7772( 3) - 09/12/97 10:08 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7772 Version: 3 Check-in Date: 12-Sep-1997 10:07:04 1.Proposal Title: The UV-upturn of super-metal-rich globular clusters ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO/CAR 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Pascale JABLONKA Observatoire de Meudon, DAEC CoI: Eduardo BICA Universidade Federal do Rio Grande do Sul N CoI: Andre MAEDER Observatoire de Geneve N CoI: Georges MEYLAN European Southern Observatory N CoI: Georges MEYNET Observatoire de Geneve N CoI: Dante MINNITI Lawrence Livermore National Laboratory N ------------------------------------------------------------------------------------ 6. Abstract We propose to use the FOS to look for strong UV upturn in the spectral energy distributions of 6 super-metal-rich star clusters in M31. Our goal is to clarify whether the stellar population responsible for strong UV fluxes in galaxies can also be present in star clusters, i.e., if bluewards of 2500Angstrom, clusters can still be considered as galaxy templates. For this purpose, we have selected clusters with metal enrichment similar to those encountered in the galaxian nuclear regions, where strong UV fluxes are observed. ------------------------------------------------------------------------------------ 7772( 3) - 09/12/97 10:08 - [ 2] Observations Description ------------------------ The domain of the G140L grating (LambdaLambda 1150--1740 Angstrom) is well suited to follow the UV rising branch. The 52X0.5 aperture corresponds to our needs. Indeed, the M31 clusters have core radii of ~0.1-0.2 arcsec Fusi Pecci et al., 1994, A&A, 284, 349. This implies that this 0.5'' aperture will collect most of the cluster flux, without suffering from field contamination. The UV radiation of field stars at the position of our clusters in M31 should be extremely faint. E.g. G177 is the closest cluster to the M31 nucleus, only 2.31 arcmin away Battistini et al., 1993, A&A, 272, 77; at this distance, the IUT photometry of the background indicates m(1520Angstrom)=25 mag and m(2500Angstrom)=22 mag (O'Connell, private communication). The lowest UV flux detected at ~1500Angstrom\\ for M31 star clusters is ~5 10^-16 erg/s/cm^2/Angstrom\\ Cowley & Burstein, 1988, AJ, 95, 1071; Bohlin et al., 1993, ApJ, 417, 127. Taking this value for G177 shows that the background will be at least 8 magnitudes below G177 level, at 1520Angstrom\\ . In our exposure time calculations, we refer to this minimum flux of 5 10^-16 erg/s/cm^2/Angstrom. Real Time Justification ----------------------- None. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7772( 3) - 09/12/97 10:08 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC224-G177 EXT-CLUSTER RA=0H 42M 34.48S +/- 0.2S, J2000 V = 16.0 DEC=41D 14' 03.28" +/- 0.2", B-V = 1.31 PLATE-ID=0738 7772( 3) - 09/12/97 10:08 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC224-G177 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 2 S ONBOARD ACQ FOR 12 CD P ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2321 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2679 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2679 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7772( 3) - 09/12/97 10:08 - [ 5] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC224-G177 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 2 S ONBOARD ACQ FOR 22 CD P ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2321 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 23 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2679 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 24 NGC224-G177 STIS/F ACCUM 52X0.5 G140L 1425 1 2679 S EXPAND UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 7772( 3) - 09/12/97 10:08 - [ 6] Summary Form for Proposal 7772 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 12 EXPAND ONBOARD ACQ FOR 22 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC224-G177 ------------------------------------------------------------------------------------------------------------------------------------