6083( 7) - 10/05/95 10:25 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6083 Version: 7 Check-in Date: ********** 1.Proposal Title: The expanding chromospheres of A stars ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Theodore Simon Institute for Astronomy, University of Hawaii CoI: Wayne Landsman STX Corporation/NASA GSFC N CoI: Thierry Lanz USRA/NASA GSFC N ------------------------------------------------------------------------------------ 6. Abstract Our Cycle 2 GHRS spectra of the C II (1334.5 Angstrom, 1335.7 Angstrom) lines of the bright A7 V star Altair reveal that the chromospheric emission of this star is blueshifted by ~ 60 kms\ or more with respect to its photospheric spectrum, making it the first normal main sequence A star known to have an expanding chromosphere, that is to say, a warm wind. To confirm this result, we now propose to obtain high quality GHRS spectra at Ly-alpha\ 1215 Angstrom\ for this star and for a representative sample of stars with mid- to late-A spectral types. Ly-alpha\ should be the strongest emission line in the UV spectrum of any A star with a chromosphere. We will look for asymmetries in the line profile due to mass loss and will model the Ly-alpha\ spectra using a NLTE moving atmosphere code in order to estimate the wind velocity and mass loss rate. ------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 2] Observations Description ------------------------ The proposed targets are listed in the table below. We tabulate the B - V color, our estimate of the flux at the peak of Ly-alpha\ (in units of 10^-14 erg cm^-2 s^-1 ang^-1), an indication (yes/no) of whether the flux was derived from an IUE high dispersion spectrum, the corresponding count rate for the small science aperture (assuming a through-put for the SSA of 50\% at Ly-alpha and a sensitivity of 3.1 x 10^11 counts s^-1 diode^-1 per incident erg cm^-2 s^ -1 ang^-1), the proposed exposure time (in seconds of on- target integration), and our estimate of the resulting S/N for a 3-diode running average. If an IUE flux value was not available, then we derived an estimate from the continuum flux at 1335 Angstrom\ multiplied by a factor of 1.5, which is the mean ratio of Ly-alpha\ flux to 1335 Angstrom\ flux for those stars having IUE data. For targets in the continuous viewing zone of HST (CVZ), we give two different exposure times and S/N ratios, one for the nominal (58 min.) visibility, the other for an extended visibility (96 min.) corresponding to an entire orbit. For Altair our objective is very high S/N over as much of its line profile as possible since we want to detect line profile asymmetries of the order of 5- 10\% and to use the data, in conjunction with our existing C II spectrum, to model the entire chromospheric structure of the star. Most stars will not have a line as bright as Altair's. However, according to model atmospheres, the photospheric brightness drops by a factor of 200 between a wavelength of 1335 Angstrom\ near the C II lines and 1215 Angstrom\ at Ly-alpha, and even a weak chromospheric line should stand out in contrast against this faint background. For Altair the contrast with the background near line center must be an impressive >400 times or more. A single spectrum will be taken of each star, centered on the wavelength of Ly-alpha with the G140M grating + D1 Digicon detector. The observations will be made though the SSA in order to minimize the impact of the geocoronal radiation, while the use of a solar-blind detector will eliminate scattered light coming from longer wavelengths. (Scattered light is one of the major reasons why high dispersion IUE spectra have such low S/N.) Geocoronal emission will be restricted to the inner 0.1 Angstrom\ of the line profile, which would normally be obliterated by interstellar absorption anyway. To reduce fixed pattern noise, detector granularity, geomagnetically-induced image motion (gimp), and undersampling, we will use the standard observing modes. begincenter begintabularllcrccrrc Star & HD & B - V & Flux & cts s^-1 & IUE & Expo. & S/N & CVZ? Tau^3 Eri & 18978 & 0.16 & 135 & 0.21 & no & 900 & 23 & , Iota UMa & 76644 & 0.19 & 80 & 0.12 & yes & 1080 & 19 & , Alpha Pic & 50241 & 0.21 & 68 & 0.10 & no & 1200 & 19 & , & & & & & & 3480 & 32 & CVZ , Alpha Aql & 187642 & 0.22 & 600 & 0.93 & yes & 840 & 48 & , Alpha Cep & 203280 & 0.22 & 90 & 0.14 & yes & 1200 & 22 & , & & & & & & 3480 & 37 & CVZ , Alpha Cir & 128898 & 0.24 & 45 & 0.07 & no & 1320 & 16 & , & & & & & & 3480 & 26 & CVZ , Alpha Hyi & 12311 & 0.28 & 80 & 0.12 & yes & 1200 & 21 & , & & & & & & 3480 & 35 & CVZ endtabular endcenter Real Time Justification ----------------------- None. Calibration Justification ------------------------- We request wavelength calibration exposures at Ly-alpha\ so that we can establish line profile wavelength shifts of 10 kms\ or less. Additional Comments ------------------- ------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD18978 STAR, A4-A9 V-IV RA= 03H 02M 23.51S +/- 0.3", 2000 V = -9.8 V = 4.09 +/- 0.02 DEC=-23D 37' 28.0" +/- 0.3" B-V = 0.16 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.011 -0.054 0.052 2 HD76644 STAR, A4-A9 V-IV RA= 08H 59M 12.44S +/- 0.3", 2000 V = +9 V = 3.14 +/- 0.02 DEC=+48D 02' 30.1" +/- 0.3" B-V = 0.19 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.044 -0.226 0.075 3 HD50241 STAR, A4-A9 V-IV RA= 06H 48M 11.44S +/- 0.3", 2000 V = V = 3.27 +/- 0.02 DEC=-61D 56' 29.0" +/- 0.3" +20.6 B-V = 0.21 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.0095 0.269 0.048 4 HD187642 STAR, A4-A9 V-IV RA= 19H 50M 47.00S +/- 0.3", 2000 V = -26 V = 0.77 +/- 0.02 DEC=+08D 52' 06.0" +/- 0.3" B-V = 0.22 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0363 0.386 0.202 5 HD203280 STAR, A4-A9 V-IV RA= 21H 18M 34.77S +/- 0.3", 2000 V = -10 V = 2.44 +/- 0.02 DEC=+62D 35' 08.1" +/- 0.3" B-V = 0.22 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0218 0.049 0.068 6 HD128898 STAR, AP RA= 14H 42M 30.41S +/-0.3", DEC= 2000 V = +7.2 V = 3.19 +/- 0.02 -64D 58' 30.5" +/-0.3" B-V = 0.24 +/- 0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.030 -0.232 0.050 7 HD12311 STAR, F0-F2 RA= 01H 58M 46.20S +/-0.3", DEC= 2000 V = +7.0 V = 2.86 +/-0.02 -61D 34' 11.4" +/-0.3" B-V = 0.28 +/-0.02 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0369 0.027 0.041 6083( 7) - 10/05/95 10:25 - [ 5] Visit: 01 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 HD18978 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 11 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 11 HD18978 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 13 KUP ------------------------------------------------------------------------------------------------------------------------------------ 13 HD18978 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 1 870.4S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 6] 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 ------------------------------------------------------------------------------------------------------------------------------------ 20 HD76644 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 21 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 21 HD76644 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 23 KUP ------------------------------------------------------------------------------------------------------------------------------------ 23 HD76644 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 1 1087.8S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 7] Visit: 03 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 30 HD50241 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 31 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 31 HD50241 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 32-33 KUP ------------------------------------------------------------------------------------------------------------------------------------ 32 WAVE HRS ACCUM SC2 G140M 1215 1 27.2S Comments: WAVELENGTH CALIB FOR 33 ------------------------------------------------------------------------------------------------------------------------------------ 33 HD50241 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 3 1088S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 8] Visit: 04 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 ------------------------------------------------------------------------------------------------------------------------------------ 40 HD187642 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 41 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 41 HD187642 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 42-43 KUP ------------------------------------------------------------------------------------------------------------------------------------ 42 WAVE HRS ACCUM SC2 G140M 1215 1 27.2S Comments: WAVELENGTH CALIB FOR 43 ------------------------------------------------------------------------------------------------------------------------------------ 43 HD187642 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 1 866.4S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 9] Visit: 05 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 HD203280 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 51 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 51 HD203280 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 52-53 KUP ------------------------------------------------------------------------------------------------------------------------------------ 52 WAVE HRS ACCUM SC2 G140M 1215 1 27.2S Comments: WAVELENGTH CALIB FOR 53 ------------------------------------------------------------------------------------------------------------------------------------ 53 HD203280 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 3 1088S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 10] Visit: 06 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 60 HD128898 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 61 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 61 HD128898 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 62-63 KUP ------------------------------------------------------------------------------------------------------------------------------------ 62 WAVE HRS ACCUM SC2 G140M 1215 1 27.2S Comments: WAVELENGTH CALIB FOR 63 ------------------------------------------------------------------------------------------------------------------------------------ 63 HD128898 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 3 1088S DOPPLER = ON, STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 11] Visit: 07 Visit Requirements: CVZ 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 ------------------------------------------------------------------------------------------------------------------------------------ 70 HD12311 HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE = 1 1.8S ONBOARD ACQ FOR 71 3, BRIGHT = RETURN ------------------------------------------------------------------------------------------------------------------------------------ 71 HD12311 HRS ACQ/PEA 0.25 MIRROR-N1 SEARCH-SIZE = 5 1 5S ONBOARD ACQ FOR 72-73 KUP ------------------------------------------------------------------------------------------------------------------------------------ 72 WAVE HRS ACCUM SC2 G140M 1215 1 27.2S Comments: WAVELENGTH CALIB FOR 73 ------------------------------------------------------------------------------------------------------------------------------------ 73 HD12311 HRS ACCUM 0.25 G140M 1215 FP-SPLIT = STD, 3 1088S DOPPLER = ON STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ 6083( 7) - 10/05/95 10:25 - [ 12] Summary Form for Proposal 6083 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE = 3 BRIGHT = RETURN SEARCH-SIZE = 5 STEP-PATT = 5 DOPPLER = ON FP-SPLIT = STD DOPPLER = ON STEP-PATT = 5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 11 ONBOARD ACQ FOR 13 ONBOARD ACQ FOR 21 ONBOARD ACQ FOR 23 CVZ ONBOARD ACQ FOR 31 ONBOARD ACQ FOR 32-33 ONBOARD ACQ FOR 41 ONBOARD ACQ FOR 42-43 ONBOARD ACQ FOR 51 ONBOARD ACQ FOR 52-53 ONBOARD ACQ FOR 61 ONBOARD ACQ FOR 62-63 ONBOARD ACQ FOR 71 ONBOARD ACQ FOR 72-73 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 G140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD18978 HD76644 HD50241 WAVE HD187642 HD203280 HD128898 HD12311 ------------------------------------------------------------------------------------------------------------------------------------