ARCSAT ID NUMBER: AS06

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

PI: Steven Souza (Williams College)

OBSERVER(S): Steven Souza

UNCERTIFIED/UNTRAINED OBSERVERS: none presently planned

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

TIME REQUESTED: 1 week from among the following, listed in decreasing preference
[11/10 - 11/16]
[12/29 - 1/4]
[1/19 - 1/25]
[1/5 - 1/11]

INSTRUMENT: SurveyCam

FILTERS: halpha_6563_50, rc_6450_50

COMMENTS: None.

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 4+ 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. As an early ARCSAT user I found that data 
obtained using SurveyCam and narrowband filters on loan to ARC from Williams College 
are compatible with those obtained at Williams. Many of the ~20 clusters in our target 
list can be observed during any of the weeks requested.