davidson UNIVERSITY OF MINNESOTA USA Nolan R. Walborn SPACE TELESCOPE SCIENCE USA INSTITUTE Bernhard Wolf LANDESSTERNWARTE, HEIDELBERG GERMANY X Immo Appenzeller LANDESSTERNWARTE, HEIDELBERG GERMANY X Otmar Stahl LANDESSTERNWARTE, HEIDELBERG GERMANY X Franz-Josef Zickgraf LANDESSTERNWARTE, HEIDELBERG GERMANY X ------------------------------------------------------------------------------------ 3. Description of proposed observations. (Edited to contain only carryover descriptions by Michelle Bullock) For each of 4 stars, we propose 3 FOS exposures using the 1" circular aperture: 39 minutes with grating G190H and the RD detector, 18 m with G270H/RD, and 20 m with G160L/BL. The G190H and G270H observations will produce good spectra in the range 1700--3200 A, with nominal S/N ratios of 20 to 30 for resolutions of 1 to 2 A (of course the S/N ratios will be better for stars that are brighter than assumed here, which we hope will be the case for at least two or three of them). A number of useful spectral lines occur in this wavelength interval. Unfortunately, in order to obtain continuum fluxes and slopes extending to wavelengths shorter than 1700 A, and in case certain important emission lines appear at such wavelengths, we must switch to the BL detector for the G160L observations, despite the overhead time that this entails. (Since the resulting count rates are low, we do not attempt to obtain good resolution at the shortest wavelengths.) ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. IUE observations of some of the visually brightest Hubble-Sandage variables have been attempted. The results have been just marginal detections even with IUE exposure times of 6 or 7 hours; they give only a few DN above background and poor S/N even for wide-band flux estimates at the wavelengths where IUE is most sensitive (Humpheys et al. 1984, 1988). These efforts have demonstrated that measurements of these stars' spectral features and accurate short-UV-wavelength fluxes cannot be done with IUE; they also confirm that the typical UV fluxes assumed in this proposal are realistic. --- Many ground-based visual-wavelength observations of H-S variables have been made since the early 1970's (see refs. in the scientific justification). Their blue-visual spectra show strong similarities to the LBVs in our Galaxy and in the LMC. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. No special scheduling is absolutely required; however, since our target stars do vary over timescales of years or months, advantageous scheduling would be helpful in several respects. Firstly, it is desirable to obtain the FOS observations during the months September--December, so that ground-based data can be obtained at nearly the same time -- even though this is not strictly a requirement. Secondly, it is always possible that a major eruption of one of our target stars might be detected by ground-based work; if so then it would be desirable to obtain the FOS data as soon thereafter as practicable. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. There are no special calibration requirements. A small "special catalog" of acquisition stars may be advisable; if so, we will provide the needed data (most likely just a few altered flags for the sets of GSC stars in these M31 and M33 fields). ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Considerations outlined in question 5 are pertinent. Since it is desirable (though not necessary) to take ground-based data at about the same time as the FOS data, September--January is the optimum time for these ST observations. Ground-based photometric and spectroscopic monitoring of the Hubble-Sandage variables will continue. We can obtain visual and near-IR (UBVRI + JHK) photometry of the H-S variables with the University of Minnesota 1.5-m telescope on Mt. Lemmon, and moderate-to-high-resolution blue-visual-red spectra with the Calar Alto 3.5-m telescope. September--January is of course the prime season for ground-based observations of M31 and M33. ---- We have measured accurate TARGET POSITIONS on a set of 4m-prime-focus plates, using appropriate sets of GSC stars to set up the coordinate grids. These same plates may provide altered flags for a few GSC stars which may be dangerous to use for acquisition. (Target positions were measured in February 1992; as of mid-March, the GSC star re-evaluations are not yet completed but probably will be within a few weeks.) ------------------------------------------------------------------------------------ 9. Description of previous HST work. -- Davidson is PI and Humphreys, Walborn and Wolf are CoI's on GO 2338, "Spectroscopy of the speckle-resolved Eta Car point sources." This is indirectly related in the sense that Eta Carinae is an LBV and so are the H-S variables. -- Davidson and Walborn are assisting D. Ebbets on Ebbets' GTO 1186, "Imagery and UV spectroscopy of matter ejected from Eta Carinae." Above comments apply to this project also. -- Davidson is a CoI on R. Dufour's GO 2416, "Imagery and spectroscopy of super metal poor galaxies." This is related only if some LBV- like stars are found in GR8 or I Zw 18 (unlikely). -----results from above-listed programs:----- Several good WFC and PC images of Eta Car were made in 1991, and good FOS data were obtained for project 2338 in August 1991. These all require rather tricky analyses, which are not yet completed as of mid-March 1992. Similar remarks apply to the data obtained for Dufour's program number 2416. There are no real publications yet, except that several of the images were used in poster papers at the January 1992 AAS meeting. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The Graduate School of the University of Minnesota provided $12,000 toward the purchase of a Sun computer for the original proposal for these observations submitted in 1988. A network of Sun computers now exists in the Minnesota Astronomy department. We have IRAF running on this system. However, since these machines are very heavily used, Humphreys is requesting funds for a dedicted work station. The data analysis facilities of ESO/ST-ECF are available to Wolf, Appenzeller, Stahl, and Zickgraf. They have also the MIDAS data reduction package on the machines at the Landessternwarte, Heidelberg. ------------------------------------------------------------------------------------ 11. Address Information Page 4 Name: ROBERTA M. HUMPHREYS Category: PI Institution: UNIVERSITY OF MINNESOTA Address: ASTRONOMY DEPT. UNIVERSITY OF MINNESOTA 116 CHURCH ST. S.E. City: MINNEAPOLIS State: MN Zip Code: 55455 Country: USA Telephone: 612-624-6530 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5688 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 M33- B,148,159 RA = 1H 34M 10.92S +/- J2000 1 V = 17.0 +/- 1.0 013411+30343 0.03S, 2 B-V = 0.0 +/- 0.2 8 M33-VAR-83 DEC = +30D 34' 37.6" +/- 3 F-CONT(2000) = 4 +/- 3 E-15 0.3", PLATE-ID = 00DV Comments: BRIGHTNESS IS VARIABLE. SPECIAL FIELD (M33). GS VERSION 1.1 (NOT 1.0) ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5688 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 M33- FOS/RD ACQ/ 4.3 MIRROR 1 20S 1 1 CYCLE 4 / 10-40 013411+3034 BINARY 2 ONBOARD ACQ FOR 11 38 ------------------------------------------------------------------------------------------------------------------------------------ 11 M33- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE-X=4 1 7S 1 ONBOARD ACQ FOR 20 013411+3034 PEAK SEARCH-SIZE-Y=4 -40 38 SCAN-STEP- X=0.172 SCAN-STEP- Y=0.172 ------------------------------------------------------------------------------------------------------------------------------------ 20 M33- FOS/RD ACCUM 1.0 G190H 1 39M 27 3 1 013411+3034 38 Comments: QUOTED S/N RATIOS FOR FOS ACCUM REFER TO 1/2 DIODE, AND ARE VERY CRUDE BECAUSE ASSUMED FLUXES ARE ROUGH. WOULD LIKE 1650 - 2311 WAVELENGTH COVERAGE. ------------------------------------------------------------------------------------------------------------------------------------ 30 M33- FOS/RD ACCUM 1.0 G270H 1 18M 27 3 1 013411+3034 1 38 2 Comments: SEE COMMENT FOR LINE 20 ABOUT S /N. WOULD LIKE 2225-3281. ------------------------------------------------------------------------------------------------------------------------------------ 40 M33- FOS/BL ACCUM 1.0 G160L 1 20M 13 3 1 013411+3034 2 38 Comments: SEE COMMENT FOR LINE 20 ABOUT S /N. WOULD LIKE 1150-2524 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5688 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=4 SEARCH-SIZE-Y=4 SCAN-STEP-X=0.172 SCAN-STEP-Y=0.172 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 1.96 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category MASSIVE STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 10-40; ONBOARD ACQ FOR 11; ONBOARD ACQ FOR 20-40; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G190H G270H G160L ------------------------------------------------------------------------------------------------------------------------------------ Target Names M33-013411+303438 M33-VAR-83 ------------------------------------------------------------------------------------------------------------------------------------