ARCSAT ID NUMBER: AS01

DESCRIPTIVE TITLE: Stromgren Photometry of Galactic Streams

PI: Dmitry Bizyaev

OBSERVER(S): Dmitry Bizyaev

UNCERTIFIED/UNTRAINED OBSERVERS: N/A

COLLABORATORS: 
 
CONTACT INFORMATION: dmbiz @ apo.nmsu.edu

TIME REQUESTED: 3 weeks in the dark time between May and October 2014
The preferred time slots (based on Mon - Sun basis) are:
May 5 - 11
June 2-8
September 22 - 28

INSTRUMENT: SurveyCam

FILTERS: Stromgren uvby, 2" square

COMMENTS: remote observations are expected

BRIEF SCIENCE JUSTIFICATION: 
Last decade numerous faint structures at the periphery of regular galaxies,
as arcs, tails, or streams, have been discovered (see e.g. 
Martinez-Delgado et al., 2010). We are still far from complete understanding
of the nature of these structures. Studying ages and metallicities 
help constraining possible progenitors of the faint structures. Since
the periphery structures are too faint for good spectroscopy, 
they have been observed in the broad-band filters. The broad-band
photometry is used for observing the faint structures, but
it does not allow to break the age-metallicity degeneracy efficiently.

I propose to perform Stromgren photometry of a sample of regular 
galaxies that have confirmed faint structures as arcs, streams and tails. 
The standard Stromgren set is available at APO. The SyrveyCam has the
advantage of large field of view, which will allow to encompass all
extended structures (typically up to 10 arcmin in the sky plane) and
to provide more field for correct background subtraction. 
The combination of uvby filters will allow to apply standard technique 
for figuring out ages and metallicities for the stellar population at the
periphery since there is a very little or no emission detected from 
there, the stellar population is essentially old, and the relatively
nearby galaxies will not require redshift-corrected filters. I will look for
the distribution of the stellar population parameters across the structures 
and at the relationship of them to those of the edges of the parent
galaxies. I will start with two confirmed large galaxies: NGC 4216 and 
NGC 4651, and then incorporate more from the sample of Martinez-Delgado. 
Finally, will observe edge-on galaxies with faint structure observed by 
SDSS and listed by Bizyaev et al. (2014). The initial integration time will 
be set to one hour per filter (split by 10-20 min exposures), and will be 
adjusted based on the results form the two pilot objects. 

Martinez-Delgado, D., Gabany, R. J., Crawford, K., et al., 
2010, AJ, 140, 962

Bizyaev, D., Kautsch, S., Mosenkov, A., et al. 2014,  arXiv-1404.3072