Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 6288 Report Date: 18-Jul-95:21:51 Version: ********** Check-in Date: ********** 1.Proposal Title: ECLIPSE MAPPING OF THE CHROMOPSHERIC AND TRANSITION REGION STRUCTURE OF HR2554 (G6 II) -- REPEAT - HOPR 0247 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO Sub Category ATMOSPHERES & WINDS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Alexander Brown U. OF COLORADO USA (303) 492-7810 SENIOR RES ASSOCIATE ------------------------------------------------------------------------------------ 7. Abstract We propose to observe an eclipse of the Zeta Aurigae-type binary HR2554 using the GHRS. Every 195 days the A1 dwarf secondary passes behind the outer atmosphere of the G6 II primary and can be used as light source to observe absorption lines from plasma in the G star atmopshere. The G star has a hybrid-chromosphere structure with hot transition region plasma and a cool stellar wind. THESE OBSERVATIONS WOULD BE THE FIRST ECLIPSE OBSRRVATIONS OF THIS TYPE OF ATMOSPHERE WITH GHRS AND COMPARED WITH OUR RESULTS FOR THE K4 SUPERGIANT Zeta Aur, which shows only the typical red supergiant wind. We shall model the observed line profiles and determine the temperature structure, density stratification, wind acceleration/turbulence/ionization as a function of distance above the G star photosphere. The hot and cool plasma are intermixed in this outer atmosphere and we will quantify this "thermal bifurcation". Both the static and outflowing components of the atmopshere will be modelled. The mass loss rate and the wind velocity and density laws as a function of radius will be determined. The vast majority of the needed modelling code will have been developed already for our Zeta Aur analysis. This project represents an opportunity to significantly advance knowledge about the spatial structuring of cool star outer atmospheres and the physical process operating within them. ------------------------------------------------------------------------------------ 8. Scientific Key Words: G6II+A1 ECLIPSING BINARY SYSTEM ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 33.2 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 6288 PI: Dr. Alexander Brown Proposal Title: ECLIPSE MAPPING OF THE CHROMOPSHERIC AND TRANSITION REGION STRUCTURE OF HR2554 (G6 II) -- REPEAT - HOPR 0247 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Alexander Brown 1764 USA Jeffrey L. Linsky 1764 USA Philip Bennett 1764 USA Graham Harper 1764 USA Robert Baade 5580 Germany X Thomas Kirsch 5580 Germany X Dieter Reimers 5580 Germany X ------------------------------------------------------------------------------------ 3. Description of proposed observations. Our proposed observations will provide the first high-quality (S/N = 60- 80) UV spectrum of HR2554 during atmospheric and photospheric eclipse. Requested exposures are listed below. The exposure times at short wavelengths during partial eclipse are increased by 50% to compensate somewhat for the decrease continuum signal. The quoted signal-to-noise values are calculated per resolution element (i.e. per two diodes on the detector). The large dynamic range and low noise of the GHRS ensures that many weak features can be accurately measured in these exposures. **** SEVERAL OBSERVATIONS FAILED IN APRIL 1994 AND NEW SPECTRA WERE ****APPROVED FOR MAY 1995 IN RESPONSE TO HOPR 0247. ****EPOCHS 2, 4, AND 8 ARE REPEATED (SUs 03, 07, and 0F) IN FULL, ****WHILE EPOCH 1 (SU 01) IS PARTIALLY REPEATED. The observations requested in Phase 1 were: ------------------------ ---------------------------------------------- Ion UV Lambda Grating Continuum Cts/ S/N Exp. mult. (A) Flux*E- 12 sec Time erg/(cm^2*s*A) (min) ----------------------- ----------------------------------------------- C IV 1 1548.20, 1550.77 G160M 5.0 2.3 80 24 (ALSO includes Si II UV2 1533.4, C I UV3 1560-61, Fe II UV45 1559.1, 1563.8, CO A-X (0-0) 1544 bandhead ) Si IV 1 1393.76, 1402.77 G160M 2.5 1.3 60 23 (ALSO includes CO A-X (5 -0;4-0) 1393,1419 bandheads, Si II UV 13.02 1409.0, 1410.2, O IV 1401.2 ) Si II 1 1816.93 G200M 4.5 3.7 80 15 (ALSO includes S I UV2 1820.3 1826.2, Al III UV1 1854.7 ) Mg II 1 2795.52, 2802.70 ECH-B 4.5 5.4 80 10 Fe II 1 2607.09, 2613.82 ECH-B 2.8 1.3 60 23 2611.87 Fe II 3 2332.80, 2338.01 ECH-B 3.6 2.4 80 23 (ALSO includes Si II UV0.01 2334.6, Fe II UV35 2331.3 ) ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The continuum of the A 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. 1992, Ap.J. Lett., 377, L45.) will allow more accurate and detailed modelling of the circumstellar environment around the G6 hybrid-atmosphere bright giant primary of HR2554. ONLY THE GHRS IS CAPABLE OF PROVIDING THE VERY HIGH PRECISION LINE PROFILES, FLUXES, AND ABSOLUTE VELOCITIES NEEDED FOR OUR MODELLING. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. The observations must be scheduled at specific phases during the eclipse of the A1 dwarf secondary by the extended atmosphere of the bright giant primary. Eclipses of HR2554 occur every 195 days and during Cycle 4 eclipses are centered on 1994 April 18 and 1994 October 30. The system lies near the ecliptic pole so the beta angle (star-antiSun angle) is always close to 90 degrees. Therefore, the star is observable by HST at all dates during Cycle 4. Coordinated IUE observations will be possible if the April eclipse is observed. Times of mideclipse are given by t = JD2447898.57 + n*195.28days. ***REPEAT OBSERVATIONS ARE REQUESTED AT +3, +4.5, +6, and +30 days ****RELATIVE TO MID-ECLIPSE. The time between first and fourth contacts is 3.2 days. (See Schroder 19 90, A&A, 236,165 for details). Eclipses during Cycle 4 occur on 1994 April 18.31, Oct 30.59, and 1995 May 13.7. ***The Exposure Logsheet of repeat observations is constructed ***specifically for the May 1995 eclipse. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. We require high wavelength accuracy in order to measure absolute velocities in the chromosphere and wind of our target star. We therefore request one WAVECAL exposure for ECH-B and G160M at each epoch. Wavelength matching between different spectra at each epoch and between epochs will be done using interstellar features. Routine SPYBAL spectra will be used to calibrate spectra without dedicated WAVCALS. The WAVCAL exposures must be taken at the same carrousel position and close in time to the science exposures to remove uncertainties caused by GIMP and thermal drifts which move the image around on the GHRS photocathode. Page 4 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be reduced and analyzed with in-house software developed for analysis of IUE and GHRS data. Software developed by the GHRS IDT will be used to optimize the calibration of the observations. Line widths, profiles, and wavelengths will be carefully measured to extract information on the temperature, density, and velocity structure of the outer atmosphere, including both random non-thermal velocities and systematic flows. Relative and absolute fluxes will be measured to estimate densities and temperatures in the outer atmosphere. The NLTE code developed at the University of Hamburg over the past decade will be used to construct models of the chromospheric and wind structure. The integral-operator method of Baade (A&A 233, 486, 1990) will be used to calculate line profiles and emergent fluxes for the 2D axisymmetric geometry of the binary system. Synthetic spectra calculated from these models will be compared with the observations and used to deduce the actual structure of the stellar atmosphere. At JILA, we will model the G star chromosphere and wind using SMULTI, a spherical version of MULTI (Scharmer & Carlsson, 1985) developed by Harper (1993). Photospheric models of the G star (needed for the boundary radiation field input to SMULTI) will be calculated using the existing ATHENA spherical code (Bennett, 1991). The A star radiation field will be calculated using the NLTE code of Hubeny & Lanz (1988). We will investigate the interaction of the G star wind dynamics with the orbital motion of the binary system. We will use a smooth particle hydrodynamics (SPH) code (Monaghan, 1988; Benz, 1988) for this purpose. In-house 2D axisymmetric radiative transfer codes, based on the 2D double-splitting iteration method (Castor, Dykema & Klein, 1990, in 'Stellar Atmospheres: Beyond Classical Models', p.49) developed for the analysis of the zeta Aurigae system will be used to construct models of the circumstellar environment consistent with the wind from the G star and the A star radiation field. Line profiles will be calculated with a comoving frame radiative transfer code using the Short Characteristic method of Kunasz & Auer (JQSRT 39, 67, 1988). Synthetic spectra and line profiles produced by this analysis will be compared with observations and used to determine structural details of the G star chromosphere and wind. This will provide an analysis independent of the binary profile fitting technique employed at Hamburg. We emphasize that this analysis is analogous to that employed for the Zeta Aurigae system, and will require only a modest amount of additional development. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. GO Program 3626 - Empirical determination of the wind velocity and density laws for the K supergiant Zeta Aurigae from eclipse ingress Spectra (A. Brown PI, J. Linsky, R. Weyman, D. Reimers, R. Baade, T. Kirsch) ------------------------------------------------------------------------------------ 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 workstation at JILA connected to the CASA cluster is available for data reduction and analysis. ------------------------------------------------------------------------------------ 11. Address Information Name: Alexander Brown Category: PI Institution: Center for Astrophysics and Space Address: University of Colorado City: Boulder State: CO Zip Code: 803090389 Country: USA Telephone: (303) 492-7810 Telex (or e-mail): 755842 JILA ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 6288 [ 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 HD50337 A,138,123 RA=06H48M46.13S+/-0.01S, 1950 V=0.0 1 V=4.40 DEC=-53D33'47.15"+/-0.2" 1 B-V=+0.92 2 F-CONT(1835) = 4.5E-12 3 F-CONT(1543) = 5.0E-12 4 F-CONT(1400) = 2.5E-12 5 F-CONT(2334) = 3.6E-12 6 F-CONT(2611) = 2.8E-12 7 F-CONT(2799) = 4.5E-12 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 -0.0004 +/- 0.0006 0.0300 +/- 0.0050 0.0000 +/- 0.0000 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6288 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE HD50337 HRS ACCUM 2.0 G200M 1835 STEP-PATT=5 1 980S 80.0 2 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 4.1 DEFINE HD50337 HRS ACCUM 2.0 G160M 1548 STEP-PATT=5 1 1523S 80.0 3 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 4.2 DEFINE WAVE HRS ACCUM SC2 G160M 1403 STEP-PATT=3 1 64S 3 CALIB FOR 4.3 NO HR2554A SLEW ------------------------------------------------------------------------------------------------------------------------------------ 4.3 DEFINE HD50337 HRS ACCUM 2.0 G160M 1403 STEP-PATT=5 1 1416S 60.0 4 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 4.4 DEFINE HD50337 HRS ACCUM 2.0 ECH-B 2334 STEP-PATT=7 1 1416S 80.0 5 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 4.5 DEFINE HD50337 HRS ACCUM 2.0 ECH-B 2611 STEP-PATT=7 1 1416S 60.0 6 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 4.6 DEFINE WAVE HRS ACCUM SC2 ECH-B 2800 STEP-PATT=3 1 64S 3 CALIB FOR 4.7 NO HR2554A SLEW ------------------------------------------------------------------------------------------------------------------------------------ 4.7 DEFINE HD50337 HRS ACCUM 2.0 ECH-B 2800 STEP-PATT=7 1 600S 80.0 7 1 HR2554A FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 10 HD50337 HRS ACQ 2.0 MIRROR-A2 BRIGHT=RETURN 1 9S 1 1 CYCLE 4 / 10-13 SEARCH-SIZE=3 2 ONBOARD ACQ FOR 11 -13 GROUP 10-13 NO GAP AT 13-JUN-95 +/- 5D Comments: STEP-TIME = 1 SEC EXPECT 1300 CT/S WITH A2 NORMALLY. PHASE IS 30 DAYS AFTER MID-ECLIPSE ------------------------------------------------------------------------------------------------------------------------------------ 11 HD50337 HRS IMAGE 2.0 MIRROR-N2 NX=16 1 51.2S 1 NY=16 DELTA-X=4 DELTA-Y=4 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 11.5 HD50337 HRS ACCUM 2.0 ECH-B 2334 STEP-PATT=7 1 1416S 80.0 5 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ 12 WAVE HRS ACCUM SC2 ECH-B 2611 STEP-PATT=3 1 64S 3 CALIB FOR 13.0 NO SLEW ------------------------------------------------------------------------------------------------------------------------------------ 13 HD50337 HRS ACCUM 2.0 ECH-B 2611 STEP-PATT=7 1 1416S 60.0 6 1 FP-SPLIT=STD ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6288 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD50337 HRS ACQ 2.0 MIRROR-A2 BRIGHT=RETURN 1 9S 1 1 CYCLE 4 / 20-22 SEARCH-SIZE=3 2 ONBOARD ACQ FOR 21 -22 GROUP 20-22 NO GAP AT JD2449855.7 +/- 0.4D Comments: STEP-TIME = 1 SEC EXPECT 1300 CT/S WITH A2 NORMALLY. PHASE IS 4.5 DAYS AFTER MID-ECLIPSE ------------------------------------------------------------------------------------------------------------------------------------ 21 HD50337 HRS IMAGE 2.0 MIRROR-N2 NX=16 1 51.2S 1 NY=16 DELTA-X=4 DELTA-Y=4 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 22 USE HR2554A ------------------------------------------------------------------------------------------------------------------------------------ 40 HD50337 HRS ACQ 2.0 MIRROR-A2 BRIGHT=RETURN 1 9S 1 1 CYCLE 4 / 40-42 SEARCH-SIZE=3 2 ONBOARD ACQ FOR 41 -42 GROUP 40-42 NO GAP AT JD2449857.2 +/- 0.5D Comments: STEP-TIME = 1 SEC EXPECT 1300 CT/S WITH A2 NORMALLY. PHASE IS 6 DAYS AFTER MID-ECLIPSE ------------------------------------------------------------------------------------------------------------------------------------ 41 HD50337 HRS IMAGE 2.0 MIRROR-N2 NX=16 1 51.2S 1 NY=16 DELTA-X=4 DELTA-Y=4 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 42 USE HR2554A ------------------------------------------------------------------------------------------------------------------------------------ 80 HD50337 HRS ACQ 2.0 MIRROR-A2 BRIGHT=RETURN 1 9S 1 1 CYCLE 4 / 80-82 SEARCH-SIZE=3 2 ONBOARD ACQ FOR 81 -82 GROUP 80-82 NO GAP AT JD2449854.2 +/- 0.3D Comments: STEP-TIME = 1 SEC EXPECT 1300 CT/S WITH A2 NORMALLY. PHASE IS 3 DAYS AFTER MID-ECLIPSE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 6288 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 81 HD50337 HRS IMAGE 2.0 MIRROR-N2 NX=16 1 51.2S 1 NY=16 DELTA-X=4 DELTA-Y=4 Comments: STEP-TIME=0.2S ------------------------------------------------------------------------------------------------------------------------------------ 82 USE HR2554A ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 6288 [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ACQ IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters STEP-PATT=5 FP-SPLIT=STD STEP-PATT=3 STEP-PATT=7 BRIGHT=RETURN SEARCH-SIZE=3 NX=16 NY=16 DELTA-X=4 DELTA-Y=4 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 33.2 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ATMOSPHERES & WINDS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CALIB FOR 4.3 NO SLEW CALIB FOR 4.7 NO SLEW CYCLE 4 / 10-13; ONBOARD ACQ FOR 11-13; GROUP 10-13 NO GAP; AT 13-JUN-95 +/- 5D CALIB FOR 13.0 NO SLEW CYCLE 4 / 20-22; ONBOARD ACQ FOR 21-22; GROUP 20-22 NO GAP; AT JD2449855.7 +/- 0.4D CYCLE 4 / 40-42; ONBOARD ACQ FOR 41-42; GROUP 40-42 NO GAP; AT JD2449857.2 +/- 0.5D CYCLE 4 / 80-82; ONBOARD ACQ FOR 81-82; GROUP 80-82 NO GAP; AT JD2449854.2 +/- 0.3D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G200M G160M ECH-B MIRROR-A2 MIRROR-N2 ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD50337 ------------------------------------------------------------------------------------------------------------------------------------