0 Assigned ID: 693 ----- Attempting Submission 1 (Fri Apr 07 17:53:09 GMT 2017) ----- This is a second re-submission to correct some minor errors which have been documented in my email exchange with Bill Fischer. -1980592940 ----- Attempting Submission 1 (Thu Jul 06 18:23:39 GMT 2017) ----- HST Phase II Proposal 15184 (tpyx_phase2.apt) successfully submitted. Receipt: # 15184-1 ----- Attempting Submission 2 (Wed Aug 09 21:11:12 GMT 2017) ----- HST Phase II Proposal 15184 (tpyx_phase2.apt) successfully submitted. Receipt: # 15184-2 ----- Attempting Submission 3 (Thu Aug 10 18:31:27 GMT 2017) ----- The SN Ia Candidate T Pyxidis: Is The Accretion Rate Declining? T Pyx is a recurrent nova that unexpectedly went into outburst in 2011. It appears to have declined to its quiescent level accreting at a very high rate, possibly driven by irradiation of the donor star by the hot white dwarf or by the hot inner disk. Our team (Godon et al. 2014) has shown, using the light echo distance of 4.8kpc (Sokoloski et al. 2013), that the white dwarf in T Pyx is actually growing in mass and might be on its way to exploding as a Type Ia supernova. However, our most recent COS spectrum reveals that the flux decline continues and, in fact, has actually fallen to a flux level that is 25% below the FUV flux levels observed with IUE between 1981 and 1996, following the 1966 outburst. Moreover, a new strong emission line (Si III + O I) and strong, broad N V (1238, 1242) absorption line appear, not detected in any prior FUV spectra of T Pyx. We propose to continue spectroscopic observations of T Pyx with HST COS during cycle 25, to obtain the first FUV spectra in early quiescence (only six years after its 44 years-delayed outburst). The first FUV spectra of T Pyx following its 1967 outburst were a full 13 years later, in 1980, when IUE was launched. By obtaining FUV COS spectra of T Pyx during cycle 25, we will detect further changes, if any, in the continuum slope, in the velocity widths and intensities of the emission lines. We will use our suite of modeling codes to study the evolution of the accretion disk. Our analysis will yield the accretion rate, and help determine whether the WD increases its mass to reach the Chandrasekhar limit. Our observations will solidify the identification of recurrent novae as Type Ia Supernova Progenitors. We request two orbits taken successively with COS of the same target. In the first COS is set to G140L 1105, in the second COS is set to G130M 1055. The second orbit/visit is to follow the first orbit/visit immediately. Stellar Physics 6 false true false false false false SUPPORTED STAR ACCRETION DISK CLASSICAL NOVA DWARF NOVA INTERACTING BINARY NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 COS/FUV Spectroscopic No No G140L 1105 COS/FUV Spectroscopic No No G130M 1055 C:\Users\Pat\AppData\Local\Temp\OPVisit3736096647359678122.xml The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15184 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "10-Aug-2017 12:59:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 313136 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15184 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15184 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2905 :al-overhead-at-end 0 :internal-dur-at-end 407 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 1 0 C:\Users\Pat\AppData\Local\Temp\OPVisit186137854078116071.xml The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15184 :visit-id "02" :proposal-version -1 :trans-version "20170613" :date "10-Aug-2017 13:00:43.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 278384 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15184 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15184 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2896 :al-overhead-at-end 0 :internal-dur-at-end 398 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 1 0