7378( 5) - 06/21/99 13:34 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7378 Version: 5 Check-in Date: 21-Jun-1999 13:33:55 1.Proposal Title: Narrow band imaging of jets and bipolar outflows from symbiotic stars ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 7 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Romano Corradi Instituto De Astrofisica De Canarias CoI: Mario Livio Space Telescope Science Institute N CoI: Ulisse Munari Osservatorio Astronomico di Padova-Asiago N CoI: Hugo Schwarz Nordic Optical Telescope N ------------------------------------------------------------------------------------ 5. Abstract We propose to obtain [NII]Lambda658.3 nm images of the extended nebulae around the symbiotic binaries CH Cyg (HD182917) and He 2-104 (PK315+09D1) using the WFPC2 camera (+ [OII]Lambda372.8 nm with STIS for CH Cyg). These large ionized nebulae, one of which has been only recently discovered, trace mass loss episodes spanning a wide range of time scales. In particular, the marked bipolar morphology of the nebulae makes them a very attractive laboratory where to study the effects of binary interactions in producing highly collimated nebulae and jets, and where to test current dynamical models of common envelope evolution. This has important implications for several astrophysical topics (e.g. shape of planetary nebulae, ejecta of classical novae, jets from young stars, efficiency of common envelope mass loss, frequency of formation of white dwarf pairs as the precursors of SN Ia). Even in the best ground--based images, these symbiotic nebulae are often poorly resolved, especially in their inner regions. A precise morphological characterization from HST images, coupled with spectroscopic data from the ground, is therefore the first and fundamental observational information needed to understand their nature and that of their progenitors. Moreover, with HST we have the unique opportunity to follow in real--time the spatial evolution of the outflows (on a time basis of very few years), and therefore to derive 3--D dynamical models of their structure. ------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 2] Observations Description ------------------------ We aim to observe the two targets in the light of NIILambda658.3nm with the WFPC2 camera. Observing in the [NII] line has the following significant advantages: 1) [NII]Lambda658.3 nm is the brightest nebular line in bipolar nebulae and jets from evolved stars in the range 350-1000 nm (no information is available in other wavelength domains). 2) the contrast in luminosity between the central source and the significantly fainter surrounding nebula is much reduced as compared, for instance, to HAlpha. As an example, the HAlpha emission of the central source of He 2-104 (the innermost 1'') is 20 times brighter than [NII], while the nitrogen line is already brighter than HAlpha at 4'' from the centre; 3) the instrumental configuration has quite a high efficiency (10%). The exposure times that we have chosen take into account the necessity of detecting faint nebular structures and, at the same time, of limiting the effects of over-saturation of the central source. It follows a table with the line surface brightness I (estimated from spectra and images that we have obtained in 1996) of the faintest nebular features that we aim to observe. Object Feature I (erg cm-2 s-1 arcsec-2) CH Cyg inner jet 1e-14 (NII) CH Cyg inner jet 1e-14 (OII) He 2-104 outer lobes and jet 3e-15 (NII) For He 2- 104 (PK315+09D1), we plan to position the bright inner regions of the crab-like nebula on the PC CCD, and the faint outer polar jets on the WF cameras. With this configuration, a total exposure time of about 3500 sec (split into 5 sub- exposures) is planned, which will allow us to reach a S/N ratio of ~10, per WF CCD pixel, for the outer jets and lobes. With these exposure times, blooming due to over-saturation of the central source on the PC CCD will be limited to few pixels, or even none if the central emission peak, which is unresolved from ground-based images, results to be produced in an extended region. A 20 sec, 80 sec, and 2 x 200 sec exposures will also be taken in order to have the inner regions well exposed without saturating. LINE dithering will be performed to improve spatial resolution. As for CH Cyg (HD182917), the whole nebula will fall inside the PC CCD. Owing to the very high luminosity of the central source, we need to limit the exposure time (per frame) to a maximum of 200 sec in order to avoid that the blooming reaches the edges of the CCD. 1 sec, 10 sec, 5 x 40 sec (with LINE dithering), and 12 x 200 sec exposures (with BOX dithering) are therefore planned. These figures will allow us to reach a S/N of ~5 in the faintest structures of the jet of the nebula. Note that the above numbers are computed in the conservative case that the central source has the same fluxes as measured in July 1995. CH Cyg is variable, and since that time, the star has (slowly but continuously) faded down. If no new outbursts of the hot component occur, during cycle 7 observing period the star fluxes (and therefore the over-saturation effects) might be lower than the ones reported here. In the long exposures (200 sec), however, CLOCK=YES will be used to avoid the blooming charge to leak back from the edges of the CCD in the case that the star had some unexpected increase in luminosity at the time of observations. CH Cyg will also be observed in the light of [OII]372.8 with STIS. At this wavelength, the central star fluxes are one order of magnitude lower than in [NII], which will allow us to penetrate deeper into the core of the jet by limiting the effects due to oversaturation of the central star. The following sequence of exposures is therefore planned: 2 sec, 15 sec, 2 x 100 sec, and 3 x 800 sec exposures, which will give a S/N ratio of about 4-5 in the jet. Real Time Justification ----------------------- None. Calibration Justification ------------------------- None. Additional Comments ------------------- [OIII] imaging was initially planned for CH Cyg, but due to the discovery of the red leak in the [OIII] filter of STIS, that programme is no longer feasible. It is replaced by [OII] imaging of the object. ------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 3] Data Distribution Paper Products: Media: DAT Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 PK315+09D1 STAR, SYMBIOTIC STAR, RA=14H 11M 52.07S +/- 0.5", DEC= J2000 V = -100 F-LINE(6583)=10+/-3e-13 ISM, PLANETARY NEBULA, -51D 26' 24.1" +/- 0.5", PLATE- W-LINE(6583)=1 BIPOLAR OUTFLOW, ID=01F7 EMISSION LINE NEBULA Comments: The given flux is the [NII] line emission from the unresolved (in ground-based images and spectra) central source. The target has a planetary nebula-like spectrum, with a weak continuum which is negligible as compared to the central [NII] line emission. 2 HD182917 STAR, SYMBIOTIC STAR, RA=19H 24M 33.08S +/- 0.3", J2000 V = -50 F(6583)=6+/-2e-12 AGB STAR, JET DEC=50D 14' 29.5" +/- 0.3" F(3728)=2+/-1e-13 V = 8.5+/-0.5 TYPE=M6III Comments: The object is variable, and is presently undergoing a deep minimum. We conservatively give the magnitude and fluxes from the central source as measured in July 1995. After that, the star has continued to fade down (up to V=10), and, if no new outbursts of the hot component occur, during cycle 7 observing period the star fluxes at lambda 658.3 nm might be lower than listed above. The given coordinates are from Hipparcos. 7378( 5) - 06/21/99 13:34 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 17D TO 53D On Hold Comments: Additional Comments: ORIENT 215D TO 233D can also be used; this latter one is rotated about 180 deg from the proposed one, but the range of ORIENT is narrower because otherwise a 13.3 mag star close to the nebula would fall in the L-shaped region around the PC CCD. The narrow range of ORIENT selected is needed in order to place the inner region of the nebula in the field of the PC camera (to get the maximum spatial resolution for the inner region) and, at the same time, its extended polar jets (P.A.~120) on the WF2 and WF4 CCDs. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 PK315+09D1 WFPC2 IMAGE PC1-FIX F658N 1 20 S POS TARG -7,-7 ------------------------------------------------------------------------------------------------------------------------------------ 30 PK315+09D1 WFPC2 IMAGE PC1-FIX F658N 2 200 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 PK315+09D1 WFPC2 IMAGE PC1-FIX F658N CR-SPLIT=NO,DITHER-TYPE=LINE 2 700 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 51 PK315+09D1 WFPC2 IMAGE PC1-FIX F658N CR-SPLIT=NO 1 700 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 PK315+09D1 WFPC2 IMAGE PC1-FIX F658N 1 80 S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 178D TO 203D On Hold Comments: Additional Comments: ORIENT 358D to 23D can also be used. This narrow range of the ORIENT parameter is needed in order to place the axis of the bended jet (P.A.~ 145 (325)) along the direction of the X-axis of the PC camera (so as to avoid both blooming and OTA diffraction spikes artifacts). Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD182917 WFPC2 IMAGE PC1-FIX F658N 1 1 S ------------------------------------------------------------------------------------------------------------------------------------ 20 HD182917 WFPC2 IMAGE PC1-FIX F658N 1 10 S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD182917 WFPC2 IMAGE PC1-FIX F658N 1 40 S ------------------------------------------------------------------------------------------------------------------------------------ 40 HD182917 WFPC2 IMAGE PC1-FIX F658N DITHER-TYPE=BOX,CLOCKS=YES 3 200 S ------------------------------------------------------------------------------------------------------------------------------------ 50 HD182917 WFPC2 IMAGE PC1-FIX F658N DITHER-TYPE=LINE 2 40 S ------------------------------------------------------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 88D TO 113D On Hold Comments: Additional Comments: The proposed ORIENT parameter is needed in order to place the axis of the jet (P.A.~ 145 (325)) along the direction of the -AXIS1 of the CCD camera (so as to avoid the blooming artifacts). ORIENT 268D to 293D can also be used, but it is less preferred since the most extended side of the bended jet would possibly overlap with the ghost annulus of the STIS CCD. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 HD182917 STIS/C ACCUM F28X50O MIRROR CR-SPLIT=NO 1 2 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 20 HD182917 STIS/C ACCUM F28X50O MIRROR CR-SPLIT=NO 1 15 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 30 HD182917 STIS/C ACCUM F28X50O MIRROR CR-SPLIT=2 1 200 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 40 HD182917 STIS/C ACCUM F28X50O MIRROR CR-SPLIT=3 1 2400 S CD II ------------------------------------------------------------------------------------------------------------------------------------ 7378( 5) - 06/21/99 13:34 - [ 8] Summary Form for Proposal 7378 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX F28X50OII ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO DITHER-TYPE=LINE CLOCKS=YES CR-SPLIT=2 CR-SPLIT=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 17D TO 53D POS TARG -7,-7 SAME POS AS 10 ORIENT 178D TO 203D ORIENT 88D TO 113D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F658N MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names PK315+09D1 HD182917 ------------------------------------------------------------------------------------------------------------------------------------