0 Assigned ID: 629 ----- Attempting Submission 1 (Fri Apr 05 18:47:25 GMT 2019) ----- ----- Attempting Submission 2 (Sun Apr 07 15:30:10 GMT 2019) ----- 0 ----- Attempting Submission 1 (Fri Jul 05 09:12:38 GMT 2019) ----- On 24 Mar 2019, using high-cadence photometry, we discovered the second white dwarf system with planetary transit events. We have confirmed the period of numerous events to all be 25 h, which corresponds to a semimajor axis well within the habitable zone of the stellar remnant. The transit activity is essentially continuous at the few to several percent level, from blue to red wavelengths with no color dependence. Here we propose STIS near-ultraviolet spectroscopy to constrain the bulk chemistry of the planetary material accreted by the white dwarf. These observations will be sensitive to silicon and carbon, which cannot be accessed via ground-based observations, and are key components of both rocky and icy planetary materials. The goal of this program is to obtain high S/N near-ultraviolet spectroscopy of the white dwarf WD1054-226 to probe for metal absorption lines. The visit structure is straigh-forward: we acquire the target with the F28X50LP broad-band filter, and then switch to G230L time-tagged spectroscopy. Farihi and Gaensicke are leaders in the observations of circumstellar debris disks and white dwarf pollution. Together, they have discovered the majority of disks at white dwarfs, led several key studies on how the accretion takes place, and in the past few years have published nine papers based on Hubble results, including: detailed abundance studies confirming Earth-like debris at numerous polluted white dwarfs; the first (indirect) identification of water in the otherwise-rocky debris orbiting a GD 61; and the detection of rocky debris in two Hyades white dwarfs. Toloza is leading the modeling of white dwarf atmospheres at the University of Warwick, and implementing a new generation of open-source code for the community which is based on the legacy of D. Koester. Redfield is a leading expert in the observation of circumstellar, interstellar, and planetary atmosphere absorption, and was the first to detect Na in ground-based observations of exoplanet transits, as well as the first to demonsrate the circumstellar gas transiting WD1145+017 has an eccentric orbit. The team have the necessary resources and experience to analyze, interpret, and scientifically exploit the requested data. Planets and Planet Formation Stellar Physics 6 false false true false false false false SUPPORTED STAR DA NO GALEX NUV= J2000 J2000 STIS/NUV-MAMA Spectroscopic No No G230L 2376 1562310849688 /tmp/OPVisit6973244859656819935.xml The scheduling data was generated by CASM 27.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15898 :visit-id "01" :proposal-version -1 :trans-version "20190514" :date "05-Jul-2019 08:14:09.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1879104 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15898 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15898 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2764 :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 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15898 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 339 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15898 :visit-id "01" :orbit-number 3 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 339 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15898 :visit-id "01" :orbit-number 4 :pcs-time 302 :si-vis-utilization 2855 :al-overhead-at-end 0 :internal-dur-at-end 601 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 4 0