13373( 4) - 21-Oct-2013 10:32:00 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13373 Version: 4 Check-in Time: 21-Oct-2013 10:32:00 STScI Edit Number: 0 Title The changing wind structure of the WR/LBV star in HD 5980 ------------------------------------------------------------------------------------ Type Cycle GO 21 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Gloria Koenigsberger Universidad Nacional Autonoma de Mexico Y (UNAM) CoI: Dr. Rodolfo H. Barba Universidad de La Serena N CoI: Dr. Roberto C. Gamen Universidad Nacional de La Plata (UNLP) N CoI: Dr. Nidia Morrell Carnegie Institution of Washington N CoI: Dr. D. John Hillier University of Pittsburgh N ------------------------------------------------------------------------------------ Abstract HD 5980 is an extraordinary system of massive stars that is located in the Small Magellanic Cloud. It contains an eclipsing binary (P=19.3 d) consisting of a luminous blue variable (LBV) and its Wolf-Rayet (WR) companion. The LBV underwent a major eruptive event in 1994 during which its bolometric luminosity increased by a factor of ~5 and it is currently approaching its minimum state of activity. The primary objective of this proposal is to determine the wind velocity and mass-loss rate of the LBV in its current state. With these observations and our earlier observations and analyses, HD 5980 offers the unprecedented opportunity of deriving all the fundamental parameters of an LBV system throughout its activity cycle, parameters which are required in order to constrain the sources of the instabilities that lead to the eruptive phenomena. To accomplish these goals, we request 2 HST orbits to observe HD 5980 with STIS in order to obtain one set of FUV MAMA and CCD spectra at the eclipse, when the LBV occults its WR companion. The study of HD 5980 and the UV spectrum that we propose to acquire are relevant to a broad range of problems including wind-wind collision phenomena, the formation of circumstellar structures powered by stellar winds and the evolution of supernova progenitors. ------------------------------------------------------------------------------------ Observations Description ------------------------ We plan to observe HD 5980 in the 1170--1730 A spectral interval with STIS using the FUV- MAMA detector, the E140M grating and the 0.2x0.2 slit. To calculate the exposure time we used the STIS spectrum obtained on 2009 Sept 9. The Exposure Time Calculator (516777) indicates that with a 4678s exposure time we will attain S/N= 47 per resolution element at 1500 A, allowing a very good measurement of the edge and saturated portions of the P Cygni profiles. We will obtain the first part of this observation with a 2608s exposure in the first orbit and then a 2070s exposure in the second orbit. We will also obtain exposures using the CCD detector and the G230LB, G430L and G750L gratings and 52x0.2 aperture. These will provide a full spectral energy distribution for the CMFGEN model fits. Using the CCD spectra obtained by STIS 13373( 4) - 21-Oct-2013 10:32:00 - [ 2] in the year 2000, we find that S/N>100 is attained with exposure times of 300s, 60s and 60 , respectively. The total exposure time+overheads for the CCD spectra is less than 25 min. The first orbit will contain the target acquisition and the first FUV-MAMA exposure. The second orbit will contain the second FUV-MAMA exposure and the CCD spectra. The mixture of MAMA and CCD observations in the same orbit is justified by the short exposure time required for the CCD spectra (HST Primer sec. 6.2.2). A CCD-FLAT will be acquired during occultation after the G750L exposure in order to correct for the fringing in this spectral region. The visit is to be carried out when the binary system is at orbital phase 0.00+/-0.01. This is the eclipse of Star B (=WR) by Star A (=LBV). The orbital period and initial epoch are P=19.2654 d (Breysacher & Sterken 1997) and T0=HJD 2443158.873 (Koenigsberger et al. 2013). Within the time slots given by the Visit Planner, windows of opportunity in 2013 for phase=0.00 for this visit are on: HJD 2456509.795, 2456567.592, 2456586.856 and 2456625.388. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13373( 4) - 21-Oct-2013 10:32:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-5980 STAR, INTERACTING RA=00H59M26.5687S +/- 0.1", J2000 V = +150 V = 11.5 +/- 0.2 1.0e-11erg/cm^2-s-A @ BINARY, LUMINOUS BLUE DEC=-72D09'53.91" +/- 0.1" NV 1240; 1.7e-11 erg/cm^2-s-A @ HeII VARIABLE, WOLF RAYET - 1640 WN Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -7.618368844090924E-4 -0.0024 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 13373( 4) - 21-Oct-2013 10:32:00 - [ 4] Visit: 01 Visit Requirements: Period 19.2654 D AND ZERO-PHASE HJD2443158.873 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 HD-5980 STIS/CCD ACQ F28X50OII MIRROR ACQTYPE=POINT 1 60 S (60 PHASE 0.99 TO 0.01 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-5980 STIS/FUV ACCUM 0.2X0.2 E140M 1425 BINAXIS1=DEF, BINAXIS2=DEF 1 2608 S -MAMA (2608 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-5980 STIS/FUV ACCUM 0.2X0.2 E140M 1425 BINAXIS1=DEF, BINAXIS2=DEF 1 2070 S -MAMA (2070 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-5980 STIS/CCD ACCUM 52X0.2 G230LB 2375 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 HD-5980 STIS/CCD ACCUM 52X0.2 G430L 4300 1 60 S (60 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 HD-5980 STIS/CCD ACCUM 52X0.2 G750L 7751 1 60 S (60 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 CCDFLAT STIS/CCD ACCUM 0.3X0.09 G750L 7751 2 0.1 S (0.2 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 | ------------------------------------------------------------------------------------------------------------------------------------ HD-5980 1 STIS/CCD ACQ F28X50OI MIRROR none none none none 1 N/A I HD-5980 2 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 1 N/A -MAMA HD-5980 3 STIS/FUV ACCUM 0.2X0.2 E140M 1425 none none none none 2 N/A -MAMA HD-5980 4 STIS/CCD ACCUM 52X0.2 G230LB 2375 none none none 1 2 N/A HD-5980 4 STIS/CCD ACCUM 52X0.2 G230LB 2375 none none none 2 2 N/A HD-5980 5 STIS/CCD ACCUM 52X0.2 G430L 4300 none none none 1 2 N/A HD-5980 5 STIS/CCD ACCUM 52X0.2 G430L 4300 none none none 2 2 N/A HD-5980 6 STIS/CCD ACCUM 52X0.2 G750L 7751 none none none 1 2 N/A HD-5980 6 STIS/CCD ACCUM 52X0.2 G750L 7751 none none none 2 2 N/A CCDFLAT 7 STIS/CCD ACCUM 0.3X0.09 G750L 7751 none none 1 none 2 N/A CCDFLAT 7 STIS/CCD ACCUM 0.3X0.09 G750L 7751 none none 2 none 2 N/A 13373( 4) - 21-Oct-2013 10:32:00 - [ 5] Summary Form for Proposal 13373 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.2, 0.3X0.09, 52X0.2, F28X50OII ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT, BINAXIS1=DEF, BINAXIS2=DEF ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PHASE 0.99 TO 0.01, Period 19.2654 D AND ZERO-PHASE HJD2443158.873 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E140M, G230LB, G430L, G750L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names CCDFLAT, HD-5980 ------------------------------------------------------------------------------------------------------------------------------------