0 Assigned ID: 7359 ----- Attempting Submission 1 (Thu Apr 16 12:18:07 GMT 2026) ----- HST Phase I Proposal 7359 successfully submitted. Receipt: # 7359-1 Could not connect to APT Status Server The visit planner runs forever and never finishes, I tried on different days multiple times. I assume that is part of the warning I got: Warning (Form) Could not connect to APT Status Server When this proposal was loaded, APT could not retrieve all the status information from STScI. This could be due to your machine's internet connection (which you should check). But a server or database at STScI could be offline. I have contacted contact apt@stsci.edu I am submitting the phase II anyway as I will be on holiday and just want to make sure it is recived in time. I will resubmit when I hear about a solution on the visit planner. -1150631296 ----- Attempting Submission 1 (Fri Aug 14 10:50:48 GMT 2026) ----- The visit planner runs forever and never finishes, I tried on different days multiple times. I assume that is part of the warning I got: Warning (Form) Could not connect to APT Status Server When this proposal was loaded, APT could not retrieve all the status information from STScI. This could be due to your machine's internet connection (which you should check). But a server or database at STScI could be offline. I have contacted contact apt@stsci.edu I am submitting the phase II anyway as I will be on holiday and just want to make sure it is recived in time. I will resubmit when I hear about a solution on the visit planner. Luminous O(He) stars - merger products or stripped stars ejected by a supernova? H-deficient stars are key probes of non-canonical stellar evolution, tracing pathways such as late He-shell flashes, double-degenerate mergers, and supernova (SN) ejections. They provide direct constraints on extreme physical processes driven by binary interaction and stellar explosions. Among them, O(He) stars represent a short-lived phase in He-dominated stellar evolution and are commonly interpreted as products of double He white dwarf mergers. However, we have identified two luminous O(He) stars that likely follow a different evolutionary pathway. They are the most massive known members of their class, appear single, and exhibit extreme halo kinematics, placing them at the boundary between CO+He white dwarf merger products and SN-ejected stripped He stars. We propose high-resolution UV spectroscopy, which uniquely enables us to derive their metal abundances and thereby distinguish between these formation channels. CO+He white dwarf mergers predict strongly sub-solar iron-group abundances, while SN-ejected stripped stars are expected to retain near-solar composition. By establishing the formation channel of these objects, the program will provide empirical constraints on the relative importance of double-degenerate mergers and SN ejection channels in producing He-dominated stars. Confirming a CO+He white dwarf merger origin provides constraints on merger nucleosynthesis and establishes luminous O(He) stars as the long-sought evolutionary link between cooler He-rich pre-white dwarfs and massive white dwarfs. Alternatively, a SN ejection origin would significantly expand the currently very small sample of such objects and place new constraints on their birthrate. For EC-21049-1330 a FUV spectrum with STIS/E140M(1425) shall be obtained within one orbit. For GALEX-J172854.3+361958 a FUV spectrum with COS/G130M(1291) shall be obtained within one orbit. Our team has led plenty of HST campaigns with numerous publications and press releases resulting from them. Our team members have expertise in HST data reduction for COS and STIS, and they are experts in the computations of metal-line blanketed, non-LTE, static and expanding model atmospheres suitable for spectroscopic analysis of the proposed objects. Nicole Reindl and Klaus Werner are expert on hot (pre-)white dwarfs and on extremely hot He-dominated pre-WDs. Stephan Geier is expert on hypervelocity stars. Stellar Physics and Stellar Types 6 false true false false false false false SUPPORTED STAR SDO 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 2.2E-12 @ 1100A (predicted by SED fit of best fit NLTE model to photometry from FUV till W2) STAR SDO 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 1.0E-13 @ 1100A (predicted by SED fit of best fit NLTE model to photometry from FUV till W1) STIS/FUV-MAMA Spectroscopic No No E140M 1425 COS/FUV Spectroscopic No No G130M 1291 D:\Windows\Dokumente\Beobachtungsanträge\HST\Cycle34\OP-cache\OHE-v01.xml STIS E140M(1425) spectrum for EC-21049-1330 (Tic-Visit :proposal-id 18365 :visit-id "01" :proposal-version -1 :trans-version "20260618" :date "14-Aug-2026 12:16:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18365 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18365 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2594 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2974 :pcs-gap 0 ) true 1 0 D:\Windows\Dokumente\Beobachtungsanträge\HST\Cycle34\OP-cache\OHE-v02.xml FUV spectrum with COS/G130M(1291) for GALEX-J172854.3+361958. (Tic-Visit :proposal-id 18365 :visit-id "02" :proposal-version -1 :trans-version "20260618" :date "14-Aug-2026 12:16:30.0" :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 174480 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18365 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18365 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2612 :al-overhead-at-end 0 :internal-dur-at-end 543 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2992 :pcs-gap 0 ) true 1 0