6001( 8) - 12/30/95 17:53 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6001 Version: 8 Check-in Date: 30-Dec-1995 17:49:09 1.Proposal Title: NGC 5253 STARBURST AS A LABORATORY FOR ENRICHMENT PROCESSES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Galaxies & Clusters GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Jean-Rene ROY Universite Laval CoI: Jeremy WALSH European Southern Observatory N CoI: Michael ROSA European Southern Observatory N ------------------------------------------------------------------------------------ 6. Abstract The nearby starburst in NGC 5253 presents a unique snapshot of the short stage of element enrichment and an unprecedented opportunity to study the interaction between evolving massive stars and the interstellar medium. We propose to observe NGC 5253 with FOS to: (i) determine the carbon abundance near a region of enhanced nitrogen found from the ground to be associated with Wolf-Rayet stars, and (ii) to study the stellar population in the central starburst knots and to model their age and IMF in order to relate the stellar properties to the ISM enrichment. HST provides the long wavelength coverage to allow determination of element abundances, IMF and starburst age from stellar signatures, together with the high spatial resolution to measure change over arcsec scales. The proposed observations should result in a fundamental understanding of the link between starbursts and enrichment mechanisms of relatively low metallicity gas. ------------------------------------------------------------------------------------ 6001( 8) - 12/30/95 17:53 - [ 2] Observations Description ------------------------ It is proposed to observe three of the starburst knots in the dwarf elliptical blue compact galaxy NGC 5253 with the FOS and the 0.86'' round aperture; one of these knots is known to be enhanced in N from ground-based spectroscopy. The emission lines of H, C, N and O will be studied for abundance derivations, and the stellar continuum from 1150 to 8200 Angstrom\\\\\\\\ will be measured to assess the stellar population from O to G stars. Spectra at identical positions in the full UV range and in the optical to 8200 Angstrom\\\\\\\\ are needed. Full wavelength coverage between 1150 and 8200 Angstrom\\\\\\\\ will be achieved by two grating exposures with the blue tube (G130H and G190H) and four grating exposures with the amber tube (G270H, G400H, G570 and G 780H) of each of the three knots. Accurate positions of the knots will be derived from archive WFPC images of NGC 5253 to be released in september 1994. From our ground-based spectroscopic mapping of NGC 5253, we have been able to measure the V surface brightness of the stellar continuum in the three knots to be observed, here named UV1, UV2 and UV3 (corresponding to regions 1, 6 and 2 respectively in Walsh & Roy (1989). The V surface brightness is 18.4 mag arcsec^-2 for both UV1 and UV3 and 18.8 for UV2. The extinction for UV1 is A_V = 0.96 mag, and similar for UV2 and UV3. We aim for a fairly uniform S/N across all the grating domains, so that we can disentangle the various stellar contributions. With S/N >= 10 on the continuum, we will get good line fluxes since the minimum H Beta\\\\\\\\ equivalent width (in UV2) is 36 and the C III 1908 Angstrom\\\\\\\\ line has an equivalent width of ~5. Section lists the requested exposure times in seconds for V = 18.5, A_V = 0.9 for each grating for a mean of 200 counts/diode (S/N ~ 12). For the G130H spectrum, the exposure time has been estimated for 100 counts per bin. Since the resolution is higher for this grating, we can bin by a factor 3, so we reduce the exposure time to 3000 s. The largest fraction of exposure time is spent on this wavelength region and is justified by its astrophysical importance. For the six grating exposures, 3 orbits are required per starburst knot. We plan to obtain the color of acquisition stars around NGC 5253 from archive HST frames, and use acq/binary; we will check the images for extended sources which would confuse the acq/binary. The centering should be ~0.5 arcsec. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- Should be scheduled in cooperation wit a related proposal, proposal number 6021 (Kobulnicky and Skillman), for best efficiency. This file is intended to be merged with 6021 to achieve a 12-orbit, 2-visit schedule file. Targets list in this file is same as 6021, for completeness, though not all targets are observed in this visit. ------------------------------------------------------------------------------------ 6001( 8) - 12/30/95 17:53 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Departement de physique*Universite Laval*Quebec, Qc G1K 7P4, Canada Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6001( 8) - 12/30/95 17:53 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-OFFSET STAR RA=13H 39M 51.7925S +/- J2000 V = 14.5+/-0.5 0.01S,DEC=-31D 39' 03.244" +/- B-V = 0.5+/-0.5 0.1" 2 NGC5253-UV1 EXT-MEDIUM, HII REGION RA-OFF=4.03S+/- 0.01S,DEC- J2000 V = +400 SURF(V) = 18.4+/-0.2 OFF=35.93"+/- 0.1",FROM 1 B-V = 0.0 A(V) = 0.9 Comments: Object in the galaxy is a stellar cluster 3 NGC5253-UV2 EXT-MEDIUM, HII REGION RA-OFF=4.08S+/- 0.01S,DEC- J2000 V = +400 SURF(V) = 18.8+/-0.2 OFF=31.54"+/- 0.1",FROM 1 B-V = 0.0 A(V) = 0.9 Comments: Object in the galaxy is a stellar cluster 4 NGC5253-UV3 EXT-MEDIUM, HII REGION RA-OFF=3.63S+/- 0.01S,DEC- J2000 V = +400 SURF(V) = 18.4+/-0.2 OFF=33.70"+/- 0.1",FROM 1 B-V = 0.0 A(V) = 0.9 Comments: Object in the galaxy is a stellar cluster 5 NGC5253-HII- EXT-MEDIUM, HII REGION RA-OFF=4.061S+/- 0.01S,DEC- J2000 V = +400 SURF(V) = 18.4+/-0.2 1 OFF=37.31"+/- 0.1",FROM 1 B-V = 0.0 A(V) = 0.9 Comments: Object in the galaxy is location in an HII region suspected to be N enriched 6 NGC5253-HII- EXT-MEDIUM, HII REGION RA-OFF=4.007S+/- 0.01S,DEC- J2000 V = +400 SURF(V) = 18.4+/-0.2 2 OFF=39.13"+/- 0.1",FROM 1 B-V = 0.0 A(V) = 0.9 Comments: Object in the galaxy is location in an HII region far from the N enriched location 6001( 8) - 12/30/95 17:53 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: To be coordinated with Kobulnicky and Skillman (6021) NGC 5253 observations which comprises an additional visit. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-OFFSET FOS/RD ACQ/PEA 4.3 MIRROR SEARCH-SIZE- 1 1S ONBOARD ACQ FOR 2 K X=1,SEARCH-SIZE -Y=3,SCAN-STEP- Y=1.23 Comments: Pattern A on offset star ------------------------------------------------------------------------------------------------------------------------------------ 2 STAR-OFFSET FOS/RD ACQ/PEA 1.0 MIRROR SEARCH-SIZE- 1 1S ONBOARD ACQ FOR 3 K X=6,SEARCH-SIZE -Y=2,SCAN-STEP- X=0.61,SCAN- STEP-Y=0.61 Comments: Pattern B1 on offset star ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-OFFSET FOS/RD ACQ/PEA 0.3 MIRROR SEARCH-SIZE- 1 1S ONBOARD ACQ FOR 4-34 K X=5,SEARCH-SIZE -Y=5,SCAN-STEP- X=0.17,SCAN- STEP-Y=0.17 Comments: Pattern D1 on offset star to achive 0."1 centering, errors will then be dominated by errors in offsets ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC5253-UV1 FOS/RD ACCUM 1.0 G270H 1 99S ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC5253-UV1 FOS/RD ACCUM 1.0 G780H 1 2000S ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC5253-UV1 FOS/RD ACCUM 1.0 G570H 1 185S ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC5253-UV1 FOS/RD ACCUM 1.0 G400H 1 90S ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC5253-UV1 FOS/RD ACCUM 1.0 G190H 1 240S ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC5253-UV1 FOS/RD ACQ 4.3 MIRROR 1 20S ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC5253-UV2 FOS/RD ACCUM 1.0 G190H 1 250S ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC5253-UV2 FOS/RD ACCUM 1.0 G270H 1 90S ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC5253-UV2 FOS/RD ACCUM 1.0 G400H 1 90S ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC5253-UV2 FOS/RD ACCUM 1.0 G570H 1 185S ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC5253-UV2 FOS/RD ACCUM 1.0 G780H 1 1870S ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC5253-UV3 FOS/RD ACCUM 1.0 G780H 1 2390S ------------------------------------------------------------------------------------------------------------------------------------ 6001( 8) - 12/30/95 17:53 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC5253-UV3 FOS/RD ACCUM 1.0 G570H 1 550S ------------------------------------------------------------------------------------------------------------------------------------ 23 NGC5253-UV3 FOS/RD ACCUM 1.0 G400H 1 300S ------------------------------------------------------------------------------------------------------------------------------------ 24 NGC5253-UV3 FOS/RD ACCUM 1.0 G270H 1 200S ------------------------------------------------------------------------------------------------------------------------------------ 25 NGC5253-UV3 FOS/RD ACCUM 1.0 G190H 1 600S ------------------------------------------------------------------------------------------------------------------------------------ 31 NGC5253-UV3 FOS/BL ACCUM 1.0 G130H 1 1380S ------------------------------------------------------------------------------------------------------------------------------------ 32 NGC5253-UV2 FOS/BL ACCUM 1.0 G130H 1 1040S ------------------------------------------------------------------------------------------------------------------------------------ 33 NGC5253-UV1 FOS/BL ACCUM 1.0 G130H 1 1000S ------------------------------------------------------------------------------------------------------------------------------------ 34 NGC5253-UV1 FOS/BL ACQ 4.3 MIRROR 1 20S SAME POS AS 33 ------------------------------------------------------------------------------------------------------------------------------------ 6001( 8) - 12/30/95 17:53 - [ 7] Summary Form for Proposal 6001 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.23 SCAN-STEP-Y=0.61 SCAN-STEP-Y=0.17 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Galaxies & Clusters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2 ONBOARD ACQ FOR 3 ONBOARD ACQ FOR 4-34 SAME POS AS 33 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G270H G780H G570H G400H G190H G130H ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-OFFSET NGC5253-UV1 NGC5253-UV2 NGC5253-UV3 ------------------------------------------------------------------------------------------------------------------------------------