1112.2356 (Costantino Sigismondi)
Costantino Sigismondi
Hundred observations of Delta Scorpii over 200 days, from April 2 to October
16, 2011, have been made for AAVSO visually and digitally from Rio de Janeiro,
Rome and Paris. The three most luminous pixels either of the target star and
the two reference stars are used to evaluate the magnitude through differential
photometry. The main sources of errors are outlined. The system of Delta
Scorpii, a spectroscopic double star, has experienced a close periastron in
July 2011 within the outer atmospheres of the two giant components. The whole
luminosity of Delta Scorpii system increased from about Mv=1.8 to 1.65 peaking
around 5 to 15 July 2011, but there are significant rapid fluctuations of 0.2 -
0.3 magnitudes occurring in 20 days that seem to be real, rather than a
consequence of systematic errors due to the changes of reference stars and
observing conditions. This method is promising for being applied to other
bright variable stars like Betelgeuse and Antares. After August the magnitude
remained constant at Mv=1.8 until the last observation on October 16 made in
twilight from Rome.
View original:
http://arxiv.org/abs/1112.2356
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