A variable star, as its name suggests, is a star whose magnitude varies intrinsically, in contrast to eclipsing
binaries whose magnitude varies as a result of one star in the binary system eclipsing the other. True variables are
one of five types, namely Mira stars, semiregular stars, cepheids, eruptive variables and, finally, cataclysmic
variables. Minimum to maximum magnitude can range from days to many months with some variables displaying irregular
periods.
A popular method for the study of variable stars, particularly short-term variables, is by the use of the technique
known as "differential photometry". Rather than measure the (variable) magnitude of a variable star on an absolute
scale, measurements are made over time relative to one or more non-variable star(s) and these differences are then
plotted so as to study and illustrate the relative or differential change in magnitude. Due to the very large number
of variables stars, the field of differential photometry represents one of the key fields in astronomy whereby the
amateur astronomer can make a meaningful and long-lasting contribution to both science and astronomy.
More recently, the search for extrasolar planets (over 750 discovered so far) has identified yet another interesting
application for the practice of differential photometry whereby the minute drops in magnitude of a star hosting an
exoplanet are studied. Further details for the interested party are available
here.
Note: The eclipsing binary star GSC 04145-00930 is a quick eclipsing binary variable star
with a period of 0.33801 days and which involves a delta mag of 0.422 (r) magnitudes during this brief time interval.
The variable nature of GSC 4145-093 was first reported by
Hoffman et al in 2009 following identification
while mining the results of the
Northern Sky Variability Survey (NSVS; Wozniak et al., 2004).
GSC 4145-0930 is an W Ursae Majoris-type eclipsing system where the ellipsoidal components are virtually in contact with each
other and, hence, for its classification, namely "EW".
Further details from the International Variable Star Index are available
here.
Note: The minimum observed below represents the primary minimum.
Variable Star: GSC 4145-0930 Other Designation: NSVS 2578605 RA / Dec: 10h 57m 23s / +61° 43' 02" Magnitude: 11.583 - 11.405 (R) Period: 0.33801 days Variability: EW Comparison Star: GSC 4145:1011 Check Star: GSC 4145:0757 |
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Date: May 24-25, 2013 22:00 - 03:00 UT+3 Location: Athens, Greece Equipment: AP 305/f3.8 Riccardi-Honders AP 1200GTO GEM SBIG ST-10XME SBIG CFW10 SBIG LRGB filters Integrations:
Temperatures:
Software: CCDSoft V5.00.201 AIP4Win V2.4.0 Processing: Reduction Differential Photometry |