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! Hubble Space Telescope Cycle 7 (1997) Phase II Proposal Template
! $Id: 7395,v 3.1 1997/05/16 19:37:22 pepsa Exp $
!
! Refer to the HST Phase II Proposal Instructions to fill this out
!
! Anything after a "!" is ignored, and may be deleted
!
! For help call your Program Coordinator: "Karla Peterson"
! Phone: "410 338-4774" , E-mail: "peterson@stsci.edu"

Proposal_Information
Title: Chromospheric Activity in Old Stars: HD106516
Proposal_Category: GO
Scientific_Category: COOL STARS
Cycle: 7

Investigators
PI_name: Ruth Peterson
PI_Institution: Astrophysical Advances

CoI_Name: Karel Schrijver
CoI_Institution: Lockheed

Abstract: ! Free format text (please update)
All normal stars cool enough to have convection zones share a
common minimum level of chromospheric activity which decreases
with advancing spectral type; most show higher emission levels
which vary with time. The ubiquity of a minimum ``basal''
level suggests that this component of chromospheric activity
is produced by some form of time- and metallicity-independent
mechanism, such as acoustic waves arising from convection,
while activity above this level most probably originates with
magnetic fields generated by a rotationally-driven dynamo.
Such a picture implies that even very old cool stars should
show a minimum level of such activity, and that ones with
rotationally-generated magnetic fields should show a higher
level. Our Cycle 5 GHRS snapshot program has confirmed the
first prediction: all nine of the old, low-metallicity,
Population II field subdwarfs that were observed do indeed
show chromospheric Mg II\ emission. In this STIS GO proposal
we are requesting a Mg II\ observation for the tenth star of
that sample, the only one with measurable rotation. Both the
profile and the level of Mg II\ emission should help indicate
to what extent rotation affects chromospheric emission in very
old solar-type stars.

Questions

Observing_Description:
The 10 solar-type subdwarfs targeted for Mg II\ measurements,
and their (V, B-V, U-B) photometry, temperatures T(eff), and
metallicities Fe/H (from Carney Etal\ 1994), are: \medskip
HD 19445 (8.06, 0.46, -0.16), 5842K, -2.12; HD 84937 (8.32,
0.40, -0.22), 6220K, -2.18; HD 94028 (8.22, 0.48, -0.18),
5898K, -1.56; HD 106516 (6.11, 0.44, -0.13), 6118K, -0.87; HD
114762 (7.30, 0.52, -0.08), 5790K, -0.79; HD 140283 (7.22,
0.49, -0.19), subgt, -2.60; HD 184499 (6.63, 0.58, -0.01),
5726K, -0.66; HD 194598 (8.34, 0.48, -0.20), 5858K, -1.28; HD
201891 (7.37, 0.51, -0.15), 5817K, -1.42; HD 219617 (8.16,
0.49, -0.20), 5857K, -1.40. We propose to obtain exposures of
the spectral region near the Mg II lines at 2800 Angstrom\
using STIS and the E230M grating with the F25MAMA clear
aperture, which gives a resolution of 5 km/s/pix. The F25MAMA
aperture will be used for consistency with the other targets
as well as for improved photometric accuracy.

Fixed_Targets

Target_Number:4
Target_Name:HD106516
Description:STAR,F3-F9
Position:RA=12H 15M 10.56S +/- 0.1S, DEC=-10D 18' 45.1" +/- 0.5"
Equinox:J2000
RV_or_Z:V = +9.
RA_PM:0.0021
Dec_PM:-1.018
Epoch:J2000
Flux:V=6.11 +/- 0.02, B-V=0.46 +/- 0.02, TYPE=F8
Comments:PPM225575 coordinates and proper motion

Visits
Visit_Number:1
Visit_Requirements:
Visit_Comments:

Exposure_Number:1
Target_Name:HD106516
Config:STIS/CCD
Opmode:ACQ
Aperture:F28X50OII
Sp_Element:MIRROR
Wavelength:
Number_of_Iterations:1
Time_Per_Exposure:0.1S
Special_Requirements:ONBOARD ACQ FOR 2

Exposure_Number:2
Target_Name:HD106516
Config:STIS/CCD
Opmode:ACQ/PEAK
Aperture:0.2X0.05ND
Sp_Element:MIRROR
Wavelength:
Number_of_Iterations:1
Time_Per_Exposure:0.1S
Special_Requirements:ONBOARD ACQ FOR 3-4

Exposure_Number:3
Target_Name:HD106516
Config:STIS/NUV-MAMA
Opmode:ACCUM
Aperture:0.2X0.2
Sp_Element:E230M
Wavelength:2707
Number_of_Iterations:1
Time_Per_Exposure:240S
Special_Requirements:

Exposure_Number:4
Target_Name:HD106516
Config:STIS/FUV-MAMA
Opmode:ACCUM
Aperture:0.2X0.2
Sp_Element:E140M
Wavelength:1425
Number_of_Iterations:1
Time_Per_Exposure:1200S
Special_Requirements:

Data_Distribution
Medium: Electronic
Ship_To: PI_Address