15112( 3) - 12-Dec-2018 19:59:42 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15112 Version: 3 Check-in Time: 12-Dec-2018 19:59:42 STScI Edit Number: 0 Title The low-metallicity starburst NGC346: massive-star population and feedback ------------------------------------------------------------------------------------ Type Cycle GO 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Lida Oskinova Universitat Potsdam Y CoI: Dr. Wolf-Rainer Hamann Universitat Potsdam N CoI: Prof. John S. Gallagher III University of Wisconsin - Madison N CoI: Dr. Rainer Hainich Universitat Potsdam N CoI: Dr. Helge Todt Universitat Potsdam N CoI: Dr. Andreas Sander Universitat Potsdam N CoI: Dr. Tomer Shenar Universitat Potsdam N CoI: Prof. You-Hua Chu Academia Sinica, Institute of Astronomy N and Astrophysics CoI: Dr. Martin Wendt Universitat Potsdam N ------------------------------------------------------------------------------------ Abstract The Small Magellanic Cloud (SMC) is ideal to study young, massive stars at low metallicity. The compact cluster NGC346 contains about half of all O-type stars in the entire SMC. The massive-star population of this cluster powers N66, the brightest and largest HII region in the SMC. We propose to use HST-STIS to slice NGC346 with 20 long-slit exposures, in order to obtain the UV spectra of most of the massive early-type stars of this cluster. Archival data of 13 exposures that cover already a minor part of this cluster will be included in our analyses. Our aim is to quantitatively analyze virtually the whole massive-star population of NGC346. We have already secured the optical spectra of all massive stars in the field with the integral-field spectrograph MUSE at the ESO-VLT. However, for the determination of the stellar-wind parameters, i.e. the mass-loss rates and the wind velocities, ultraviolet spectra are indispensable. Our advanced "Potsdam Wolf-Rayet (PoWR)" code will be used for modeling the stellar and wind spectra in the course of the analysis. Finally, we will obtain: (a) the fundamental stellar and wind parameters of all stars brighter than spectral type B2V in the field, which, e, g, , will constrain the initial mass function in this young low-metallicity starburst; (b) mass-loss rates of many more OB-type stars at SMC metallicity than hitherto known, allowing to better constrain their metallicity dependence; (c) the integrated feedback by ionizing radiation and stellar winds of the whole massive-star population of NGC346, which will be used as input to model the ecology of the giant HII region N66. These HST UV data will be of high legacy value. ------------------------------------------------------------------------------------ Observations Description ------------------------ The observations shall map major parts of the young stellar cluster NGC346 in 15112( 3) - 12-Dec-2018 19:59:42 - [ 2] the SMC. We want to take STIS long-slit UV spectra arranged in mosaic of adjacent slit positions. The slit is 52" x 2", and the positions should overlap by 0.2" in dispersion direction. The aim is to extract as many as possible stellar spectra of the blue cluster stars. The fields are carefully chosen, taking into account that a minor part of the cluster has already been observed with a similar technique with STIS before (GO-8629, PI Bruhweiler), see Figure3 of the Phase I proposal. For the visual brightness that is requested in the "target" forms we have always given the UV-brightes star in the whole mosaic field (Cl* NGC346 W3, V=12.8mag), although this star is only covered by one of the slit postions. For the precise positioning of the slit exposures, we use first a reference star for target acquisition and peakup. Then, the slit is positiond with relative offsets using the "STIS PERP-TO-SLIT" pattern. In addition to the coordinate offsets, we apply an offset ot 3" in slit direction in order to account for the spectral offset of the MAMA detector described in Sect. 7.6 of the "STIS Instrument Handbook for Cycle 25" (Version 16.0). Our mosaic coverage requires a position angle of the slit of about 35deg. We specify here a tolerance of plus/minus 10deg in order to allow for larger windows of visibility. If this would still lead to scheduling problems, we could release this constraint further. In any case, we would ask to contact us when the orbits have been scheduled and the exact position angle of the slit is known, so that we could check and re-adjust the position offsets in order not to miss any interesting star. Following the special note for Cycle 25, we have structured our 5 orbits into visits of 3 + 2 orbits. If it would finally happen that the orbits can be scheduled back-to-back, the target acquision and peakup at the beginning of orbit 4 would not be necessary and the time can be distributed for the science exposures. In each orbit we have left 165s at the end unused, because we noticed that otherwise the visibility is strongly redued. Of course, finally all available time should be evenly distributed to extend the science exposures to the maximum possible. ------------------------------------------------------------------------------------ 15112( 3) - 12-Dec-2018 19:59:42 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-346-W3-O STAR, OF RA=00H59M0.7500S, J2000 V = 12.8 FFSET DEC=-72D10'28.20" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC346-A STELLAR CLUSTER, OPEN RA-OFF=0.359S, DEC-OFF=-0.91", J2000 V = 12.8 +/- 0.04 abmag=12.8 in filter CLUSTER FROM 1 WFC3/UVIS/F225W ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC346-B STELLAR CLUSTER, OPEN RA-OFF=5.636S, DEC-OFF=5.12", J2000 V = 12.8 abmag>13.06 in filter CLUSTER FROM 1 WFC3/UVIS/F225W ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC346-C STELLAR CLUSTER, OPEN RA-OFF=3.236S, DEC-OFF=-17.88", J2000 V = 12.8 abmag>13.06 in filter CLUSTER FROM 1 WFC3/UVIS/F225W ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC346-C2 STELLAR CLUSTER, OPEN RA-OFF=4.525S, DEC-OFF=-21.98", J2000 V = 12.8 abmag>13.06 in filter CLUSTER FROM 1 WFC3/UVIS/F225W ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC346-D STELLAR CLUSTER, OPEN RA-OFF=6.736S, DEC-OFF=-19.88", J2000 V = 12.8 abmag>13.06 in filter CLUSTER FROM 1 WFC3/UVIS/F225W ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-346-W3 STAR, OF RA=00H59M0.7500S, J2000 V = 12.8 DEC=-72D10'28.20" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 15112( 3) - 12-Dec-2018 19:59:42 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-PERP-TO-SLIT Pattern_Purpose MOSAIC Number_Of_Points 4 Point_Spacing 1.8 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type STIS-PERP-TO-SLIT Pattern_Purpose MOSAIC Number_Of_Points 3 Point_Spacing 1.8 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 0.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 15112( 3) - 12-Dec-2018 19:59:42 - [ 5] Visit: 01 Visit Requirements: ORIENT 70D TO 90 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-346-W3- STIS/CCD ACQ F28X50LP MIRROR 1 1.0 S (1 OFFSET S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-346-W3- STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 0.5 S (0.5 OFFSET K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC346-B STIS/FUV ACCUM 52X2 G140L 1425 1 520 S POS TARG 0., 3.; PATTERN -MAMA (2080 S) 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC346-C STIS/FUV ACCUM 52X2 G140L 1425 1 686 S POS TARG 0., 3.; PATTERN -MAMA (2744 S) 1 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC346-A STIS/FUV ACCUM 52X2 G140L 1425 1 625 S POS TARG 0., 3.; PATTERN -MAMA (1875 S) 2 5 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-346-W3 STIS/CCD ACQ F28X50LP MIRROR 1 1.0 S (1 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-346-W3 STIS/FUV ACCUM 52X0.2 G140L 1425 1 225 S (225 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-346-W3-OFFSET 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A NGC-346-W3-OFFSET 2 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC346-B 3 STIS/FUV ACCUM 52X2 G140L 1425 1 none none none 1 N/A -MAMA NGC346-B 3 STIS/FUV ACCUM 52X2 G140L 1425 2 none none none 1 N/A -MAMA NGC346-B 3 STIS/FUV ACCUM 52X2 G140L 1425 3 none none none 1 N/A -MAMA NGC346-B 3 STIS/FUV ACCUM 52X2 G140L 1425 4 none none none 1 N/A -MAMA NGC346-C 4 STIS/FUV ACCUM 52X2 G140L 1425 1 none none none 2 N/A -MAMA NGC346-C 4 STIS/FUV ACCUM 52X2 G140L 1425 2 none none none 2 N/A -MAMA 15112( 3) - 12-Dec-2018 19:59:42 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC346-C 4 STIS/FUV ACCUM 52X2 G140L 1425 3 none none none 2 N/A -MAMA NGC346-C 4 STIS/FUV ACCUM 52X2 G140L 1425 4 none none none 2 N/A -MAMA NGC346-A 5 STIS/FUV ACCUM 52X2 G140L 1425 1 none none none 3 N/A -MAMA NGC346-A 5 STIS/FUV ACCUM 52X2 G140L 1425 2 none none none 3 N/A -MAMA NGC346-A 5 STIS/FUV ACCUM 52X2 G140L 1425 3 none none none 3 N/A -MAMA NGC-346-W3 6 STIS/CCD ACQ F28X50LP MIRROR none none none none 3 N/A NGC-346-W3 7 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 3 N/A -MAMA 15112( 3) - 12-Dec-2018 19:59:42 - [ 7] Visit: 02 Visit Requirements: ORIENT 70D TO 90 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-346-W3- STIS/CCD ACQ F28X50LP MIRROR 1 1.0 S (1 OFFSET S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-346-W3- STIS/CCD ACQ/PEA 52X0.1 MIRROR 1 0.5 S (0.5 OFFSET K S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC346-C2 STIS/FUV ACCUM 52X2 G140L 1425 1 520 S POS TARG 0., 3.; PATTERN -MAMA (2080 S) 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC346-D STIS/FUV ACCUM 52X2 G140L 1425 1 686 S POS TARG 0., 3.; PATTERN -MAMA (2744 S) 1 4 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-346-W3-OFFSET 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A NGC-346-W3-OFFSET 2 STIS/CCD ACQ/PEA 52X0.1 MIRROR none none none none 1 N/A K NGC346-C2 3 STIS/FUV ACCUM 52X2 G140L 1425 1 none none none 1 N/A -MAMA NGC346-C2 3 STIS/FUV ACCUM 52X2 G140L 1425 2 none none none 1 N/A -MAMA NGC346-C2 3 STIS/FUV ACCUM 52X2 G140L 1425 3 none none none 1 N/A -MAMA NGC346-C2 3 STIS/FUV ACCUM 52X2 G140L 1425 4 none none none 1 N/A -MAMA NGC346-D 4 STIS/FUV ACCUM 52X2 G140L 1425 1 none none none 2 N/A -MAMA NGC346-D 4 STIS/FUV ACCUM 52X2 G140L 1425 2 none none none 2 N/A -MAMA NGC346-D 4 STIS/FUV ACCUM 52X2 G140L 1425 3 none none none 2 N/A -MAMA NGC346-D 4 STIS/FUV ACCUM 52X2 G140L 1425 4 none none none 2 N/A -MAMA 15112( 3) - 12-Dec-2018 19:59:42 - [ 8] Summary Form for Proposal 15112 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.1, 52X0.2, 52X2, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ, ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 70D TO 90 D, PATTERN 1 3, PATTERN 1 4, PATTERN 2 5, POS TARG 0., 3. ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-346-W3, NGC-346-W3-OFFSET, NGC346-A, NGC346-B, NGC346-C, NGC346-C2, NGC346-D ------------------------------------------------------------------------------------------------------------------------------------