Previous Article
Next Article
Table of Contents

Opportunities for Solar-Stellar Research at KPNO (1Mar96)
(from KPNO, NOAO Newsletter No. 45, March 1996)

With the closure of the McMath-Pierce solar-stellar program, many of
the research goals of solar-stellar astrophysics that require optical
and infrared observations can be served by the current and planned
facilities that reside within KPNO and CTIO. In this note, we briefly
review some of the key areas in solar-stellar physics that can be
addressed through the use of KPNO facilities.

The Coude Feed Telescope includes a classical coude echelle spectrograph
that can achieve spectral resolving powers greater than 200,000. This
facility is successfully used for Doppler imaging of active RS CVn
systems. Observing runs as long as two weeks have been conducted
recently for this purpose. Magnetic field measurements on late-type
stars that rely on the detection of the subtle signature of Zeeman
broadening in the wings of magnetically sensitive lines can be
accomplished at the feed for bright objects. Another research area that
requires the high spectral resolutions available with the spectrograph
at the feed is convection; i.e., the measurement of line bisectors and
their variation due to global convective motions in the stellar
photosphere.

The WIYN Telescope with the Hydra multi-object spectrograph and the CCD
Imager includes a queue observing mode. Hence, variability studies as
well as surveys can be carried out efficiently. The wide-field
capability is especially useful for the study of cluster members and
the evolution of parameters related to stellar activity. Examples of
long-term projects might include investigations of magnetic activity
cycles, luminosity variability and rotational modulation of activity in
the members of open clusters. The Hydra bench-mounted spectrograph
includes gratings for moderate-low dispersion work along with an
echelle grating. The echelle grating is limited to resolving powers of
about R=20,000.

The Phoenix Infrared Spectrograph will offer an important new
capability for solar-stellar physics. Phoenix will provide resolutions
from R=50,000 to R=100,000 in the K and H bands where there are
important magnetic line diagnostics. Its eventual placement at the
2.1-m and 4-m will enable the acquisition of high quality spectra of
faint stars, thereby enabling an important expansion of the database of
cool stars for which we have reliable magnetic field measurements.

The Echelle Spectrograph at the 4-m yields "intermediate" resolutions
up to about R=67,000. Combined with its large aperture, Doppler imaging
experiments on some rapidly rotating, active stars are feasible. In
addition, time-resolved spectroscopy of stellar flares can be carried
out with this instrument/telescope combination. We are investigating
the prospects for placing a new, high resolution (R=150,000)
bench-mounted spectrograph at the Mayall 4-m.

Finally, we are actively exploring the use of current KPNO
instrumentation in the exciting area of asteroseismology. The initial
experiments involve the observations of nearby, bright late-type
subgiants using the Coude Feed and the 2.1-m. We will report on our
progress in this initiative in the next Newsletter. If you have any
comments or questions about adapting your research programs in
solar-stellar astrophysics to existing KPNO instrumentation and
facilities, please contact Mark Giampapa (giampapa@noao.edu).

Mark Giampapa, Caty Pilachowski

Previous Article
Next Article
Table of Contents