! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 5874,v 17.1 1996/04/30 17:20:45 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: Karla Peterson ! Phone: 410 338-4774, E-mail: peterson@stsci.edu ! ! This partially completed template was generated from your Phase I proposal. ! Proposal_Information ! Section 4 Title: UV echoes in X-ray Pulsars: LMC X-4 Proposal_Category: GO Scientific_Category: Hot Stars Cycle: 5 Investigators PI_name: Saeqa Vrtilek PI_Institution: University of Maryland CoI_Name: Richard McCray CoI_Institution: Joint Institute for Laboratory Astrophysics Contact: ! Y or N (designate at most one contact) CoI_Name: Bram Boroson CoI_Institution: Joint Institute for Laboratory Astrophysics Contact: ! Y or N (designate at most one contact) CoI_Name: Francis Primini CoI_Institution: Smithsonian Astrophysical Observatory Contact: ! Y or N (designate at most one contact) CoI_Name: Fu-Hua Cheng CoI_Institution: University of Maryland Contact: ! Y or N (designate at most one contact) CoI_Name: Richard Kelley CoI_Institution: Goddard Space Flight Center Contact: ! Y or N (designate at most one contact) CoI_Name: Fumiaki Nagase CoI_Institution: Institute for Space and Advanced Studies Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) UV emission in many X-ray binaries is dominated by X-rays reprocessed in the accretion disk. For pulsars illumination of the accretion disk by a rotating beam of X-rays should result in pulsed UV emission lines with Doppler shifts corresponding to projected gas velocities. Simultaneous high time resolution UV and X-ray spectra thus offer a fundamentally new approach to understanding gas flows in these systems. We propose to observe pulsations and rapid variations in the spectra of the 13.5s pulsar LMC X-4. We will use the GHRS G160M in the RAPID mode to look for spectrum variability at timescales ranging from 0.5s - 30m. The HST observations will be coordinated with ASCA to look for correlations of UV variability with X- ray variability and to look for lags in pulse waveforms. By observing UV echoes of X-ray variations with the GHRS, we can map the dynamics of a precessing accretion disk and other structures in the accretion flow. The UV lines, X-ray Fe lines at 6-7 keV, and soft X-ray lines will complement each other as plasma diagnostics. Questions ! Free format text (please update) Observing_Description: We will observe LMC X-4 during the high state of the 30 day cycle. We would like to schedule observations to cover the binary phases 0.5 - 0.9 which will permit us to observe the eclipse ingress and will give us a good chance of catching a pre-eclipse ``dip'' in the X-ray light curve. We will coordinate simultaneous X-ray observations with the ASCA telescope. Observations will be taken with the GHRS G160M grating centered alternately at 1240 Angstrom (N V) and 1550 Angstrom (C IV) in the RAPID mode with a time resolution of 0.5s. The observed flux from N V Lambda 1240 measured with IUE (van der Klis Etal 1982) ranges from F ~ 3 * 10^-12ergs cm^-2 s^-1 at maximum (orbital phase Phi ~ 0.9) to F ~ 1 * 10^-12 ergs cm^-2 s^-1 at minimum (Phi ~ 0.5). We obtain count rates R ~ 0.25 counts/s/diode at Phi~ 0.9 for the measured line width of 7Angstrom. One spectral resolution element corresponds to ~ 1 diode, giving a resolution DeltaLambda ~ 0.08 Angstrom at 1240 Angstrom, or velocity resolution Delta V ~ 19 km s^-1. Thus, in a 40 minute observation at Phi ~ 0.9 one can expect ~ 5.8 * 10^4 counts in the line which spans ~ 95 diodes. A 60-minute observation at Phi ~ 0.5 will give us 2.9 * 10^4 counts. The number of counts required to detect pulsations at the 5Sigma level is roughly (depending on the assumed waveform) N ~ 25 f^-2, where f is the fractional pulse amplitude. Thus, we see that it should be possible in a 40 minute observation at Phi ~ 0.9 to detect (5Sigma) pulsations with amplitude f ~ 0.02 in the net line flux and f ~ 0.2 in a single 19 km s^-1 resolution element. At Phi ~ 0.5 the values for a 60 minute integration are f ~ 0.03 in the net line flux and f ~ 0.09 in a single 19 km s^-1 resolution element. The number of counts required to determine the UV pulse phase will be greater, depending on the pulse waveform, which we do not know a priori, and on the desired accuracy of the phase. However, we note that since the line width measured by IUE is an upper limit our estimated count rates are a lower limit. For the CIV (Lambda1550) line with a measured flux F ~ 6.6 * 10^-13ergs cm^-2 s^-1 roughly constant over orbital phase, a 60 minute observation would give a count rate of ~ 1.7 * 10^4 in the line with a corresponding f ~ 0.04 in the net line flux and f ~ 0.4 in a single 19 km s^-1 resolution element. We would like a total of 8 observations: 2 each for each of the lines at each of 2 binary phases. The total time on source would be 440 minutes. Assuming a 60-minute viewing window for LMC X-4, with one guide star acquisition (12 minutes), one target acquisition (11 minutes), 8 target re- acquisitions of 6 minutes each, and 8 instrument read-outs of 4 minutes each, the total number of satellite orbits we require is 9. Real_Time_Justification: There are four times during the year (for a total of 160 days) when LMC X-4 falls in a CVZ. While we do not need the CVZ to accomplish our goals, the opportunity exists to utilize the HST at high efficiency. If we are allocated time during a CVZ interval we will be able to observe the SIV line in addition to the NV and CIV lines. We have submitted a proposal to obtain simultaneous time on LMC X-4 with the ASCA X-ray satellite. We are only asking for HST time if simultaneous X-ray observations can be scheduled. LMC X-4 is always visible to ASCA and HST has four CVZ opportunities for a total of 160 days during the year so scheduling coordinated times should not be a problem. Simultaneous X-ray observations with ASCA are intrinsic to this proposal and add a vital dimension to the proposed program. By observing brightness and phase correlations among the X-ray continuum, Fe-K lines, and UV line profiles, we can measure the light-travel times and angles from the neutron star to the fluorescing gas. We have obtained high quality data on LMC X-4 during an ASCA AO1 observation in April 1994. The analysis of the high time resolution data is yet to be accomplished, however, a 6.4 keV Fe-K line is seen that comes from X-ray illumination of cold gas in the system, part of which may be the same gas that is responsible for the UV fluorescence (Vrtilek Etal 1994). We can test this conjecture by comparing the phase shift of the pulsation of the Fe-K line with that of the UV line pulsations. We are proposing for more time on ASCA since simultaneous observations with HST will yield far more scientific return. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: SIMULTANEOUS OBSERVATIONS WILL BE TAKEN BY THE ASCA X-RAY TELESCOPE. LMC X-4 is always visible to ASCA. There is a second period (30.33D) To= JD2449727.33 with a phase restriction of 0.5-0.9. We are coordinating with ASCA. The ASCA observations will last for 100,000s. We will need at least a one-month lead time on the week in which the observations takes place and a two weeks lead time on the exact time. Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: 4U0532-664 Alternate_Names: LMC X-4 Description: STAR, MXB, Giant O Position: RA = 5H 32M 49.61S +/- 0.08S, DEC = -66D 22' 13.6" +/- 0.5", PLATE-ID = 06B0 Equinox: J2000 Flux: V = 14.0 +/- 0.1, B-V = -0.1 +/- 0.01, TYPE = O7III-V, F-LINE(1240) = 2.0 +/- 1.0 E-12, W-LINE(1240) = 7.0 +/- 2.0, F-LINE(1550) = 6.6 +/- 2.0 E-13, W-LINE(1550) = 7.0 +/- 2.0, Comments: Coordinates are from a parabolic centroid GASP measurement Visits ! Section 6 Visit_Number: 1 Visit_Requirements: ! Section 7.1 PCS MODE F PERIOD 33.80H AND ZERO-PHASE JD2447742.4904 Visit_Comments: SIMULTANEOUS OBSERVATIONS WILL BE TAKEN BY THE ASCA X-RAY TELESCOPE. LMC X-4 is always visible to ASCA. There is a second period (30.33D) To= JD2449727.33 with a phase restriction of 0.5-0.9. We are coordinating with ASCA. The ASCA observations will last for 100,000s. We will need at least a one-month lead time on the week in which the observations takes place and a two weeks lead time on the exact time. Exposure_Number: 1 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: Mirror-N2 Optional_Parameters: SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4.95s Special_Requirements: ONBOARD ACQ FOR 2-15 PHASE 0.15 to 0.40 SEQ 1-2 NON-INT Exposure_Number: 2 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1225-1255 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4445S Special_Requirements: Exposure_Number: 3 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1535-1565 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4600S Exposure_Number: 5 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1225-1255 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4380S Exposure_Number: 7 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1535-1565 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4320S Special_Requirements: Exposure_Number: 9 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1225-1255 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4320S Exposure_Number: 11 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1535-1565 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4440S Exposure_Number: 13 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1225-1255 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 4620S Exposure_Number: 15 ! Section 6.5 Target_Name: 4U0532-664 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G160M Wavelength: 1535-1565 Optional_Parameters: SAMPLE-TIME = 0.5,SAA-CONTOUR=HIGH-NOISE Number_of_Iterations: 1 Time_Per_Exposure: 6540S Data_Distribution ! Defaults indicated; change if desired Medium: 8MM ! 8MM or 6250BPI or 1600BPI Blocking_Factor: 10 ! 10 or 1 ! Only astronomers with very old 9- ! track tape drives should consider ! a blocking factor of 1 Ship_To: PI_Address ! STSCI or PI_Address or ! PI Address from Phase I is: ! ! CSS 1104, Dept. of Astronomy, ! College Park, MD 20742 ! ! Ship_Via: UPS ! UPS (2-day) or OVERNIGHT ! Overnight shipping done at PI expense Recipient_Email: ! Needed if Ship_To: is not PI_Address ! ! Let us know what you think of this template and software! ! Please send a list of your likes and dislikes to your Program Coordinator