! Proposal 6409, submission 1 ! PI: MIRIAM PENA ! Received Thu Feb 15 15:06:01 EST 1996 ! From: miriam@astroscu.unam.mx ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6409,v 4.1 1996/09/18 14:36:02 pepsa Exp $ ! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6409,v 4.1 1996/09/18 14:36:02 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: Taylor ! Phone: 410-338-4824 , E-mail: dctaylor@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. ! Name of Phase I Proposal: archive-0035.pena.prop ! Date generated: Fri Dec 22 18:28:46 EST 1995 ! Proposal_Information ! Section 4 Title: SPECTROPHOTOMETRY OF THE WR CENTRAL STAR OF THE LMC-PN N66 Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_name: MIRIAM PENA PI_Institution: INSTITUTO DE ASTRONOMIA, UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO CoI_Name: MARIA T. RUIZ CoI_Institution: DEPTO. DE ASTRONOMIA, UNIVERSIDAD DE CHILE Contact: ! Y or N (designate at most one contact) CoI_Name: MANUEL PEIMBERT CoI_Institution: INSTITUTO DE ASTRONOMIA, UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO Contact: ! Y or N (designate at most one contact) CoI_Name: SILVIA TORRES-PEIMBERT CoI_Institution: INSTITUTO DE ASTRONOMIA, UNIVERSIDAD NACIONAL AUTONOMA DE MEXICO CoI_Name: JOSE MAZA CoI_Institution: DEPTO. DE ASTRONOMIA, UNIVERSIDAD DE CHILE Contact: ! Y or N (designate at most one contact) CoI_Name: ROBERTO H. MENDEZ CoI_Institution: MUNCHEN UNIVERSITY Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) This is a CONTINUATION PROPOSAL (Cycle 5 \# 6055), it was awarded 4 orbits for Cycle 5 and 4 for Cycle 6. We propose to follow the extraordinary event occurring in the central star of the LMC-PN N66. Before 1987, it showed a weak continuum with a T_eff >= 120000 K and L_bol ~eq 25000 L_\odot and in few years it developed strong WR features (P-Cygni profiles in N V Lambda1240 and C IV Lamnda1550 lines, wide He II emission, etc.) typical of a WN4.5. The continuum increased by large factors and recently it has shown large variability. The present T_eff is ~ 50000 K and its M_V is similar to that of faint Population I WR in the LMC. To explain these changes Pe\ na et al. (1994) proposed that the star is undergoing a ``final thermal pulse". The ejecta consists of highly H-deficient He- and N-rich material which is most unusual since the known PNe with WR nucleus show He- and C-rich winds. Small aperture HST observations are needed to obtain the stellar spectrum without contamination of the nebular emission. The Cycle 5 visit was already performed successfully. We used the FOS with a combination of gratings covering the wavelength range 1150-4800 A with a resolving power of 1300. The data is being analyzing to determine the present stellar parameters (mass loss, T_eff, L_bol) and the chemical composition of the wind by means of specifically developed atmosphere models. The star is undergoing dramatic changes in a timescale of months (it faded two magnitudes in Sept. 95 and re-gain some brightness from October to the present), therefore we insist that it is paramount to re-observe the object in Cycle 6 as soon as possible to follow its evolution. Questions ! Free format text (please update) Observing_Description: We plan to use the FOS, with an aperture of 0sec point3 and a combination of gratings to cover the wavelength range from 1150 to 4800 Angstrom with resolution of 1300. This will allow us to obtain the important UV lines, particularly N V Lambda1240 and C IV Lambda1550 resonant lines and all the optical stellar emission lines. The 0sec point3 aperture (circular), centered in the star, will contain only a small fraction of the ionized nebula avoiding most of its emission. A S/N of about 30 is necessary to accomplish a fair analysis of the stellar continuum and emission lines. The exposure times (needed to obtain this S/N) are presented below, where we have included the time required for Guide Star acquisition, and target acquisition. The total time estimated for this proposal is about 384 min. This will be accomplished with four CVZ orbits. Cycle 6 Primary orbits: 4 (CVZ) Scientific exposures: 3 1) Guide star acquisition:..........................8 min 2) target acquisition (4 steps: 8+17+13+26):.......64 min 3) FOS/BL + G130H:....................190 min exp time + OH (23 min) 4) FOS/BL + G190H:.....................45 min exp time + OH (10 min) 5) FOS/BL + G400H:.....................35 min exp time + OH (9 min) ---------------------------------- Total time:............................384 min Real_Time_Justification: We are requesting CVZ because it is the most efficient way to observe the proposed target. Besides the exposure with FOS/BL + G130H filter requires 190 min to achieve an appropriate S/N, so "long duration" orbits are necessary for this observation. In this way, the target acquisition and the scientific observations will be accomplished in 4 orbits with visibility of 96 min each. In the non- CVZ mode, the total number of orbits required would be 6. The target has been followed in the optical each 2 or 3 months from different observatories (CTIO, ESO). IUE - 19th episode: we have been granted 16 hours of observing time, distributed along the cycle to study variability and to obtain one high resolution spectrum of the central star emission. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: IUE - 19th cycle: 16 hours have been awarded Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: LMC-N66-CS Alternate_Names: SMP-83, WS-35 Description: EXT-STAR, PLANETARY NEBULA CENTRAL STAR Position: RA=05H 36M 20.8S +/- 0.2S, DEC= -67D 18' 08" +/-0.5", PLATE-ID=06B0 Equinox: J2000 ! Rv_or_z: RA_PM: ! Units are seconds of time per year Dec_PM: ! Units are seconds of arc per year Epoch: Annual_Parallax: Flux: V = 16.7+/-0.5 , ! Include at least V and B-V B-V = -0.2, E(B-V) = 0.1 +/- 0.05, TYPE= WN4.5, F-CONT(1300) = 13 +/- 3 E-15, F-CONT(5500) = 6.1 +/- 0.3 E-16, F-LINE(1640) = 7 +/- 0.3 E-13, COMMENTS: highly variable target ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! 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