26 research outputs found
Photometry of Variable Stars from Dome A, Antarctica
Dome A on the Antarctic plateau is likely one of the best observing sites on
Earth thanks to the excellent atmospheric conditions present at the site during
the long polar winter night. We present high-cadence time-series aperture
photometry of 10,000 stars with i<14.5 mag located in a 23 square-degree region
centered on the south celestial pole. The photometry was obtained with one of
the CSTAR telescopes during 128 days of the 2008 Antarctic winter.
We used this photometric data set to derive site statistics for Dome A and to
search for variable stars. Thanks to the nearly-uninterrupted synoptic
coverage, we find 6 times as many variables as previous surveys with similar
magnitude limits. We detected 157 variable stars, of which 55% are
unclassified, 27% are likely binaries and 17% are likely pulsating stars. The
latter category includes delta Scuti, gamma Doradus and RR Lyrae variables. One
variable may be a transiting exoplanet.Comment: Accepted for publication in the Astronomical Journal. PDF version
with high-resolution figures available at
http://faculty.physics.tamu.edu/lmacri/papers/wang11.pd
PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA: RESULTS FROM THE 2010 OBSERVING SEASON
We present results from a season of observations with the Chinese Small
Telescope ARray (CSTAR), obtained over 183 days of the 2010 Antarctic winter.
We carried out high-cadence time-series aperture photometry of 20,000 stars
with i<15.3 mag located in a 23 square-degree region centered on the south
celestial pole.
We identified 188 variable stars, including 67 new objects relative to our
2008 observations, thanks to broader synoptic coverage, a deeper magnitude
limit and a larger field of view.
We used the photometric data set to derive site statistics from Dome A. Based
on two years of observations, we find that extinction due to clouds at this
site is less than 0.1 and 0.4 mag during 45% and 75% of the dark time,
respectively.Comment: Accepted for publication in the Astronomical Journal. Light curves
and finding charts of all variable stars will be made available at
http://casdc.china-vo.org/data/csta
STELLAR VARIABILITY AND FLARE RATES FROM DOME A, ANTARCTICA, USING 2009 AND 2010 CSTAR OBSERVATIONS
The Chinese Small Telescope ARray (CSTAR) carried out high-cadence
time-series observations of 20.1 square degrees centered on the South Celestial
Pole during the 2008, 2009 & 2010 winter seasons from Dome A in Antarctica. The
nearly-continuous 6 months of dark conditions during each observing season
allowed for >10^6 images to be collected through gri and clear filters,
resulting in the detection of >10^4 sources over the course of 3 years of
operation. The nearly space-like conditions in the Antarctic plateau are an
ideal testbed for the suitability of very small-aperture (<20 cm) telescopes to
detect transient events, variable stars and stellar flares. We present the
results of a robust search for such objects using difference image analysis of
the data obtained during the 2009 & 2010 winter seasons. While no transients
were found, we detected 29 flaring events and find a normalized flaring rate of
5+\-4x10^-7 flare/hour for late-K dwarfs, 1+\-1x10^-6 flare/hour for M dwarfs
and 7+\-1x10^-7 flare/hour for all other stars in our sample. We suggest future
small-aperture telescopes planned for deployment at Dome A would benefit from a
tracking mechanism, to help alleviate effects from ghosting, and a finer pixel
scale, to increase the telescope's sensitivity to faint objects. We find that
the light curves of non-transient sources have excellent photometric qualities
once corrected for systematics, and are limited only by photon noise and
atmospheric scintillation.Comment: Accepted for Publication in the Astronomical Journal, 14 pages, 12
figures and 2 table
PULSATIONS AND PERIOD CHANGES OF THE NON-BLAZHKO RR LYRAE VARIABLE Y OCT OBSERVED FROM DOME A, ANTARCTICA
Recommended from our members