Assigned ID: 2031 ----- Attempting Submission 1 (Sat Jan 08 15:05:29 GMT 2011) ----- HST Phase I Proposal 2031 (kpd.apt) successfully submitted. ----- Attempting Submission 2 (Fri Jan 14 21:43:31 GMT 2011) ----- HST Phase I Proposal 2031 (kpd.apt) successfully submitted. Hi Shelly, I hope I did everything right. In contrast to my PhaseI estimates I have some more time for science exposures available. I hope that I did not forget soemthing. Best regards, Klaus ----- Attempting Submission 1 (Fri Jun 10 15:59:13 GMT 2011) ----- What is the origin of the hottest known white dwarf? KPD0005+5106 is the hottest known white dwarf (Teff=200,000 K). It has a helium-dominated atmosphere with trace amounts of light metals. Our recent analysis places the star in a region of the HRD where very weak stellar winds prevent gravitational settling of heavy elements. Therefore, the surface composition allows to conclude on the evolutionary history. We speculate that KPD0005+5106 represents a third post-AGB evolutionary sequence, which is distinct from the canonical hydrogen-rich and hydrogen-deficient sequences. The star could be the long-searched progeny of the RCrB stars, which are believed to be the result of a double-degenerate merger. We found that the metal abundances in KPD0005+5106 are rather similar to those in RCrB stars, however, a claim on the evolutionary link is premature. The abundance determinations for KPD0005+5106 are afflicted with large errors because of the relatively large uncertainty in Teff. Our immediate aim is to use ionization balances of metals in order to determine Teff to high precision, which is a prerequisite to tightly constrain abundances. HST-UV spectroscopy is the only means to reach this goal.
We will perform short-slit (0.2"x0.2") medium-dispersion UV spectroscopy of KPD0005 in the STIS/FUV-MAMA and NUV-MAMA configurations with gratings E140M and E230M (two wavelength settings), respectively, in order to cover the wavelength range 1150-3100A. This provides the spectral resolution (~30,000) needed for the quantitative analysis of narrow metal lines. STIS ETC was used to determine exposure times necessary to achieve the required S/N~20-40. HOT STARS 12 false 0.0 0.0 false false false false SUPPORTED STAR WDO J2000 J2000 STIS/FUV-MAMA Spectroscopic No No E140M 1425 STIS/NUV-MAMA Spectroscopic No No E230M 1978 STIS/NUV-MAMA Spectroscopic No No E230M 2707 C:\Users\werner\Documents\HST_proposals\proposal cycle19\OP-cache\kpd-v01.xml The scheduling data was generated by CASM 19.3. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12483 :visit-id "01" :proposal-version -1 :trans-version "20110509" :date "10-Jun-2011 17:25:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 348432 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12483 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12483 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3112 :al-overhead-at-end 0 :internal-dur-at-end 115 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12483 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3223 :al-overhead-at-end 81 :internal-dur-at-end 396 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3445 :pcs-gap 0 ) true 2 0