Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5448 Report Date: 18-Jul-95:17:25 Version: ********** Check-in Date: ********** 1.Proposal Title: SPECTRALLY RESOLVED MAPS OF OPTICALLY THICK ACCRETION DISKS: CYCLE4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Sub Category ERUPTIVE BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Knox S. Long 3470 USA 410-338-4862 ------------------------------------------------------------------------------------ 7. Abstract We will derive the structure of the steady state optically thick accretion disk in the novalike variable UX UMa by using the FOS in RAPID readout mode to monitor eclipses of its UV/optical spectra as the companion star progressively occults the accretion disk and the white dwarf. From the observed eclipse light curves at different wavelengths we will construct monochromatic maps of the disk and then extract the spectrum from any desired region of the disk surface, including annuli at different radii in the disk, the hot spot on the outer rim of the disk, and the white dwarf / boundary layer at the inner edge. Our maps from Earth-based optical spectroscopy are of sufficient quality to reveal not only changes in continuum intensity and slope but also Balmer lines transitioning from absorption in the inner disk to emission in the outer disk. Our HST experiment extends this analysis into the ultraviolet to pin down the hot parts of the disk. We will use our results to test our models of accretion disk atmospheres and chromospheres. By observing the spectrum at each radius rather than from the disk as a whole, the quality of the information is such that will constrain the radial dependences of the effective temperature, surface density, and microturbulent Mach number, and the vertical temperature structure. Observations of this type will drive fundamental new insights into the physics of accretion disks. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.04 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5448 PI: Knox S. Long Proposal Title: SPECTRALLY RESOLVED MAPS OF OPTICALLY THICK ACCRETION DISKS: CYCLE4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Knox S. Long 3470 USA Raymundo Baptista 3470 USA Keith Horne 6890 THE NETHERL Ivan Hubeny 2856 USA Christopher W. Mauche 2460 USA Rene' Rutten 7680 SPAIN X Richard A. Wade 3150 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will observe 4 eclipses of the novalike variable UX UMa. We are primarily interested in studying continuum and emission line time variability, and therefore we will use the FOS in "RAPID READOUT" mode with SUB-STEP=2 and READ- TIME=6 to obtain high temporal resolution. Ideally binary phases -0.15 thru 0.15 should be covered to include the eclipse of the disk with enough baseline on either side to establish the out-of-eclipse spectrum. This requires 85 m for UX UMa (Porbit = 283m). UX UMa is very near the continuous viewing zone (satisfying the night-time FGS limit of 12 deg) and therefore optimal or nearly optimal exposure times should be possible. Observing four eclipses will help us to distinguish systematic eclipse features from random flickering variations that are characteristic of cataclysmic variables. The mean of the four eclipses will be used to study the disk structure, while the residuals after subtracting the mean eclipse will inform us about the variability properties of different parts of the disk. The observations should be spaced as closely in time as possible in order to minimize the effect of secular variations in the disk structure. We will use the Blue Digicon with the G160L disperser, which gives spectral coverage at 6.5A/pixel from 1150 to 2400 A, and the Red Digicon with the PRISM disperser, which covers 1600 to 8000 A with variable resolution. These low dispersions provide the broadest possible wavelength coverge with sufficent resolution to isolate the strong, but widely spaced emission lines from the continuum. The zero-order spectrum available with the G160L grating will provide a simultaneous "optical" light curve with a bandpass of 1900A FWHM centered at 3400A. We will acess flickering effects on the mean eclipse light curve using the 4 independent eclipse light curves obtained from the 1600-2300A region in which the G160L and PRISM coverages overlap. We will observe the first and third eclipses with the G160L disperser and the second/fourth with the PRISM. The red spectra are needed to cover Mg II emission and the Balmer continuum and line emission region; the G160L observations are needed to study the hottest portions of the disk and the higher ionization state lines--N V and C IV. The above program assumes we are able to use ACQ/BINARY target acquisition. If we are forced to use ACQ/PEAK - which is much more time consuming - we will have to remove the last eclipse observation (with FOS/RD,PRISM). Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. HST is the only experiment with sufficient sensitivity, spectral resolution, and temporal resolution in the UV to carry out this type of observation. We have studied this system previously in the UV. Other spacecraft (IUE, Voyager, etc.) have collecting areas that are too small to achieve the S/N and the time resolution we need. (In this regard, it is important to note that the WD in this system is eclipsed in a period of about 50 sec). Our team has extensive experience in observing and modeling the eclipses of cataclysmic variables. We have observed eclipses with Earth-based telescopes and have published analyses for a half-dozen systems. However, the inner region of the accretion disk, the boundary layer, and the WD should be most apparent in the UV and therefore high time-resolution UV observations are crucial to significant new advances in our understanding of CVs. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. These observations are time critical and must cover specific orbital phases. The orbital ephemeris of this system is well known so the conditions can be specified well in advance. We must observe four eclipses of the star so we can separate flickering variations from orbital variations. The target is a novalike variable and therefore it does not undergo the periodic outbursts associated with dwarf novae (Very occassionally it is found in a low state). The object do vary somewhat and therefore all four of the observations should be scheduled as close together as is possible to minimize the effects of any secular variations and the joining together of the light curves from the various eclipses. Whole eclipses must be observed whenever possible. To observe whole eclipse light curves, it is necessary to have uninterrupted long exposures; as discussed above the object is in or very near the continuous viewing zone. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. none Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. GO-2380 "Instabilities in Accretion Disks and the Outbursts of Dwarf Novae" (HORNE, CO-I) - This program is related to our proposal. Data were obtained and are under analysis. A first paper is nearly ready for submission. Eclipses of the accretion disk were observed in quiescence and during a superoutburst. The white dwarf dominates the quiescent spectrum and has deep FeII absorption from intervening material in the upper atmosphere of the disk. Strange dips are seen during the superoutburst light curve, probably because outer disk material obscures the inner disk. The white dwarf is brighter after superoutburst than before. These data are not suitable for our study because the quiescent disk is optically thin, too faint, and not in a steady state, while the superoutbursting disk is also not in a steady state and suffers severe obscuration of the inner disk by intervening material. GO-3232 "Observations of X-Ray Nova Muscae 1991" (HORNE, CO-I) - This program is only periferally related to our proposal. By combining HST/FOS, IUE, optical and X-ray spectra of Nova Muscae on the decline from outburst we place limits on the mass of the putitive black hole in this system, and show that the cooling front predicted by disk instability model was not seen in this object. Results are published in Ap.J. GO-3578 "Line Eclipse Mapping of an Accretion Disk Wind" (HORNE, CO-I) The program is related to this proposal. HRS was used to investigate line profile changes during the eclipses of UX UMa. Deep eclipses were observed in the UV, showing that the UV light from UX UMa's disk is concentrated toward the disk center. The data are not suitable for our present study because the HRS data were taken at high resolution to focus on eclipse effects in line profiles. We are currently analyzing these data with our eclipse mapping programs, but they will cover only 40A regions near 1550 and 1640A. Our present proposal aims to observe the entire optical and ultraviolet. GO-3683 "Accretion Disk Mapping in Eclipsing Cataclysmic Variables" (HORNE, PI; RUTTEN, LONG, WADE, CO-I) - This program is related to our proposal. Data on the dwarf nova IP Peg were obtained and are under analysis. The bright spot dominates the ultraviolet light and it flickers strongly in quiescence. This data is not suitable for our present program because the IP Peg disk is not in a steady state. GO-3600 "Oscillations, Flares, and Tomography of AE Aquarii" (HORNE, PI) This program is only periferally related to our proposal. Data were obtained and are under analysis. Oscillations and flares have enormous amplitude in the ultraviolet. Emission lines flare but do not oscillate. GO-4271 "Testing the Star -Disk Connection: CIV and MgII Maps of Disks" (HORNE, PI; LONG, RUTTEN, COI) - This program is periferally related to our proposal. Data have been taken and are under analysis. The disk of dwarf nova T Leo will be mapped by Doppler tomography in CIV and MgII emission lines to study the accretion disk chromosphere. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Salary and basic computer facilities are provided for Long, Horne, Rutten, Hubeny, and Wade. Support is needed for postdoc Baptista. ------------------------------------------------------------------------------------ 11. Address Information Name: KNOX S. LONG Category: PI Institution: 3470 Address: 3700 San Martin Drive City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410-338-4862 Telex (or e-mail): long@stsci.edu ------------------------------------------------------------------------------------ Page 5 Name: Category: CON Institution: Address: City: State: Zip Code: Country: Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5448 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 UX-UMA A,151,161,906 RA = 204.1711D +/- 0.0001D, J2000 1 V = 12.8 +/- 0.2 DEC = +51.9137D +/- 0.0001D 1 B-V = 0.1 +/- 0.1 2 F-CONT(1500) = 2.0 +/- 0.5 E-13 Comments: ECLIPSING STAR, V=14.2 IN ECLIPSE THIS IS A NEAR CVZ TARGET ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5448 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE UX-UMA FOS/BL ACQ/ 4.3 G160L SEARCH-SIZE-X=1 1 0.05S 1 1 CYCLE 4 B PEAK SEARCH-SIZE-Y=3 ONBOARD ACQ FOR SCAN-STEP- 1.1 Y=1.204 AT 10-MAY-94 +/- 90D Comments: BRIGHT VARIABLE STAR. TO PERMIT COORDINATED OBSERVATIONS. PLEASE NOTIFY P.I. WHEN DATES ARE SCHEDULED OR CHANGED. ------------------------------------------------------------------------------------------------------------------------------------ 1.1 DEFINE UX-UMA FOS/BL ACQ/ 1.0 G160L SEARCH-SIZE-X=6 1 0.18S 1 1 CYCLE 4 B PEAK SEARCH-SIZE-Y=2 ONBOARD ACQ FOR SCAN-STEP- 1.2 X=.602 SCAN-STEP- Y=.602 ------------------------------------------------------------------------------------------------------------------------------------ 1.2 DEFINE UX-UMA FOS/BL ACQ/ 0.3 G160L SEARCH-SIZE-X=5 1 5S 1 1 CYCLE 4 B PEAK SEARCH-SIZE-Y=5 ONBOARD ACQ FOR SCAN-STEP- 2.0 X=.172 SCAN-STEP- Y=.172 ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE UX-UMA FOS/BL RAPID 1.0 G160L SUB-STEP=2 1 62M 1 CYCLE 4 B READ-TIME=6 NON-INT ZERO-PHASE JD2443904.87872 +/ - 0.00003D PERIOD 0.196671278D +/- 0.00000002D PHASE 0.89 +/- 0.01 ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE UX-UMA FOS/RD ACQ/ 4.3 PRISM SEARCH-SIZE-X=1 1 2.3S 1 1 CYCLE 4 R PEAK SEARCH-SIZE-Y=3 ONBOARD ACQ FOR SCAN-STEP- 3.1 Y=1.204 Comments: BRIGHT VARIABLE STAR. ------------------------------------------------------------------------------------------------------------------------------------ 3.1 DEFINE UX-UMA FOS/RD ACQ/ 1.0 PRISM SEARCH-SIZE-X=6 1 2.3S 1 1 CYCLE 4 R PEAK SEARCH-SIZE-Y=2 ONBOARD ACQ FOR SCAN-STEP- 4.0 X=.602 SCAN-STEP- Y=.602 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5448 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE UX-UMA FOS/RD RAPID 4.3 PRISM SUB-STEP=2 1 78M 1 CYCLE 4 R READ-TIME=6 NON-INT ZERO-PHASE JD2443904.87872 +/ - 0.00003D PERIOD 0.196671278D +/- 0.00000002D PHASE 0.86 +/- 0.02 ------------------------------------------------------------------------------------------------------------------------------------ 5 USE B SEQ 5-6 WITHIN 5 D ------------------------------------------------------------------------------------------------------------------------------------ 6 USE B Comments: AS SOON AS POSSIBLE AFTER 5 ------------------------------------------------------------------------------------------------------------------------------------ 7 USE R SEQ 7-8 WITHIN 5 D ------------------------------------------------------------------------------------------------------------------------------------ 8 USE R Comments: AS SOON AS POSSIBLE AFTER 7 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5448 [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.204 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=.602 SCAN-STEP-Y=.602 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-X=.172 SCAN-STEP-Y=.172 SUB-STEP=2 READ-TIME=6 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.04 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ERUPTIVE BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; ONBOARD ACQ FOR 1.1; AT 10-MAY-94 +/- 90D ONBOARD ACQ FOR 1.2 ONBOARD ACQ FOR 2.0 NON-INT; ZERO-PHASE JD2443904.87872 +/- 0.00003D; PERIOD 0.196671278D +/- 0.00000002D; PHASE 0.89 +/- 0.01 ONBOARD ACQ FOR 3.1 ONBOARD ACQ FOR 4.0 PHASE 0.86 +/- 0.02; SEQ 5-6 WITHIN 5 D SEQ 7-8 WITHIN 5 D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G160L PRISM ------------------------------------------------------------------------------------------------------------------------------------ Target Names UX-UMA ------------------------------------------------------------------------------------------------------------------------------------