Current Research at the MSU Observatory
The main emphasis is the study of variable stars, particularly
pulsating variable stars of shorter period. These include
RR Lyrae variable stars, which have a pulsation period of about
half a day, and Delta Scuti stars, which have a pulsation period
shorter than 0.2 days. Much of the observing is carried out by
students, both graduate students and undergraduates.
The observed light curve of the RR Lyrae star XZ Cygni is
shown below. XZ Cygni has a pulsation period of about 0.466 days.
Its light curve is not the same from one pulsation cycle to the
next, but changes in a longer 57 day secondary cycle. This
secondary variation, called the Blazhko Effect, has been known
for almost a century, but is still without adequate explanation.
Light curve of XZ Cygni
The light curve of the Delta Scuti star AN Lyn is shown below. AN Lyn
is a short period pulsating star. It takes only 0.098 days to go
through one pulsation. The amplitude of its light curve shows
significant changes on a longer year-to-year timescale.
Light curve of AN Lyn
Some recently published papers, based upon observations obtained wholly
or partially with
the MSU 24-inch telescope, are listed below. Many of these papers
are coauthored by student observers.
- Anderson et al. 1991, "CCD Photometry of the RR Lyrae Star SS Leonis",
Journal of the AAVSO, 20, 28.
- Kuhn, J. R., Lin, H., and Loranz, D. 1991, "Gain calibrating nonuniform image-array data using only the image data", Publ. Astronomical Society of the
Pacific, 103, 1097.
- Lin, H. and Kuhn, J. R. 1992, "Precision IR and Visible Solar
Photometry", Solar Physics, 141, 1.
- Smith, H. A. 1993, "CCD Photometry of Variable Stars in a Sophomore
Level Astronomy Course", Journal of the AAVSO, 22, 35.
- Smith, H. A. et al. 1994, "AH Cam: A Metal-rich RR Lyrae Star
with the Shortest Known Blazhko Period", Astronomical Journal,
- Korista, K. T. et al. 1995, "Steps toward determination of the size and structure of the broad-line region in active galatic nuclei. 8:
an intensive HST, IUE, and ground-based study of NGC 5548",
Astrophysical Journal Supplement, 97, 285.
- Silbermann, N. A. and Smith, H. A. 1995, "Period changes of RR Lyrae stars in the globular cluster M15", Astronomical Journal, 109, 1119.
- Silbermann, N. A. and Smith, H. A., 1995, "The RR Lyrae Variable
Stars in the Globular Cluster M15", Astronomical Journal, 110, 704.
- Purdue, Patricia, Silbermann, N. A., Gay, Pamela, and Smith, H. A.
1995, "Double-Mode RR Lyrae Stars in the Globular Cluster M15",
Astronomical Journal, 110, 1712.
- Lee, K., Gay, P., and Smith, H. A., 1996, "The Blazhko Effect
of the RR Lyrae Star V421 Herculis", Publ. Astronomical Society of
the Pacific, 108, 659.
- Smith, H. A., Barnett, M., Silbermann, N. A., and Gay, P., 1999,
"The Blazhko Effect of AR Herculis",
Astronomical Journal, 118, 572.
- Bragaglia, A. et al. 2000, "Anomalous Pulsation of Field
RR Lyrae Variables", IAU Colloquium No. 186, ASP Conference Series, 271
- Stark, M. et al. 2000, "The Light Curve of the Eclipsing Binary
Star XX Leo", Journal of the American Association of Variable Star
Observers, 28, 25.
- LaCluyze A. et al. 2001, "The Changing Amplitude of the Delta Scuti
Star AN Lyn", Information Bulletin on Variable Stars, No. 5180.
- LaCluyze A. et al. 2002, "The Changing Blazhko Effect of XZ Cygni",
IAU Colloquium No. 185, p. 416.
- Smith, H.A. et al. 2003 "The Blazhko Effect of RR Lyrae in 1996",
Publications of the Astronomical Society of the Pacific, 115, 43.
- LaCluyze, A., et al. 2004, "The Changing Blazhko Effect of XZ
Cygni", Astronomical Journal, 127, 1653
- Rabidoux, K. et al. 2005 "Light Curves for Type II Cepheids in
M3 and M5", Bulletin of the American Astronomical Society, 37, 1364
- Kolenberg, K., et al. 2006 "How to Make Progress in Understanding
the Blazhko Effect", Mem. S.A.I., 77, 498
- Oaster, Lindsay, Smith, H.A., & Kinemuchi, K., 2006, "A Double-Mode
RR Lyrae Star with a Strong Fundamental Mode Component", Publications of
the Astronomical Society of the Pacific, 118, 405
- Kolenberg, K.,et al., 2006, "The Blazhko Effect of RR Lyrae in
2003-2004", Astronomy & Astrophysics, 459, 577
- Stark, M. et al., 2008, "A New, Bright Short-Period Emission
Line Binary in Ophiuchus", Astronomical Journal, 135, 991
Jurcsik, J. et al.2008, "An extensive photometric study of the Blazhko
RR Lyrae star MW Lyr. I. The Light Curve Solution.", Monthly Notices of the
Royal Astronomical Society, 391, 164
Jurcsik, J. et al.,2009, An extensive photometric study of the Blazhko RR
Lyrae star MW Lyr - II. Changes in the physical parameters", Monthly Notices
of the Royal Astronomical Society, 393, 1553
Rabidoux, K.,et al., 2010, Light Curves and Period Changes of Type II Cepheids
in the Globular Clusters M3 and M5, Astronomical Journal, 139, 2300
Richmond, M.W. and Smith, H.A., 2012, BVRI Photometry of SN2011fe in M101, Journal
of the American Association of Variable Stars Observers, 40, 1