0 Assigned ID: 1171 ----- Attempting Submission 1 (Fri Oct 18 16:52:45 GMT 2019) ----- INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS 0 ----- Attempting Submission 1 (Thu Nov 07 17:43:45 GMT 2019) ----- We can only use FP-POS 3+4 cycling for G130M, they are organized such that 4->3 changes occur between orbits. WD0145+234 was recently reported in the literature to have undergone an outburst in the mid-infrared. It previously was host to atmospheric pollution and infrared excess emission indicating that the white dwarf star was consuming a rocky body from its remnant planetary system. The infrared excess emission is now brighter by over a magnitude, likely due to a fresh disintegration event off of a massive rocky body. Such an event has never been observed before and it promises to revolutionize our understanding of the white dwarf pollution process if we can capitalize on it. While we have detected a few elements in optical spectroscopy, it is critical to obtain as soon as possible a complete inventory of the current atmospheric pollution such that we may chart its evolution as the infrared outburst progresses. It is our expectation that atmospheric line strengths will start to increase (due to a higher accretion rate from the recent infusion of fresh dust) and that we could possibly see a change in the overall composition of the accreted material. HST is the only facility in existence that can provide a baseline characterization of the rocky body composition and the total accretion rate before these changes begin to occur. Our primary goal is to determine (or place tight upper limits on) the abundances in the atmosphere of WD0145+234 for a number of elements that are key to determine the nature of the disrupting parent body. In particular, we will probe for the presence of volatiles (C, O), crust elements (Al, Ti), mantle elements (Mg, Si), and core-elements (Cr, Mn, Fe, Ni). Modeling of absorption lines shows that the desired elements can be measured or sufficiently strongly constrained with observations in the 1130-1700 Angstrom range. We will perform medium spectral resolution ultraviolet spectroscopy with COS and the G130M+G160M gratings to cover the 1130-1700 Angstrom range. In accordance with the COS2025 policies, we will only use two FP-POS positions (3 and 4) for G130M observations. For the GALEX-measured UV flux level of WD0145+234 (given in the target information area) it should be possible to obtain average S/N~35 in the 1130- 1700 Angstrom wavelength range with total on-source exposure time of approximately 7,500 seconds. These estimates are made using the COS ETC assuming standard background parameters and with a white dwarf spectral energy distribution matched to the parameters and flux level of our target. An average signal-to-noise ratio of ~35 for the 1130-1700 Angstrom wavelength range will enable detection or tight limits on the abundances of elements listed above. Our requested time estimates for COS are increased assuming 20 minutes of instrument overhead (including all acquisition and exposure overheads as suggested in the COS manual) per visit and 6 minutes of observatory overhead per orbit (spacecraft acquisition). In sum, we request 3 orbits for each instrument setup (G130M and G160M) and a total of 6 orbits for this project. Observations will be done in the TIME-TAG mode using TAG-FLASH wavelength calibration. The target white dwarf is an ICRS object (Gaia DR2 position with less than 0.4" positional uncertainty), has a measured UV flux, and is safe for the COS detectors in our desired setups. The proposal team is a collection of the world's foremost experts in polluted white dwarf science. We all have extensive experience with obtaining, reducing, and analyzing COS data for polluted white dwarf stars. The proposal team comprises a significant fraction of the polluted white dwarf community. Different teams have joined together in recognition of the importance of this object and in obtaining a timely measurement of its polluting material. PI Melis has led 5 separate COS polluted white dwarf projects, one of which has been published (Melis & Dufour 2017, ApJ 834, 1), another is soon to be published (Todd et al. 2019 submitted), and two others are in preparation to be submitted as of the writing of this statement. Co-Is Zuckerman, Xu, and Klein (with now-deceased Prof. Mike Jura) have been obtaining COS spectra of polluted white dwarfs for several years and have produced several publications (see proposal body). Co-I Dufour has substantial experience in modeling white dwarf spectra, especially to get atmospheric parameters and abundances, and has also led his own COS projects that have resulted in publications (e.g., Dufour et al. 2011, ApJL 733, 19). Co-I Toloza has expertise in modeling white dwarf stars and obtaining abundances from optical and ultraviolet data. Co-Is Gaensicke and Farihi have led numerous COS polluted white dwarf projects resulting in many publications, several of them in high profile journals (see references in proposal body). Co-I Young specializes in geophysics and planetary sciences and provides valuable insight into the evolution of rocky material and relevant physical processes. Co-Is Swan and Doyle are graduate students contributing significantly in this research area. Co-I Johnson is an undergraduate student at UCLA working on white dwarf science with our team. All members of the proposal team are devoting significant fractions of their time to studying polluted white dwarf stars. They will continue to do so with this project if time is awarded. Melis, Gaensicke, Klein, Farihi, and Xu will contribute to data reduction and analysis. Co-I Dufour will be take responsiblity for modeling spectra and measuring abundances and will be aided by Co-Is Toloza and Johnson. All will contribute to interpretation and publication. We will seek to publish these data within a few months of their observation by HST. Planets and Planet Formation Stellar Physics 0 false SUPPORTED STAR DA NO J2000 J2000 mFUV=14.66 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G160M 1600 1573147967214 The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. /Users/cmelis/observing/hst/cycle27/ddt/phaseii/OP-cache/wd0145_cycle27ddt_phaseii-v01.xml G130M COS/FUV observation of WD0145+234. (Tic-Visit :proposal-id 16032 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "07-Nov-2019 09:32:46.0" :trans-errors '(:WARNINGS 2 :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 539520 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16032 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16032 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2764 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16032 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16032 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 3 0 1573147968936 The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. /Users/cmelis/observing/hst/cycle27/ddt/phaseii/OP-cache/wd0145_cycle27ddt_phaseii-v02.xml G160M COS/FUV observation of WD0145+234. (Tic-Visit :proposal-id 16032 :visit-id "02" :proposal-version -1 :trans-version "20190514" :date "07-Nov-2019 09:32:48.0" :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 539520 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16032 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16032 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2764 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16032 :visit-id "02" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16032 :visit-id "02" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 3 0