0 Assigned ID: 3264 ----- Attempting Submission 1 (Fri Mar 25 15:10:11 GMT 2022) ----- 0 ----- Attempting Submission 1 (Thu Jun 30 09:11:36 GMT 2022) ----- A very low mass, highly irradiated survivor of the common envelope phase The common envelope (CE) phase is a key driver in the evolution of close binary stars, causing their periods to shrink dramatically, or the two stars to merge altogether. An important parameter for the survival of many systems, including planets enveloped by host giant branch stars, is the minimum companion mass that can survive a CE. No certain survivor of a CE has been found with a mass less than 50 Jupiter masses (M_J), well above the lowest theoretical prediction of 5 M_J. With the theory itself uncertain, it is important to establish firmer observational limits. A recently discovered hot white dwarf / brown dwarf binary with a period of 2.4 hours promises to do just this. Optical data of this system indicate a mass for the brown dwarf lying between 11 and 44 M_J. Better constraints require a measurement of the temperature of the hot white dwarf, which translates to a better mass for the brown dwarf through a combination of distance, model atmosphere, gravitational red-shift and dynamical constraints. Preliminary indications from optical spectra suggest a white dwarf temperature of order 100,000 K and a brown dwarf mass of order 20 M_J, substantially reducing the current gap between theory and observation. However, optical spectra have relatively few and weak features compared to the FUV, and suffer significant contamination from light emitted by the heated face of the brown dwarf in this compact system. The aim of this proposal is to acquire FUV spectra to measure the white dwarf's effective temperature and to obtain improved values for the dynamical and red-shift constraints upon which the mass estimates hinge. The goal of this proposal is to obtain far-ultraviolet, orbital phase-resolved, high-resolution spectroscopy of WD 2003+0838 to measure the effective temperature and orbital velocity of the white dwarf, in order to determine its mass and hence the mass of its brown dwarf companion, and to look for evidence of mass loss and/or accretion in the system and circumstellar material. The observations will be split into 2 x 3 orbits, following standard STIS procedures: target acquisition with the F28X50LP long-pass filter, followed by E140M time-tag spectroscopy (such that we can bin the data into arbitrary phase bins during the analysis) using the 0.2"x0.2" aperture. The two visits can be scheduled totally independently. Dr Nicole Reindl has long expertise in the analysis of HST spectroscopy and leads the computation of metal-line blanketing non-LTE (NLTE) model atmospheres suitable for spectroscopic analysis of the proposed object using the Tuebingen Model Atmosphere Package (TMAP). Prof. Tom Marsh has wide experience of the optical, infrared and UV analysis of white dwarfs and close binary stars, and is author of light curve modelling and radial velocity analysis software commonly used for their analysis. Prof. Boris Gaensicke has in-depth experience in planning, carrying out, and analysing HST far-ultraviolet observations of white dwarfs. Dr Veronika Schaffenroth is an expert on hot star close binaries, in particular in modelling reflection effect systems. Stellar Physics and Stellar Types 6 false false false false false false false false SUPPORTED STAR DA NO Coordinates and proper motions were taken from Gaia EDR3. J2000 J2000 GALEX NUV=13.5 STIS/FUV-MAMA Spectroscopic No No E140M 1425 The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. /private/var/folders/zc/ljhf1lgn10b1yd9ytmwlp4jr00070l/T/OPVisit68200500611210638.xml (Tic-Visit :proposal-id 17107 :visit-id "01" :proposal-version -1 :trans-version "20240604" :date "14-Jun-2024 11:06:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 1 :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 1861728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17107 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17107 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2630 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2630 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "01" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2630 :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 3010 :pcs-gap 0 ) true 3 0 At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to V=14.1 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. 1699155641000 71.1 (Tic-Visit :proposal-id 17107 :visit-id "02" :proposal-version -1 :trans-version "20220516" :date "30-Jun-2022 10:11:01.0" :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 2000896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17107 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17107 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2752 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3145 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2753 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3145 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "02" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2753 :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 3145 :pcs-gap 0 ) true 3 0 At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to V=14.1 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. /private/var/folders/zc/ljhf1lgn10b1yd9ytmwlp4jr00070l/T/OPVisit6232559823691430611.xml HOPR repeat of visit 02. (Tic-Visit :proposal-id 17107 :visit-id "52" :proposal-version -1 :trans-version "20240604" :date "14-Jun-2024 11:06:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 1 :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 1861728 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17107 :visit-id "52" :obset-id "52" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17107 :visit-id "52" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2630 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "52" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2630 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3010 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17107 :visit-id "52" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2630 :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 3010 :pcs-gap 0 ) true 3 0 At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to V=14.1 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation. At the estimated Teff=100000K for the white dwarf in this binary, the spectrum will closely resemble a blackbody, hence we chose a blackbody with T=100000K and scaled it to GALEX NUV=13.5 for the STIS ETC calculation.