----- Attempting Submission 1 (Thu May 10 15:24:06 GMT 2007) ----- Assigned ID: 1184 ----- Attempting Submission 1 (Thu Feb 08 22:17:23 GMT 2007) ----- The Morphology of the Post-Red Supergiant IRC+10420's Circumstellar Ejecta The extremely luminous post-red supergiant and powerful OH/IR source IRC +10420 is surrounded by a complex circumstellar nebula. Numerous small condensations, arcs, jet-like rays of knots, and intriguing semi-circular structures are easily visible in our previous WFPC2 images. We have suggested that these spatially recognizable features may be evidence for episodic mass loss events possibly from localized active regions. We now propose to obtain second epoch WFPC2 images with the Planetary Camera to measure the transverse motions of these ejecta. Spatially resolved spectra from STIS showed that the embedded arcs are kinematically distinct from the spherically expanding diffuse nebulosity. The transverse motions in combination with radial velocities from the STIS spectra, will let us determine the morphology of IRC +10420's nebula and the structures embedded in it, its mass loss history, and provide clues to the mass loss mechanism responsible for the discrete ejections.
Our proposed second epoch images will repeat the 1996 obervations with the Planetary Camera. We used the F547M and F467M filters with a wide range of exposure times to image the bright embedded star, material close to it, and the faint outer nebulosity. These observations take one orbit. In addition to repeating the 1996 imaging we also propose to add a series of images with the F675W filter with a range of integration times, including a long exposure intended to look or a faint outer reflection shell at about 8 arcsec reported by Kastner & Weintraub (1995) at 1.25 microns. This feature was not visible in our first epoch blue and visual images, and at its distance from the star, it may be a remnant of a prior red supergiant stage. The F675W filter will be dominated by the flux of IRC +10420's very strong Halpha emission line and so will in effect be an Halpha image. However, since IRC +10420 is a reflection nebula we are not trying to separate the Halpha emission from the continuum. We are also adding a series of exposures with the F1042M filter. The images of VY CMa (Smith et al 2001) with this filter yielded a different view of the ejecta showing the distribution of the reddest and dustiest features. We don't know what this may show for IRC +10420, but its 2 micron image showed evidence for bipolarity not apparent in the visual HST images and the 8 arcsec shell was detected at 1.25 microns. The F675W and F1042M images together will take one additional orbit. COOL STARS 12 false 0.0 false false false false false false SUPPORTED STAR A4-A9 III-I This object was generated by the targetselector and retrieved from the SIMBAD database. B-V = 2.7 J2000 19 26 48.0300 +11 21 16.70 J2000 WFPC2 Imaging No F467M WFPC2 Imaging No F547M WFPC2 Imaging No F675W WFPC2 Imaging No F1042M POS-TARG DITHER 0.3535 LINE false false 3 45 WFPC2-LINE 1 false POS-TARG DITHER 0.322 LINE false false 2 45 WFPC2-LINE 2 false POS-TARG DITHER 0.161 LINE false false 2 45 WFPC2-LINE 3 false /tmp/OPVisit13033.xml (Tic-Visit :proposal-id 11180 :visit-id "01" :proposal-version -1 :trans-version "20070325" :date "10-May-2007 10:21:58.0" :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 941136 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11180 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11180 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2640 :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 3137 :pcs-gap 0 ) (Tic-Orbit :proposal-id 11180 :visit-id "01" :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 3137 :pcs-gap 0 ) true 2 0 /home/rmh/HSTcy16/Phase2/OP-cache/prop5-v01.xml Short exposure to avoid bleeding of central star. two 30s exposures dithered to duplicate the dither used in GO 6475. two 140s exposures dithered with same spacing used in GO 6475. Short exposure to avoid bleeding by central star. Short exposure to avoid bleeding by central star Three 30s exposures in a line dither pattern Short exposure to avoid bleeding