6085( 11) - 11/22/95 14:54 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6085 Version: 11 Check-in Date: ********** 1.Proposal Title: The Nature of the AM Canum Venaticorum Variables, The Cataclysmic-DB White Dwarf Connection? ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Hot Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Edward Sion Villanova University CoI: Dr. Jan-Erik Solheim University of Tromso N CoI: Dr. Gerard Vauclair Observatoire Midi-Pyrenees N CoI: Dr. Klaus Werner Universitat Der Kiel N CoI: Dr. John Cannizzo NASA GSFC N CoI: Dr. Darragh O'Donoghue University of Cape Town N CoI: Dr. Min Huang Villanova University N CoI: Dr. James Liebert University of Arizona N CoI: Dr. Tom Marsh University of Southampton N CoI: Dr. Judith Provencal University of Delaware N CoI: Dr. Harry Shipman University of Delaware N ------------------------------------------------------------------------------------ 6. Abstract The fundamental nature of the AM Canum Venaticorum (AM CVn) objects remains a mystery. Unlike their helium purity in the optical, far UV spectra of AM CVn objects reveal a broad mix of metal absorption features and He II (1640). We propose two GHRS observations of AM CVn to gain fundamental insight: (1) a single GHRS G140L exposure in RAPID mode with a spectrum every 20 seconds (over 2.5 cycles of the 1120s period= 46 minutes) delivering the first rapid time-resolved monitoring of the far UV line profiles and continuum levels over the range of the putative rotational/orbital periods (175s~1100s) reported for the systems and; (2) a single deep exposure with GHRS G160M in ACCUM mode to secure and model the first fully- resolved line profile for the complex He II (1640) region and detect circumbinary/circumstellar features. Are they really helium- transferring binary white dwarfs or single (merged?) rotating degenerates? Do they manifest wind outflow in the far UV? Are they related to the helium-rich DO/DB degenerates? Are they surrounded by circumstellar/circumbinary shells? What is the rotation rate of the underlying hot degenerate? A single very noisy, 15 hour IUE HIRES image of AM CVn (Solheim and Sion 1994, A&A (Letters), in press) revealed evidence for a hot circumbinary/circumstellar shell and a strong, complex asymmetric He II (1640) profile with broad emission reversal, remarkably similar to the He II (1640) profile structure of the "cool" DO star HZ21. ------------------------------------------------------------------------------------ 6085( 11) - 11/22/95 14:54 - [ 2] Observations Description ------------------------ First, we will use the GHRS with the G140L grating in RAPID operating mode to obtain a spectrum every 20 seconds for a total exposure time of 2750 seconds, covering 2.5 cycles on the photometric period of 1100s. All of the above scientific objectives are achievable with two observations using GHRS. The first will use G140L in RAPID mode covering the region (1365-1651Angstrom) to obtain spectra every 20 seconds, probing for ultraviolet continuum and line strength variations around the putative orbital or rotational cycles, time- resolved on the range of reported periods (175s to 1100s). Our target visibility of 53 minutes and G140L RAPID observation will give us 42 minutes of uninterrupted RAPID mode spectra during the second orbit following setup/acquisition in the first orbit and a G160M bonus spectrum of the NV region (1227-1262 Angstrom) to fill in 19 minutes of free time before earth occultation. The second ``deep" observation will use GHRS and the G160M disperser in ACCUM mode to cover the He II (1640) region, resolve the complex profile structure model it and bring out any cirumstellar/circumbinary features stationary with respect to the putative rotational/orbital periods. Our observations will provide the first fully resolved far UV line profile for these systems and reveal line profile variations around the putative orbital or rotational period of AM CVn. GHRS G140L Observation: For AM CVn, F-CONT(1300) = (4+/- 1)* 10^-13; We will utilize GHRS side 1, G140L (1365-1651Angstrom) in RAPID operating mode, 1.68 cts/sec/diode; require 2.2 min to reach S/N = 15; will obtain a spectrum every 20 seconds. GHRS G160M Observation: For AM CVn,F- CONT(1300) = (4+/- 1)* 10^-13; We will utilize side 2 of GHRS, G160M, LSA (1615 -1650Angstrom), require 44 minute exposure to reach S/N = 15/diode, =60/Angstrom resolution = 0.07 Angstrom/diode. We will use the Accumulation mode. we will split exposures to obtain a spectrum every 5 minutes Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6085( 11) - 11/22/95 14:54 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AM-CVN STAR, WDO, NOVA-LIKE, RA=12H 34M 54.58S +/- 0.1S, J2000 V=14.0 INTERACTING BINARY DEC=+37D 37' 43.4" +/- 0.3", B-V=-0.1 PLATE-ID=01PQ F-CONT(1300) = 4 +/- 1 E-13 6085( 11) - 11/22/95 14:54 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 AM-CVN HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN, 1 25S ONBOARD ACQ FOR 2-6 SEARCH-SIZE=5 ------------------------------------------------------------------------------------------------------------------------------------ 2 AM-CVN HRS ACCUM 2.0 G160M 1632 STEP-PATT=5 15 57.6S ------------------------------------------------------------------------------------------------------------------------------------ 3 AM-CVN HRS ACCUM 2.0 G160M 1245 STEP-PATT=5 20 57.6S ------------------------------------------------------------------------------------------------------------------------------------ 4 AM-CVN HRS RAPID 2.0 G140L 1401.5 SAMPLE-TIME=1 15 20S ------------------------------------------------------------------------------------------------------------------------------------ 5 AM-CVN HRS RAPID 2.0 G140L 1401.5 SAMPLE-TIME=1 15 20S ------------------------------------------------------------------------------------------------------------------------------------ 6 AM-CVN HRS RAPID 2.0 G140L 1401.5 SAMPLE-TIME=1 15 20S ------------------------------------------------------------------------------------------------------------------------------------ 6085( 11) - 11/22/95 14:54 - [ 5] Summary Form for Proposal 6085 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=5 STEP-PATT=5 SAMPLE-TIME=1 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Hot Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 2-6 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names AM-CVN ------------------------------------------------------------------------------------------------------------------------------------