8323( 3) - 01/27/00 07:53 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8323 Version: 3 Check-in Date: 18-Feb-1999 15:38:35 1.Proposal Title: Herbig-Haro Jets Irradiated by Massive OB Stars ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Bo Reipurth University of Colorado at Boulder CoI: Dr. John Bally CASA, University of Colorado, Boulder N CoI: Dr. Steve Heathcote Cerro Tololo Interamerican Observatory Y ------------------------------------------------------------------------------------ 5. Abstract Despite significant recent advances in the investigation of Herbig-Haro jets powered by young stars, a number of fundamental problems remain unsolved. Among these are the precise determination of the mass loss rate through a jet, and the nature of the flow behavior in the jet launch and collimation region. We have discovered a class of HH jets which are irradiated by the UV radiation from nearby OB stars and are therefore photoionized. Such jets hold the promise of a direct measurement of the mass flow rate through a jet. Furthermore, our observations show that the opaque envelopes that normally obscure jet sources have been removed from these objects. We propose to use HST to study the brightest of these irradiated jets, HH 444. STIS spectra will be used to measure the distribution of electron density, the mass flux through the jet, and the kinematics and excitation conditions in or near the jet collimation region which will constrain models of jet formation. We will also use WFPC2 to determine the sub- arcsecond structure of the jet so that we can correctly interpret the STIS spectra, to search for evidence of a circumstellar disk needed to fuel the jet, and to probe the nature of the asymmetry seen in this jet. ------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 2] Observations Description ------------------------ Spectra of the HH 444 jet will be obtained with STIS using grating G750M, the 52x0.1 aperture, and a central wavelength of 6581A. Narrow band images of HH 444 and of a second adjacent "naked jet", HH 445, will be obtained using WFPC2 and the filters F656N (H-Alpha) and F673N (S[II]6717+31). The surface brightness of the HH 444 jet has been estimated from ground based flux calibrated spectra and narrow band images (which provide an estimate of the emitting area). The emission knots have sizes, corrected for seeing, which range from 0.5 to 2.5 arcsec. Assigning the flux measured in our spectra to an appropriately sized Gaussian then provides an estimate of the peak surface brightness of each knot. Sub-structure not resolvable from the ground could boost these surface brightnesses. However, structure similar to that seen in HST images of other HH jets result in an enhancement by at most a factor of 2- 3. These fluxes are for the brightest point in the brightest knots. Elsewhere the jet is fainter by at least an order of magnitude. We will use the star, V510-Ori, which drives the HH 444 jet for the acquisition and peakup exposures for the STIS spectra. This is a T-Tauri/YY-Ori type star which varies irregularly over an extreme range of 13.7 < B < 15.7 on a time scale of several days. The acquisition and peakup exposure time has been chosen to ensure a successful acquisition for any magnitude in this range. Ground based photometry is being performed to verify the mean magnitude colours, and amplitude of variability of the star. We will review our acquisition strategy in light of this and if neccessary we can fall back on an offset acquisition using a nearby field star. 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. A looser roll angle constraint has also been imposed on the WFPC2 observations in order (a) to fit both HH 444 and HH 445 within the fieled of view; and (b) to ensure diffraction spikes and blooming from the very bright driving sources do not overlie the faint science targets. In parallel with the STIS spectroscopy we will obtain F656N and F673N images of an arbitrary nearby field within the Sigma Ori HII region in which HH 444 is embedded. Similarly during the WFPC2 observations of HH 444 we will use STIS in imaging mode to obtain images of the background nebula in [OII]3727. Irrespective of the exact pointings there is a high probability of discovering new proplyd-like objects or micro jets in these fields. Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- As originally conceived in Phase I the STIS spectra where to be collected in a single 6 orbit visit with a single long exposure in each orbit. This has been changed in Phase II to comply with the maximum of 5 orbits per visit. Also after lengthy consultation with the CS and PC we are now taking a CR-SPLIT exposure pair in each orbit because of concerns over the impact of cosmic rays and hot pixels in the longer exposures. Since the the spectra are expect to be read noise dominated this change does have a significant impact on the S/N we will achieve and the resulting science. The phase II proposal as submitted represents the best compromise between CR rejection concerns and S/N based on the information available. However, a further review of this issue during post submission processing has been suggested by the CS and would be very valuable. ------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 3] Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HH444-SOURCE ISM, Herbig-Haro RA=05H 39M 39.72S +/-0.3", DEC=- J2000 V = -100 SURF-LINE(6563)=48+/-5e-16 Object, Jet, Bipolar 02D 31' 21.7" +/-0.3", PLATE- W-LINE(6563)=0.7+/-0.2 Outflow ID=02NB SURF-LINE(6717)=10+/-1e-16 W-LINE(6717)=0.7+/-0.2 SURF-LINE(6731)=8+/-1e-16 W-LINE(6731)=0.7+/-0.2 V = 13.54+/-0.5 B-V = 0.54+/-0.08 Comments: For STIS spectroscopy of HH444 Jet Coordinates are for the driving source V510 Ori = GSC04771-00851, which will also be used for acquisition and peakup. V and B- V are also for this star which is variable with the stated mean magnitude and colours having an extreme range of 13.7 < B < 15.7. Line fluxes are the estimated peak surface brightness of the brightest knots in the HH444 Jet. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1984.007 0.0 0.0 0.0 2 HH444-445 ISM, Herbig-Haro RA=05H 39M 39.72S +/-0.5", DEC=- J2000 V = -100 SURF-LINE(6563)=48+/-5e-16 Object, Jet, Bipolar 02D 31' 38.7" +/-0.5", PLATE- W-LINE(6563)=0.7+/-0.2 Outflow ID=02NB SURF-LINE(6717)=10+/-1e-16 W-LINE(6717)=0.7+/-0.2 SURF-LINE(6731)=8+/-1e-16 W-LINE(6731)=0.7+/-0.2 V = 13.54+/-0.5 B-V = 0.54+/-0.08 Comments: For WFPC2 imaging of HH444 and HH445 (coordinates are for a point between HH444 and HH445 (17" due south of the source) so that HH444 falls on WF2, HH445 on WF3. V and B-V are for the driving source. Line fluxes are the estimated peak surface brightness of the brightest knots in the HH444 Jet. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B1984.007 0.0 0.0 0.0 8323( 3) - 01/27/00 07:53 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENTation 30.0D TO 48.5D On Hold Comments: Additional Comments: ORIENT 310.0D TO 318.5D is also possible, but this requires that the target be centered on WF2-FIX. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 101 HH444-445 WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1200 S POS TARG 0.0, 0.0 PAR 105 with 101, 102 Comments: POS TARGs are used to produce a 2 position integer pixel dither with 2 exposures at each position for hot-pixel identification. ------------------------------------------------------------------------------------------------------------------------------------ 102 HH444-445 WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1300 S POS TARG 0.0, 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 105 ANY STIS/C ACCUM F28X50O MIRROR CR-SPLIT=2 1 2676 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 110 HH444-445 WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=DEF 1 2600 S POS TARG 0.5, 0.5 PAR 115 with 110 ------------------------------------------------------------------------------------------------------------------------------------ 115 ANY STIS/C ACCUM F28X50O MIRROR CR-SPLIT=2 1 2774 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 120 HH444-445 WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=DEF 1 2600 S POS TARG 0.5, 0.5 PAR 125 with 120 Comments: POS TARGs are used to produce a 2 position integer pixel dither with 2 exposures at each position for hot-pixel identification. ------------------------------------------------------------------------------------------------------------------------------------ 125 ANY STIS/C ACCUM F28X50O MIRROR CR-SPLIT=2 1 2774 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 130 HH444-445 WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=DEF 1 2600 S POS TARG 0.0, 0.0 PAR 135 with 130 ------------------------------------------------------------------------------------------------------------------------------------ 135 ANY STIS/C ACCUM F28X50O MIRROR CR-SPLIT=2 1 2771 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENTation 296.0D TO 296.0D GROUP 2, 3 WITHIN 90D On Hold Comments: Additional Comments: PA of HH444 Jet is 70.96D, offset angle used 45.02, giving ORIENT=295.98. ORIENT 116.0D TO 116.0D is also acceptible but requires flipping sign of Y motion on POS-TARGs The GROUP WITHIN 90D requirement is only intended to keep visit 2 and 3 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 ------------------------------------------------------------------------------------------------------------------------------------ 200 HH444-SOURC STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ FOR 210, 220, E CD P 230 ------------------------------------------------------------------------------------------------------------------------------------ 201 HH444-SOURC STIS/C ACQ/PEA 52X0.1 MIRROR 1 3 S ONBOARD ACQ FOR 210, 220, E CD K 230 ------------------------------------------------------------------------------------------------------------------------------------ 210 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2007 S POS TARG 0.0, 5.90 PAR E CD 215, 216 with 210 Comments: POS TARG displaces source 5.90" towards +Y end of slit so that brightest section of jet falls at slit center This is the first exposure pair in a 3 position integer pixel dither pattern (9 pixel spacing) for hot pixel detection and to fill gaps left by occulting bars ------------------------------------------------------------------------------------------------------------------------------------ 215 ANY WFPC2 IMAGE WF2-FIX F656N CR-SPLIT=NO 1 900 S ------------------------------------------------------------------------------------------------------------------------------------ 216 ANY WFPC2 IMAGE WF2-FIX F656N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 220 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2756 S POS TARG 0.0, 6.4109 PAR E CD 225, 226 with 220 Comments: Second exposure pair in 3 position dither pattern POS TARG shifts target by 9 pixels relative to 1st pair ------------------------------------------------------------------------------------------------------------------------------------ 225 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 226 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 230 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2753 S POS TARG 0.0, 6.9217 PAR E CD 235, 236 with 230 Comments: Third exposure pair in 3 position dither pattern POS TARG shifts target by a further 9 pixels ------------------------------------------------------------------------------------------------------------------------------------ 235 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 236 ANY WFPC2 IMAGE WF4-FIX F656N CR-SPLIT=NO 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 7] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENTation as 2 GROUP 2, 3 WITHIN 90D On Hold Comments: Additional Comments: Want to reproduce the same pointing as visit 2 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 ------------------------------------------------------------------------------------------------------------------------------------ 300 HH444-SOURC STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 1 S ONBOARD ACQ FOR 310, 320, E CD P 330 ------------------------------------------------------------------------------------------------------------------------------------ 301 HH444-SOURC STIS/C ACQ/PEA 52X0.1 MIRROR 1 3 S ONBOARD ACQ FOR 310, 320, E CD K 330 ------------------------------------------------------------------------------------------------------------------------------------ 310 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2007 S POS TARG 0.0, 5.90 PAR E CD 315, 316 with 310 Comments: We repeat the same pointing (to within ACQ jitter) and same dither pattern as for visit 2. POS TARG displaces source 5.90" towards +Y end of slit so that brightest section of jet falls at slit center. ------------------------------------------------------------------------------------------------------------------------------------ 315 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 900 S ------------------------------------------------------------------------------------------------------------------------------------ 316 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 800 S ------------------------------------------------------------------------------------------------------------------------------------ 320 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2756 S POS TARG 0.0, 6.4109 PAR E CD 325, 326 with 320 Comments: Second exposure pair in 3 position dither pattern POS TARG shifts target by 9 pixels relative to 1st pair ------------------------------------------------------------------------------------------------------------------------------------ 325 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 326 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 330 HH444-SOURC STIS/C ACCUM 52X0.1 G750M 6581 CR-SPLIT=2 1 2753 S POS TARG 0.0, 6.9217 PAR E CD 335, 336 with 330 Comments: Third exposure pair in 3 position dither pattern POS TARG shifts target by a further 9 pixels ------------------------------------------------------------------------------------------------------------------------------------ 335 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 1200 S ------------------------------------------------------------------------------------------------------------------------------------ 336 ANY WFPC2 IMAGE WF4-FIX F673N CR-SPLIT=NO 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 8323( 3) - 01/27/00 07:53 - [ 8] Summary Form for Proposal 8323 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WF4-FIX F28X50OII F28X50LP 52X0.1 WF2-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACCUM ACQ ACQ/PEAK ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO CR-SPLIT=2 CR-SPLIT=DEF ACQTYPE=POINT ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENTation 30.0D TO 48.5D POS TARG 0.0, 0.0 PAR 105 with 101, 102 POS TARG 0.0, 0.0 POS TARG 0.5, 0.5 PAR 115 with 110 POS TARG 0.5, 0.5 PAR 125 with 120 POS TARG 0.0, 0.0 PAR 135 with 130 ORIENTation 296.0D TO 296.0D GROUP 2, 3 WITHIN 90D ONBOARD ACQ FOR 210, 220, 230 POS TARG 0.0, 5.90 PAR 215, 216 with 210 POS TARG 0.0, 6.4109 PAR 225, 226 with 220 POS TARG 0.0, 6.9217 PAR 235, 236 with 230 SAME ORIENTation as 2 GROUP 2, 3 WITHIN 90D ONBOARD ACQ FOR 310, 320, 330 POS TARG 0.0, 5.90 PAR 315, 316 with 310 POS TARG 0.0, 6.4109 PAR 325, 326 with 320 POS TARG 0.0, 6.9217 PAR 335, 336 with 330 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N MIRROR F673N G750M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HH444-445 ANY HH444-SOURCE ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 6581 ------------------------------------------------------------------------------------------------------------------------------------