Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3845c Report Date: 09-May-96:18:52 Version: ********** Check-in Date: ********** 1.Proposal Title: DECIPHERING THE UV EMISSION LINES IN T TAURI SYSTEMS ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO 3845 Sub Category EARLY EVOLUTION ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Gibor Basri UNIV. OF CALIFORNIA, BERKELE USA 415-642-8198 ------------------------------------------------------------------------------------ 7. Abstract Currently there is complete confusion as to the physical origin of the UV emission lines in T Tauri stars, although they are the strongest known UV emissions from cool stars. Possibilities include closed magnetic field loops in analogy to active main sequence stars, a hot region in an Alfven wind, the accretion boundary layer between star and disk, accretion columns in the stellar magnetic field, or some other region associated with a disk-generated wind. Emission measure analyses have been unable to distinguish between the possibilities listed above. What is clearly needed is line profile information: in particular a good measurement of the breadth of the profiles and a reasonable idea of their symmetry. Narrow lines will indicate plasma originating either on the stellar surface or in closed magnetic loops. Broad lines will indicate a turbulent boundary layer or wind region. The asymmetry of the lines will indicate whether they arise in accretion, outflow, or relatively static plasma, and something about the size of the region (via occulation effects). Taken with some emission measures, density diagnostics, and wind diagnostic information, the current mystery about the origin of these strong hot emission lines can be illuminated. We propose to measure enough profiles and emission measures in a representative small sample of stars to constrain, support or eliminate the above hypotheses. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 5.42 par: 0 10. Num targs pri: 5 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: HRS ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3845c PI: Gibor Basri Proposal Title: DECIPHERING THE UV EMISSION LINES IN T TAURI SYSTEMS ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Gibor Basri UNIV. OF CALIFORNIA, BERKELEY USA Frederick M Walter STATE UNIV. OF NEW YORK AT STONY USA BROOK Lee Hartmann HARVARD-SMITHSONIAN CENTER FOR USA ASTROPHYSICS Nuria Calvet CENTRO DE INVESTIGACIONES DE VENEZUELA ASTRONOMIA ------------------------------------------------------------------------------------ 3. Description of proposed observations. Our program for each star will be: (1) an exposure using G160M to achieve S/N of 20 in the Si IV lines at a resolution of 20000; this will also include the density sensitive O IV lines, (2) exposures using G160M to obtain line fluxes in the 1345A, 1555A, and 1640A regions as feasible (which include C I, O I, CII, He II, Fe II and other ions) to get profiles and deblend complexes, and (3) an exposure using G270M to obtain a high resolution profile of Mg II at 2800A. We will read out the spectra every 5 minutes in order to mitigate against geo- magnetically induced image motion. This will also give some indication if there is very short time-scale variability in the lines. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. We are pursuing observations of the UV lines in TTS for several reasons. 1) They are the only direct diagnostics of the transition region plasma and accretion shock plasma available. 2) Because they are not very optically thick their interpretation is much easier than optical lines. 3) They are the only lines with which to distinguish a number of competing hypotheses about the relation between coronae and winds in TTS, and should be very helpful in understanding the wind generation region and the interface between star and disk. IUE observations at low resolution have been pursued for many TTS (Imhoff and Appenzeller 1987). These are primarily longward of 2000A, and concentrated on the flux in the Mg II lines (which are analogous to the Ca II lines). There are some low S/N low resolution observations of the lines shortward of 2000A, and those provide the justification for this proposal without accomplishing its science. That data has been insufficient to allow examination of the many hypotheses tested here, and has been only interpretable in terms of a solar analogy which misses the main properties unique to CTTS - the wind and disk accretion. The IUE data suffers severe blending, which precludes use of the denstiy diagnostics in this proposal. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. One of the scientific goals is to interpret the profiles and features in them in terms of accretion and outflow. To be sure about this, we must have the velocity in the stellar frame accurately known (to a few km/s). Previous experience has shown that sometimes features are near line center and an accurate velocity scale is crucial to their interpretation. To be safe, we are requesting wavelength calibration exposures for the Si IV profile observations, so there will be no question whether a profile peak or dip is red or blue shifted, and by how much. The other exposures can be interpreted safely with only the standard calibration, once we have done this. Page 3 ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Since one of us (FW) is a GTO and intimately familiar with GHRS, he will be primarily responsible for receiving the data from the Institute, and putting it into a form that is amenable for analysis. FW and GB will concentrate on the "active star" analysis. This will include an emission measure analysis of the low dispersion spectrum, and any measurements we have managed with other instruments on chromospheric or coronal diagnostics. GB and LH will compare the profiles with their extensive collections of optical echelle spectra (lines of H, Ca II, Na I, He I, etc.). They will also consider to what extent the UV data is consistent with an origin in the boundary layer. This will include looking for the double-peaked signature of ring-like regions, and comparing the velocity width to the Keplarian expectation near the star. The primary profile modelling will be done by NC, in collaboration with LH and GB and his students. The general procedure for hydrogen is given by Hartmann et al.(1990). GB has a number of optically thin codes also available which work in a variety of geometries. NC is presently working on extending the escape probability treatment to more generalized geometries, in particular to a dipole-type geometry, to obtain a better description of the flow in the magnetosphere. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. We will use the GASP astrometric system to improve target coordinates prior to scheduling of the observations. GB will obtain optical echelle spectra of the targets as close to the HST observations as possible. FW will obtain data on NTTS as part of his GTO program which will be very useful in understanding what the purely stellar component of the UV emissions looks like. His program 1209 will look at HDE283572, SAO76411A, and V410 Tau with high resolution in the Mg II and Si IV regions, and also obtain low resolution spectra of these stars without disks which will be directly comparable to the spectra obtained in this program. That program does not overlap with this one, but is very complementary. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Fred Walter is involved with the following programs: 1207 Ultraviolet Tomography This observation has yet to be undertaken. of V471 Tauri It bears no relation to this proposal. (GTO, cycle 2) 1208 Doppler Imaging of the This observation has yet to be undertaken. Chromospheres and It bears no relation to this proposal. Transition Regions of AR Lacertae (GTO, cycle 1) 1209 Non-radiative Heating This observation has yet to be undertaken. in Pre-Main Sequence This proposal, including augmentation targets, Stars studies NTTS and extreme CTTS at high dispersion, (GTO, cycle 1) and using G140L with shorter exposure times (no overlap in targets; no normal CTTS done) 1210 Age Dependence of Two spectra have been obtained to date. Non- radiative Heating There is no relation to this proposal, but the in Stellar Chromospheres spectra will be useful for comparison. (GTO, cycle 0) Lee Hartmann is involved with the following program: ???? The Formation and Evolution This proposal has yet to be undertaken. of Solar Nebulae Surrounding It bears no direct relation to this Pre-Main Sequence Stars program (it involves imaging). (GO, cycle 1) (S.Strom, PI) Page 4 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). FW has access to the full range of GHRS team software for data extraction and analysis. GB has access to IDL and various radiative transfer codes. LH and NC have many powerful radiative transfer codes. We all have computer facilities which will allow both analysis of spectra and the running of various models to interpret the data. We are requesting some computing funds to support this, but no hardware or software acquisitions. GB and FW have thesis students who are working on aspects of this problem and will include work on this proposal in their dissertations. GB has the use of Lick Observatory which is flexible about getting echelle data on reasonably short notice (using a coude feed and the Hamilton spectrograph). We also have access to automated photometric monitoring, which will be valuable in assessing the activity state of the targets. ------------------------------------------------------------------------------------ 11. Address Information Name: GIBOR BASRI Category: PI Institution: UNIV. OF CALIFORNIA Address: ASTRONOMY DEPARTMENT City: BERKELEY State: CA Zip Code: 94720 Country: USA Telephone: 415-642-8198 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3845c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 BP-TAU GSC- A,156,139 PLATE-ID=0051, 2000 V = +16 1 V = 11.6 +/- 0.5, TYPE = K7 IV 554 RA = 04H 19M 15.86S +/- 1 A(V) = 1.0 +/- 0.3, B-V = 1.1 +/- 0.3S, 1 0.3 DEC = +29D 06' 27.22" +/- 1 F-LINE(1550) = 1 +/- 0.5 E-13 0.3S 1 W-LINE(1550) = 1 +/- 0.5 1 F-LINE(2880) = 9 +/- 1 E-13 W-LINE(2880) = 2.4 +/- 0.3 Comments: SOURCE IS QUITE VARIABLE PARTICULARLY IN THE ULTRAVIOLET ------------------------------------------------------------------------------------------------------------------------------------ 2 DF-TAU GSC- A,156,139 PLATE-ID=000L, 2000 V = +16 1 V = 11.8 +/- 0.5, TYPE = K7 IV 525 RA = 04H 27M 02.80S +/- 1 A(V) = 1.0 +/- 0.3, B-V = 1.1 +/- 0.3S, 1 0.3 DEC = +25D 42' 23.11" +/- 1 F-LINE(1550) = 1.5 +/- 0.5 E-13 0.3S 1 W-LINE(1550) = 1 +/- 0.5 1 F-LINE(2880) = 1 +/- 1 E-12 W-LINE(2880) = 2 +/- 0.5 Comments: SOURCE IS QUITE VARIABLE PARTICULARLY IN THE ULTRAVIOLET ------------------------------------------------------------------------------------------------------------------------------------ 3 DR-TAU GSC- A,156,139 PLATE-ID=00FI, 2000 V = +16 1 V = 11.05 +/- 0.5, TYPE = M0 IV 1233 RA = 04H 47M 06.22S +/- 1 A(V) = 1.0 +/- 0.3, B-V = 0.8 +/- 0.3S, 1 0.2 DEC = +16D 58' 43.39" +/- 1 F-LINE(1550) = 1 +/- 0.5 E-13 0.3S 1 W-LINE(1550) = 1 +/- 0.5 1 F-LINE(2880) = 1.3 +/- 1 E-12 W-LINE(2880) = 2 +/- 0.5 Comments: SOURCE IS QUITE VARIABLE PARTICULARLY IN THE ULTRAVIOLET ------------------------------------------------------------------------------------------------------------------------------------ 4 RW-AUR GSC- A,156,139 PLATE-ID=00DH, 2000 V = +16 1 V = 10.35 +/- 0.5, TYPE = K5 IV 955 RA = 05H 07M 49.51S +/- 1 A(V) = 1.0 +/- 0.3, B-V = 0.7 +/- 0.3S, 1 0.2 DEC = +30D 24' 05.47" +/- 1 F-LINE(1550) = 2 +/- 0.5 E-13 0.3S 1 W-LINE(1550) = 1.5 +/- 0.5 1 F-LINE(2880) = 8 +/- 2 E-13 W-LINE(2880) = 2.8 +/- 0.4 Comments: SOURCE IS QUITE VARIABLE PARTICULARLY IN THE ULTRAVIOLET ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3845c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 BP-TAU HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 5.4S 1 CYCLE 2 ONBOARD ACQ FOR 1.3-1.6 ------------------------------------------------------------------------------------------------------------------------------------ 1.3 BP-TAU HRS ACCUM 2.0 G270M 2800 STEP-PATT=DEF 2 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 1.4 WAVE HRS ACCUM SC2 G160M 1400 STEP-PATT=DEF 1 1M 2 CYCLE 2 CALIB FOR 1.5 SEQ 1.4-1.5 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 1.5 BP-TAU HRS ACCUM 2.0 G160M 1400 STEP-PATT=DEF 6 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 1.6 BP-TAU HRS ACCUM 2.0 G160M 1550 STEP-PATT=DEF 5 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2 DF-TAU HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 3.6S 1 CYCLE 2 ONBOARD ACQ FOR 2.3-2.7 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 DF-TAU HRS ACCUM 2.0 G270M 2800 STEP-PATT=DEF 2 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2.4 WAVE HRS ACCUM SC2 G160M 1400 STEP-PATT=DEF 1 1M 2 CYCLE 2 CALIB FOR 2.5 SEQ 2.4-2.5 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 2.5 DF-TAU HRS ACCUM 2.0 G160M 1400 STEP-PATT=DEF 4 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2.6 DF-TAU HRS ACCUM 2.0 G160M 1550 STEP-PATT=DEF 4 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2.7 DF-TAU HRS ACCUM 2.0 G160M 1345 STEP-PATT=DEF 5 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 DR-TAU HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 1 CYCLE 2 ONBOARD ACQ FOR 3.3-3.8 ------------------------------------------------------------------------------------------------------------------------------------ 3.3 DR-TAU HRS ACCUM 2.0 G270M 2800 STEP-PATT=DEF 1 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3.4 WAVE HRS ACCUM SC2 G160M 1400 STEP-PATT=DEF 1 1M 2 CYCLE 2 CALIB FOR 3.5 SEQ 3.4-3.5 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 3.5 DR-TAU HRS ACCUM 2.0 G160M 1400 STEP-PATT=DEF 6 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3.6 DR-TAU HRS ACCUM 2.0 G160M 1550 STEP-PATT=DEF 6 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3.7 DR-TAU HRS ACCUM 2.0 G160M 1345 STEP-PATT=DEF 5 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3.8 DR-TAU HRS ACCUM 2.0 G160M 1650 STEP-PATT=DEF 4 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4 RW-AUR HRS ACQ 2.0 MIRROR-N2 BRIGHT=RETURN 1 1.8S 1 CYCLE 2 ONBOARD ACQ FOR 4.3-4.6 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3845c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 4.3 RW-AUR HRS ACCUM 2.0 G270M 2800 STEP-PATT=DEF 1 5M 10 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4.4 WAVE HRS ACCUM SC2 G160M 1400 STEP-PATT=DEF 1 1M 2 CYCLE 2 CALIB FOR 4.5 SEQ 4.4-4.5 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 4.5 RW-AUR HRS ACCUM 2.0 G160M 1400 STEP-PATT=DEF 3 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4.6 RW-AUR HRS ACCUM 2.0 G160M 1550 STEP-PATT=DEF 3 5M 10 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3845c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations HRS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BRIGHT=RETURN STEP-PATT=DEF ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 5.42 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category EARLY EVOLUTION ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 2; ONBOARD ACQ FOR 1.3-1.6 CYCLE 2 CYCLE 2; CALIB FOR 1.5; SEQ 1.4-1.5 NO GAP CYCLE 2; ONBOARD ACQ FOR 2.3-2.7 CYCLE 2; CALIB FOR 2.5; SEQ 2.4-2.5 NO GAP CYCLE 2; ONBOARD ACQ FOR 3.3-3.8 CYCLE 2; CALIB FOR 3.5; SEQ 3.4-3.5 NO GAP CYCLE 2; ONBOARD ACQ FOR 4.3-4.6 CYCLE 2; CALIB FOR 4.5; SEQ 4.4-4.5 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR-N2 G270M G160M ------------------------------------------------------------------------------------------------------------------------------------ Target Names BP-TAU GSC-554 DF-TAU GSC-525 DR-TAU GSC-1233 RW-AUR GSC-955 ------------------------------------------------------------------------------------------------------------------------------------