0 Assigned ID: 5071 ----- Attempting Submission 1 (Sat Mar 23 03:15:48 GMT 2024) ----- HST Phase I Proposal 5071 successfully submitted. Receipt: # 5071-1 ----- Attempting Submission 2 (Tue Mar 26 04:00:39 GMT 2024) ----- HST Phase I Proposal 5071 successfully submitted. Receipt: # 5071-2 ----- Attempting Submission 3 (Tue Mar 26 22:17:44 GMT 2024) ----- The number of orbits used exceeds the number allocated Phase II submission : re-submission with less exposure time per orbit so SNR does not exceed maximum allowed from fixed pattern noise for G130M. Obs1 failed so re-submitting. -455677529 ----- Attempting Submission 1 (Mon Aug 12 14:06:10 GMT 2024) ----- ----- Attempting Submission 2 (Mon Sep 30 08:30:46 GMT 2024) ----- ----- Attempting Submission 3 (Fri Sep 12 19:51:06 GMT 2025) ----- Obs1 failed and the program was granted 2 more orbits to re-do the failed observations. WD0106-038: the first variable metal polluted white dwarf? This proposal aims to re-observe a white dwarf polluted with planetary material to confirm whether the amount of planetary material in the atmosphere has changed over time. This would be the first confirmed variable metal polluted white dwarf. Ground based observations revealed an increase of 35% in the equivalent width of the Mg II doublet over a timescale of 10 years. However, this is based off of one spectral line. A previous UV spectrum of WD0106-038 has been obtained which revealed a plethora of absorption lines; by obtaining a follow up UV spectrum we will confirm whether this is the first variable metal polluted white dwarf. Due to the short sinking timescales of approximately days-weeks depending on the element, we propose 2 observations to assess both the long-term (yearly) and short-term (monthly) variability of the absorption lines. This would be the first evidence for sporadic accretion and will have a significant impact on how we use metal polluted white dwarfs to measure bulk planetary compositions. Technical Set-up: We propose to use the G130M grating in the FUV module with a central wavelength of 1291 A. In accordance with the COS2025 policies, we will only use two FP-POS positions (3 and 4). COS safety: Our target is sufficiently faint that COS safety is not a problem. Reduced gyro observations: our observations are not time critical, we just require the 2 visits to be separated by more than 60 days, so reducing the possible observing windows will not affect this proposal. Using the visit planner tool, there are plenty of schedulable opportunities across the cycle for the target. Target acquisition is required in order to sucessfully complete the proposed observations. Scheduling: This proposal observes the same object to search for variability, therefore the gap between observations needs to be at leat 2 months. SNR: We require a SNR of at least 30 around 1320A, close to important lines of carbon. Dr Laura Rogers, Dr Amy Bonsor, Dr Siyi Xu, Dr John Debes, Dr Simon Hodgkin, and Prof Patrick Dufour have been PI or CoI on a number of successful HST/COS proposals related to polluted white dwarfs, and have extensive experience with the preparation of observations, data reduction, and data analysis. Prof Patrick Dufour is an expert on models of white dwarfs, and will fit models to the obtained FUV spectra in order to get updated white dwarf parameters, and the abundances of the exo-planetary material that have polluted the atmospheres of the white dwarfs. Our team have all contributed to the extensive ground based work that has been done as part of the project. Dr Laura Rogers has vast experience analysing spectra, including that of Hubble/COS, and will perform a similar analysis on the HST/COS data as on the optical data to search for and confirm variability. All team members have experience with and knowledge of observations of polluted white dwarfs and dust discs, and will all be of valuable help with the analysis. Everyone will contribute to the analysis of the data and the preparation of the publications resulting from this proposal. Exoplanets and Exoplanet Formation 6 false true false false false false SUPPORTED STAR DA DZ NO WD0106-328 GAIA-DR3-5026963661794939520 J2000 J2000 FUV=15.22 COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1291 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. First visit for WD0106-038 1757171218000 304.4476381147738 (Tic-Visit :proposal-id 17819 :visit-id "01" :proposal-version -1 :trans-version "20240627" :date "30-Sep-2024 09:25:20.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 243648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17819 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17819 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2389 :al-overhead-at-end 0 :internal-dur-at-end 67 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3034 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17819 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2119 :al-overhead-at-end 0 :internal-dur-at-end 379 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3034 :pcs-gap 0 ) true 2 0 Timing link suitability includes constraints ([02 After 03 by 60.0 to 1000.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /private/var/folders/1r/vdh8rvy55f11y5p5bwlty25h0000gp/T/OPVisit9709364139988538690.xml First visit for WD0106-038 (Tic-Visit :proposal-id 17819 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "12-Sep-2025 12:40:35.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 243648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17819 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17819 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2388 :al-overhead-at-end 0 :internal-dur-at-end 67 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2987 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17819 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2119 :al-overhead-at-end 0 :internal-dur-at-end 377 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2987 :pcs-gap 0 ) true 2 0 /private/var/folders/1r/vdh8rvy55f11y5p5bwlty25h0000gp/T/OPVisit10529616200827386748.xml Timing link suitability includes constraints ([02 After 03 by 60.0 to 1000.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Second visit for WD0106-038, needs to be > 60 days after the first visit. (Tic-Visit :proposal-id 17819 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "12-Sep-2025 12:40:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 243648 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17819 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17819 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2388 :al-overhead-at-end 0 :internal-dur-at-end 67 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2987 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17819 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2119 :al-overhead-at-end 0 :internal-dur-at-end 377 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2987 :pcs-gap 0 ) true 2 0