6076( 7) - 06/19/96 11:35 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6076 Version: 7 Check-in Date: 19-Jun-1996 11:32:12 1.Proposal Title: Xi Boo A: Structure and Non-Thermal Heating ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Carole Jordan University of Oxford CoI: Andrew McMurry University of Oxford Y CoI: Neil Griffiths University of Oxford N CoI: Dr. HongChao Pan University of Oxford N ------------------------------------------------------------------------------------ 6. Abstract Xi Boo A is a G8 V star which is substantially more active than the Sun. It is an ideal target for the GHRS instrument which can make observations of density sensitive emission line ratios and line widths that are impossible with IUE. We have used our existing observations of xi Boo A, made with IUE, the PSPC and WFC instruments on ROSAT, and EUVE, to make models of the atmosphere from the photosphere to the corona, using the MULTI radiative transfer code to model the chromosphere. Discrimination between these requires an improved measurement of the electron density. Comparisons of transition region and coronal pressures provide constraints on the geometry, including non-homogeneity. Line widths enter the turbulent pressure and non-thermal energy density, and are required for comparisons between empirical energy losses and specific heating mechanisms. Xi Boo A has a measured magnetic field and follows a variety of field, rotation and line flux correlations found from wider studies of main-sequence stars.These can be understood only by elucidating the physics within a given stellar atmosphere. Xi Boo B can be observed separately to aid the interpretation of X-ray and EUVE fluxes. We will also apply for observing time with the HRI on ROSAT. ------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 2] Observations Description ------------------------ The observations requested are summarized in the Table below (c/f Table 3 of Phase I proposal). The tabulated wavelength is the centre of the passband required. The ions of interest for each exposure are given in decreasing order of priority. We acquire xi Boo A on Side 2, carry out AQU/PEAKUP, use G160M to observe fluxes and widths of lines of Si II, Si III] and CI], and the profiles of the Mg II lines with ECH-B. We then move to Side 1, use G140M to resolve lines of interest and to obtain the widths of the stronger lines, and G140L to obtain the fluxes in a wide range of lines, to determine the emission measure distribution. The observations will also give flux ratios from which the electron density can be determined. Because of the limit on the number of orbits at each visit, a second visit to xi Boo A is needed. We will again acquire on Side 2, and there is time to observe the Mg II profiles with ECH-B and the Si II lines with G160M before moving to Side 1. The remainder of the G140M exposures can then be made, and there is also time to repeat the G140L exposures, to check for flux variations between visits. (Observations with IUE show rotationally modulated variations of up to 20 percent). The exposure times for low and medium resolution observations have been calculated to give a S/N of about 20 on the weakest lines of interest. The ECH-B exposures will give a S/N of 20 in the region of the profiles which best constrain the chromospheric models. In the G140L and G140M exposures centered at 1293 and 1207 Angstroms, respectively, the geocoronal H Lyman alpha line will be the strongest feature; interstellar absorption will remove the core of the stellar line. In the G140M exposure centered at 1307 Angstroms the OI resonance lines will be the strongest feature, but the weaker Si III lines are the prime target. At the third visit, xi Boo B will be acquired on Side 2, and observations made of the Mg II profiles. We will then move to Side 1 where only low resolution spectra are proposed, to measure the fluxes. The exposure times have been calculated so that the most important line (usually the strongest) has a S/N of 20. The time per exposure allows for FP-SPLIT = STD. The fluxes in all the lines (xi Boo A plus B) are known from observations with IUE, and estimates of the contributions from the two stars are also available. Approximate line widths are available from IUE. The Large Science Aperture is requested throughout. The aquisitions should be made with the N2 mirror on Side 2. Summary of Observations: wave label grating length exp(S) lines ========================================================= Visit 1 - Xi Boo A 10 G160M 1812 652.8 Si II 11 G160M 1894 4243.2 Si III], C III] 12 ECH-B 2800 108.8 Mg II 13 G160M 1981 2937.6 C I] 30 G140M 1207 1088.0 Si III 31 G140M 1405 1740.8 Si IV, O IV] 32 G140M 1307 3590.4 Si III, O I, Si II 33 G140L 1593 217.6 C IV, He II, C I 34 G140L 1293 435.2 C III, N V, Si III Visit 2 - Xi Boo A 55 ECH-B 2800 108.8 Mg II 56 G160M 1812 435.2 Si II 60 G140L 1293 435.2 C III, N V, Si III 61 G140L 1593 217.6 C IV, He II, C I 62 G140M 1547 2828.8 C IV 63 G140M 1345 1088.0 C II, O I] Visit 3 - Xi Boo B 110 ECH-B 2800 217.6 Mg II 130 G140L 1293 2611.2 N V, C II, Si IV, SI III 131 G140L 1593 2176.0 C IV, He II, Si II 132 G140L 1757 2611.2 Si II, Si III] ========================================================= Real Time Justification ----------------------- None Calibration Justification ------------------------- None Additional Comments ------------------- We will apply for observations with the HRI on ROSAT, to spatially resolve the two stars in the X-ray band. Observations with ASCA will be made by J. Drake, with whom we are negotiating a collaboration. ------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD131156A STAR, G V-IV RA=14H 51M 23.28S +/- 0.1S, 2000 V=4 V = 4.55 DEC=+19D 06' 4.1" +/- 1.0" B-V = 0.72 TYPE=G8V F-LINE(1817)=4.7+/-0.4e-12 W-LINE(1817)=0.15+/-0.06 F-CONT(1830)=2.5+/-0.3e-13 F-LINE(1892)=3.0+/-0.3e-13 W-LINE(1892)=0.20+/-0.05 F-CONT(1905)=3.6+/-0.4e-13 Comments: The Lyman Alpha flux is dominated by Geocoronal F-LINE(1994)=2.8+/-0.3e-13 emmission. W-LINE(1994)=0.13+/-0.07 F-CONT(2007)=1.4+/-0.14e-12 F-LINE(2796)=2.8+/-0.14e-11 W-LINE(2796)=0.52+/-0.07 F-CONT(2785)=5.0+/-0.5e-12 F-LINE(1302)=1.4+/-0.14e-12 W-LINE(1302)=0.07+/-0.03 F-LINE(1394)=7.4+/-0.7e-13 W-LINE(1394)=0.26+/-0.05 F-LINE(1336)=8.5+/-0.8e-13 W-LINE(1336)=0.27+/-0.04 F-LINE(1216)=1.1e-12 W-LINE(1216)=0.47 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0096 -0.098 0.0 2 HD131156B STAR, K V-IV R = 6.7", PA=39.5D, FROM 1 2000 TYPE=K4V V = 6.6 B-V = 1.17 F-LINE(2796)=6.9+/-0.7e-12 W-LINE(2796)=0.52+/-0.07 Comments: The position offset of Xi Boo B will be confirmed when we are told the date that the observations are scheduled for. The Lyman Alpha flux is dominated by Geocoronal emmission. 6076( 7) - 06/19/96 11:35 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 HD131156A HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE = 3 1 5 S ONBOARD ACQuisition FOR 2 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 2 HD131156A HRS ACQ/PEA 2.0 MIRROR-N2 1 20.4 S ONBOARD ACQuisition FOR KUP 10-13 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 10 HD131156A HRS ACCUM 2.0 G160M 1812 FP-SPLIT = STD 1 652.8 S ------------------------------------------------------------------------------------------------------------------------------------ 11 HD131156A HRS ACCUM 2.0 G160M 1894 FP-SPLIT = STD 3 1414.4 ------------------------------------------------------------------------------------------------------------------------------------ 12 HD131156A HRS ACCUM 2.0 ECH-B 2800 FP-SPLIT = STD 1 108.8 S ------------------------------------------------------------------------------------------------------------------------------------ 13 HD131156A HRS ACCUM 2.0 G160M 1981 FP-SPLIT = STD 3 979.2 S ------------------------------------------------------------------------------------------------------------------------------------ 30 HD131156A HRS ACCUM 2.0 G140M 1207 FP-SPLIT = STD 1 1088 S ------------------------------------------------------------------------------------------------------------------------------------ 31 HD131156A HRS ACCUM 2.0 G140M 1405 FP-SPLIT = STD 2 870.4 S ------------------------------------------------------------------------------------------------------------------------------------ 32 HD131156A HRS ACCUM 2.0 G140M 1307 FP-SPLIT = STD 3 1196.8 ------------------------------------------------------------------------------------------------------------------------------------ 33 HD131156A HRS ACCUM 2.0 G140L 1593 FP-SPLIT = STD 1 217.6 S ------------------------------------------------------------------------------------------------------------------------------------ 34 HD131156A HRS ACCUM 2.0 G140L 1293 FP-SPLIT = STD 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 51 HD131156A HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE = 5 1 5 S ONBOARD ACQuisition FOR 52 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 52 HD131156A HRS ACQ/PEA 2.0 MIRROR-N2 1 20.4 S ONBOARD ACQuisition FOR KUP 55-56 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 55 HD131156A HRS ACCUM 2.0 ECH-B 2800 FP-SPLIT = STD 1 108.8 S ------------------------------------------------------------------------------------------------------------------------------------ 56 HD131156A HRS ACCUM 2.0 G160M 1812 FP-SPLIT = STD 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 60 HD131156A HRS ACCUM 2.0 G140L 1293 FP-SPLIT = STD 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 61 HD131156A HRS ACCUM 2.0 G140L 1593 FP-SPLIT = STD 1 217.6 S ------------------------------------------------------------------------------------------------------------------------------------ 62 HD131156A HRS ACCUM 2.0 G140M 1547 FP-SPLIT = STD 2 1414.4 ------------------------------------------------------------------------------------------------------------------------------------ 63 HD131156A HRS ACCUM 2.0 G140M 1345 FP-SPLIT = STD 1 1088 S ------------------------------------------------------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 7] Visit: 03 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 ------------------------------------------------------------------------------------------------------------------------------------ 101 HD131156B HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE = 5 1 5 S ONBOARD ACQuisition FOR 102 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 102 HD131156B HRS ACQ/PEA 2.0 MIRROR-N2 1 20.4 S ONBOARD ACQuisition FOR KUP 110 Comments: STEP-TIME = 0.2S ------------------------------------------------------------------------------------------------------------------------------------ 110 HD131156B HRS ACCUM 2.0 ECH-B 2800 FP-SPLIT = STD 1 217.6 S ------------------------------------------------------------------------------------------------------------------------------------ 130 HD131156B HRS ACCUM 2.0 G140L 1293 FP-SPLIT = STD 2 1305.6 ------------------------------------------------------------------------------------------------------------------------------------ 131 HD131156B HRS ACCUM 2.0 G140L 1593 FP-SPLIT = STD 2 1088 S ------------------------------------------------------------------------------------------------------------------------------------ 132 HD131156B HRS ACCUM 2.0 G140L 1757 FP-SPLIT = STD 2 1305.6 ------------------------------------------------------------------------------------------------------------------------------------ 6076( 7) - 06/19/96 11:35 - [ 8] Summary Form for Proposal 6076 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACQ/PEAKUP ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE = 3 FP-SPLIT = STD SEARCH-SIZE = 5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQuisition FOR 2 ONBOARD ACQuisition FOR 10-13 ONBOARD ACQuisition FOR 52 ONBOARD ACQuisition FOR 55-56 ONBOARD ACQuisition FOR 102 ONBOARD ACQuisition FOR 110 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ECH-B G140M G140L ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD131156A HD131156B ------------------------------------------------------------------------------------------------------------------------------------