6691( 6) - 09/24/96 11:07 - [ 0] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6691 Version: 6 Check-in Date: 24-Sep-1996 11:03:50 1.Proposal Title: Probing the Dynamo for Stars with Shallow Convection Zones: The Young F0V Star 47 Cas ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COOL STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Edward Guinan VILLANOVA UNIVERSITY CoI: Manuel Guedel Paul Scherrer Institut N CoI: Juergen H.M.M. Schmitt Max Planck Institut fuer N Extraterrestrische Physik CoI: Paul Etzel San Diego State University N ------------------------------------------------------------------------------------ 6. Abstract Our target 47 Cas = HD 12230, a single main-sequence star of spectral type F0V, has recently been recognized as one of the most active stars on the cooler half of the main sequence. Its unusually luminous X-ray (logL_ X = 30.5) and radio corona finds its lower temperature analog in very intense chromospheric and transition region line emissions as evidenced in our first IUE spectra. Evidence for high-level magnetic activity is unusual for an F0 star, but the probable age of 47 Cas, ~ 50-70 Myr, puts it close to the Zero-Age Main-Sequence. High-level magnetic dynamo activity could perhaps be related to particular, probably brief evolutionary stages in such young stars. We have searched for evidence of a close, cooler companion to 47 Cas, but have found no evidence for such a star. With the present proposal, we will address a series of questions relevant to studies of magnetic activity for which 47 Cas is an important target: i) How does extreme chromospheric activity on an F0 star with a very shallow convective zone compare with the more familiar solar counterpart? ii) Is the chromosphere structured as possibly evidenced in rotational modulation? iv) Do winds co-exist with the corona (asymmetries in the emission line profiles and possibly P Cygni features in the UV)? v) Are the line profiles compatible with a single star? It is only with HST that these important questions can be fully answered. ------------------------------------------------------------------------------------ Observations Description ------------------------ In an investigation of chromospheric and transition-region activity, most of the important diagnostic lines lie in the UV, between 1150--2000Angstrom. Although the strong chromospheric line emissions of MgII h+k Lambda2795+2802Angstrom\\ and CaII H+K Lambda3934+3968 are also important, it is difficult to measure these lines against the very intense photospheric continuum background of the F0V star at the wavelengths where these features occur. With the HRS (using grating G160M) we can obtain medium resolution (R~ 23,000) spectra with good signal-to-noise of most of the important spectral features. The bandwidths of the G160M/HRS spectra are about 33--35Angstrom\\ which is frequently wide enough to contain two or more emission lines and at longer wavelengths will include numerous photospheric features of the F0V star. The chromospheric and transition- region emission lines chosen here include NV Lambda1240 (T ~ 2-3\\cdot 10^5 K), CII Lambda1335 (T ~ 15\\cdot 10^3 K), SiIV Lambda1393,Lambda1402 (T ~ 50-100\\cdot 10^3 K), CIV Lambda1550 (T ~ 1\\cdot 10^5 K), HeII Lambda1640 (T ~ 2- 5\\cdot 10^5 K), CI Lambda1658 (T ~ 8\\cdot 10^3 K), and the intersystem lines of SiIII Lambda1892 and CIII Lambda1909 (T ~ 30-70\\cdot 10^3 K). The above lines cover temperatures from 8\\cdot 10^3 K up to 500\\cdot 10^3 K and are sufficient to carry out volume emission measure (VEM) analysis of the atmosphere from the low chromosphere to the edge of the transition region/corona boundary. From there on, ROSAT/ASCA spectral analysis can be used for coronal temperatures between 10^6 K and 10^8 K. Most of these features are expected to be strong (based on our low dispersion IUE spectra), except the SiIII Lambda1892 and the CIII Lambda1909 intersystem lines. However, the latter two lines provide an extremely important and unique diagnostic for determining the pressure and density of the emitting TR plasma (see Jordan & Linsky 1987). In models of active regions on the Sun, the SiIII/CIII line ratio is directly correlated with the density of the emitting plasma (Doschek et al. 1978) We will further use the spectral lines to investigate whether a hidden chromospherically active secondary star is present. This is done by measuring the radial velocities and the vsini's of the strongest emission features such as C II Lambda 1335, C IV Lambda 1550, and He II Lambda 1640 + C I Lambda 1660. The RV's and the vsini of the absorption lines of the F star have been measured in the optical from an ongoing spectroscopic program being conducted at SDSU. Also, the RV's and the line profiles of the F star's photospheric absorption lines that appear in the HST spectra will be identified and measured. For a single star, RV and vsini will be unique for the chromospheric/TR emission line and photospheric absorption line features. noindentunderbarWe request 9 orbits for this project, starting with 4 consecutive orbits (to increase efficiency, and to avoid too much intrinsic stellar variability for line comparisons): beginitemize item Orbit 1: Wavecal, then , 30 min G160M centered at Lambda 1240 to get NV Lambda 1240 and SiII Lambda 1260. item Orbit 2: Wavecal, then , 20 min at CII Lambda 1335, then, 25 min at SiIV Lambda 1393 and Lambda 1402. item Orbit 3: Wavecal, then , 25 min at CIV Lambda 1550 and continuum absorption lines of F0 V star, then , 20 min at HeII Lambda 1640 and CI Lambda 1660 and photospheric lines of F0V star. item Orbit 4: Wavecal, then , two 23 min exposures centered at Lambda1900 to include SiIII Lambda 1892 and CIII Lambda 1909 plus photospheric features of F0V star (co-added to yield higher S/N for these weaker lines) item Orbit 5: Wavecal, then , 25 min at CIV Lambda1550, then , 20 min at CII Lambda1335 item Orbit 6-9: Four orbits spread over the next 1--1.5 d (simP_ rot of F star), similar to Orbit 5, to study variability of RV, strengths and profile shapes of the CII Lambda1335 (exp.=20min) and CIV Lambda 1550 (exp.=20min) lines (investigate winds, outflows/inflows, flares), and attempt crude Doppler Imaging if moving features are present within the profiles. enditemize 7.0in begincenter begintabularlrrrrrr multicolumn7c Table 2. Exposure estimates for selected lines; HRS/Side 2/G160M LSA , spectral & f_Lambda^a 1truecm \\ & Sensitivity ^b & ct/s/ & expos. & Estim. & S/N , lines, Angstrom &(erg/cm^2/s/Angstrom) & & \\quad diode & (s) & ct/diode & , NV 1240, SiII 1260 & 2.5\\cdot 10^-14& 5.99\\cdot 10^11 & 0.015 & 1800 & 27 & ~5 , CII 1335 doublet & 8\\cdot 10^-14 & 7.90\\cdot 10^11 & 0.063 & 1200 & 76 & ~9 , SiIV 1393/1402 & 9\\cdot 10^-14& 5.48\\cdot 10^11 & 0.049 & 1500 & 74 & ~8 , CIV 1548/51 & 23\\cdot 10^-14 & 4.05\\cdot 10^11 & 0.093 & 1500 & 140 & ~12 , HeII 1640, CI 1658 & 40\\cdot 10^-14 & 3.89\\cdot 10^11 & 0.156 & 1200 & 187 & ~14 , SiIII 1892, CIII 1909&~80\\cdot 10^-14 & 4.36\\cdot 10^11 & 0.35 & 1400 & 490 & ~22 , endtabular endcenter Notes: ^a Obtained from IUE SWPLLO spectra. ^b From HRS Instrument Handbook 0.5truecm par Data Reduction and Analysis 0.5truecm The data will be reduced using CALHRS routines produced by the HRS Science Team in IDL and available at GSFC and at Villanova University. The observations will be reduced and analyzed chiefly by Guinan and Guedel. Schmitt will collaborate in using his expertise in stellar magnetic activity in particular in coronal emissions (X-rays, also FUV). Etzel will be conducting spectroscopic observations of the target from Mt. Laguna Observatory and also will be collaborating in the analysis and interpretation of the UV emission and absorption line profiles. He is familiar with IRAF routines. Guinan and Guedel will coordinate ground- based optical, VLA, ASCA, & EUVE observations if feasible. Modeling of the UV data will be carried out with existing codes available at Villanova University or at Harvard- Smithsonian CfA. The lines will be analyzed for variability in the net flux, radial velocity, and shape; further, for indication of local plasma outflows/inflows, and winds. With an observed projected rotation velocity of \\nopagebreak vsini ~ 95 km s^-1, the HRS/G160M grating would provide about 6 resolution elements across the star. This would allow us to perform crude Doppler Imaging if discrete features are visible in the lines. Real Time Justification ----------------------- There are no special requirements for this observation except that the observations be carried out over the course of about 1-1.5 days. The first five orbits should be contiguous to save time so that the target does not have to be re-acquired. During the last several years, we and our collaborators have been carrying out intensive ground-based optical (photometry and spectroscopy) and VLA/VLBI radio observations of the target. Further, we have obtained ROSAT/PSPC X-ray observations (from the Survey), and additional ROSAT/HRI observations have been approved for 1996 together with a new VLA run. During 1994/95, several IUE SWP low resolution spectra were obtained, showing strong chromospheric/transition region lines. While the HRS observations proposed here do not require supporting observations and the scientific goals can be achieved with these observations alone, we will continue our diverse programs and will in particular coordinate ongoing ground- based photoelectric photometry (Villanova Univ. telescope) and spectroscopy (SDSU, 1M reflector) with the requested HRS observations. Also, we are submitting proposals for ASCA (0.5 -10 keV X-rays) and the EUVE (80--800 Angstrom) satellite for 1996/97 (proposals due Sept./Oct. 1995). If feasible, we will try to coordinate satellite time with HST. If the HST observations are approved, we will request additional VLA (3.6--20 cm) observing time simultaneous with HST. As far as possible, we will attempt a multi-frequency campaign to coincide with the HRS observations. This will be of particular interest to monitor time-variable phenomena, i.e., rotational modulation and flaring. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6691( 6) - 09/24/96 11:07 - [ 1] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 47CAS STAR,F0-F2, RA=02H 05M 7.39S +/- J2000 V = -6 V = 5.30 0.03S,DEC=77D 16' 52.6" +/- 0.1" B-V = 0.42+/-0.02 Comments: Coordinates from Hipparcos INCA Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J2000.000 0.039 -0.053 0.025 6691( 6) - 09/24/96 11:07 - [ 2] 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 47CAS HRS ACQ 2.0 MIRROR-N1 SEARCH-SIZE=5 1 30 S SEQ 10-30 NON-INT ONBOARD ACQ FOR 20-110 Comments: steptime = 1.2 ------------------------------------------------------------------------------------------------------------------------------------ 20 47CAS HRS ACCUM 2.0 G140L 1300 FP-SPLIT=FOUR 1 761.6 S ------------------------------------------------------------------------------------------------------------------------------------ 30 47CAS HRS ACCUM 2.0 G140L 1580 FP-SPLIT=FOUR 1 544.0 S ------------------------------------------------------------------------------------------------------------------------------------ 40 47CAS HRS ACCUM 2.0 G140M 1215 FP-SPLIT=FOUR 1 1196.8 SEQ 40-50 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 50 47CAS HRS ACCUM 2.0 G140M 1345 FP-SPLIT=FOUR 1 1305.6 ------------------------------------------------------------------------------------------------------------------------------------ 60 47CAS HRS ACCUM 2.0 G140L 1300 FP-SPLIT=FOUR 1 435.2 S SEQ 60-80 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 70 47CAS HRS ACCUM 2.0 G140L 1580 FP-SPLIT=FOUR 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 80 47CAS HRS ACCUM 2.0 G140M 1550 FP-SPLIT=FOUR 1 1196.8 ------------------------------------------------------------------------------------------------------------------------------------ 90 47CAS HRS ACCUM 2.0 G140M 1640 FP-SPLIT=FOUR 1 1196.8 SEQ 90-110 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 100 47CAS HRS ACCUM 2.0 G140L 1300 FP-SPLIT=FOUR 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 110 47CAS HRS ACCUM 2.0 G140L 1580 FP-SPLIT=FOUR 1 435.2 S ------------------------------------------------------------------------------------------------------------------------------------ 6691( 6) - 09/24/96 11:07 - [ 3] Summary Form for Proposal 6691 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE=5 FP-SPLIT=FOUR ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 10-30 NON-INT ONBOARD ACQ FOR 20-110 SEQ 40-50 NON-INT SEQ 60-80 NON-INT SEQ 90-110 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N1 G140L G140M ------------------------------------------------------------------------------------------------------------------------------------ Target Names 47CAS ------------------------------------------------------------------------------------------------------------------------------------