0 Assigned ID: 7460 ----- Attempting Submission 1 (Thu Apr 16 16:31:30 GMT 2026) ----- After each FP-POS exposure, a wavecal exposure is required. Therefore we do not have sufficient time to also take a 1291A exposure as stated in Phase I. However, a 1291A exposure was only going to be taken if there was time leftover in the orbit after taking the critical 1222A exposure, and hence because it is more important to take a high quality 1222A exposure, we have not included a 1291A exposure. -1225846074 ----- Attempting Submission 1 (Wed Jul 29 12:44:21 GMT 2026) ----- The interior of low density rocky planets currently remains a mystery. Although there are theories that their interiors are dominated by carbon species or they are devoid of iron cores, there is no method to accurately probe their interior chemical compositions. However, white dwarfs accreting planetary material can be used to measure the chemical abundances of the accreted material. Their atmospheres are purely hydrogen or helium, hence measurements of any metal abundances can be used to determine the nature of planets in other systems. We have identified a white dwarf which is accreting a planet(esimal) with an enormous aluminium enhancement, much greater than that of mantle or crustal material. This could indicate it is a fragment or a building block of a low density rocky planet dominated by aluminium oxide which formed under an extremely high temperature, where iron was lost resulting in a planet with no core. With our exploratory spectrum, we are unable to detect or place strict upper limits on oxygen and iron. Oxygen is vital to confirm it can form oxides which dominate the interior. A stricter upper limit on iron is necessary to confirm it contains little or no iron core. Additional species such as chromium or nickel will further constrain the core mass fraction. At the high temperature of this white dwarf, oxygen and iron only have strong transitions in the far-ultraviolet, so we require one orbit of COS spectroscopy to search for these absorption features. We aim to detect oxygen and iron in the atmosphere of a white dwarf with a very large aluminium abundance. We will use the COS G130M grating with a central wavelength of 1222A which is sensitive to both oxygen and iron lines. We aim for a S/N ~ 30 at the lines of interest. All four FP-POS are used to minimise fixed pattern noise. J Williams is an expert in the analysis of ultraviolet observations of white dwarfs accreting planetary debris, and he will lead the analysis of the data from this program. B Gaensicke is an expert in the use of Hubble's far-ultraviolet spectrographs, and will support the data analysis and modelling. S Sahu is an expert in the analysis of COS spectra of white dwarfs, and will support the analysis of the data of this program. D Wilson is an expert in the use of COS and will support the implementation of observations and overall data analysis of this program. T Wilson is an expert in metal-poor planets around thick disk and halo white dwarfs and will help in the interpretation of the accreted material. A Bonsor is an expert in rocky planets accreting rocky planets and will support the interpretation of the accreted material. Exoplanets and Exoplanet Formation 6 false true false false false false false SUPPORTED STAR DA NO This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. J2000 J2000 The scheduling data was generated by CASM 34.0. CASM was run in Phase I mode. COS/FUV Spectroscopic No No G130M 1291 COS/FUV Spectroscopic No No G130M 1222 1785323163430 /tmp/OPVisit17439843673267389776.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18420 :visit-id "02" :proposal-version -1 :trans-version "20260618" :date "29-Jul-2026 12:06:03.0" :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 487216 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18420 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18420 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2597 :al-overhead-at-end 0 :internal-dur-at-end 613 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2977 :pcs-gap 0 ) true 1 0