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 04145-00857 is a quick eclipsing binary variable star
with a period of 0.79300866 days and which involves a delta mag of 0.63 (r) magnitudes during this brief time interval.
The variable nature of GSC 4145-0857 was discovered by
Shaw et al while mining the results of the Northern
Sky Variability Survey (NSVS,
Wozniak et al., 2004).
GSC 4145-0857 is an Algol-type eclipsing system with spherical or slightly ellipsoidal components and, hence, for its
classification, namely "EA".
Further details from the International Variable Star Index are available
here.
Variable Star: GSC 4145-0857 Other Designation: NSVS 2577267 RA / Dec: 10h 52m 25s / +61° 55' 33" Magnitude: 12.50 - 13.13 (R) Period: 0.79300866 days Variability: EA Comparison Star: GSC 4145:0955 Check Star: GSC 4145:1052 |
|
Date: Apr 25-26, 2013 21:10 - 04:10 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 |