6647( 4) - 06/11/96 15:39 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6647 Version: 4 Check-in Date: 11-Jun-1996 15:34:59 1.Proposal Title: A NEW TOOL FOR PROBING MAGNETIC ACTIVITY WITH CIV LINE PROFILES ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COOL STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: OSMI VILHU UNIVERSITY OF HELSINKI CoI: Juhani Huovelin University of Helsinki Observatory N CoI: Panu Muhli University of Helsinki Observatory N CoI: Diana Hannikainen University of Helsinki Observatory N CoI: Pasi Hakala University of Oxford Physics Dept. N ------------------------------------------------------------------------------------ 6. Abstract One of the major discoveries of the GHRS has been the detection of bimodal structures and broad wings of the CIV 1550 lines in some cool stars. In AB Doradus (Vilhu et al. 95), for example, the quiescent (rotationally deconvolved) profile is well fitted by two Gaussians with roughly equal emission measures: a 'narrow' component with FWHM = 70 km/sec and a broad one with FWHM = 330 km/sec. Qualitatively similar profiles were found earlier in Capella (Linsky et al. 95), AU Mic (Linsky and Wood, 94) and recently HR 1099 (Wood et al. 95). These two distinct velocity fields may be related to the observed two-temperature coronal structures and might be crucial in understanding how coronal heating takes place. To put the idea into a more quantitative basis we shall observe two solar type dwarfs ( Chi1 Ori = HD39587 and Sigma2 CrB = TZ CrB = HD146361) with medium and high activity levels, respectively) using HRS/G160M during the 4 orbits allocated (2 orbits for both targets). These data will be complemented with solar spectra from the SUMER spectrometer on board SOHO. One expects the broad component to become broader and more dominant with increasing activity level. Further, the line widths and intensities should correlate with the coronal temperatures and emission measures, respectively. If this is true, the energetic reservoir of the coronal heating lies in the kinetic energies of these two velocity fields (microflaring regions on stellar surfaces). ------------------------------------------------------------------------------------ 6647( 4) - 06/11/96 15:39 - [ 2] Observations Description ------------------------ Our aim is to obtain CIV line profiles of Chi1 Ori and Sigma2 CrB using the HRS with the G160M grating (in the ACCUM mode). Two orbits will be used for both targets. The G160M grating is ideal since its resolution is the same (15 km/sec) as the thermal broadening. A higher resolution gives nothing better for our purposes and the lower one loses the stellar velocity fields we are studying. The exposure times were estimated using our experience in observing AB Doradus (Fig.1 on p.6 , from our cycle 4 program 5310). The total line fluxes are known for each of the targets from previous IUE observations. The 30 minute exposure time (in the quiescent) gives a good spectrum for AB Doradus: this can be fitted with narrow and broad components with a sufficiently high statistics. We expect that the same is true for the other targets if 30 minutes is multiplied by f_CIV(AB Dor)/f_CIV(star). Actually, both targets are expected to have narrower profiles because AB Dor is an extremely rapid rotator (100 km/s) and its intrinsic lines are broad. Hence, for our targets we expect to obtain a somewhat better S/N. We estimated that 2 orbits give a sufficient S/N spectrum for both targets. By dividing the exposure into smaller pieces we can eliminate possible flares. Real Time Justification ----------------------- We have no requirements. We shall use efforts to find the accurate binary phases of Sigma2 CrB (= TZ CrB) during the ST observations (needed for the line profile modelling). This will not be a problem since the star is frequently observed by many observers. We shall contact people observing it and if needed apply for our own time at the Nordic Optical Telescope NOT. The stars are well studied in all wavelengths: to correlate our CIV line profiles with other activity indicators will not be a problem. It should be remarked that most of our scientific goals can be performed just with the proposed HRS observations: to study the line component widths and relative intensities as a function of the total line emission. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6647( 4) - 06/11/96 15:39 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD39587 STAR,G V-IV, RA=05H 54M 22.94S +/- J2000 V = - V = 4.403+/-0.002 0.1",DEC=20D 16' 34.3" +/- 0.1" 13.4 B-V = 0.594+/-0.008 TYPE=G0V F-LINE(1550)=1.1+/-0.2e-12 W-LINE(1550)=0.5+/-0.2 F-CONT(1550)=1e-13 Comments: Coordinates are from Hipparcos INCA. Target is an astrometric binary. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0135 -0.090 0.101 2 HD146361 STAR,F3-F9,RS CVN STAR, RA=16H 14M 41.19S +/- J2000 V = - V = 5.80+/-0.10 0.1",DEC=33D 51' 31.6" +/- 0.1" 14.6 TYPE=F8V B-V = 0.58+/-0.04 F-LINE(1550)=3.1+/-0.1e-12 W-LINE(1550)=0.5+/-0.2 F-CONT(1550)=1e-13 Comments: Coordinates are from Hipparcos INCA. Target is a known variable with a variation amplitude smaller than 0.2 mag. There is another star 0.9 mag fainter 1.6 arcseconds (epoch J2000) away from the target. Based on IUE observations there should be no significant contamination from the other star even though LSA is used. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000 -0.0218 -0.079 0.042 6647( 4) - 06/11/96 15:39 - [ 4] 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 HD39587 HRS ACQ 2.0 MIRROR-N2 1 1.8 S ONBOARD ACQ FOR 20 Comments: STEP-TIME=2.0S ------------------------------------------------------------------------------------------------------------------------------------ 20 HD39587 HRS ACCUM 2.0 G160M 1533-15 FP-SPLIT=STD 20 217.6 S 67 ------------------------------------------------------------------------------------------------------------------------------------ 6647( 4) - 06/11/96 15:39 - [ 5] 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 HD146361 HRS ACQ 2.0 MIRROR-N2 SEARCH-SIZE=5 1 5.0 S ONBOARD ACQ FOR 20 Comments: STEP-TIME=2.0S There is another star 0.9 mag fainter and about 1.5 arcseconds away from the target. ------------------------------------------------------------------------------------------------------------------------------------ 20 HD146361 HRS ACCUM 2.0 G160M 1533-15 FP-SPLIT=STD 19 217.6 S 67 ------------------------------------------------------------------------------------------------------------------------------------ 6647( 4) - 06/11/96 15:39 - [ 6] Summary Form for Proposal 6647 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FP-SPLIT=STD SEARCH-SIZE=5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 20 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names HD39587 HD146361 ------------------------------------------------------------------------------------------------------------------------------------