10528( 3) - 05/13/05 12:55 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10528 Version: 3 Check-in Date: 13-May-2005 16:55:19 1.Proposal Title: Ram Pressure Stripping and Dense Cloud Ablation in the Virgo Spiral NGC 4402 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 14 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Jeffrey D.P. Kenney Yale University CoI: Mr. Hugh H. Crowl Yale University N ------------------------------------------------------------------------------------ 6. Abstract We propose to image in BVI with HST ACS the highly inclined Virgo cluster spiral galaxy NGC 4402, which is an outstanding example of a galaxy undergoing stripping of its ISM by an ICM-ISM interaction. Ground-based images at 0.5" resolution appear to show active dust stripping, triggered star formation, and ablation of dense molecular clouds by the ICM wind. The near side of NGC 4402 contains the leading edge of interaction, giving us a relatively unobscured view of the processes which occur as the ICM wind impacts the ISM. High resolution HST B-I images of dust in NGC 4402 can reveal the fate of giant molecular clouds during a stripping event, including whether clouds above some size get left behind as the rest of the ISM is stripped from around them, how decoupled clouds become ablated by the ICM wind, and how the survival time varies with cloud mass. We will identify and estimate the ages of stars and star clusters in the stripped outer disk and halo, and from the spatial distributions of the younger objects, constrain the stripping history of the galaxy. Its proximity, orientation, stage of evolution, and direction of travel through the ICM make NGC 4402 an outstanding subject for a detailed HST study of ICM-ISM stripping. An in-depth study of this galaxy will provide new insight into the physical processes of ISM-ICM interactions and give us greater understanding of cluster galaxy evolution, both in Virgo and at higher redshifts. ------------------------------------------------------------------------------------ 10528( 3) - 05/13/05 12:55 - [ 2] Observations Description ------------------------ We propose to image NGC~4402 with ACS WFC in 3 bands: F435W (Johnson B), F606W (Broad V), and F814W (Broad I). The 202"x202" field of view of the WFC is well- suited for imaging the entire active stripping region of NGC 4402. It includes all the HI and H-alpha emission detected in the galaxy, which has a total extent of 160. In order to detect enough star clusters to be statistically meaningful, we need to reach ~3 magnitudes fainter than the peak of the globular cluster luminosity function in each of BVI. This is about the same depth which will allow us to detect enough isolated young stars to enable mapping of distinct concentrations. Going ~0.5 magnitude deeper in V than the other bands, and given the various constraints of HST, we have settled on the following request. To reach magnitudes of F435W (B)=27.8, F606W (V)=27.5, and F814W (I)=26.3 with a signal-to-noise of 10 requires integration times of 120, 40 and 40 minutes respectively, according to the Exposure Time Calculator. At 2 exposures per orbit, there are about 40 minutes of exposure time per orbit, given 52 minutes of visibility time at the low declination of Virgo, minus 5-6 minutes for guide star acquisition time and 6.5 minutes of overhead. This corresponds to 5 orbits. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10528( 3) - 05/13/05 12:55 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4402 GALAXY, SPIRAL RA=12H26M7.5000S +/- 0.1", J2000 V = 12.55+/-0.1 DEC=+13D06'46.00" +/- 0.1" Coordinate Source: Other_Source: 2MASS 10528( 3) - 05/13/05 12:55 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10528( 3) - 05/13/05 12:55 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 10.0D TO 350.0 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4402 ACS/WFC ACCUM WFC F435W 1 2400 S PATTERN 1 1 see below ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4402 ACS/WFC ACCUM WFC F606W CR-SPLIT=NO 1 800 S PATTERN 1 2 see below ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4402 ACS/WFC ACCUM WFC F814W CR-SPLIT=NO 1 800 S PATTERN 1 3 see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NGC4402 1 ACS/WFC ACCUM WFC F435W 1 none none 1 1 1253.0 S NGC4402 1 ACS/WFC ACCUM WFC F435W 1 none none 2 1 1253.0 S NGC4402 1 ACS/WFC ACCUM WFC F435W 2 none none 1 2 1294.0 S NGC4402 1 ACS/WFC ACCUM WFC F435W 2 none none 2 2 1294.0 S NGC4402 1 ACS/WFC ACCUM WFC F435W 3 none none 1 3 1292.0 S NGC4402 1 ACS/WFC ACCUM WFC F435W 3 none none 2 3 1292.0 S NGC4402 2 ACS/WFC ACCUM WFC F606W 1 none none none 4 779.0 S NGC4402 2 ACS/WFC ACCUM WFC F606W 2 none none none 4 779.0 S NGC4402 2 ACS/WFC ACCUM WFC F606W 3 none none none 4 779.0 S NGC4402 3 ACS/WFC ACCUM WFC F814W 1 none none none 5 791.0 S NGC4402 3 ACS/WFC ACCUM WFC F814W 2 none none none 5 791.0 S NGC4402 3 ACS/WFC ACCUM WFC F814W 3 none none none 5 791.0 S 10528( 3) - 05/13/05 12:55 - [ 6] Summary Form for Proposal 10528 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 10.0D TO 350.0 D PATTERN 1 1 PATTERN 1 2 PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F435W F606W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4402 ------------------------------------------------------------------------------------------------------------------------------------