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,
preferrably with one in the beginning of Q1 and
one in the Fall.

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).  We have got two clear
and four partly cloudy nights for this project in October 2014 and now
can adjust the exposure time to balance the signal between the
Stromgren filters.

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