ARCSAT ID NUMBER: AS10

DESCRIPTIVE TITLE: Monitoring H-alpha Variability in Be Stars in Young Clusters

PI: Steven Souza (Williams College)

OBSERVER(S): Steven Souza

UNCERTIFIED/UNTRAINED OBSERVERS: Michael May, Sarah Stevenson (Williams College summer 
research students; "week 1" dates only)

COLLABORATORS: none
 
CONTACT INFORMATION: Steven Souza; ssouza@williams.edu; 413-441-9892

TIME REQUESTED: 2 separate 1-week periods are requested:
week 1:	EITHER  [7/21 - 7/27] or [7/28 - 8/3]   - no preference
week 2:	EITHER  [8/18 - 8/24] or [8/25 - 8/31]  - no preference

INSTRUMENT: SurveyCam

FILTERS: halpha_6563_50, rc_6450_50

COMMENTS: The first week requested is intended to provide data for two undergraduate 
students who will be working with me during our summer science research session. After 
the first night or two I would like permission to allow the students to operate the 
system, although I would be present and supervise them at all times.

BRIEF SCIENCE JUSTIFICATION:
In Be stars both continuum and emission lines vary irregularly, but spectroscopic 
monitoring has been undertaken for only a few individual bright stars. A larger sample 
can be reached via narrowband imaging using matched on-band (656nm) and off-band (645nm) 
filters, as we have been doing on the Williams College 0.6-m DFM telescope for the last 
4 years. Our program to monitor early-type emission-line stars is focused on young open 
clusters and associations. To date we have characterized H-alpha and continuum variations 
in 10 Be stars in NGC659 and NGC663, found 3 new Be stars and ~20 new candidate 
variables, and incidentally refined the orbital period of an eclipsing binary in the 
Cygnus OB2 association.

Observations at ARCSAT, using a camera and filters similar to those we use at Williams, 
are intended to add short periods of good temporal coverage to complement the longer-
term, but sparser, observations at Williams. In initial testing as an early ARCSAT user 
during March and April of this year, I have found that data obtained using SurveyCam and 
narrowband filters on loan to ARC from Williams College are compatible with those 
obtained at Williams. A significant portion of our target list of ~20 clusters can be 
observed during any of the weeks requested.