8277( 5) - 06/08/99 14:43 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8277 Version: 5 Check-in Date: 08-Jun-1999 14:42:01 1.Proposal Title: The Kinematics of Knots along Herbig-Haro Jets at High Spatial Resolution ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Bo Reipurth University of Colorado CoI: Dr. Alejandro Raga Instituto de Astronomia, Universidad N Nacional Autonoma de Mexico CoI: Dr. Karl-Heinz Boehm Astronomy Department, University of N Washington CoI: Dr. Alberto Noriega-Crespo Infrared Processing and Analysis Center N CoI: Dr. Peter Garnavich Harvard-Smithsonian Center for N Astrophysics CoI: Dr. Salvador Curiel Instituto de Astronomia, Universidad N Nacional Autonoma de Mexico ------------------------------------------------------------------------------------ 5. Abstract Since the beginning of this decade, it has been speculated that the aligned knots of Herbig-Haro (HH) jets may correspond to "internal working surfaces" resulting from a time-dependent ejection velocity. This interpretation has received substantial support from recent HST images of some HH jets, which show that at least some knots do have morphologies that resemble internal working surfaces. However, the principal signatures of a jet with a time-dependent ejection velocity are kinematic, having a systematic spatial velocity variability (with spatial variations over distances comparable to the knot sizes) along the jet beam. Given the fact that the knots have typical sizes (along the jet axis) of ~ 0.5" and knot separations of ~ 2", the spatially resolved kinematic characteristics within the knots can only be observed with HST. We propose to obtain STIS spectra of one very well studied HH jet: HH 111. HST images have shown that some of the knots along this jet show the bow shock morphology expected from internal working surface models. The proposed spectroscopic observations will provide the kinematical information necessary for a clear confirmation of the identification of the knots along the HH 111 jet as internal working surfaces. ------------------------------------------------------------------------------------ 8277( 5) - 06/08/99 14:43 - [ 2] Observations Description ------------------------ In the HH 111 jet, the [O I]6300A and [S II]6717/31 lines dominate the optical spectra, so our STIS observations will cover this spectral region. Spectra of the HH 111 jet will be obtained with STIS using grating G750M, the 52x0.1 aperture, and a central wavelength of 6581A. In this mode we can achieve a velocity resolution of FWHM ~50 kms, and measure velocity shifts of ~1/5 of a pixel (~10 kms). The slit will be placed along the brightest section of the jet passing through or near the photocenters of knots E2, F, H, J, K and L. The H- alpha and [SII] surface brightness and structure of the jet on 0.1 arcsec scales are known from the WFPCII images of Reipurth et al. (1998) while the relative strengths of other lines can be estimated from the spectra of Morse et al (1993). The brightest knot, H, reaches a peak [SII]6717+31 surface brightness of 3.8x10^-14 erg/s/cm^2/Angstrom/arcsec^2 within an 0.1" pixel. Other knots of interest have surface brightnesses 0.1-0.5 times this, while the inter knot medium is around 0.02-0.05 of this brightness. Based on calculations with the STIS ETC the planned series of observations will yield S/N ~10:1 for the brighter knots, and ~2-3 in the inter knot regions. The full set of observations requires 7 orbits which will be divided into two visits of 4 and 3 orbits respectively. We have selected the optimum slit position for this study based on our WFPC2 images. However, since the HH111 jet is relatively broad (~1") and sinuous this inevitably involves a compromise. Consequently, in a certain sense, the exact pointing for the first visit is not critical at the +/ - 0.1" level. We can determine the actual pointing post facto by reference to the images. However, it is important that the pointing in the first visit is reproduced in the second in order that we can add signal from all our exposures. To that end we have developed the following acquisition strategy: we will perform the acquisition exposure on a field star, and then execute a blind offset to the target position. The offset has been measured from the WFPC2 images and has an estimated uncertainty of +/-0.1" and a magnitude of ~85". Consequently although the absolute pointing is uncertain by +/-0.1" we expect the pointings for the two visits to agree to 0.02" or better (the stated error for a 120" SAM) which is acceptable. No peak up exposure will be performed on the offset star because the positioning uncertainty of the acquisition exposure (~ +/-0.01) is smaller than that introduced by the subsequent SAM. A comment on proper motions is necessary. The average PM of the HH111 jet is 0.15+/- 0.3"/year which is certainly significant. However, this motion is parallel to the axis of the jet and hence just produces a translation of features along the length of the slit. Thus the only concern is avoiding having important features fall on one of the occulting bars. According to section 3.7 on page 3-17 of the Phase 2 instructions a proper motion CANNOT be supplied when the target position is specified via an offset. We have therefore included a correction for proper motion between the epoch of the WFPC2 images (1994.83) and the anticipated epoch of observation 1999.92 in the offset. However, there is enough "slack" that the same offset could be used at anytime during Cycle 8 or 9 without problems. Our program requires that the spectra are obtained at a very precise spacecraft roll angle so that the STIS long slit runs parallel to the jet. This imposes a severe scheduling constraint such that for the default schedulability the program could only be executed during two periods of 5 and 4 days in cycle 8. Allowing a range of +/-0.5D in the roll angle, about the maximum we could tolerate, makes no difference to the width of these scheduling windows. Consequently we have relaxed the schedulability requirement to 90% which opens the windows to 30 and 15 days at the cost of 130s visibility per orbit (smaller values of sched e.g. 80% only widen the windows by a few days) Real Time Justification ----------------------- None None Calibration Justification ------------------------- Real_Time_Justification Additional Comments ------------------- ------------------------------------------------------------------------------------ 8277( 5) - 06/08/99 14:43 - [ 3] Data Distribution Paper Products: NO Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8277( 5) - 06/08/99 14:43 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HH111-OFFSET STAR, G V-IV RA=5H 51M 39.3522S +/- 0.3", J2000 V = 15.7+/-0.5 DEC=+2D 49' 23.8196" +/- 0.3", B-V = 1.2+/-0.5 PLATE-ID=04YQ R = 15.2+/-0.25 Comments: The offset star to acquire science target HH 111. Position measured from "Phase 2 version" of DSS. V and B-V from USN0 A2.0 catalog (by applying B-O and V-E relationships). R estimated from WFPC2 F656N and F673N observations transformed to broad band using synphot. The R magnitude, which we expect to be more reliable, has been used to estimate the acquisition exposure time. 2 HH111 ISM, HERBIG-HARO RA-OFF=+4.579S+/- 0.0067S, DEC- J2000 V = -70 V = 17+/-1 OBJECT, BIPOLAR OFF=-49.75"+/- 0.1", FROM 1, SURF-LINE(6563)=13+/-1e-15 OUTFLOW, JET PLATE-ID=04YQ W-LINE(6563)=1.4+/-0.1 SURF-LINE(6717)=19+/-1e-15 W-LINE(6717)=1.1+/-0.1 SURF-LINE(6731)=19+/-1e-15 W-LINE(6731)=1.1+/-0.1 Comments: Science target. The slit runs along the HH111 jet passing through, or near, the photocenters of knots F1, H, J and L. The offset was measured on WFPC2 F656N and F673N images obtained at epoch J1994.83. This offset INCLUDES the correction for Proper motion to epoch J1999.92. See description for detailed discusion of PMs. SURF-LINE gives the surface brightness of the brightest 0.1" pixel in knot H measured from the WFPC2 images. This is the brightest point anywhere along the slit. Other knots have surface brightnesses 0.1-0.5 times this, and the interknot medium around 0.02-0.05. 8277( 5) - 06/08/99 14:43 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 321.41D TO 321.41D SCHED 90% GROUP 1, 2 WITHIN 90D On Hold Comments: Additional Comments: PA of HH111 jet is 276.39D, offset angle used 45.02, giving ORIENT = 321.41D. The alternate orient 141.41D cannot be scheduled. The GROUP WITHIN 90D requirement is only intended to keep visit 1 and 2 in the same year. The 90D period is longer than the period for which the ORIENT requirement is satisfied Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HH111-OFFSE STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 5 S ONBOARD ACQ FOR 100 T CD P Comments: Acquire offset star ------------------------------------------------------------------------------------------------------------------------------------ 100 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN=1 1 2052.3 PAR 101 WITH 100 CD Comments: first position of 3 position dither pattern (9 pixel spacing) for hot/cold pixel detection and to fill gaps left by occulting bars. ------------------------------------------------------------------------------------------------------------------------------------ 101 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=DEF 1 1800 S ------------------------------------------------------------------------------------------------------------------------------------ 105 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN= 1 1 2578.8 PAR 106 WITH 105 CD Comments: first position of 3 position dither pattern (continued). ------------------------------------------------------------------------------------------------------------------------------------ 106 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=DEF 1 2200 S ------------------------------------------------------------------------------------------------------------------------------------ 115 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN= 1 1 2578.8 POS TARG 0.0, -0.5109 PAR CD 116 WITH 115 Comments: second position of 3 position dither pattern. POS TARG shifts target 9 pixels, relative to first position (exposures 100, 105), towards -Y end along slit. ------------------------------------------------------------------------------------------------------------------------------------ 116 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=DEF 1 2200 S ------------------------------------------------------------------------------------------------------------------------------------ 125 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN=1 1 2578.8 POS TARG 0.0, -1.0218 PAR CD 126 WITH 125 Comments: third position of 3 position dither pattern. POS TARG shifts target 18 pixels, relative to first position (exposures 100, 105), towards -Y end along slit. ------------------------------------------------------------------------------------------------------------------------------------ 126 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=DEF 1 2200 S ------------------------------------------------------------------------------------------------------------------------------------ 8277( 5) - 06/08/99 14:43 - [ 6] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENTation as 1 SCHED 90% GROUP 1, 2 WITHIN 90D On Hold Comments: Additional Comments: We need to reproduce the pointing of visit 1 as closely as possible. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 200 HH111-OFFSE STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 5 S ONBOARD ACQ FOR 210 T CD P Comments: Acquire offset star ------------------------------------------------------------------------------------------------------------------------------------ 210 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN=1 1 2052.3 PAR 211 WITH 210 CD Comments: first position of 3 position dither pattern (9 pixel spacing) for hot/cold pixel detection and to fill gaps left by occulting bars. ------------------------------------------------------------------------------------------------------------------------------------ 211 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=DEF 1 1800 S ------------------------------------------------------------------------------------------------------------------------------------ 220 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN=1 1 2578.8 POS TARG 0.0, -0.5109 PAR CD 221 WITH 220 Comments: second position of 3 position dither pattern. POS TARG shifts target 9 pixels, relative to first position (exposure 210), towards -Y end along slit. ------------------------------------------------------------------------------------------------------------------------------------ 221 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=DEF 1 2200 S ------------------------------------------------------------------------------------------------------------------------------------ 230 HH111 STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=3,GAIN=1 1 2578.8 POS TARG 0.0, -1.0218 PAR CD 231 WITH 230 Comments: third position of 3 position dither pattern. POS TARG shifts target 18 pixels, relative to first position (exposure 210), towards -Y end along slit. ------------------------------------------------------------------------------------------------------------------------------------ 231 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=DEF 1 2200 S ------------------------------------------------------------------------------------------------------------------------------------ 8277( 5) - 06/08/99 14:43 - [ 7] Summary Form for Proposal 8277 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.1 WF4-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT GAIN=1 CR-SPLIT=DEF GAIN= 1 CR-SPLIT=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 321.41D TO 321.41D SCHED 90% GROUP 1, 2 WITHIN 90D ONBOARD ACQ FOR 100 PAR 101 WITH 100 PAR 106 WITH 105 POS TARG 0.0, -0.5109 PAR 116 WITH 115 POS TARG 0.0, -1.0218 PAR 126 WITH 125 SAME ORIENTation as 1 SCHED 90% GROUP 1, 2 WITHIN 90D ONBOARD ACQ FOR 210 PAR 211 WITH 210 POS TARG 0.0, -0.5109 PAR 221 WITH 220 POS TARG 0.0, -1.0218 PAR 231 WITH 230 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G750M F656N F673N ------------------------------------------------------------------------------------------------------------------------------------ Target Names HH111-OFFSET HH111 ANY ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6581 ------------------------------------------------------------------------------------------------------------------------------------