! Hubble Space Telescope Cycle 6 (1996) Phase II Proposal Template ! $Id: 6722,v 6.1 1996/10/28 22:24:54 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Karla Peterson ! Phone: 410-338-4774 , E-mail: peterson@stsci.edu ! ! This partially completed template was generated from a Phase I proposal. Proposal_Information ! Section 4 Title: Probing the Chromospheric Structure of Alpha Tau Proposal_Category: GO Scientific_Category: COOL STARS Cycle: 6 Investigators PI_name: Kenneth Carpenter PI_Institution: Laboratory for Astronomy and Solar Physics CoI_Name: Richard Robinson CoI_Institution: Computer Sciences Corporation Contact: ! Y or N (designate at most one contact) CoI_Name: Carole Jordan CoI_Institution: Oxford University Contact: ! Y or N (designate at most one contact) CoI_Name: Andrew McMurry CoI_Institution: Oxford University Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) Fluorescent H_2 lines (excited by Hydrogen LyAlpha) and Ca II lines formed by recombination after photoionization by H LyAlpha were recently seen in GHRS spectra of the K5 III star Alpha Tau. This is the first time these lines have been seen in a giant star. The presence of these lines provides an opportunity to probe the structure of the upper chromosphere (Ca II) and of the low chromosphere/temperature minimum region (H_2) in this star and to test existing and new theoretical models of the outer atmosphere of Alpha Tau. In addition, the H_2 lines allow us to probe cooler regions than possible using the standard atomic emission line diagnostics and thus enable us to test the hypothesis of Wiedemann et al. (1994 ApJ 423, 806) that the atmosphere of cool giants are thermally bifurcated in the region above the photosphere. We propose to obtain, during Cycle 6, observations of the full set of Ca II and H_2 lines needed to perform these analysis and tests and to use these data to create new models of the chromosphere of Alpha Tau. Questions ! Free format text (please update) Observing_Description: We propose to acquire spectra of five wavelength regions, previously unobserved by GHRS, in the UV spectrum of Alpha Tau to obtain the additional H_2 and Ca II lines required for the analyses described above. In addition, we propose to obtain repeat spectra of the region around C IV to get contemporaneous measurements of the H_2 and Ca II lines discovered in the Cycle 4 data, to guard against variability in these lines which would render ratios to the lines in other regions meaningless. This repeat spectrum will also allow us to check for variability in the broad C IV emission or, if little variability is seen, to create a higher signal/noise spectrum of the region (which would be of great interest because the signal/noise on the very complex C IV profile is low and could greatly benefit from this additional integration). Finally, we propose relatively short repeat exposures on the very valuable C II (UV 0.01) and Mg II h & k lines which provide density information (C II) and constraints on the warmer (primary?) component of the chromosphere, to complement the data we will obtain on the cooler component. The desired observations are summarized in Table 1. TABLE 1 , Proposed GHRS Observations of Alpha Tau in Cycle 6 Grating & Wavelength & Exp. & Primary & approx. & Range & Time & lines in & #orbits & (Angstroms) & (min) & region & A2 & targ. acq. & 37.0 & & 1 G160M & 1320-1354 & 39.0 & H_2, Ca II & 1 G160M & 1354-1387 & 39.0 & H_2, Ca II & 1 G160M & 1430-1464 & 40.0 & H_2, Ca II & 1 G160M & 1484-1518 & 60.0 & H_2 & 1.5 G160M & 1531-1569 & 61.0 & C IV, H_2, Ca II & 1.5 G200M & 1795-1835 & 36.0 & Ca II, Si II, S I & 1 G200M & 1880-1920 & 39.9 & Si III, C III & 1 (A2 & targ. acq. & 37.0 & & 1) G270M & 2322-2366 & 20.0 & C II, Fe II, Si II & 0.6 ECH-B & 2793.5-2806.5 & 13.0 & Mg II & 0.4 The exposure times will produce a signal/noise of around 10 for the weaker lines of Ca II and H_2 and around 15 for the stronger lines. We use predicted fluxes from our theoretical models to estimate the required exposure times for the new Ca II and H_2 lines. We expect higher signal/noise in the C II and Mg II exposures where we wish to examine the profiles in detail, and in the case of Mg II, look for weak superposed absorption features. We will obtain dedicated wavecal's with each science exposure to allow the most accurate possible determination of flow velocities for these species. The approximate number of orbits for each exposure, including wavecal's and overhead, are listed in Table 1 as a rough guide to the time allocation. We have filled-out the orbit worksheet and designed our program in detail to ensure that all of the exposures fit with our total orbit request of 10 orbits. The Phase 2 submission is structured as a single visit with 10 orbits. If it is necessary to break the program into 2 visits, we would replace the 1880-1920 A G200M exposure with the acquisition listed in parenthesis in Table 1. Real_Time_Justification: If the program is scheduled as two visits, we request that they be scheduled as close in time as possible to ensure contemporaneous data on all lines. No coordinated observations are planned for this program. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: Fixed_Targets ! Section 5.1 Target_Number: 1 Target_Name: HD29139 Alternate_Names: Alpha-Tau, GSC1266-1416 Description: STAR,K III-I Position: RA=04H35M55.24S+/-0.1", ! Most common specification format is DEC=+16D30'33.39"+/-0.1" ! RA=0H 0M 0.00S +/- 0S, ! DEC=0D 0' 0.0" +/- 0", ! PLATE-ID=0000 Equinox: 2000.0 RV_or_Z: V=+54 RA_PM: 0.0045 ! Units are seconds of time per year Dec_PM: -0.1890 ! Units are seconds of arc per year Epoch: J2000 ! was listed as B2000 in Cycle 4 Annual_Parallax: 0.054 Flux: V=0.84+/-0.2, ! Include at least V and B-V B-V=1.54 ! from almanac TYPE=K5 III, F(1655)=7.7E-13, F(2327)=4.E-12, F(2799)=8.E-11 Comments: The coordinates are from the Hipparcos Catalogue ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits ! Section 6 Visit_Number: 1 Visit_Requirements: GROUP 1-2 WITHIN 7D ! Uncomment or copy visit level special requirements needed ! Most of these requirements (including ORIENT) will limit scheduling ! PCS MODE [Fine | Gyro] ! GUIDing TOLerance ! DROP TO GYRO IF NECESSARY [NO REACQuisition] ! ORIENTation TO ! ORIENTation TO FROM ! ORIENTation TO FROM NOMINAL ! SAME ORIENTation AS ! CVZ ! PARallel ! SCHEDulability ! AFTER [BY [TO ]] ! AFTER ! BEFORE ! BETWEEN AND ! GROUP WITHIN