6343( 8) - 06/11/96 09:43 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6343 Version: 8 Check-in Date: 11-Jun-1996 09:40:43 1.Proposal Title: Finding the Lyman-alpha Cloud Around 51 Peg B with GHRS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO/DD 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Hyron Spinrad University of California, Berkeley CoI: Gibor Basri University of California at Berkeley N CoI: Frederick Walter State University of New York at Stony N Brook CoI: Geoff Marcy N CoI: Michel Mayor N ------------------------------------------------------------------------------------ 6. Abstract One of the most exciting recent developments in Astronomy has been the discovery of radial velocity variations in the solar-type star 51 Peg which imply the existence of a Jupiter sized planet around it. The orbit is astonishingly close to the star (0.05 AU) for a giant planet. Analysis shows, however, that the planet could retain its atmosphere even so close. The chromospheric inactivity of the star, combined with a detectable rotational velocity, imply that the system is viewed nearly edge on. Attempts to find a photometric eclipse have turned up nothing. The exosphere of the planet is subject to strong high energy fluxes from the star, making it likely that there is a neutral hydrogen corona around the planet. This might be quite extensive, depending on its magnetosphere. We propose to look for absorption of stellar Lyman-alpha by the planetary corona, which would constitute hard physical evidence that a body is really there. In particular, we will compare the profile during and away from transit. ------------------------------------------------------------------------------------ 6343( 8) - 06/11/96 09:43 - [ 2] Observations Description ------------------------ We will observe the Lyman-alpha line at medium resolution for 3 successive orbits centered on the transit of the putative planet. We hope to see an absorption feature in the stellar Lyman-alpha line due to a possible cloud of Hydrogen surrounding the planet. Observations are phase-critical: the second of the observations is centered on the expected time of transit. The uncertainties in the ephemeris become large (a few hours) when extrapolated to mid-1996. We will update the ephemeris in the spring. (Note: this has been done). Observations are in the SSA to minimize geocoronal contamination. 51 Peg has a radial velocity of -31 km/s. In June the Earth's orbital motion around the Sun gives 51 Peg a 60 km/s separation from the geocoronal emission. The observation is time critical in order to maximize the separation of the stellar and geocoronal lines. Real Time Justification ----------------------- N/A Calibration Justification ------------------------- N/A Additional Comments ------------------- NOTE: THIS OBSERVATION IS TIME- and PHASE- CRITICAL. SEE Visit-Comments ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Frederick M. Walter*ESS Dept, Z=2100*SUNY*Stony Brook, NY*11794-2100 Ship Via: UPS Email: fwalter@astro.sunysb.edu , ------------------------------------------------------------------------------------ 6343( 8) - 06/11/96 09:43 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 51-PEG STAR, G V-IV RA=22H 57M 27.96S +/- .03S, J2000 V=-31.2 V = 5.49+/-0.02 DEC=20D 46' 7.1" +/- .3" B-V = 0.67+/-0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0142 0.059 0.073 6343( 8) - 06/11/96 09:43 - [ 4] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Visit must be scheduled when geocentric radial velocity is <-55, between 15 -JUN-96 AND 20-JUL-96, to facilitate separation of stellar and geocoronal Lyman-alpha. Phase 0 must occur in second orbit. Ephemeris will be updated be early May, hence the restricted range of dates. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 51-PEG HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN,SEARCH-SIZE=3 1 1.8 S ONBOARD ACQ FOR 12 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 12 51-PEG HRS ACQ/PEA 0.25 MIRROR-N2 SEARCH-SIZE=5 1 5.0 S ONBOARD ACQ FOR 20-41 KUP Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 20 51-PEG HRS ACCUM 0.25 G160M 1215 STEP-PATT=5 4 272.0 S SEQ 20 NON-INT Comments: TIME CRITICAL. MUST START BETWEEN 15-JUN-96 AND 20-JUL-96 ------------------------------------------------------------------------------------------------------------------------------------ 30 51-PEG HRS ACCUM 0.25 G160M 1215 STEP-PATT=5 9 272.0 S SEQ 30-31 NON-INT Comments: CENTER ON PLANET TRANSIT ------------------------------------------------------------------------------------------------------------------------------------ 31 51-PEG HRS ACCUM 0.25 G160M 1215 STEP-PATT=5 1 27.2 S ------------------------------------------------------------------------------------------------------------------------------------ 40 51-PEG HRS ACCUM 0.25 G160M 1215 STEP-PATT=5 9 272.0 S SEQ 40-41 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 41 51-PEG HRS ACCUM 0.25 G160M 1215 STEP-PATT=5 1 27.2 S ------------------------------------------------------------------------------------------------------------------------------------ 6343( 8) - 06/11/96 09:43 - [ 5] Summary Form for Proposal 6343 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN SEARCH-SIZE=3 SEARCH-SIZE=5 STEP-PATT=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO/DD ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 12 ONBOARD ACQ FOR 20-41 SEQ 20 NON-INT SEQ 30-31 NON-INT SEQ 40-41 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names 51-PEG ------------------------------------------------------------------------------------------------------------------------------------