! Proposal 6571, submission 1 ! PI: Dr. Judith Provencal ! Received Thu Feb 1 13:12:58 EST 1996 ! From: jlp@UDel.Edu ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6571,v 4.1 1996/07/16 15:05:45 pepsa Exp $ ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6571,v 4.1 1996/07/16 15:05:45 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Manning ! Phone: 410-338-4456 , E-mail: manning@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-0454.provencal.prop ! Date generated: Fri Dec 22 16:52:43 EST 1995 ! Proposal_Information ! Section 4 Title: Carbon and Convective Mixing in Hot Helium Rich White Dwarf Stars Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_name: Dr. Judith Provencal PI_Institution: University of Delaware CoI_Name: Prof. Harry Shipman CoI_Institution: University of Delaware Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) The key to understanding main sequence evolution is hidden in the detailed knowledge of the interiors of white dwarfs, the endpoints of stellar evolution. Unfortunately, we do not understand these objects. We find structural differences among the two major groups of white dwarfs (hydrogen vs helium photospheres) that demand differences in origin which are not clearly understood by our current models. In 1992, HST obtained high quality, high resolution spectra of the well studied helium (DB) white dwarf PG1645+325 (GD358), a multiperiodic g-mode pulsator, detecting CII (1335 Angstrom) and HeII (1640Angstrom). Our results imply a thin helium layer mass, in agreement with the asteroseismology (10^-6\ rmMSUN) and in disagreement with the conventional wisdom of stellar evolution. We propose using carbon to probe the envelope structure of the hotter DB white dwarfs. Questions ! Free format text (please update) Observing_Description: The observations will be done with GHRS in ACCUM mode, centered on 1335\ Angstrom, and using the large science aperture. We have calculated the exposure times using previous observations of PG1645+325 as a flux model. The exposure times are calculated to give a signal to noise ratio of ~20. Real_Time_Justification: Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: GD190 Alternate_Names: PG1542+182 Description: STAR, DB Position: RA=15H 44M 19.45S +/- 0.030S,DEC=+18D 06' 46.38" +/- 0.40", PLATE-ID=00GM Equinox: J2000 RV_or_Z: RA_PM: 0.001 ! Units are seconds of time per year Dec_PM: -0.113 ! Units are seconds of arc per year Epoch: 1982.384033203 Annual_Parallax: Flux: V=14.72,B-V=-0.10 ! Include at least V and B-V Comments: Target_Number: 2 Target_Name: PG0112+104 Alternate_Names: WD0112+104 Description: STAR, DB Position: RA=01H 14M 37.68S +/- 0.030S,DEC=+10D 41' 05.45" +/- 0.40", PLATE-ID=00GR Equinox: J2000 RV_or_Z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: 1982.7950439453 Annual_Parallax: Flux: V=15.33,B-V=-0.03 ! Include at least V and B-V Comments: ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits 2 ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! DROP TO GYRO IF NECESSARY [NO REACQuisition] ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! SCHEDulability ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN