Proposal for 5 orbits Assigned ID: 857 ----- Attempting Submission 1 (Sat Feb 27 00:09:52 GMT 2010) ----- This proposal is the merger of proposals 12207 (PI C.Badenes) and 12175 (PI T. Marsh). Hi David & Beth, I updated the COS visit, splitting the exposures across two FP-POS positions to help dealing with fixed pattern noise. Boris ----- Attempting Submission 1 (Wed Jul 07 13:26:03 GMT 2010) ----- HST Phase II Proposal 12207 (12207_merged.apt) successfully submitted. ----- Attempting Submission 2 (Wed Jul 07 14:35:18 GMT 2010) ----- HST Phase II Proposal 12207 (12207_merged.apt) successfully submitted. ----- Attempting Submission 3 (Fri Jul 09 08:54:08 GMT 2010) ----- The past and future evolution of the unique double white dwarf binary SDSS1257+5428 The past 15 years has seen the unmasking of a vast population of close double white dwarfs (DWDs) with over 100 million in our Galaxy alone. So numerous are DWDs that they may themselves be the progenitors of significant populations such as accreting ultra-compact binary stars, isolated millisecond pulsars, hot subdwarfs and Type Ia supernovae. They are also expected to be the dominant sources for space-based gravitational wave astronomy. We have discovered a unique DWD, SDSS1257+5428, composed of two white dwarfs with masses of 0.2 and > 1 Msun, from the low and high-mass extremes of the white dwarf mass distribution. The high mass white dwarf is rapidly rotating, suggestive of accretion-induced spin-up, and yet in current models of the evoluton of such systems in which the low mass white dwarf should have emerged from a common envelope phase, there could not have been time for such spin-up to have occurred. Our current knowledge of the system, particular! ly the fainter high mass white dwarf, is limited by the blending of the two spectra at optical wavelengths. We don't know for instance whether or not the total system mass exceeds the Chandrasekhar mass. We will acquire ultraviolet spectra of SDSS1257+5428 which will pin down the masses and temperatures of the compoanent white dwarfs to define the past and future evolution of this puzzling system.
The aim of these observations is to record the FUV/NUV spectrum of the double-degenerate white dwarf SDSS1257+5428, and to use these data to determine accurate masses and temperatures for both components. This binary is composed of a cool, low-mass (~0.2Msun, ~8000K) plus a more massive, somewhat hotter (~0.8Msun, ~12000K) component (see arXiv:0910.2709, arXiv:1002.4677, arXiv:1003.2169). COS/G140L observations will occupy three orbits and cover the quasimolecular H2+ (1400A) and H2 (1600A) absorption lines, which are very temperature/pressure sensitive. Two orbits of STIS/G230L observations will delineate the spectral energy distribution across the NUV range. HOT STARS 12 false 0.0 0.0 false false false false false false SUPPORTED STAR DA No GALEX data, but the UV fluxes are well-established from Swift/UVOT observations (Swift target 31472, observations 001 - 007). Swift: UVW2(2030A) 1.3e-15erg/cm2/s/A UVW1(2634A) 1.0e-15erg/cm2/s/A J2000 12 57 33.6400 +54 28 50.50 J2000 COS/FUV Spectroscopic No No G140L 1105 STIS/NUV-MAMA Spectroscopic No No G230L 2376 /home/astro/btg/tex/Proposals/hst/PhaseII/OP-cache/12207-v01.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12207 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "08-Jul-2010 17:03:22.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 487216 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12207 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12207 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3112 :al-overhead-at-end 0 :internal-dur-at-end 97 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12207 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3223 :al-overhead-at-end 0 :internal-dur-at-end 107 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12207 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3223 :al-overhead-at-end 0 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) true 3 0 /home/astro/btg/tex/Proposals/hst/PhaseII/OP-cache/12207-v02.xml The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12207 :visit-id "02" :proposal-version -1 :trans-version "20100505" :date "08-Jul-2010 17:01:23.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1722608 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12207 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12207 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3112 :al-overhead-at-end 0 :internal-dur-at-end 343 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12207 :visit-id "02" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3223 :al-overhead-at-end 0 :internal-dur-at-end 605 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) true 2 0