Assigned ID: 449 ----- Attempting Submission 1 (Fri Feb 24 15:40:33 GMT 2012) ----- HST Phase I Proposal 449 (HD188112.apt) successfully submitted. ----- Attempting Submission 2 (Fri Feb 24 16:03:12 GMT 2012) ----- Buffer times changed to 130s, exposure times for orbit 1 and 3 adjusted to multiple buffer times. ----- Attempting Submission 1 (Mon Jul 09 07:40:29 GMT 2012) ----- ----- Attempting Submission 2 (Sat Aug 18 14:44:01 GMT 2012) ----- Several different explosion channels have been proposed for Type Ia Supernovae (SNe Ia), and tested against observations through hydrodynamic explosion simulations and radiative-transfer calculations. A promising scenario is the double detonation of a sub-Chandrasekhar-mass C/O white dwarf (WD), where a surface detonation in freshly accreted He subsequently triggers a detonation in the C/O core. The companion and He donor would likely be a low-mass He WD. Potential progenitor systems (i.e., binaries of a sufficiently massive C/O WD with a low-mass He WD) have never been observed so far. However, HD~188112 might be part of such a system. HD~188112 is a nearby, bright, radial-velocity variable He WD of 0.24 M$_\odot$, whose unseen companion has been inferred to be another WD of at least 0.73 M$_\odot$. The exact mass of the companion depends on the unknown inclination of the system. Assuming tidally locked rotation, the inclination can be determined measuring the broadening of metal lines due to rotation. Since the metallicity of HD 188112 is extremely low (1/100 solar), this measurement can only be performed in the UV, making the use of HST mandatory. If the mass of the companion of HD 188112 is confirmed to be between 0.95 and 1.05 M$_\odot$, the first candidate double-detonation SN Ia progenitor system has been found. The project requires time series spectroscopy with E140H and E230. Time tag mode ist used for the NUV. The star is too bright in the FUV to use Time Tag mode. Thererfore observations are broken into a series of 22 exposures of 2 minutes duration. No standard No HOT STARS 12 false 0.0 0.0 false false false false SUPPORTED STAR SDB This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 STIS/NUV-MAMA Spectroscopic No No E230H 2812 STIS/FUV-MAMA Spectroscopic No No E140H 1343 1345300756398 /tmp/OPVisit444904721685136634.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12865 :visit-id "01" :proposal-version -1 :trans-version "20120615" :date "18-Aug-2012 16:39:13.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 3705872 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12865 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12865 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2917 :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 3253 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12865 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2961 :al-overhead-at-end 0 :internal-dur-at-end 2267 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3253 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12865 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2890 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3253 :pcs-gap 0 ) true 3 0