Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4490c Report Date: 09-May-96:19:38 Version: ********** Check-in Date: ********** 1.Proposal Title: THE CHROMOSPHERE OF ALPHA TAU - CYC3 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO Sub Category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Kenneth G. Carpenter NASA GODDARD LASP USA ------------------------------------------------------------------------------------ 7. Abstract We propose observations of the K5 III star Alpha Tau using the Goddard High- Resolution Spectrograph (GHRS), to follow-up on the exciting initial SAO observations of this star and the SV observations of the K5 III hybrid star Gamma Dra. These data will also allow a detailed comparison of its spectrum and the thermodynamic properties of its outer atmosphere with those of the cooler M giant and supergiant stars Gamma Cru and Alpha Ori, observed during previous cycles. We shall check for variations in the C II downflow discovered in the SAO observations and search for evidence of systematic flows in other emission lines. We shall make detailed comparisons of the chromospheric emission lines and wind signatures in the UV spectra of two stars of the same spectral class, where one is a hybrid and one is not. We shall search for evidence of shocks and/or propagating waves in the line variations predicted by our recent calculations. We will also determine the variation of wind velocity with height using semi-empirical non-LTE models assuming spherical symmetry, search for evidence of circumstellar and interstellar absorptions on resonance lines of O I, Fe II, and Mg II, and compare the short- wavelength continuum measured in this star with that detected in observations of Gamma Dra, Gamma Cru and Alpha Ori. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.35 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4490c PI: Kenneth G. Carpenter Proposal Title: THE CHROMOSPHERE OF ALPHA TAU - CYC3 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Kenneth G. Carpenter NASA GODDARD LASP USA Philip G. Judge HIGH ALTITUDE OBSERVATORY USA Manfred Cuntz HIGH ALTITUDE OBSERVATORY USA Alexander Brown U.COLORADO JILA USA Richard D. Robinson COMPUTER SCIENCES CORPORATION USA Glenn M. Wahlgren COMPUTER SCIENCES CORPORATION USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. The observations requested are: Central GHRS grating Wavelength(s) Aperture Exposure Time(s) Strong Feature G160M 1296 SSA 60 min Fe II/O I G160M 1550 LSA 60 min C IV/CO/contin G160M 1655 LSA 48 min C I/O I/O III G200M 1994 LSA 20 min CI] G270M 2345 SSA 20 min (3x) C II]/Si II] G270M 2499 SSA 10 min Fluor. Fe II G270M 2609, 2753, 2803 SSA 10, 5, and 5 min Fe II/MgII/Fe ECH-B 2596, 2799 SSA 30, 10 min Fe II/Mg II The G270M 2345 A exposures will be taken at the start, middle and end of the main observing session to check for short term changes in the chromospheric turbulence and flow velocities. The project is pure Cycle 3. The spacecraft time is: Primary Hours: Parallel Hours: Exposures: 9.35 0.0 18 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The data required for this program consists of UV spectra not obtainable from the ground. IUE has been used to study this star to the limits of its ability (e.g. Brown and Jordan, 1981, MNRAS, 191,37; Judge, 1986, MNRAS, 223, 239) and a small number of exposures have been obtained with the GHRS as part of the Science Assessment Program. These observations clearly demonstrate the increased sensitivity, wavelength resolution, dynamic range and S/N characteristics of the GHRS over that obtainable with the IUE (Carpenter et al. 1991, Ap.J. (letters), 377, L45). 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. The three C II] G270M exposures (at 2345 A) should be taken at the beginning, middle, and end of the SSA observation sequence to allow the study of changes in turbulence, flow velocities and line profiles, all of which are sensitive probes of shock and wave passage through the atmosphere. The exposure logsheet contains "SEQ" special requirements to ensure the proper scheduling and no special handling should be required. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. We require the highest possible wavelength accuracy in order to measure absolute flow velocities in the chromosphere, wind and circumstellar shell of our target star (down to the 1 km/sec level in the medium and echelle observations) as well as aiding in the identification of the many weak features we expect in the low resolution data. Experience with SV and SAO data (Carpenter et al. 1991, HST Workshop) has demonstrated that the default calibration will produce uncertainties of up to 3 diodes due to magnetic and thermal drifts within the spectrograph. Using internal Pt lamp spectra taken during the SPYBAL procedures we can estimate the amount of drift and can therefore reduce the degree of uncertainty to about 0.5 diodes. To obtain the greatest possible wavelength accuracy we require dedicated WAVECAL exposures using the internal Pt lamps to be connected to each GHRS science exposure. Experience has shown that with care calibrations good to 0.1 diode can be obtained using this data. To do this the wavelength calibrations must be taken at the same carrousel position and close in time to the science exposures to remove uncertainties caused by the geomagnetic (GIMP) and thermal drifts which move the image around on the GHRS photocathode. Long exposures must also broken into times sequences of 5 minute integrations so that the drifts can be identified and corrected. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The data will be reduced and analyzed primarily with software developed at Goddard for analysis of IUE and GHRS data. Line widths, profiles, and wavelengths will be carefully measured to extract information on the velocity structure of the outer atmosphere, including both random non-thermal velocities and systematic flows. Methods are described in Carpenter et al. (1991 ApJ Letters, 377, L45) and in Carpenter (1984, ApJ. 285, 181 ). Relative and absolute fluxes will be measured to estimate densities and temperatures in the outer atmosphere. Planar and spherical versions of the NLTE MULTI code will be used to construct model chromospheres and spectra which will be compared with the observations and used to deduce the actual structure of the stellar chromosphere. The time dependence of the line profiles will be studied using the shock models of Cuntz (1987) with updated treatments of radiative transfer as described by Judge & Cuntz (1992, ApJL, submitted). Both reduced spectra and inferred chromospheric structures of Alpha Tau and the other giant and supergiant stars in our sample will be compared to study dependences on Teff and gravity. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. none Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. a. List HST program numbers and titles, and specify whether they are related to this project or not. GTO 1195: Outer Atmospheres of Cool Luminous Stars - Cycle 0 (Alpha Ori) 3212: Outer Atmospheres of Cool Luminous Stars - Cycle 1 (Gamma Cru) GTO 1198: Physical Conditions and Velocity Structures in the Red Giant 3934: Winds in the Binaries CI Cyg and EG And - Cycle 2 (2 targets) GTO 1199: Alpha Ori Team Project - Cycle 1 These proposals represent the GTO science program, as adjusted for spherical abberation, of GHRS IDT Co-I K. Carpenter. Programs 1195, 3212, and 1199 are related to this proposal. Proposals 1198 & 3934 are studies of symbiotic stars and not directly related to the current proposal. SAO program 3023 (Alpha Tau) observations have been used to assess the feasibility of programs such as these which involve observations of narrow emission-line sources (see the Ap.J. reference below). NO FURTHER OBSERVATIONS OF ALPHA TAU ARE INCLUDED IN THE GTO PROPOSALS, AND NO ADDITIONAL GTO OBSERVATIONS, BEYOND THE CYCLE 0-1 OBSERVATIONS LISTED ABOVE, ARE PLANNED OF SINGLE COOL, LUMINOUS STARS. b. Summarize the main results obtained from previous related programs. Highlights include 1) the unambiguous detection of a far-UV continuum in Alpha Ori and Gamma Cru, which will provide a very important and previously unrecognized diagnostic of their chromospheric plasmas (formation temperature in Alpha Ori ranges from 3500-5000 K and increases steadily with decreasing wavelength), 2) the discovery of circumstellar CO (4th positive A-X system) absorption bands superposed on the far-UV continuum from Alpha Ori, providing a probe of regions of the circumstellar shell not available at visible or IR wavelengths (initial analysis indicates T=500 K, Vturb=5 km/s, N(CO)=1.0e18 cm-2), 3) detection of myriad new Fe II fluorescent line products, producing by Lyman Alpha radiation in Alpha Ori, 4) the determination that the O I and C I resonance line flux deficiences are due to self-absorption in the chromosphere, 5) the determination that the differing Mg II (UV 1) line asymmetries are due to differing velocity shifts between the emission and self-absorption components rather than primarily due to overlying circumstellar absorption from Fe I and Mn I, and 5) the first direct measurement of the chromospheric turbulence (24 km/sec) and the detection of a downflow of about 4 km/sec in chromospheric C II] plasma in Alpha Tau. c. List publications resulting from the above data (Format: Title, Authors,Journal, Volume, Page, and Year.) Results have been presented: in the Ap.J. & MNRAS, at AAS meeting (1/91, 5/91 & 1/92), the HST Joint Discussion at the IAU General Assembly (7/91), the 7th Cambridge Cool Star Workshop (10/91), and at both HST Workshops (5/91 & 7/92), including two invited reviews (AAS 1/91 and Cool Star Workshop 10/91). "First Results from the Goddard High Resolution Spectrograph: The Chromospher of Alpha Tauri", Carpenter, K., Robinson, R., Wahlgren, G., Ake, T., Linsky, J., Brown, A., and Walter, F., Ap.J. (Letters), 377, L45, 1991. "Si II Emission Line Diagnostics," Judge, P. G., Carpenter, K. G., and Harper, G.M., MNRAS, 253, 123, 1991. "Early Scientific Results from the Goddard High Resolution Spectrograph" Carpenter, K. G. , Invited Review presented at the AAS Meeting, 1/13-17/91. "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., in `The First Year of HST Observations,' 1991. "Chromospheres and Winds of Cool Stars", Carpenter, K.G., IAU General Assembly Joint Discussion, 'First Results from the Hubble Space Telescope', 7/31/91. "HST Observations of Late-Type Stars," (Invited Review) Carpenter, K. G., in `Proceedings of the 7th Cambridge Workshop on Cool Stars, Stellar Systems, an the Sun,' eds. M. Giampapa & J. Bookbinder, A.S.P. Conference Series, 26, 17, 1992. "Molecular Absorption in the UV Spectrum of Alpha Ori," Wahlgren, G. M., Robinson, R. D., and Carpenter, K. G., Proceedings of the Seventh Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, eds. M. Giampap and J. Bookbinder, A.S.P. Conference Series, 26, 37, 1992. "The Chromosphere and Circumstellar Shell of Alpha Orionis as Observed with th Goddard High Resolution Spectrograph," Carpenter, K. G., Robinson, R. D., Wahlgren, G. M., Linsky, J. L., Brown, A., in Science with the Hubble Space Telescope, eds. P. Benvenuti and E. Schreier, in press, 1992. "The Far-UV Spectrum of Alpha Ori," Carpenter, K. G., Robinson, R. D., Wahlgren, G. M., Linsky, J.L., and Brown, A., Ap. J., submitted, 1992. "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 Stars. II. Gamma Draconis," Brown, A., Linsky, J., Carpenter, K., Robinson, R., Ebbets, D., BAAS, 23, #2, 910, 1991. "Molecular Absorption in the Ultraviolet Spectrum of Alpha Ori," Wahlgren, G.M., Robinson, R. D., and Carpenter, K. G., BAAS, 23, #4, 1386, 1991. Page 5 ------------------------------------------------------------------------------------ 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 VAX cluster is available for data reduction and analysis at GSFC. ------------------------------------------------------------------------------------ 11. Address Information Name: KENNETH G. CARPENTER Category: PI Institution: NASA Goddard LASP Address: CODE 681 NASA/GSFC - LAB. FOR ASTRONOMY AND SOLAR PHYSICS City: GREENBELT State: MD Zip Code: 20771 Country: USA Telephone: (301)-286-3453 Telex (or e-mail): 89675 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4490c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 HD29139 A,140 RA=04H33M02.896S+/-0.1", 1950.0 V=+54 1 V=0.84+/-.2,TYPE=K5 III ALPHA-TAU DEC=+16D24'37.51"+/-0.1" 2 F(1314)=3.E-14 3 F(1655)=7.7E-13 4 F(1994)=4.E-13 5 F(2327)=4.E-12 6 F(2759)=1.5E-12 7 F(2770)=1.5E-12 8 F(2799)=8.E-11 Comments: NOTE: RA PROPER MOTION IS IN SEC OF TIME/YR **** Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) B 1950.00 0.0045 +/- 0.0010 -0.1890 +/- 0.0010 0.0540 +/- 0.0050 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4490c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD29139 HRS ACQ 2.0 MIRROR-A2 SEARCH-SIZE=5 1 10S 1 1 CYCLE 3 / 10-74 BRIGHT=RETURN ONBOARD ACQ FOR 11 SEQ 10-74 NO GAP Comments: STEP TIME = 0.4 SEC EXPECT 226 CTS/400 MSEC ------------------------------------------------------------------------------------------------------------------------------------ 11 HD29139 HRS ACQ/ 0.25 MIRROR-A2 SEARCH-SIZE=5 1 40.0S 1 1 ONBOARD ACQ FOR 12 PEAKUP -74 Comments: CENTER IN SSA AFTER NEW DEFCAL STEP-TIME=1.6SEC ------------------------------------------------------------------------------------------------------------------------------------ 12 WAVE HRS ACCUM SC2 G270M 2345.5 STEP-PATT=3 1 3.2S 1 CALIB FOR 13 NO SLEW SEQ 12-13 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 13 HD29139 HRS ACCUM 0.25 G270M 2345.5 STEP-PATT=5 4 5.0M 35 5 1 Comments: FIRST C II EXPOSURE (1 OF 3) ------------------------------------------------------------------------------------------------------------------------------------ 31 WAVE HRS ACCUM SC2 G160M 1296 STEP-PATT=3 1 3.2S 1 CALIB FOR 32 NO SLEW SEQ 31-32 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 32 HD29139 HRS ACCUM 0.25 G160M 1296 STEP-PATT=5 12 5.0M 13 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 33 WAVE HRS ACCUM SC2 G270M 2345.5 STEP-PATT=3 1 3.2S 1 CALIB FOR 34 NO SLEW SEQ 33-34 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 34 HD29139 HRS ACCUM 0.25 G270M 2345.5 STEP-PATT=5 4 5.0M 35 5 1 Comments: SECOND C II EXPOSURE (2 OF 3) ------------------------------------------------------------------------------------------------------------------------------------ 35 WAVE HRS ACCUM SC2 G270M 2499.0 STEP-PATT=3 1 3.2S 1 CALIB FOR 36 NO SLEW SEQ 35-36 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 36 HD29139 HRS ACCUM 0.25 G270M 2499.0 STEP-PATT=5 2 5.0M 1 ------------------------------------------------------------------------------------------------------------------------------------ 37 WAVE HRS ACCUM SC2 G270M 2609.0 STEP-PATT=3 1 3.2S 1 CALIB FOR 38 NO SLEW SEQ 37-38 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 38 HD29139 HRS ACCUM 0.25 G270M 2609 STEP-PATT=5 2 5.0M 1 ------------------------------------------------------------------------------------------------------------------------------------ 39 WAVE HRS ACCUM SC2 G270M 2753 STEP-PATT=3 1 3.2S 1 CALIB FOR 40 NO SLEW SEQ 39-40 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 40 HD29139 HRS ACCUM 0.25 G270M 2753 STEP-PATT=5 2 5.0M 30 6 1 ------------------------------------------------------------------------------------------------------------------------------------ 41 WAVE HRS ACCUM SC2 G270M 2807.0 STEP-PATT=3 1 3.2S 1 CALIB FOR 42 NO SLEW SEQ 41-42 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4490c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 42 HD29139 HRS ACCUM 0.25 G270M 2807.0 STEP-PATT=5 2 5.0M 8 1 ------------------------------------------------------------------------------------------------------------------------------------ 51 WAVE HRS ACCUM SC2 ECH-B22 2596.0 STEP-PATT=3 1 3.2S 1 CALIB FOR 52 NO SLEW SEQ 51-52 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 52 HD29139 HRS ACCUM 0.25 ECH-B22 2596.0 STEP-PATT=7 6 5M 27 1 ------------------------------------------------------------------------------------------------------------------------------------ 53 WAVE HRS ACCUM SC2 ECH-B20 2799.0 STEP-PATT=3 1 3.2S 1 CALIB FOR 54 NO SLEW SEQ 53-54 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 54 HD29139 HRS ACCUM 0.25 ECH-B20 2799.0 STEP-PATT=7 2 5M 8 1 ------------------------------------------------------------------------------------------------------------------------------------ 60 WAVE HRS ACCUM SC2 G270M 2345.5 STEP-PATT=3 1 3.2S 1 CALIB FOR 61 NO SLEW SEQ 60-61 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 61 HD29139 HRS ACCUM 0.25 G270M 2345.5 STEP-PATT=5 4 5.0M 35 5 1 Comments: THIRD C II EXPOSURE (3 OF 3) ------------------------------------------------------------------------------------------------------------------------------------ 71 HD29139 HRS ACCUM 2.0 G160M 1550 STEP-PATT=5 12 5.0M 8 1 ------------------------------------------------------------------------------------------------------------------------------------ 72 HD29139 HRS ACCUM 2.0 G160M 1655 STEP-PATT=5 9 5.0M 10 3 1 ------------------------------------------------------------------------------------------------------------------------------------ 74 HD29139 HRS ACCUM 2.0 G200M 1994 STEP-PATT=5 2 10.0M 4 1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4490c [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 BRIGHT=RETURN STEP-PATT=3 STEP-PATT=5 STEP-PATT=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.35 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR ATMOSPHERES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 3 / 10-74; ONBOARD ACQ FOR 11; SEQ 10-74 NO GAP ONBOARD ACQ FOR 12-74 CALIB FOR 13 NO SLEW; SEQ 12-13 NON-INT CALIB FOR 32 NO SLEW; SEQ 31-32 NO GAP CALIB FOR 34 NO SLEW; SEQ 33-34 NON-INT CALIB FOR 36 NO SLEW; SEQ 35-36 NON-INT CALIB FOR 38 NO SLEW; SEQ 37-38 NON-INT CALIB FOR 40 NO SLEW; SEQ 39-40 NON-INT CALIB FOR 42 NO SLEW; SEQ 41-42 NON-INT CALIB FOR 52 NO SLEW; SEQ 51-52 NON-INT CALIB FOR 54 NO SLEW; SEQ 53-54 NON-INT CALIB FOR 61 NO SLEW; SEQ 60-61 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-A2 G270M G160M ECH-B22 ECH-B20 G200M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD29139 ALPHA-TAU ------------------------------------------------------------------------------------------------------------------------------------