Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5384 Report Date: 18-Jul-95:17:16 Version: ********** Check-in Date: ********** 1.Proposal Title: RESOLVED AND COMPOSITE PROPERTIES OF THE GIANT HII REGIONS IN M33 CYCLE4MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Sub Category CLUSTERS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone William Waller HUGHES STX USA (301)513-5475 SENIOR SCIENTIST ------------------------------------------------------------------------------------ 7. Abstract We propose to evaluate the degree to which metal abundance affects stellar population at the high-mass end. We will target the galaxy M33, whose proximity and large sample of HII regions of differing metallicity make it ideally suited for such a study. Rather than relying on COMPOSITE spectral indices of stellar population, we will exploit the superior acuity of the HST to RESOLVE the individual stars that underly and power 6 of the brightest HII regions in M33. Through multi-band imaging with the WFPC2 camera and subsequent photometry, we will be able to differentiate among the upper main-sequence, giant, supergiant, and Wolf-Rayet stars. Once we resolve and decompose the ionizing clusters, we will then be able to provide a critical evaluation of the relationship between metallicity and stellar population. Moreover, by comparing the resolved stellar populations in M33's giant HII regions with their composite colors and emission-line properties, we will be able to provide an essential foundation for interpreting the composite spectral indices of starburst regions in more distant galaxies. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GALAXY;M33 CLUSTERS;OB ASSOCIATIONS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.23 par: 0 10. Num targs pri: 6 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5384 PI: William Waller Proposal Title: RESOLVED AND COMPOSITE PROPERTIES OF THE GIANT HII REGIONS IN M33 CYCLE4MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ William Waller 3480 USA Laurent Drissen 3470 USA Sara Heap 2866 USA Paul Hodge 3760 USA Eliot Malumuth 1780 USA Joel Parker 2866 USA David Taylor 1780 USA Christine Wilson 4642 CANADA ------------------------------------------------------------------------------------ 3. Description of proposed observations. To resolve and characterize the brightest and hottest stars in M33's giant HII regions, we propose to use the WFPC2 to obtain PC images of 6 HII regions through filters that approximate the Johnson UBV passbands. The filters used will be the F336W (U), F439W (B), and F547M (V), the later of which avoids the strong [OIII] and H-beta emission lines. To maximize the prominence of the hottest stars in the crowded fields and to provide further constraints on the reddening and spectral types of the stars, we will also obtain frames through the F170W ultraviolet filter. The 6 targets are giant HII regions which span a wide range of metallicities and environments --- from the near-nuclear HII region CC 93 (O/H x 10e4 = 10.5) to the outer-disk HII region NGC 588 (O/H x 10e4 = 2.0). All exposure times are based on our desire to achieve photometric accuracies of 10 percent or better down to V=21.1 magnitude. This can be done, if we obtain a S/N ratio of about 30 in the central pixel of each resolved star. To obtain this S/N ratio will require exposures of 360S, 320S, 360S, and 200S respectively for the F170W, F336W, F439W, and F547M filters. Each exposure will be split into two equal exposures using the CR-SPLIT=0.5 optional parameter to facilitate the removal of cosmic-ray events. Since the HII regions are extended sources, they will be centered in the PC1 field of view by using the PC1-FIX aperture. These exposures will allow us to achieve a photometric accuracy of 0.10 mag or better for any main sequence star earlier than B0, and yet avoid saturation of the brighter O-type supergiants. In addition, a narrow-band image of NGC 588 will be obtained through filter F469N with the intention of identifying Wolf-Rayet stars through their HeII (4686A) line emission. A 600S CR-SPLIT=0.5 exposure will achieve a S/N similar to those obtained by Drissen et al. (1993) in their WF/PC-1 imaging of NGC 595 and NGC 604. The narrow-band imaging of NGC 588 is motivated by spectroscopic evidence for HeII emission from W-R stars in this HII regions (Conti and Massey 1981). NGC 588 is of special interest because of its exceptionally low metallicity. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Ground-based resolution of ionizing clusters into individual stars has been achieved with limited success for some galaxies of the Local Group (cf. Massey et al. 1989). HST observations during Cycles 1-3 have provided much clearer views of such objects as 30 Doradus in the LMC, NGC 346 in the SMC, and NGC 604 in M33. At the distance of M33, the superior acuity of the HST enabled Drissen et al. (1993) to resolve a multitude of hot luminous stars -- even in the most crowded cores of the HII regions. To classify these stars and the stellar populations in M33's other giant HII regions, it is necessary to conduct U,B,V, abd UV imaging using the HST. The additional narrow band imaging at 4690 A will enable us to isolate the extremely hot WR-type stars. By targeting 6 HII regions of differing metallicity, we will be able to characterize their ionizing stellar populations and evaluate their sensitivity to metallicity -- all in the same galaxy. This cannot be done via ground-based imaging, nor can it be done with any of the prior or currently scheduled HST programs. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. For each of the 6 targets, all of the exposures of that target must be taken at the same pointing and roll-angle. This is achieved through the use of the SEQ NO GAP special requirement. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Provided that flat field exposures are obtained through the F170W, F336W, F439W, F547M, and F469N filters as part of the regular calibration plan, no special calibration exposures are required for this program. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ------------------------------------------------------------------------------------ 9. Description of previous HST work. See phase 1 proposal. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). See phase 1 proposal. ------------------------------------------------------------------------------------ 11. Address Information Name: WILLIAM WALLER Category: PI Institution: 3480 Address: Code 681 Goddard Space Flight Center City: Greenbelt State: MD Zip Code: 20771 Country: USA Telephone: (301) 513-5475 Telex (or e-mail): WALLER@STARS.GSFC.NASA.GOV ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5384 [ 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 M33-NEB1 D, RA = 01H 33M 52.51S +/- J2000 V=-180 1 V=20.6 CC93 203 0.15S, 1 B-V=-0.3 DEC = +30D 39' 17.4" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ 2 M33-NEB2 D, RA = 01H 33M 55.70S +/- J2000 V=-180 1 V=20.6 IC142 203 0.15S, 1 B-V=-0.3 DEC = +30D 45' 26.0" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ 3 M33-NEB3 MA2 D, RA = 01H 34M 15.39S +/- J2000 V=-180 1 V=20.6 203 0.15S, 1 B-V=-0.3 DEC = +30D 37' 07.0" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ 4 M33-NEB4 D, RA = 01H 32M 45.56S +/- J2000 V=-180 1 V=20.6 NGC588 203 0.15S, 1 B-V=-0.3 DEC = +30D 38' 57.6" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ 6 M33-NEB6 D, RA = 01H 33M 33.61S +/- J2000 V=-180 1 V=20.6 NGC595 203 0.15S, 1 B-V=-0.3 DEC = +30D 41' 32.0" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ 7 M33-NEB7 D, RA = 01H 34M 32.85S +/- J2000 V=-180 1 V=20.6 NGC604 203 0.15S, 1 B-V=-0.3 DEC = +30D 47' 01.6" +/- 2 E(B-V)=0.16 2.0" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5384 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 M33-NEB1 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 SEQ 1.1-1.4 NO GAP TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 1.2 M33-NEB1 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5 1 320S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 1.3 M33-NEB1 WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=0.5 1 360S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 1.4 M33-NEB1 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5 1 200S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.1 M33-NEB2 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 SEQ 2.1-2.4 NO GAP TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.2 M33-NEB2 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5 1 320S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 M33-NEB2 WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=0.5 1 360S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2.4 M33-NEB2 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5 1 200S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3.1 M33-NEB3 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 SEQ 3.1-3.4 NO GAP TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3.2 M33-NEB3 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5 1 320S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3.3 M33-NEB3 WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=0.5 1 360S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3.4 M33-NEB3 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5 1 200S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.1 M33-NEB4 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 SEQ 4.1-4.5 NO GAP TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5384 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 4.2 M33-NEB4 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5 1 320S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.3 M33-NEB4 WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=0.5 1 360S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.4 M33-NEB4 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5 1 200S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.5 M33-NEB4 WFPC2 IMAGE PC1-FIX F469N CR-SPLIT=0.5 1 600S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6.1 M33-NEB6 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 SEQ 6.1-6.4 NO GAP TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6.2 M33-NEB6 WFPC2 IMAGE PC1-FIX F336W CR-SPLIT=0.5 1 320S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6.3 M33-NEB6 WFPC2 IMAGE PC1-FIX F439W CR-SPLIT=0.5 1 360S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6.4 M33-NEB6 WFPC2 IMAGE PC1-FIX F547M CR-SPLIT=0.5 1 200S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ 7.1 M33-NEB7 WFPC2 IMAGE PC1-FIX F170W CR-SPLIT=0.5 1 700S 30 1 1 CYCLE 4 CR- 2 TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5384 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT CR-TOLERANCE=0.0 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.23 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; SEQ 1.1-1.4 NO GAP SEQ 2.1-2.4 NO GAP SEQ 3.1-3.4 NO GAP SEQ 4.1-4.5 NO GAP SEQ 6.1-6.4 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F170W F336W F439W F547M F469N ------------------------------------------------------------------------------------------------------------------------------------ Target Names M33-NEB1 CC93 M33-NEB2 IC142 M33-NEB3 MA2 M33-NEB4 NGC588 M33-NEB6 NGC595 M33-NEB7 NGC604 ------------------------------------------------------------------------------------------------------------------------------------