8251( 4) - 03/26/99 15:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8251 Version: 4 Check-in Date: 26-Mar-1999 15:57:05 1.Proposal Title: The Second-Parameter Effect in Metal- Rich, Globular Clusters: A Snapshot Study of NGC 6441 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle SNAP 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Horace Smith Michigan State University CoI: Dr. Andrew Layden^\dag Bowling Green State University N CoI: Dr. Marcio Catelan^\dag NASA/Goddard Space Flight Center N CoI: Dr. Allen Sweigart NASA/Goddard Space Flight Center N CoI: Dr. R. Michael Rich University of California at Los Angeles N CoI: Mr. Barton Pritzl Michigan State University N ------------------------------------------------------------------------------------ 5. Abstract While it has long been known that at least one parameter besides the metallicity, Fe/H, determines the horizontal- branch (HB) morphology of Galactic globular clusters (GCs), our ignorance as to the nature of this second parameter (or parameters) has been a major stumbling block in understanding the formation history and age of the GC system. The newly- discovered hot HB populations in the metal-rich GCs NGC 6388 and NGC 6441 provide an unique opportunity for unraveling this second- parameter effect. Sweigart & Catelan (1998) have presented second-parameter models which predict unusually bright HBs for these GCs. We propose to test these models by obtaining B, V, I time-series photometry of the RR Lyrae variables in the core of NGC 6441 in order to determine whether, as predicted, the pulsation periods are unusually long as implied by a bright HB luminosity. If confirmed, this would argue against age or mass loss as the second parameter in NGC 6441 and, more generally, wo uld have implications for the use of RR Lyrae stars as standard candles for determining GC distances and ages. A possible new class of bright RR Lyrae-like variables will also be investigated. The interplay between stellar evolution and cluster dynamics will be studied by comparing the radial distribution of the RR Lyrae stars to those of blue and red HB stars. We waive proprietary rights to any data obtained. ------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 2] Observations Description ------------------------ From Figure 2 in Piotto et al. (1997; see Fig. 1, from Sosin et al. 1997), we find that the RR Lyrae in NGC 6441 lie at = 17.5 mag, and have a mean color of = 0.85 mag. For the F439W, F555W, and F814W filters, we then obtain [the integral of Q(lambda)T(lambda)d(lambda)/lambda, AB(nu)] = 0.00501, 0.60, 0.02727, 0.03, and 0.01799, -0.42, respectively. For the exposures with the V and I filters, we intend to go as deep as Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 5] Visit: 02 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 6] Visit: 03 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 7] Visit: 04 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 8] Visit: 05 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 9] Visit: 06 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 10] Visit: 07 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 11] Visit: 08 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 12] Visit: 09 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 13] Visit: 10 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 14] Visit: 11 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 15] Visit: 12 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 50 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 16] Visit: 13 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 17] Visit: 14 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 18] Visit: 15 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 19] Visit: 16 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 20] Visit: 17 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 21] Visit: 18 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 22] Visit: 19 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 23] Visit: 20 Visit Priority: Visit Requirements: PCS MODE GYRO 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6441 WFPC2 IMAGE WF3-FIX F439W 1 80 S ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6441 WFPC2 IMAGE WF3-FIX F555W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6441 WFPC2 IMAGE WF3-FIX F814W 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 8251( 4) - 03/26/99 15:58 - [ 24] Summary Form for Proposal 8251 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF3-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category SNAP ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE GYRO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6441 ------------------------------------------------------------------------------------------------------------------------------------