Our recent abundance survey of a large sample of Galactic planetary nebulae (PNe) has led to the discovery of a group of super-metal-rich nebulae whose spectra are characterized by prominent optical recombination lines (ORLs) from C, N, O, & Ne ions and a large Balmer discontinuity jump. The heavy element abundances derived from ORLs for several PNe are more than an order of magnitude higher than those derived from the traditional method based on collisionally excited lines (CELs), while the Balmer jump yields electron temperatures (Te) significantly lower than values derived from the [O III] 5007/4363 CEL line ratio. A proposition that aspires to explain both the nebular abundance and Te problems is one according to which these nebulae contain (at least) two distinct emission regions - one of "normal" Te (~ 10000 K) and chemical composition (~solar) and another of very low Te that is H-deficient, thus having high helium and metal abundances relative to hydrogen. The latter component emits strong He and heavy element ORLs but essentially no CELs. The consistent picture that emerges from fitting a 2-component photoionization model to the spectroscopic data is that the H-poor component is in high-density inclusions, which provide only a minor fraction of the total nebular mass. We propose to directly detect these inclusions in the planetary nebula M 1-42 using WFPC2 (PC) to make a high spatial resolution image in the He I 5876 A ORL and ratio it to Halpha. With NICMOS (NIC1), we plan to observe the He I 10830 A line, which is substantially collisionally excited, along with Palpha 18760 A. The ratio image of He I 10830 to Palpha is expected to be less likely to show the inclusions, thus serving as an important control to the optical imaging. M 1-42 is one of the most extreme cases of the abundance and Te problem; it is reasonably bright and compact. This program has the potential to resolve a serious challenge to our current understanding of nebular astrophysics.

We have 2 parts to this program - observations with WFPC2 and with NICMOS [primary and coordinated parallel] of the bulge planetary nebula (PN) M 1-42. WFPC2 Images with the PC ------------------------ M 1-42 will be covered fully by the Planetary Camera, which provides a spatial sampling of 0.046", close to the diffraction limit of HST at the optical wavelengths of our observations. We take images with four narrow-band filters that cover emission lines of interest. Individual filters are listed below, as well as the dominant line they are designed to cover. Exposure times are based on existing spectroscopy (Liu et al. 2001). F588N He I 5876 - This is a very important line and requires the longest time. Multiple exposures in Visit 1 in 4 orbits will provide for a very robust CR removal. For the other filters, we have a sufficient number of exposures to be able to essentially remove all CR-damaged pixels. We use an A/D gain of 7. For this filter as well as the others, we use a PATTERN with a standard 2-point dither. This is a single dither from the original pixel position [say (0,0)] to one offset diagonally (in both x and y) to (5.5,5.5) pixels for the PC (~0.35"). This is a recommended pattern WFPC2-LINE (section 7.6, WFPC2 Handbook) in order to minimize loss from chip blemishes and improve spatial sampling. F502N [O III] 5007 - An A/D gain of 15, which provides the potential for a larger dynamic range, is used for the this line and the other bright lines (Halpha and [N II] 6584). The dither pattern also provides 2 exposures for CR removal. F656N Halpha 6565 - The dither pattern also provides 2 exposures for CR removal. F658N [N II] 6584 - The dither pattern also provides 2 exposures for CR removal. Both F656N and F658N are crucial to separate the contributions of [N II] 6548 and 6584 (almost as bright as Halpha) to the F656N bandpass and of the Halpha line to the F658N bandpass. The central star is very faint (V=17.40, B= 18.30) and was not even detected in the Liu et al. slit spectra. All WFPC2 exposures need to be reasonably close in time to promote pixel registration. This is the reason for Visit 1 with all 5 WFPC2 orbits. NICMOS Images ------------- We use a single pointing with NIC1 to provide line maps in He I 10830 A using F108N and F113N (to subtract the adjacent continuum) and Pa_alpha 18756 A using F187N and F190N (to subtract the adjacent continuum). The respective continuum maps are made by using the F113N and F190N together with off-source measurements taken with the coordinated parallels, albeit at the lower spatial resolution of the NIC2 and NIC3 parallel data. The NIC1 field of view of 11" x 11" covers the bulk of M 1-42. It is somewhat enlarged (to ~12"-square) by our 4-point dither from the original pixel position (0,0) to (23.5,0), (23.5,23.5), (0,23.5) for NIC1 with 0.043" pixels. It is important to have the PN well centered in the NIC1 field-of-view (FOV). Therefore we use NIC1-FIX and require that the 4-point "spiral" dither pattern be CENTERED. The average surface brightness is based on Liu et al. (2001) spectroscopy, differential extinction analysis, and recombination theory to estimate the Pa_alpha flux from the flux of Halpha and Hbeta [see phase I proposal]. The exposure times are designed to provide a S/N ~10 for the He I and Pa_alpha lines. Equal matching time exposures are taken in the adjacent continuum filters F113N and F190N. All NICMOS exposures need to be reasonably close in time to promote pixel registration. Coordinated Parallel NICMOS Images ---------------------------------- With NIC1 (F108N/F113N), we do NIC3 (F108N/F113N) parallels and with the NIC1 (F187N/F190N) primaries, NIC2 (F187N/F190N) parallels. These are for the purpose of providing an off-source measurement to subtract from the on-source continuum images only. The respective values for the offset from the centers of NIC1 to NIC2 and NIC3 parallel FOV are 32.59 and 47.78". We note that these are not precision off-source measurements; there is no need to spend the considerable extra time to take off-source measurements with NIC1. We emphasize that even if we do not measure the absolute continuum, this is not at all crucial to our program of measuring the line emission above the continuum and the science of detecting H-deficient [He-rich] inclusions. ISM AND CIRCUMSTELLAR MATTER 12 false 0.0 0.0 false false false false false SUPPORTED ISM EMISSION LINE NEBULA PLANETARY NEBULA B = 18.3 These are magnitudes of the central star. J2000 18 11 5.0000 -28 58 59.00 J2000 ISM EMISSION LINE NEBULA PLANETARY NEBULA B = 18.3 These are magnitudes of the central star. J2000 18 11 5.0000 -28 58 59.00 J2000 WFPC2 Imaging No F588N WFPC2 Imaging No F502N WFPC2 Imaging No F656N WFPC2 Imaging No F658N NIC1 Imaging No No F108N NIC1 Imaging No No F113N NIC1 Imaging No No F187N NIC1 Imaging No No F190N NIC3 Imaging No No F108N NIC3 Imaging No No F113N NIC2 Imaging No No F187N NIC2 Imaging No No F190N POS-TARG DITHER 0.3535 LINE false false 2 45.0 WFPC2-LINE 1 false POS-TARG DITHER DITHER 1.0105 NIC-XSTRIP-DITH false true 4 0.0 POS-TARG NIC-SPIRAL-DITH 0.0 2 false The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11185 :visit-id "01" :proposal-version -1 :trans-version "20071214" :date "06-May-2008 10:14:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 582608 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11185 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11185 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "01" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "01" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "01" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2760 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "01" :orbit-number 5 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 5 0 The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11185 :visit-id "02" :proposal-version -1 :trans-version "20071214" :date "07-May-2008 09:26:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "23" :si-bright-earth-limb-angle 20.0 :data-volume 1113136 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11185 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11185 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2746 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "02" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2744 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "02" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2766 :al-overhead-at-end 0 :internal-dur-at-end 117 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 3 0 ORIENTATION CAN BE anything on ALL parallels. Somewhere we should be entering TARGET: ANY The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11185 :visit-id "10" :proposal-version -1 :trans-version "20071214" :date "06-May-2008 10:43:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 492976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11185 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11185 :visit-id "10" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "10" :orbit-number 2 :pcs-time 355 :si-vis-utilization 2780 :al-overhead-at-end 160 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "10" :orbit-number 3 :pcs-time 355 :si-vis-utilization 2400 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11185 :visit-id "10" :orbit-number 4 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) false 4 0