Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5069c Report Date: 09-May-96:20:23 Version: ********** Check-in Date: ********** 1.Proposal Title: EMPIRICAL DETERMINATION OF THE WIND VELOCITY AND DENSITY LAWS FOR THE K SUPERGIANT ZETA AURIGAE - HOPR 130 REPEAT ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS RPT/GO 3626 Sub Category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Alexander Brown COLORADO, UNIVERSITY OF USA (303) 492-7810 SENIOR RES ASSOCIATE ------------------------------------------------------------------------------------ 7. Abstract We will derive the velocity and density laws and mass loss rate for the K4 supergiant in the eclipsing Zeta Aurigae binary system. The slow passage of the geometrically small B dwarf with its bright UV continuum behind the extended atmosphere of the K supergiant provides a splendid opportunity to probe the column densities and velocities of many absorption lines of various strengths as a function of stellar impact parameter. Our empirical determination of the wind physical parameters throughout the acceleration region will place tight constraints on the physical processes responsible for mass loss in evolved, massive stars that contribute significantly to the enrichment of the interstellar medium with chemically processed material. We request time for observations of lines of Fe I-II, Si II, Ti II, and V II at 6 orbital phases, including the terminal velocity wind, wind aceleration region, eclipse by the K star chromosphere, and total eclipse. This program is time critical but with typical tolerances of 1-7 days due to the long (972 day) orbital period. ------------------------------------------------------------------------------------ 8. Scientific Key Words: K4IB+B8 ECLIPSING BINARY SYSTEM ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 13.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5069c PI: Dr. Alexander Brown Proposal Title: EMPIRICAL DETERMINATION OF THE WIND VELOCITY AND DENSITY LAWS FOR THE K SUPERGIANT ZETA AURIGAE - HOPR 130 REPEAT ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Alexander Brown COLORADO, UNIVERSITY OF USA Jeffrey L. Linsky COLORADO, UNIVERSITY OF USA Ray Weyman MT. WILSON AND LAS CAMPANAS USA OBSERVATORIES Dieter Reimers HAMBURG, UNIVERSITY OF GERMANY X Robert Baade HAMBURG, UNIVERSITY OF GERMANY X Thomas Kirsch HAMBURG, UNIVERSITY OF GERMANY X ------------------------------------------------------------------------------------ 2. Scientific Justification. _______________________________________________________________________ Ion UV Mult Mode Lambda(A) Epochs Phase ______________________________________________________________________ Si II 5 G160M 1194.5,1197.4 1,6 wind, totality Fe II 9 G160M 1253.8,1266.7,1277.6 1,2,3,6 wind,w.acc.,tot. (+S II 1 1253.8 ) Si II 2 G160M 1526.7,1533.4 1,6 wind, totality Fe II 44,45 G160M 1563.8,1580.6,1588.3 2,3 wind acc. Fe II 8 G160M 1629.2,1631.1 2,3 wind acc. (+Fe II 43 1640.2 ) Fe II 39 ECH-B 1704.6 2,3,4,5 w. acc., chrom. Fe II 191 ECH-B 1785.3,1786.8,1788.0 6 totality Fe II 6 ECH-B 2146.1,2153.9 4,5 chrom. Fe II 3 ECH-B 2332.8,2338.0 1,2,3,6 wind,w.acc.,tot. Fe II 1 ECH-B 2607.1,2613.8 1,6 wind, totality Fe I 9 ECH-B 3001.0,3008.1 4,5 chrom. Fe I 9 ECH-B 3047.6 4,5 chrom. Ti II 5 ECH-B 3072.1,3073.0 2,3,4,5 w. acc., chrom. 3075.2,3078.7 V II 1 ECH-B 3126.2,3133.3 4,5 chrom. _____________________________________________________________________ ------------------------------------------------------------------------------------ 3. Description of proposed observations. The exposures requested are summarized above. The exposure times have been estimated using absolute fluxes previously measured with the IUE. The echelle exposure times were estimated from pre-launch calibrations and increased by a factor of 1.4 to account for reduced throughput of the large science aperture (LSA). The effect of the echelle ripple was included. The LSA allows high signal- to-noise spectra to be obtained in much shorter exposures than with the SSA. The resulting observed resolution will be 43,500 (7.5 km/s), but spectral deconvolution using the observed point-spread function should allow spectra with a resolution of at least 60,000 (5.0 km/s) to be retrieved without loss of spectral fidelity. Medium resolution grating (G160M) spectra will be obtained below 1700A using the small science aperture (SSA) to reach the orignal design resolution (17,000- 22,000) for this mode. IN-orbit sensitivities and aperture throughputs were used to estimate exposure times for G160M. The choosen lines will provide optimum modelling information for each particular phase of the eclipse. The list of lines to be observed has been reduced as requested by the TAC; HOWEVER, it was not possible to retain the 8 phases originally proposed due to the severely reduced time allocation provided by the TAC. Mid-totality of the eclipse occurrs on 1993 April 2.7; total eclipse lasts 36.8 days but the partial eclipse lasts only 1.4 days. THESE OBSERVATIONS ARE TIME-CRITICAL. This program is a repeat of only one sequence of the total observation set, using the WACC sequence. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The continnuum of the B dwarf secondary of Zeta Aur is prominent only in the ultraviolet and data required for this program are not therefore obtainable from the ground. IUE has been used extensively to study this target and further observational advances depend on the acquisition of higher S/N spectra with GHRS. The increased sensitivity, wavelength resolution, dynamic range and S/N characteristics of the GHRS over those obtainable with the IUE (Carpenter et al. 1991, Ap.J. (letters), in press.) will allow more accurate and detailed modelling of the circumstellar environment around the K5 mass-losing supergiant primary of Zeta Aur. Only the GHRS is capable of providing us with the very high precision line profiles, fluxes, and absolute velocities required for our program. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. These observations during the Zeta Aur eclipse are TIME-CRITICAL. The phases and dates for the required observations are: Epoch Days before eclipse Date DOY +/- range Eclipse Phase ______________________________________________________________________ 1 - 221 +/- 14 1992 Aug 25 238 +/- 14 Wind 2 -55 +/- 5 1993 Feb 07 38 +/- 5 Wind Acceleration 3 -40 +/- 5 1993 Feb 22 53 +/- 5 " " 4 -28 +/- 1 1993 Mar 06 65 +/- 1 Chromospheric Ecl. 5 -22 +/- 1 1993 Mar 12 71 +/- 1 " " 6 0 +/- 6 1993 Apr 03 93 +/- 6 Totality ______________________________________________________________________ Note that epoch 6 observations failed. This program is a HOPR repeat, and should be scheduled in the August 10+/-3 timeframe. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. At each epoch one WAVE observation will be obtained to provide a more accurate velocity measurement than given by default SPYBALs. This additional accuracy will greatly benefit our modelling. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be reduced and anlayzed primarily with software developed by us for analysis of IUE and GHRS data. Software developed by the GHRS team will be used to optimize calibration of the observations. Line profiles and wavelengths will be carefully measured to extract information on the density, velocity, and temperature structure of the K supergiant outer atmosphere. The non-spherical three-dimensional NLTE radiative transfer code developed at the University of Hamburg over the past decade will be used to construct models of the chromospheric and wind structure. The MULTI code will be used to perform consistency checks. The Hamburg code was written by Hempe (A&A 115, 133 (1982)) and used by Che et al. (A&A 126, 225 (1983)) to model IUE spectra of three Zeta Aurigae systems. Synthetic spectra calculated from these models will be compared with the observations and used to deduce the actual structure of the stellar atmosphere. The analysis and modelling effort will be divided between Dr. Alex Brown (the PI), Dr. Philip Bennett (a new postdoctoral researcher hired specifically for this project), an as-yet-unappointed graduate student, and our German collaborators (Drs. Baade and Kirsch). Trips by both groups to the other institution are planned to allow full collaboration in this research effort. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. GTO Programs with J. Linsky as PI include: GTO 1175: Local Interstellar Medium and D/H Ratio - One star observed in Cycle 0, further observations planned in Cycles 2-4. GTO 1176: Dynamics and Energy Balance in Stellar Transition Regions - Cycles 0-4. Data for one star (Capella, also in GTO1175) has been obtained in Cycle 0. GTO 1177: Search for Hot Plasma in the Outer Atmospheres of K Giants - Cycles 2 and 4. NO DATA YET OBTAINED. GTO 1179: Hybrid Star Winds and Transition Regions - Cycle 2. NO DATA YET OBTAINED. GTO 1180: Transition Regions in Very Late M Dwarfs - Cycles 1-4. NO DATA YET OBTAINED. NONE OF THE ABOVE GTO PROGRAMS IS RELATED TO THE TOPIC OF THIS PROPOSAL. GTO 1175/1176 We observed Capella at phase 0.25 on 15 April 1991. This excellent data set consisted of low resolution spectra covering the 1150-1700 A region, moderate resolution spectra centered on the O I 1304A, Si IV 1400A, and C IV 1550A lines, and echelle spectra centered on Lyman alpha, the FeII 2600A, and the MgII 2800 liners. These spectra contain a wealth of information that we are now analyzing to develope a model for the chromosphere and transition region of this system. An unexpected discovery was the detection of the SIV intersystem lines near 1404A. We will soon submit a paper giving definitive values for them cosmically-important D/H ratio along the line of sight to Capella. "First Results from the Goddard High Resolution Spectrograph: The Chromosphere of Alpha Tauri", Carpenter, K., Robinson, R., Wahlgren, G., Ake, T., Linsky, J., Brown, A., and Walter, F. ApJL 377, L45 1991. "GHRS Spectroscopy of Cool Stars. I. O I and CO as Diagnostics of Winds and Circumstellar Shells" Carpenter, K., Robinson, R., Ebbets, D., Brown, A., Linsky, J., BAAS, 23, #2, 910, 1991. "GHRS Spectroscopy of Cool Star. II. The Hybrid Giant Gamma Dra (K5 III)", Brown, A., Linsky, J.L., Carpenter, K., Robinson, R., Ebbets, D., BAAS, 23, #2, 910, 1991. "GHRS Far-Ultraviolet Spectra of the Coronal Giant Capella Binary", Linsky, J.L., Brown, A., Carpenter, K., Robinson, R., BAAS, 23, #2, 910, 1991. "GHRS Chromospheric Emission Line Spectra of the Red Giant Alpha Tau" Carpenter, K. G., Robinson, R. D., Ebbets, D. C., Brown, A., and Linsky, J., "HST Workshop: The Year of First Light", May 1991. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Software developed by the GHRS IDT and the proposers will be used in the reduction and analysis of these observations. A SUN workstation at JILA connected to the CASA cluster will be used for data reduction and analysis. ------------------------------------------------------------------------------------ 11. Address Information Name: ALEXANDER BROWN Category: PI Institution: COLORADO, UNVERSITY OF Address: JOINT INSTITUTE FOR LABORATORY ASTROPHYSICS UNIVERSITY OF COLORADO CAMPUS BOX 440 City: BOULDER State: CO Zip Code: 803090440 Country: USA Telephone: (303) 492-7810 Telex (or e-mail): (303) 492-5235 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5069c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 HD32068 ZETA A,140,112 RA = 04H 58M 58.68S +/-.01S, 1950.0 V = +13 1 V = 3.75 -AUR DEC = +41D 00' 17.8" +/-.1" Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 0.0008 +/- 0.0001 -0.0220 +/- 0.0010 0.0050 +/- 0.0000 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5069c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 7 HD32068 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=3 1 1.8S 1 ONBOARD ACQ FOR 8- BRIGHT=RETURN 9.5 AT 10-AUG-93 +/- 3D SEQ 7-10.5 NO GAP CYCLE 2/7-10.5 Comments: STEP TIME = 200 MSEC FAINT=3400 OBSERVATIONS IS WELL AFTER ECLIPSE. NO ACQ/PEAKUP PER INST SCIENTIST INSTRUCTIONS. IF NO AUTOMATIC PEAKUP IN SSA, REVISION NEEDED. ------------------------------------------------------------------------------------------------------------------------------------ 8 HD32068 HRS ACCUM 0.25 G160M 1573.0 STEP-PATT=5 1 544S 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 8.5 WAVE HRS ACCUM SC2 G160M 1263.5 STEP-PATT=3 1 64S 1 CALIB FOR 9.0 NO SLEW Comments: NO CARROUSEL MOTION BETWEEN 8.5 AND 9.0. ------------------------------------------------------------------------------------------------------------------------------------ 9 HD32068 HRS ACCUM 0.25 G160M 1263.5 STEP-PATT=5 1 544S 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 9.5 HD32068 HRS ACCUM 0.25 G160M 1643.5 STEP-PATT=5 1 653S 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 10 HD32068 HRS ACCUM 2.0 ECH-B33 1705.0 STEP-PATT=7 1 653S 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 10.3 HD32068 HRS ACCUM 2.0 ECH-B24 2335.4 STEP-PATT=7 1 218S ^ FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 10.5 HD32068 HRS ACCUM 2.0 ECH-B18 3075.0 STEP-PATT=7 1 653S 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5069c [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=3 BRIGHT=RETURN STEP-PATT=5 FP-SPLIT=STD STEP-PATT=3 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for RPT/GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 13.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 8-9.5; AT 10-AUG-93 +/- 3D; SEQ 7-10.5 NO GAP; CYCLE 2/7-10.5; CALIB FOR 9.0 NO SLEW; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-A2 G160M ECH-B33 ECH-B24 ECH-B18 ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD32068 ZETA-AUR ------------------------------------------------------------------------------------------------------------------------------------