13059( 3) - 10-Jul-2012 23:42:20 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13059 Version: 3 Check-in Time: 10-Jul-2012 23:42:20 STScI Edit Number: 1 Title The White Dwarf Mass-Radius Relation Based on Dynamical Masses: STIS Observations of Close Double Degenerates ------------------------------------------------------------------------------------ Type Cycle GO 20 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Edmund Nelan Space Telescope Science Institute Y CoI: Dr. Howard E. Bond Space Telescope Science Institute N CoI: Dr. Gail Schaefer Georgia State University Research N Foundation ------------------------------------------------------------------------------------ Abstract This is the second part of a proposal to add six new white dwarfs (WDs) to the mass-radius relation for WDs, thus providing a stringent new test of our understanding of WD physics. The first part (12594) observed white dwarf binaries G107-70 and WD 1818+126. This proposal observes WD1639+153 as it achieve its maximum projected component separation (0.13") between August 2013 and Feb 2014. For the past several years, we have had underway programs of HST/FGS astrometry of three close visual binaries in which both components are WDs. The astrometry is yielding precise, model-independent dynamical masses for these six WDs. To complete the investigation, we need to obtain flux-calibrated spectra of the individual WDs in these binaries, which, combined with the accurate parallaxes from the FGS data, yield the radii. All three binaries are too close together for individual spectra to be obtained from the ground, but they can be obtained easily with STIS. By using an optimal telescope roll angle, we can obtain both spectra simultaneously in a single STIS exposure. Two of the binaries are bright enough to obtain the spectra in one orbit. Our faintest target requires 2 orbits to obtain the necessry S/N on the V=17.4 secondary. In order to observe the closest of the binaries at maximum separation (WD 1639+153 at 0.132"), its observation should be done a few months after the beginning of Cycle 20. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to use HST/STIS to obtain low resolution broad-band spectroscopy & photometry of the six WD stars in our three DD binary systems. From the FGS observations of these binaries we know precisely the component position angle and separation at a given time. With this knowledge, for each binary we propose to align the binary position angle with the 52"x2" STIS long slit (to within 1 degree) by specification of a date-dependent HST ORIENT, and place the object near the center of the aperture, using the STIS target acquisition capability. A peak-up will not be needed for the 2" wide slit. The stars will be observed using the G430L and the G750L low resolution elements, with a CR-SPLIT = 2, and a 2-point dither along the slit in the spatial direction, of 0.650", to accomodate the widest binary in this proposal (G107-70, sep = ~450 mas at the proposed observing time. In accordance with guidance from the STIS INS HDBK, we obtain CCD flats with the G750L to calibrate away the red fringing. 13059( 3) - 10-Jul-2012 23:42:20 - [ 2] Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 13059( 3) - 10-Jul-2012 23:42:20 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 G107-70 STAR, DC RA=07H30M47.2846S +/- 0.1", J2000 V = 15.0 +/- 0.1 DEC=+48D10'27.40" +/- 0.1" Reference Frame: ICRS Comments: Target coordinates are updated from observed "miss distance" in the FGS observations (dRA= +1", dDec = +0.8"). This is a binary system with sep = 0.430", PA = 269.9 deg, and dmag = 0.3 at epoch Feb 2012. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.022 -1.271 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 2 WD1818+126 STAR, DC RA=18H20M30.8800S +/- 0.1", J2000 V = 16.06 +/- 0.05 DEC=+12D39'17.70" +/- 0.1" Reference Frame: ICRS Comments: binary system with sep = 173", PA = 189.5 deg, dmag = 0.9, at epoch Nov, 2011. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.007 0.271 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 WD1639+153 STAR, DC RA=16H41M36.7000S +/- 0.1", J2000 V = 15.7 +/- 0.1 DEC=+15D12'36.38" +/- 0.1" Reference Frame: ICRS Comments: This target will be observed by the "Cycle 20 continuation proposal" associated with this proposal. We wish to wait for the projected separation of the binary components to approach apastron (0.132"), which occurs in early Cycle 20. We retain the target in this proposal for bookkeeping purpose. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.005 -0.736 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 13059( 3) - 10-Jul-2012 23:42:20 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.6350 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 90.0 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 13059( 3) - 10-Jul-2012 23:42:20 - [ 5] Visit: 01 Visit Requirements: ORIENT 308D TO 312 D; ORIENT 128.0D TO 132.0 D; BETWEEN 01-AUG-2013 AND 02-FEB-2014 On Hold Comments: Additional Comments: Optimal orientation (133 deg) for aligning binary position angle with spatial direction of 52x2 slit has no guide stars. The selection of 127 deg (has guide stars) will be acceptable. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WD1639+153 STIS/CCD ACQ 50CCD MIRROR ACQTYPE=POINT 1 2.0 S GS ACQ SCENARIO BASE1B3 Comments: binary star system, sep = 0.6", dmag = 0.3, PA = ------------------------------------------------------------------------------------------------------------------------------------ 2 WD1639+153 STIS/CCD ACCUM 52X2E1 G430L 4300 CR-SPLIT=2 1 420.0 S PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 WD1639+153 STIS/CCD ACCUM 52X2E2 G750L 7751 CR-SPLIT=2 1 400 S PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 CCDFLAT STIS/CCD ACCUM 52X0.1 G750L 7751 2 DEF ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ WD1639+153 1 STIS/CCD ACQ 50CCD MIRROR none none none none 1 N/A WD1639+153 2 STIS/CCD ACCUM 52X2E1 G430L 4300 1 none none 1 1 N/A WD1639+153 2 STIS/CCD ACCUM 52X2E1 G430L 4300 1 none none 2 1 N/A WD1639+153 2 STIS/CCD ACCUM 52X2E1 G430L 4300 2 none none 1 1 N/A WD1639+153 2 STIS/CCD ACCUM 52X2E1 G430L 4300 2 none none 2 1 N/A WD1639+153 3 STIS/CCD ACCUM 52X2E2 G750L 7751 1 none none 1 1 N/A WD1639+153 3 STIS/CCD ACCUM 52X2E2 G750L 7751 1 none none 2 1 N/A WD1639+153 3 STIS/CCD ACCUM 52X2E2 G750L 7751 2 none none 1 1 N/A WD1639+153 3 STIS/CCD ACCUM 52X2E2 G750L 7751 2 none none 2 1 N/A CCDFLAT 4 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 1 none 1 N/A CCDFLAT 4 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 2 none 1 N/A 13059( 3) - 10-Jul-2012 23:42:20 - [ 6] Summary Form for Proposal 13059 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 50CCD, 52X0.1, 52X2E1, 52X2E2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT, CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-AUG-2013 AND 02-FEB-2014, GS ACQ SCENARIO BASE1B3, ORIENT 128.0D TO 132.0 D, ORIENT 308D TO 312 D, PATTERN 1 2, PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G430L, G750L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names CCDFLAT, WD1639+153 ------------------------------------------------------------------------------------------------------------------------------------