13780( 4) - 08-Oct-2014 10:47:33 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13780 Version: 4 Check-in Time: 08-Oct-2014 10:47:33 STScI Edit Number: 0 Title The Nature of Newly Discovered Wolf-Rayet Stars in the LMC ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Philip Massey Lowell Observatory Y CoI: Dr. D. John Hillier University of Pittsburgh N CoI: Kathryn Forbes Neugent Lowell Observatory N CoI: Dr. Nidia Morrell Carnegie Institution of Washington N ------------------------------------------------------------------------------------ Abstract We have recently discovered five Wolf-Rayet (WR) stars in the LMC which might be naively classified as "WN3+O3 V." However, such a pairing is unlikely for a number of reasons: (a) O3 V stars are very rare, as they are the hottest and most luminous of the dwarfs; (b) the absolute visual magnitudes of our stars are quite faint (Mv=-3) compared to even an O3 V star by itself (Mv=-5.5); (c) these stars do not exhibit radial velocity variations, although our data on this are admittedly limited; and (d) such a pairing would be hard to understand from a stellar evolution point of view, since a massive star will evolve out of the O3 V phase in about a million years, while it takes several million years to form a WN star. We are forced to conclude that we have discoverd a new class of WRs. We have excellent optical spectra with Magellan, and our modeling of these data suggest a very high effective temperature (70, 000 K), strongly enhanced nitrogen, and a very low mass-loss rate. However, these physical parameters are poorly constrained by the optical data alone, and we now seek UV spectra that will contain lines that will better determine the temperatures, and the important resonance lines that provide crucial diagnostics of the stellar winds. The results of this modeling will allow us to understand the nature of these objects, and where they fit in the evolution of massive stars. If they are the products of single star evolution, they indicate we have some fundamental misconceptions. If they are the products of binary evolution, how do we explain the absence of any companions? We can only address these questions by having reliable stellar parameters and abundances. ------------------------------------------------------------------------------------ Observations Description ------------------------ Overview: We will observe each of these three WN3/O3V stars using COS/FUV and the G140L grating in the standard two settings (G140L/1105, G140L/1280) for complete wavelength coverage in the FUV. Each star will be observed in a 2-orbit visit. Target Acquisitions: Our coordinates have been measured directly from our survey frames; all three targets are also listed in the GSC-II with coordinates that agree to <0.1". The only complication is that our targets are too bright for acquisition through the Primary Science Aperture with Mirror A. We therefore do PEAKXD and PEAKD in 13780( 4) - 08-Oct-2014 10:47:33 - [ 2] dispersed light. Exposure times have been estimated by (a) our preliminary CMFGEN 100K model, (b) flux distribution of an O3 V star, and (c) a 120, 000 black-body, all with good agreement. ------------------------------------------------------------------------------------ 13780( 4) - 08-Oct-2014 10:47:33 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 LMC079-1 EXT-STAR, WOLF RAYET, RA=05H07M13.2830S +/- 0.2", J2000 V = 16.06 +/- 0.1 B-V=0.03, U-B=-1.02 WOLF RAYET - WN DEC=-70D33'34.05" +/- 0.2" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 LMC170-2 EXT-STAR, WOLF RAYET, RA=05H29M18.1390S +/- 0.2", J2000 V = 16.04 +/- 0.1 B-V=-0.25, U-B=-1.03 WOLF RAYET - WN DEC=-69D19'43.03" +/- 0.2" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 LMC277-2 EXT-STAR, WOLF RAYET, RA=05H04M32.5920S +/- 0.2", J2000 V = 15.83 +/- 0.1 B-V=-0.16, U-B=-0.87 WOLF RAYET - WN DEC=-68D00'59.34" +/- 0.2" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 13780( 4) - 08-Oct-2014 10:47:33 - [ 4] Visit: 01 Visit Requirements: 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 LMC079-1 COS/FUV ACQ/PEA PSA G140L 1105 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 LMC079-1 COS/FUV ACQ/PEA PSA G140L 1105 NUM-POS=5, STEP-SIZE=0.9, 1 2 S (2 S) KD CENTER=FLUX-WT-FLR ------------------------------------------------------------------------------------------------------------------------------------ 3 LMC079-1 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=360 1 510 S G see below (2404 S) Comments: Buffer-time returned is 550 sec both by using our CMFGEN model a input to the ETC (622040) and by using a 100, 00 K black body with V=16.0 and E(B-V)=0.13 with LMC reddening law. 360 is roughly 2/3rds of that. ------------------------------------------------------------------------------------------------------------------------------------ 4 LMC079-1 COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, BUFFER-TIME=470 1 600 S G see below (2896 S) Comments: We obtain a buffer-time of 712-714 sec either with a 100K black-body or with our CMFGEN model; we have taken 2/3rds of that and used 470 sec. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC079-1 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD LMC079-1 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD LMC079-1 3 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 601.0 S G LMC079-1 3 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 601.0 S G LMC079-1 3 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 601.0 S G LMC079-1 3 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 601.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC079-1 4 COS/FUV TIME-TA PSA G140L 1280 none none none 1 2 724.0 S G LMC079-1 4 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 724.0 S G LMC079-1 4 COS/FUV TIME-TA PSA G140L 1280 none none none 3 2 724.0 S G LMC079-1 4 COS/FUV TIME-TA PSA G140L 1280 none none none 4 2 724.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 6] Visit: 02 Visit Requirements: 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 LMC170-2 COS/FUV ACQ/PEA PSA G140L 1105 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 LMC170-2 COS/FUV ACQ/PEA PSA G140L 1105 NUM-POS=5, STEP-SIZE=0.9, 1 2 S (2 S) KD CENTER=FLUX-WT-FLR ------------------------------------------------------------------------------------------------------------------------------------ 3 LMC170-2 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=360 1 510 S G see below (2388 S) Comments: Buffer-time returned is 550 sec both by using our CMFGEN model a input to the ETC (622040) and by using a 100, 00 K black body with V=16.0 and E(B-V)=0.13 with LMC reddening law. 360 is roughly 2/3rds of that. ------------------------------------------------------------------------------------------------------------------------------------ 4 LMC170-2 COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, BUFFER-TIME=470 1 600 S G see below (2856 S) Comments: We obtain a buffer-time of 712-714 sec either with a 100K black-body or with our CMFGEN model; we have taken 2/3rds and used 470 sec. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC170-2 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD LMC170-2 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD LMC170-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 597.0 S G LMC170-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 597.0 S G LMC170-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 597.0 S G LMC170-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 597.0 S G LMC170-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 1 2 714.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC170-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 714.0 S G LMC170-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 3 2 714.0 S G LMC170-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 4 2 714.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 8] Visit: 03 Visit Requirements: 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 LMC277-2 COS/FUV ACQ/PEA PSA G140L 1105 1 2 S (2 S) KXD ------------------------------------------------------------------------------------------------------------------------------------ 2 LMC277-2 COS/FUV ACQ/PEA PSA G140L 1105 NUM-POS=5, STEP-SIZE=0.9, 1 2 S (2 S) KD CENTER=FLUX-WT-FLR ------------------------------------------------------------------------------------------------------------------------------------ 3 LMC277-2 COS/FUV TIME-TA PSA G140L 1105 FP-POS=ALL, BUFFER-TIME=360 1 510 S G see below (2388 S) Comments: ETC estimates BUFFER-TIME of 532 sec using our CMFGEN 100K model. 2/3rds of this is 350 sec. Decreased to 150sec to be conservative ------------------------------------------------------------------------------------------------------------------------------------ 4 LMC277-2 COS/FUV TIME-TA PSA G140L 1280 FP-POS=ALL, BUFFER-TIME=470 1 600 S G see below (2856 S) Comments: We obtain a buffer-time of 712-714 sec either with a 100K black-body or with our CMFGEN model; we have taken 2/3rds of that and used 470 sec. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC277-2 1 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KXD LMC277-2 2 COS/FUV ACQ/PEA PSA G140L 1105 none none none none 1 N/A KD LMC277-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 1 1 597.0 S G LMC277-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 2 1 597.0 S G LMC277-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 3 1 597.0 S G LMC277-2 3 COS/FUV TIME-TA PSA G140L 1105 none none none 4 1 597.0 S G LMC277-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 1 2 714.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ LMC277-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 2 2 714.0 S G LMC277-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 3 2 714.0 S G LMC277-2 4 COS/FUV TIME-TA PSA G140L 1280 none none none 4 2 714.0 S G 13780( 4) - 08-Oct-2014 10:47:33 - [ 10] Summary Form for Proposal 13780 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAKD, ACQ/PEAKXD, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=360, BUFFER-TIME=470, CENTER=FLUX-WT-FLR, FP-POS=ALL, NUM-POS=5, STEP-SIZE=0.9 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names LMC079-1, LMC170-2, LMC277-2 ------------------------------------------------------------------------------------------------------------------------------------