----- Attempting Submission 1 (Mon Jan 26 00:02:15 GMT 2009) ----- Phase II Proposal 11985 (11985.apt) successfully submitted. ----- Attempting Submission 2 (Mon Jan 26 00:02:46 GMT 2009) ----- Phase II Proposal 11985 (11985.apt) successfully submitted. ----- Attempting Submission 3 (Mon Jan 26 21:33:33 GMT 2009) ----- Assigned ID: 2096 ----- Attempting Submission 1 (Mon Dec 08 20:15:30 GMT 2008) ----- Polarimetric WFPC2 Imaging of the Dust Torus around the Born-Again Star V605 Aquilae We propose the first WFPC2 polarimetric imaging of the ejecta surrounding the helium shell final flash (FF) star V605 Aql. Polarimetry is a novel, little-used capability of WFPC2, which can provide confirmation of our proposed morphology of the compact ejecta.. Evolutionary models suggest that V605 Aql is experiencing a very late and very fast thermal pulse. Its evolution from a PN central star on the white-dwarf cooling track, to a cool luminous giant, and then back again, took place in only a few decades or less. V605 Aql, central star of the large, faint, and old planetary nebula A 58, has evolved from a hot central star before the 20th century, to Teff = 5000 K in 1921, and back to 95,000 K at the present time. A compact, but resolved, dusty nebula lies at the site of V605 Aql. In addition to an extremely hydrogen-deficient nebular emission spectrum, this knot shows stellar features, even though no star-like object is seen within the knot. Therefore, we are probably seeing light from the star scattered around the edge of a thick dust torus viewed nearly edge-on, ejected during the FF event in the early 20th century. Why a star that had already reached the top of the white-dwarf cooling track, and then expanded to become a red giant again, would be capable of such non-spherical ejection is one of the leading mysteries in late stellar evolution. We will use the high resolution of the WFPC2 PC chip to investigate the nature of the V605 Aql torus, employing filters that isolate nebular emission lines. The novel feature of our program is polarimetric imaging in the WF2 chip, using a filter that isolates scattered starlight and rejects nebular emission. If our model is correct, this scattered starlight will be very highly polarized. We will also measure the angular expansion rate of the central knot to constrain the distance. V605 Aql is a unique link between the young FF star Sakurai's Object (10 years old), and the extended FF objects A30 and A78 (few 1000 years old).
We will use WFPC2 to carry out direct and polarimetric imaging of the compact nebulosity surrounding the "born-again" star V605 Aquilae. For the direct imaging, we will place the target in the corner of the PC chip (for less degradation by CTE) and taken 2 dithered exposures each in the nebular emission lines [O III] (F502N) and [N II] (F658N). For the polarimetric imaging, we will use Strategy 2c as outlined by Biretta & Sparks in their 1995 WFPC2 ISR on WFPC2 polarimetry. The observations will be taken with the target fixed at 12.5, -12.5 in the WF2 chip (with small dithers about this position), the same telescope ORIENT throughout, and the polarizer quad at four different filter rotations. The polarizers are combined with the F547M filter, which isolates an emission line of the central star and rejects light from gas in the nebula, thus giving information on the light from the star that is scattered by dust in the nebula. We are using CLOCKS=YES throughout, since this yields significantly less time lost to overheads. ISM AND CIRCUMSTELLAR MATTER 12 false 0.0 0.0 false false false false false SUPPORTED ISM BIPOLAR OUTFLOW EJECTA EMISSION LINE NEBULA DUST LANE PLANETARY NEBULA J2000 19 18 20.4760 +01 46 59.62 J2000 WFPC2 Imaging No F502N WFPC2 Imaging No F658N WFPC2 Imaging Yes F547M The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. /user/bond/klingsor1/hstcycle16s/v605aql/OP-cache/11985-v01.xml (Tic-Visit :proposal-id 11985 :visit-id "01" :proposal-version -1 :trans-version "20080807" :date "25-Jan-2009 18:19:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 179264 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11985 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11985 :visit-id "01" :orbit-number 1 :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 3132 :pcs-gap 0 ) true 1 0 Same orient constraint links visits (02 03 04) The scheduling data was generated by CASM 17.2. 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CASM was run in Phase II mode. /var/tmp/OPVisit19265.xml (Tic-Visit :proposal-id 11985 :visit-id "04" :proposal-version -1 :trans-version "20080807" :date "26-Jan-2009 16:10:33.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 179264 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11985 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11985 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :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 3132 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11985 :visit-id "04" :orbit-number 2 :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 3132 :pcs-gap 0 ) true 2 0