6722( 6) - 10/28/96 17:31 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6722 Version: 6 Check-in Date: 28-Oct-1996 17:24:56 1.Proposal Title: Probing the Chromospheric Structure of Alpha Tau ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COOL STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: KENNETH G. CARPENTER NASA GODDARD SPACE FLIGHT CENTER CoI: Richard Robinson Computer Sciences Corporation N CoI: Carole Jordan Oxford University N CoI: Andrew McMurry Oxford University N ------------------------------------------------------------------------------------ 6. Abstract Fluorescent H_2 lines (excited by Hydrogen LyAlpha) and Ca II lines formed by recombination after photoionization by H LyAlpha were recently seen in GHRS spectra of the K5 III star Alpha Tau. This is the first time these lines have been seen in a giant star. The presence of these lines provides an opportunity to probe the structure of the upper chromosphere (Ca II) and of the low chromosphere/temperature minimum region (H_2) in this star and to test existing and new theoretical models of the outer atmosphere of Alpha Tau. In addition, the H_2 lines allow us to probe cooler regions than possible using the standard atomic emission line diagnostics and thus enable us to test the hypothesis of Wiedemann et al. (1994 ApJ 423, 806) that the atmosphere of cool giants are thermally bifurcated in the region above the photosphere. We propose to obtain, during Cycle 6, observations of the full set of Ca II and H_2 lines needed to perform these analysis and tests and to use these data to create new models of the chromosphere of Alpha Tau. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to acquire spectra of five wavelength regions, previously unobserved by GHRS, in the UV spectrum of Alpha Tau to obtain the additional H_2 and Ca II lines required for the analyses described above. In addition, we propose to obtain repeat spectra of the region around C IV to get contemporaneous measurements of the H_2 and Ca II lines discovered in the Cycle 4 data, to guard against variability in these lines which would render ratios to the lines in other regions meaningless. This repeat spectrum will also allow us to check for variability in the broad C IV emission or, if little variability is seen, to create a higher signal/noise spectrum of the region (which would be of great interest because the signal/noise on the very complex C IV profile is low and could greatly benefit from this additional integration). Finally, we propose relatively short repeat exposures on the very valuable C II (UV 0.01) and Mg II h & k lines which provide density information (C II) and constraints on the warmer (primary?) component of the chromosphere, to complement the data we will obtain on the cooler component. The desired observations are summarized in Table 1. TABLE 1 , Proposed GHRS Observations of Alpha Tau in Cycle 6 Grating & Wavelength & Exp. & Primary & approx. & Range & Time & lines in & #orbits & (Angstroms) & (min) & region & A2 & targ. acq. & 37.0 & & 1 G160M & 1320-1354 & 39.0 & H_2, Ca II & 1 G160M & 1354-1387 & 39.0 & H_2, Ca II & 1 G160M & 1430- 1464 & 40.0 & H_2, Ca II & 1 G160M & 1484-1518 & 60.0 & H_2 & 1.5 G160M & 1531- 1569 & 61.0 & C IV, H_2, Ca II & 1.5 G200M & 1795-1835 & 36.0 & Ca II, Si II, S I & 1 G200M & 1880-1920 & 39.9 & Si III, C III & 1 (A2 & targ. acq. & 37.0 & & 1) G270M & 2322-2366 & 20.0 & C II, Fe II, Si II & 0.6 ECH-B & 2793.5-2806.5 & 13.0 & Mg II & 0.4 The exposure times will produce a signal/noise of around 10 for the weaker lines of Ca II and H_2 and around 15 for the stronger lines. We use predicted fluxes from our theoretical models to estimate the required exposure times for the new Ca II and H_2 lines. We expect higher signal/noise in the C II and Mg II exposures where we wish to examine the profiles in detail, and in the case of Mg II, look for weak superposed absorption features. We will obtain dedicated wavecal's with each science exposure to allow the most accurate possible determination of flow velocities for these species. The approximate number of orbits for each exposure, including wavecal's and overhead, are listed in Table 1 as a rough guide to the time allocation. We have filled-out the orbit worksheet and designed our program in detail to ensure that all of the exposures fit with our total orbit request of 10 orbits. The Phase 2 submission is structured as a single visit with 10 orbits. If it is necessary to break the program into 2 visits, we would replace the 1880-1920 A G200M exposure with the acquisition listed in parenthesis in Table 1. Real Time Justification ----------------------- If the program is scheduled as two visits, we request that they be scheduled as close in time as possible to ensure contemporaneous data on all lines. No coordinated observations are planned for this program. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD29139 STAR,K III-I RA=04H35M55.24S+/-0.1", 2000.0 V=+54 V = 0.84+/-0.2 DEC=+16D30'33.39"+/-0.1" B-V = 1.54 TYPE=K5III F(1655)=7.7e-13 F(2327)=4.e-12 F(2799)=8.e-11 Comments: The coordinates are from the Hipparcos Catalogue Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 0.0045 -0.1890 0.054 6722( 6) - 10/28/96 17:31 - [ 2] Visit: 01 Visit Requirements: GROUP 1-2 WITHIN 7D 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 HD29139 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=5 1 10 S ONBOARD ACQ FOR 11 Comments: STEP-TIME=0.400 SECONDS, EXPECT 226 CTS/400 MSEC, Orbit 1 ------------------------------------------------------------------------------------------------------------------------------------ 11 HD29139 HRS ACQ/PEA 0.25 MIRROR-A2 1 40.0 S ONBOARD ACQ FOR 20-51 KUP Comments: Exp. Time assumes 5x5 search & STEP-TIME=1.6sec, Orbit 1 ------------------------------------------------------------------------------------------------------------------------------------ 20 WAVE HRS ACCUM SC2 G160M 1337.0 STEP-PATT=3 1 28.8 S SEQ 20-21 NON-INT Comments: Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 21 HD29139 HRS ACCUM 0.25 G160M 1337.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 25 WAVE HRS ACCUM SC2 G160M 1370.5 STEP-PATT=3 1 28.8 S SEQ 25-26 NON-INT Comments: Orbit 3 ------------------------------------------------------------------------------------------------------------------------------------ 26 HD29139 HRS ACCUM 0.25 G160M 1370.5 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 3 ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G160M 1447.0 STEP-PATT=3 1 28.8 S SEQ 30-31 NON-INT Comments: Orbit 4 ------------------------------------------------------------------------------------------------------------------------------------ 31 HD29139 HRS ACCUM 0.25 G160M 1447.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 4 ------------------------------------------------------------------------------------------------------------------------------------ 35 WAVE HRS ACCUM SC2 G160M 1501.0 STEP-PATT=3 1 28.8 S SEQ 35-36 NON-INT Comments: Orbit 5 ------------------------------------------------------------------------------------------------------------------------------------ 36 HD29139 HRS ACCUM 0.25 G160M 1501.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 5 ------------------------------------------------------------------------------------------------------------------------------------ 37 WAVE HRS ACCUM SC2 G160M 1501.0 STEP-PATT=3 1 28.8 S SEQ 37-38 NON-INT Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 38 HD29139 HRS ACCUM 0.25 G160M 1501.0 STEP-PATT=5,FP-SPLIT=STD 1 870.4 S Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 45 WAVE HRS ACCUM SC2 G160M 1550.0 STEP-PATT=3 1 28.8 S SEQ 45-46 NON-INT Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 46 HD29139 HRS ACCUM 0.25 G160M 1550.0 STEP-PATT=5,FP-SPLIT=STD 1 979.2 S Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 3] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 47 WAVE HRS ACCUM SC2 G160M 1550.0 STEP-PATT=3 1 28.8 S SEQ 47-48 NON-INT Comments: Orbit 7 ------------------------------------------------------------------------------------------------------------------------------------ 48 HD29139 HRS ACCUM 0.25 G160M 1550.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 7 ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G200M 1815.0 STEP-PATT=3 1 28.8 S SEQ 50-51 NON-INT Comments: Orbit 8 ------------------------------------------------------------------------------------------------------------------------------------ 51 HD29139 HRS ACCUM 0.25 G200M 1815.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 8 ------------------------------------------------------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 4] Visit: 02 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 ------------------------------------------------------------------------------------------------------------------------------------ 57 HD29139 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=5 1 10 S ONBOARD ACQ FOR 58 Comments: STEP-TIME=0.400 SECONDS, EXPECT 226 CTS/400 MSEC, Orbit 9 alternative if two visits needed ------------------------------------------------------------------------------------------------------------------------------------ 58 HD29139 HRS ACQ/PEA 0.25 MIRROR-A2 1 40.0 S ONBOARD ACQ FOR 60-66 KUP Comments: Exp. Time assumes 5x5 search & STEP-TIME=1.6sec, Orbit 9 alternative if two visits needed ------------------------------------------------------------------------------------------------------------------------------------ 60 WAVE HRS ACCUM SC2 G270M 2345.0 STEP-PATT=3 1 16.0 S SEQ 60-61 NON-INT Comments: Orbit 10/Visit 1 or Orbit 2/Visit 2 ------------------------------------------------------------------------------------------------------------------------------------ 61 HD29139 HRS ACCUM 0.25 G270M 2345.0 STEP-PATT=5,FP-SPLIT=STD 1 1088.0 Comments: Orbit 10/Visit 1 or Orbit 2/Visit 2 ------------------------------------------------------------------------------------------------------------------------------------ 65 WAVE HRS ACCUM SC2 ECH-B 2799.0 STEP-PATT=3 1 28.8 S SEQ 65-66 NON-INT Comments: Orbit 10/Visit 1 or Orbit 2/Visit 2 ------------------------------------------------------------------------------------------------------------------------------------ 66 HD29139 HRS ACCUM 0.25 ECH-B 2799.0 STEP-PATT=7,FP-SPLIT=STD 1 761.6 S Comments: Orbit 10/Visit 1 or Orbit 2/Visit 2 ------------------------------------------------------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 5] Visit: 51 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD29139 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=5 1 10 S ONBOARD ACQ FOR 11 Comments: STEP-TIME=0.400 SECONDS, EXPECT 226 CTS/400 MSEC, Orbit 1 ------------------------------------------------------------------------------------------------------------------------------------ 11 HD29139 HRS ACQ/PEA 0.25 MIRROR-A2 1 40.0 S ONBOARD ACQ FOR 20-51 KUP Comments: Exp. Time assumes 5x5 search & STEP-TIME=1.6sec, Orbit 1 ------------------------------------------------------------------------------------------------------------------------------------ 20 WAVE HRS ACCUM SC2 G160M 1337.0 STEP-PATT=3 1 28.8 S SEQ 20-21 NON-INT Comments: Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 21 HD29139 HRS ACCUM 0.25 G160M 1337.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 2 ------------------------------------------------------------------------------------------------------------------------------------ 25 WAVE HRS ACCUM SC2 G160M 1370.5 STEP-PATT=3 1 28.8 S SEQ 25-26 NON-INT Comments: Orbit 3 ------------------------------------------------------------------------------------------------------------------------------------ 26 HD29139 HRS ACCUM 0.25 G160M 1370.5 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 3 ------------------------------------------------------------------------------------------------------------------------------------ 30 WAVE HRS ACCUM SC2 G160M 1447.0 STEP-PATT=3 1 28.8 S SEQ 30-31 NON-INT Comments: Orbit 4 ------------------------------------------------------------------------------------------------------------------------------------ 31 HD29139 HRS ACCUM 0.25 G160M 1447.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 4 ------------------------------------------------------------------------------------------------------------------------------------ 35 WAVE HRS ACCUM SC2 G160M 1501.0 STEP-PATT=3 1 28.8 S SEQ 35-36 NON-INT Comments: Orbit 5 ------------------------------------------------------------------------------------------------------------------------------------ 36 HD29139 HRS ACCUM 0.25 G160M 1501.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 5 ------------------------------------------------------------------------------------------------------------------------------------ 37 WAVE HRS ACCUM SC2 G160M 1501.0 STEP-PATT=3 1 28.8 S SEQ 37-38 NON-INT Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 38 HD29139 HRS ACCUM 0.25 G160M 1501.0 STEP-PATT=5,FP-SPLIT=STD 1 870.4 S Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 45 WAVE HRS ACCUM SC2 G160M 1550.0 STEP-PATT=3 1 28.8 S SEQ 45-46 NON-INT Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 46 HD29139 HRS ACCUM 0.25 G160M 1550.0 STEP-PATT=5,FP-SPLIT=STD 1 979.2 S Comments: Orbit 6 ------------------------------------------------------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 47 WAVE HRS ACCUM SC2 G160M 1550.0 STEP-PATT=3 1 28.8 S SEQ 47-48 NON-INT Comments: Orbit 7 ------------------------------------------------------------------------------------------------------------------------------------ 48 HD29139 HRS ACCUM 0.25 G160M 1550.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 7 ------------------------------------------------------------------------------------------------------------------------------------ 50 WAVE HRS ACCUM SC2 G200M 1815.0 STEP-PATT=3 1 28.8 S SEQ 50-51 NON-INT Comments: Orbit 8 ------------------------------------------------------------------------------------------------------------------------------------ 51 HD29139 HRS ACCUM 0.25 G200M 1815.0 STEP-PATT=5,FP-SPLIT=STD 2 1196.8 Comments: Orbit 8 ------------------------------------------------------------------------------------------------------------------------------------ 6722( 6) - 10/28/96 17:31 - [ 7] Summary Form for Proposal 6722 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 STEP-PATT=3 FP-SPLIT=STD STEP-PATT=5 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 1-2 WITHIN 7D ONBOARD ACQ FOR 11 ONBOARD ACQ FOR 20-51 SEQ 20-21 NON-INT SEQ 25-26 NON-INT SEQ 30-31 NON-INT SEQ 35-36 NON-INT SEQ 37-38 NON-INT SEQ 45-46 NON-INT SEQ 47-48 NON-INT SEQ 50-51 NON-INT ONBOARD ACQ FOR 58 ONBOARD ACQ FOR 60-66 SEQ 60-61 NON-INT SEQ 65-66 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-A2 G160M G200M G270M ECH-B ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD29139 WAVE ------------------------------------------------------------------------------------------------------------------------------------