9094( 2) - 03/11/02 07:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9094 Version: 2 Check-in Date: 08-Feb-2001 13:44:12 1.Proposal Title: The Wind-Wind Interactions in HD 5980 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Gloria Koenigsberger Universidad Nacional Autonoma de Mexico (UNAM) CoI: Dr. Leonid Georgiev UNAM-Instituto de Astronomia N CoI: Dr. Svetozar Zhekhov JILA, University of Colorado N CoI: Dr. Jorge Canto UNAM-Instituto de Astronomia N CoI: Dr. Lawrence Auer Los Alamos National Laboratory N ------------------------------------------------------------------------------------ 5. Abstract HD 5980 is the visually brightest object in the SMC. It contains a close eclipsing binary LBV+WR (=Star A+Star B), the only one known to exist, with the possible exception of Eta Carinae. The LBV underwent a great eruption in 1994, ejecting <10^- 3 M_\odot at velocities in the range of 200-800 km s^-1. After the eruption, its wind velocity has been steadily increasing, and producing a circumstellar (CSM) fast - wind/slow-wind interaction region, which has now become visible spectroscopically in the C IV and Si IV lines at an expansion velocity of -680 km s^-1. These narrow features varied over a 1 year timescale. It is likely that HD 5980 is forming an H II region analogous to the Homunculus in Eta Carinae. In addition, the wind-wind collision shocked region between the two stars currently (1999-2000) forms a shock cone that winds tightly around the WR star. The purpose of this proposal is to: a) Determine the LBV's wind velocity close to the time when it will be observed with XMM and CHANDRA; b) follow the changes in the high velocity CSM absorption features; and c) Constrain the radial velocity variability of the third component, Star C, in order to determine whether it is bound to the A+B pair. The three objectives can be achieved with just two visits, using STIS to obtain the FUV+NUV spectrum. HST is the only observatory capable of providing these data. A reduced 3 month proprietary period is proposed. ------------------------------------------------------------------------------------ 9094( 2) - 03/11/02 07:58 - [ 2] Observations Description ------------------------ We propose to observe HD 5980 at orbital phase Phi=0.00, which is the eclipse of the system when Star A (=the LBV) is ``in front" of the companion. This guarantees that the P Cygni absorption components observed are formed primarily in the wind of Star A, thus providing its wind velocity. A total of 2 orbits is required for this visit. During the first orbit a FUV-MAMA echelle spectrum will be obtained using the E140M grating and 0.2X0.2 arcsec slit. Taking into account the overheads, we expect to be able to dedicate 44 minutes to the exposure for this spectrum. Using the previously obtained STIS/HST spectrum o550o1070, the exposure time calculator predicts a S/N for this spectrum of 42 at Lambda1500 Angstrom. The second orbit will be dedicated to obtaining the two NUV-MAMA echelle spectra with the E230M grating and the 0.2X0.2 arcsec slit, with central wavelengths Lambda1978 Angstrom and Lambda2707 Angstrom. We used the spectrum o550o1010 to calculate the exposure times. Taking into account the overheads, we expect to be able to get exposure times of 25 and 12 minutes, respectively, for each of the two central wavelengths, obtaining S/N~40 in each case at those wavelenths. HD 5980 is being monitored continuously from ground- based observatories which would allow us to forsee any unexpected brightening or fading of the system at the time of HST observation. .2cm begintabularlrl & EXAMPLE & , FIRST ORBIT & & , Guide star acquisition & 6 min &, FUV-MAMA E140M & 44 min & S/N=42 at 1500 A , FUV-MAMA overhead & 8 min & , SECOND ORBIT & & , Guide star acquisition & 6 min & , NUV-MAMA E230M (1978 A) & 25 min &S/N=44 at 1978 A , NUV-MAMA overhead & 8 min & , NUV-MAMA E230M (2700 A)& 25 min & S/N=40 at 2700 A , NUV-MAMA overhead & 8 min &, endtabular Real Time Justification ----------------------- beginitemize em Time-critical observations enditemize The proposed observations should be carried out at orbital phase 0.00+/-0.03 in order to guarantee that the P Cygni absorption components of He II 1640 are formed basically in the wind of Star A (the LBV). This is required for the first objective of the proposal, the determination of the wind velocity of Star A near the time of the X-ray observations. The second and third objectives of the proposal do not require time-critical observations. The ephemeris to be used for calculating the time of the proposed observation is: P=19.2654 days; T0=2443158.705. It is desirable to schedule the HST observations as close as possible to the XMM observations, although in its present state of variability, the wind velocity of Star A should be fairly stable over a few months period. The XMM observations have not yet been scheduled. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9094( 2) - 03/11/02 07:58 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD5980 EXT-STAR, WOLF RAYET - RA=00H 59M 26.53S +/- 0.3", DEC= J2000 F(1640)=1.8+/-0.2e-11 WN, LUMINOUS BLUE -72D 9' 54.3" +/- 0.3", PLATE- V = 11.2+/-0.2 VARIABLE, INTERACTING ID=06B1 BINARY Coordinate Source: GUIDE_STAR_CATALOG 9094( 2) - 03/11/02 07:58 - [ 4] Visit: 01 Visit Priority: Visit Requirements: PERIOD 19.2654 D AND ZERO-PHASE JD2443158.705000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD5980 STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S PHASE 0.98 TO 0.02 CD P ------------------------------------------------------------------------------------------------------------------------------------ 20 HD5980 STIS/F ACCUM 0.2X0.2 E140M 1425 1 2776 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 30 HD5980 STIS/N ACCUM 0.2X0.2 E230M 1978 1 1609 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 40 HD5980 STIS/N ACCUM 0.2X0.2 E230M 2707 1 1300 S UV-MAM A ------------------------------------------------------------------------------------------------------------------------------------ 9094( 2) - 03/11/02 07:58 - [ 5] Summary Form for Proposal 9094 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 0.2X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 19.2654 D AND ZERO-PHASE JD2443158.705000 PHASE 0.98 TO 0.02 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR E140M E230M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD5980 ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 1978 2707 ------------------------------------------------------------------------------------------------------------------------------------