Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5703 Report Date: 18-Jul-95:17:52 Version: ********** Check-in Date: ********** 1.Proposal Title: ULTRAVIOLET EVOLUTION OF ELLIPTICAL GALAXIES AT MODERATE REDSHIFT - CYCLE 4 CARRY- OVER ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO/CAR 3448 Sub Category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Alvio Renzini UNIVERSITY OF BOLOGNA, DEPAR ITALY 39-51-259402 ------------------------------------------------------------------------------------ 7. Abstract WFPC2 ultraviolet imaging of a sample of early-type galaxies with redshift in the range from 0.28 to 0.37 is proposed to determine the evolution with lookback time of the ``UV rising branch''commonly exhibited by nearby elliptical galaxies. This feature can be attributed to various types of old, hot stars in advanced evolutionary stages. The most promising of these hot star candidates appear to be hot, super metal rich horizontal branch stars, in combination with ``Post-early- AGB'' stars; other candidates include various types of binary stars, in particular accreting white dwarfs. Among the various complications of the problem, one attractive characteristics however exist: the strength and slope of UV rising branch is predicted to evolve very rapidly with redshift, and in a few Gyr lookback time the rest frame (1550A-V) color should have reddened by over one magnitude. The proposed observations provide an elegant way of indeed checking the nature of the hot stars present in ellipticals, while at the same time opening the way to a first attempt at directly measuring the lookback time to galaxies at low to moderate redshifts. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 8.8 par: 0.00 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5703 PI: Alvio Renzini Proposal Title: ULTRAVIOLET EVOLUTION OF ELLIPTICAL GALAXIES AT MODERATE REDSHIFT - CYCLE 4 CARRY- OVER ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Alvio Renzini 6460 ITALY X Roberto Gilmozzi 3470 USA X Laura Greggio 6460 ITALY X Enrico Held 6426 ITALY X ------------------------------------------------------------------------------------ 3. Description of proposed observations. The present HST configuration offers several advantages for reaching the scientific goal of this project, over the configuration that was available at the time of our Cycle 2 application. Now WFPC 2 has a set of high performance UV filters that are much less affected by the red leak problem, and the CCD responce in the UV is much better than it was on WFPC 1. Clearly, the best strategy for achieving the stated goals of this project is now to use WFPC 2, and it is so not just because of lower red leak and less scattered light problems, but also for the large field of view that allows UV imaging of more than one of our original targets with just one exposure. Indeed, the original target list included two galaxies in the field of the cluster A1758 and two galaxies in A370. In each cluster one of the two galaxies was not observed during Cycles 2 and 3. Now, with just one WFPC 2 frame one collects not only the two target galaxies, but most galaxies in the cluster core, thus allowing to measure the UV flux of many elliptical galaxies at once. More specifically, according to Couch et al. (1994, preprint) who analyzed WFC1 data on A895, we expect about 18-19 galaxies classified E/S0 in the field of WFPC2. This would allow us to achieve the scientific goals of the project with much greater confidence than was possible with the scientific instrumentation available before the rescue mission. For the the Abell 895 cluster (z=0.37), by taking one WFPC 2 frame through the F218W filter we shall measure the rest frame 1550 A flux (1550 x 1.37 = 2120 A). The contribution of the red-leak to the UV flux can be estimated as a function of an independent color obtained by short exposures through the filters F555W and F785LP. In particular F785LP, when taking into account the full system response, provides a bandpass very similar to the red-leak component of F218W. In addition, a short exposure through F791W will be obtained to sample the rest-frame V flux at a redshift z=0.36. In this way the rest-frame 1550-V color of each galaxy in the image will be easily derived. NOTE: F814W HAS REPLACED F785LP IN THIS NEW VERSION. The other failed FOS observation was for two galaxies in the field of the cluster A1758 (z=0.28). Now the F218W filter will sample the 1700 A flux on the rest frame, still on the UV rising branch of zero redshift ellipticals. Additional short exposures through F555W and F785LP will be used for estimating the red-leak, and F702W will sample the rest-frame V passband. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Ultraviolet imaging at these wavelengths is clearly impossible from the ground. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Data reduction will be carried out initially at the Space Telescope Science Institute, using the most up-to-date software available in-house. However, the analysis of the wfpc2 images is fairly straightforward and although we will use the software available at the STScI, any reduction package contains the necessary tools to reduce these data. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. The P.I. (A.R.) is Co-I in two scientifically related Cycle 2 proposals. The first proposal (P.I. F. Bertola) seeks at accurately studying with FOC the UV surface brightness distribution of a sample of ZERO REDSHIFT ellipticals. The second proposal (P.I. R. Windhorst) concerns WFPC imaging and FOS ultraviolet spectroscopy of moderate to high redshift RADIOGALAXIES. There is a clear complementarity among the three proposals, and the scientific output of each of them would be enhanced by the completion of the two other projects. ------------------------------------------------------------------------------------ 9. Description of previous HST work. a1) GO Proposal ID 2579: THE CALIBRATION OF THE DWARF DISTANCE SCALE FOR GLOBULAR CLUSTERS. (PI A. Renzini) The GO cycle 1 program received 45.80 hours of unocculted spacecraft time with SUPPLEMENTAL priority. The program then completed the Phase 2, and was cleared for the HST observations. Subsequent to the spherical aberration problem the PI asked to DEFER the program to the first HST cycle with fully recovered WF/PC capabilities. The project 2579 is not closely related to the present proposal. a2) GO Proposal ID 2570: RECENT MASS EJECTION FROM PLANETARY NEBULA NUCLEI.(PI H. BOND). The program was submitted for the GO cycle 1 and received 3.73 hours of unocculted spacecraft time, with HIGH priority. The observations have been virtually completed (1 spectrum yet to be taken). The project is not related to the present proposal. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Computing: Bologna: Our Institute is equipped with one VAX 8800, 3 Microvaxes, five Decstations 3100 one of which could be entirely dedi- cated to the present project, 5Gby mass memory(of which one private 0.5 Gby disk), one Gould-DeAnza image processor, one Microvax GPX workstation, plus numerous peripherals. There is also ready access to the Cray 2 of the Bologna University.Research Assistance and Students: there are typically 10 graduate students in Astronomy at our Department, part of which already work on HST-related projects. Research assistance will be secured. Funds: Bologna: Our research grants are sufficient to cover all the expenses conceivably required to complete this together the other HST projects in which we may be involved. The facilities of the ESA/ESO ST-ECF are also available, if needed. ------------------------------------------------------------------------------------ 11. Address Information Name: ALVIO RENZINI Category: PI Institution: 6460 Address: Dipartimento di Astronomia CP 596, I-40100 City: BOLOGNA State: Zip Code: Country: ITALY Telephone: 39-51-259402 Telex (or e-mail): ALVIO@astbo3.bo.astro.it, 39-51-259407 ------------------------------------------------------------------------------------ Page 4 Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5703 [ 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 A895 E,303 RA = 09H 53M 30.0S +/- 0.4", B1950 Z=0.36 1 V=19.2 +/- 0.1 DEC = 49D 44' 00.2" +/- 0.4" 1 B-V =2.48 +/-0.01 3 F(2180)=2.43e-17 4 F(7850)=2.38e-16 5 F(7910)=2.31e-16 6 F(5550)=9.90e-17 Comments: FLUXVAL_3=Flam through F218W for NGC4649 scaled for z&V_mag to A895 FLUXVAL_4= as ()_3, through f785LP FLUXVAL_5=same as ()_3, thr. f791W FLUXVAL_6= same as ()_3,thr. f555W ------------------------------------------------------------------------------------------------------------------------------------ 2 A1758G7 E,303 RA = 13H 30M 36.32S +/- B1950 Z=0.28 1 V=19.1 +/- 0.1 0.4", 1 B-V = 1.85 +/-0.01 DEC = +50D 48' 59.2" +/- 3 F(2180)=1.48e-17 0.4" 4 F(7850)=1.62e-16 5 F(7020)=1.49e-16 6 F(5550)=9.08e-17 Comments: FLUXVAL_3:Flam through the filter f218w of a strong-UV elliptical galaxy (ngc4649) scaled for redshift and distance to A1758. FLUXVAL_3=Flam through 218W x N4649 scaled for redshift & dist.to A1758 FLUXVAL_4= as ()_3, through f785LP FLUXVAL_5=same as ()_3, thr. f702W FLUXVAL_6= same as ()_3,thr. f555W ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5703 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1.1 A895 WFPC2 IMAGE WFALL F814W 1 200S 58 4 1 CYCLE 4 10S SEQ 1.1-1.7 NO GAP SAME ORIENT FOR 1.2-1.7 AS 1.1 ------------------------------------------------------------------------------------------------------------------------------------ 1.2 A895 WFPC2 IMAGE WFALL F555W 1 500S 33 6 1 CYCLE 4 10S ------------------------------------------------------------------------------------------------------------------------------------ 1.3 A895 WFPC2 IMAGE WFALL F791W 1 150S 70 5 1 CYCLE 4 10S ------------------------------------------------------------------------------------------------------------------------------------ 1.4 A895 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 32 3 1 CYCLE 4 SUM=2X2 4000S ------------------------------------------------------------------------------------------------------------------------------------ 1.5 A895 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 32 3 1 CYCLE 4 SUM=2X2 4000S ------------------------------------------------------------------------------------------------------------------------------------ 1.6 A895 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 32 3 1 CYCLE 4 SUM=2X2 4000S POS TARG +0.4,+0.4 Comments: SMALL OFFSET TO DEAL WITH HOT PIXELS, ETC. ------------------------------------------------------------------------------------------------------------------------------------ 1.7 A895 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 32 3 1 CYCLE 4 SUM=2X2 4000S POS TARG +0.4,+0.4 Comments: SMALL OFFSET TO DEAL WITH HOT PIXELS, ETC. ------------------------------------------------------------------------------------------------------------------------------------ 2.1 A1758G7 WFPC2 IMAGE WFALL F814W 1 300S 46 4 1 CYCLE 4 10S SEQ 2.1-2.7 NO GAP SAME ORIENT FOR 2.2-2.7 AS 2.1 ------------------------------------------------------------------------------------------------------------------------------------ 2.2 A1758G7 WFPC2 IMAGE WFALL F555W 1 450S 31 6 1 CYCLE 4 10S ------------------------------------------------------------------------------------------------------------------------------------ 2.3 A1758G7 WFPC2 IMAGE WFALL F702W 1 150S 68 5 1 CYCLE 4 10S ------------------------------------------------------------------------------------------------------------------------------------ 2.4 A1758G7 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 23 3 1 CYCLE 4 SUM=2X2 4000S ------------------------------------------------------------------------------------------------------------------------------------ 2.5 A1758G7 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 23 3 1 CYCLE 4 SUM=2X2 4000S ------------------------------------------------------------------------------------------------------------------------------------ 2.6 A1758G7 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 23 3 1 CYCLE 4 SUM=2X2 4000S POS TARG +0.4,+0.4 Comments: SMALL OFFSET TO DEAL WITH HOT PIXELS, ETC. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5703 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 2.7 A1758G7 WFPC2 IMAGE WFALL F218W CR-SPLIT=NO 1 2400S 23 3 1 CYCLE 4 SUM=2X2 4000S POS TARG +0.4,+0.4 Comments: SMALL OFFSET TO DEAL WITH HOT PIXELS, ETC. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5703 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO SUM=2X2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 8.8 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category EVOLUTION/COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; SEQ 1.1-1.7 NO GAP; SAME ORIENT FOR 1.2-1.7 AS 1.1; POS TARG +0.4,+0.4; SEQ 2.1-2.7 NO GAP; SAME ORIENT FOR 2.2-2.7 AS 2.1; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W F791W F218W F702W ------------------------------------------------------------------------------------------------------------------------------------ Target Names A895 A1758G7 ------------------------------------------------------------------------------------------------------------------------------------