6086( 9) - 03/25/96 09:49 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6086 Version: 9 Check-in Date: 25-Mar-1996 09:25:24 1.Proposal Title: Searching for Flaring Activity on the Be star Gamma Cas ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Hot Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Myron Smith Computer Sciences Corporation CoI: Richard D. Robinson Computer Science Corporation N CoI: Kenneth Carpenter NASA/GSFC/LASP N ------------------------------------------------------------------------------------ 6. Abstract Gamma Cas is one of the most active of the classical Be stars, showing pronounced optical emission lines as well as variable optical, UV and X-ray continua. The X-ray variability is often assumed to be caused by the interaction of the stellar wind with a hypothetical degenerate companion. Recent evidence, however, suggests that the X-rays may be generated by flare- like activity originating in localized regions on the surface of the star (Smith, 1995). This interpretation is based on a variety of evidence, including FUV continuum variations observed with Voyager and transient emission and absorption features in various optical spectral lines seen from the ground. The observations are far from conclusive, however. In the proposed observations we will use the GHRS to obtain high quality UV spectral time sequences, which will allow us to test the flare/active region hypothesis. Flares are commonly assumed to be related to magnetic energy releases. If flares and active regions are proven to exist on Be stars, it will have a dramatic influence on the theoretical interpretation of the Be phenomena. ------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 2] Observations Description ------------------------ We will use the GHRS in rapid readout mode to take UV spectral time sequences of the B0.5e IV star Gamma Cas. The observations will be taken with the G160M grating through the LSA to ensure accurate spectrophotometry. The data will cover a 34 Angstrom\\ spectral range centered at 1400 Angstrom\\ and will contain the Si IV resonance doublet as well as a good samples of the FUV continuum. With this configuration a spectral resolution of about 26 km s^-1 is expected. This is comparable to the narrowest features observed in the optical profiles and substantially narrower than the average fine structure. Therefore it should be sufficient for our purposes. Using existing IUE spectra we estimate that the continuum will have a count rate of approximately 2000 counts diode^-1 s^-1. We hope to obtain data with a 1s time resolution, allowing us to study the most rapidly varying phenomena. High time resolution data will help in differentiating the various possible emission processes. In most cases the data will be integrated by as much as 60s, giving spectra with S/N in excess of 300:1 and allowing a detailed examination of the profile fine-structure and its evolution. Since we are interested in variations from the mean rather than the absolute flux, the pronounced (but stable) fixed pattern noise of the GHRS in rapid readout mode should cause no difficulty in the analysis. The requested 14 orbits would cover one complete rotation cycle of the star. This will allow us to follow features across the stellar surface as well as determine the number of activity centers which are present. It will also give us a large enough sample to allow a statistical evaluation of the flaring phenomena, if found. Real Time Justification ----------------------- We will require scheduling of these observations in coordination with X-ray satellite programs. Ground-based observations will also be requested for time driven by the HST schedule. Coordinated ground-based monitoring in the US, Japan (Hirata), and India (Anandarao) will be used to verify that the fine- structure in the Si IV lines is equivalent to that previously seen in the optical line profiles. In a previous campaign with the EUVE satellite we were successful in observing rapid optical activity from a Japanese observatory exactly when EUV flux variations were being monitored. The different temperature responses of the lines will also help in differentiating between flare-like phenomena and non- radial pulsations. We will also attempt to obtain coordinated X-ray monitoring of the star with the X-ray Timing Explorer (XTE). Simultaneous FUV/X-ray observations should allow us to conclusively differentiate between the flare and X-ray binary hypothesis for the origin of the X-ray flux. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Richard Robinson*Code 681/CSC*Goddard Space Flight Center*Greenbelt, MD 20771 Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD5394 STAR, BE, IRREGULAR RA=0H 56M 42.52S +/- .05S , J2000 V = 2.28 VARIABLE DEC=60D 43' 00.3" +/- 0.5" TYPE=B0IVE B-V = -0.15 F(1390)=1.3e-8 Comments: Coordinates are from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0 6086( 9) - 03/25/96 09:49 - [ 5] Visit: 01 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD5394 HRS ACQ 2.0 MIRROR-A2 SEARCH- 1 5S ONBOARD ACQ FOR 20 SIZE=5,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 20 HD5394 HRS ACQ/PEA 2.0 MIRROR-A2 SAA- 1 20.4S ONBOARD ACQ FOR 30-310 KUP CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 30 HD5394 HRS ACCUM 2.0 G160M 1399.0 FP- 1 652.8S SPLIT=FOUR,STEP -PATT=5,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 40 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 50 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 60 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 70 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 80 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 90 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 100 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 110 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 120 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 130 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 140 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 150 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 160 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 170 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 180 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 190 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 90M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 200 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 210 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 68M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 220 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 230 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 65M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 240 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 250 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 65M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 260 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 270 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 65M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 280 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 290 HD5394 HRS RAPID 2.0 G160M 1399.0 SAMPLE-TIME=1.0 1 49M ,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 300 WAVE HRS ACCUM SC2 G160M 1399.0 STEP-PATT=3,SAA 1 32S -CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 310 HD5394 HRS ACCUM 2.0 G160M 1399.0 FP- 1 652.8S SPLIT=FOUR,STEP -PATT=5,SAA- CONTOUR=HIGH- NOISE ------------------------------------------------------------------------------------------------------------------------------------ 6086( 9) - 03/25/96 09:49 - [ 8] Summary Form for Proposal 6086 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM RAPID ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 SAA-CONTOUR=HIGH-NOISE STEP-PATT=5 STEP-PATT=3 SAMPLE-TIME=1.0 FP-SPLIT=FOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Hot Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CVZ ONBOARD ACQ FOR 20 ONBOARD ACQ FOR 30-310 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-A2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD5394 WAVE ------------------------------------------------------------------------------------------------------------------------------------