Assigned ID: 188 ----- Attempting Submission 1 (Thu Feb 25 21:59:12 GMT 2010) ----- ----- Attempting Submission 1 (Sat Jul 10 21:57:15 GMT 2010) ----- HST Observations of Astrophysically Important Visual Binaries We propose to continue three long-term programs. All three consist of astrometry of close visual binaries, with the primary goal of determining dynamical masses for 3 important main-sequence stars and 6 white dwarfs (WDs). A secondary aim is to set limits on third bodies in the systems down to planetary mass. Since all 3 programs needed to be proposed for Cycle 18 continuation, we are simplifying the review process by combining them into a single proposal. Three of our 5 targets are naked-eye stars with much fainter companions that are very difficult to image from the ground. Our other 2 targets are double WDs, whose small separations and faintness likewise make them difficult to measure using ground-based techniques. The bright stars, to be imaged with WFC3, are: (1) Procyon (P = 40.9 yr), for which our first HST images yielded an accurate angular separation of the bright F star and its much fainter WD companion. Combined with ground-based astrometry of the bright star, our observation significantly revised downward the derived masses, and brought Procyon A into much better agreement with theoretical evolutionary masses. With the continued monitoring proposed here, we will obtain masses to an accuracy of better than 1%, providing a testbed for theories of both Sun-like stars and WDs. (2) Sirius (P = 50.1 yr), an A-type star also having a faint WD companion, Sirius B, the nearest and brightest of all WDs. (3) Mu Cas (P = 21.0 yr), a nearby metal-deficient G dwarf for which accurate masses will lead to the stars' helium contents, with cosmological implications. The faint double WDs, to be observed with FGS, are: (1) G 107-70 (P = 18.8 yr), and (2) WD 1818+126 (P = 12.7 yr). Our astrometry of these systems will add 4 accurate masses to the handful of WD masses that are directly known from dynamical measurements. The FGS measurements will also provide precise parallaxes for the systems, a necessary ingredient in the mass determinations.
This is the Cycle 18 continuation of several programs in which we are determining the orbits of visual binaries. The targets for Cycle 18 are Procyon, mu Cas, Sirius, and G 107-70. We have been observing G 107-70 with FGS, and this part of the program will continue as before, with 1 orbit of POS mode observations of the target and reference stars. Procyon, mu Cas, and Sirius will be observed with WFC3/UVIS. For the two very bright stars, Procyon and Sirius, we will use the long-wavelength F953N filter to reduce the signal. Since even with this filter Procyon A and Sirius A would saturate in the minimum WFC3 exposure, we will let them saturate and use the diffraction spikes to centroid the bright components. For Procyon there will be a series of dithered 38-sec exposures, which will provide good unsaturated exposures for Procyon B at the same telescope pointing. For Sirius there will be a series of 6- and 12-sec dithered exposures. For mu Cas, we will use 1.5-sec exposures in F225W, which will not be saturated. These will be followed at each dither position with a 265-sec exposure, which will be well exposed for the cool dM companion. HOT STARS 12 false 0.0 0.0 false false false false false false SUPPORTED STAR DA F3-F9 Coords are for center of gravity of binary. Accuracy confirmed by 2000 Nov 28 WFPC2 observations. 6/14/06: updated to ICRS system using galex website. B-V = 0.42 ALPHA-CMI HR2943 J2000 00 00 0.0000 +00 00 0.00 J2000 STAR G V-IV Coordinate accuracy confirmed by 2000-01 WFPC2 observations. 6/14/06: updated to ICRS system using galex website. B-V = 0.70 HR321 HD6582 J2000 00 00 0.0000 +00 00 0.00 J2000 STAR A0-A3 V-IV DA Coordinates are for center of mass of the Sirius A-B binary, determined from a WFPC2 observation in January 2008. ALPHA-CMA HR2491 J2000 06 45 8.9000 -16 42 58.00 J2000 STAR DC double degenerate binary system, separation ~0.6" J2000 00 00 0.0000 +00 00 0.00 J2000 STAR M V-IV CPM companion to G107-70, ~1 arcmin distant J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 CALIBRATION ASTROMETRIC J2000 00 00 0.0000 +00 00 0.00 J2000 WFC3/UVIS Imaging No No F953N WFC3/UVIS Imaging No No F953N WFC3/UVIS Imaging No No F225W FGS POS No F583W FGS POS No F583W POS-TARG DITHER 0.173 LINE 0.112 false true 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /var/tmp/OPVisit38761.xml ORIENT requirement is done so that companion star will not lie near diffraction spikes or charge bleeding from the very bright primary star. (Tic-Visit :proposal-id 12296 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "10-Jul-2010 17:53:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 146448 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12296 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12296 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2898 :al-overhead-at-end 40 :internal-dur-at-end 199 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3242 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /var/tmp/OPVisit38762.xml ORIENT requirement is done so that companion star will not lie near diffraction spikes or charge bleeding of primary star. (Tic-Visit :proposal-id 12296 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "10-Jul-2010 17:54:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 73232 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12296 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12296 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2924 :al-overhead-at-end 38 :internal-dur-at-end 119 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3292 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /var/tmp/OPVisit38759.xml ORIENT requirement is done so that companion star will not lie near diffraction spikes or charge bleeding from the very bright primary star. (Tic-Visit :proposal-id 12296 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "10-Jul-2010 16:36:34.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 499088 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12296 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12296 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2702 :al-overhead-at-end 76 :internal-dur-at-end 584 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3249 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. /var/tmp/OPVisit38763.xml Maximum parallax factors April 10, October 11. This ORIENT can schedule up to April 6, and results in a favorable projection of the G107-70 components (PA ~ 189 degrees) in the FGS frame. (Tic-Visit :proposal-id 12296 :visit-id "04" :proposal-version -1 :trans-version "20100505" :date "10-Jul-2010 17:54:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "05" :si-bright-earth-limb-angle 15.5 :data-volume 0 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12296 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12296 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2995 :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 3391 :pcs-gap 0 ) true 1 0