ISSN 2309-5539 (online)
Published by The VS-COMPAS Project © 2011-2014
Hrodna, 230005, Belarus

Variable Stars Observer Bulletin is all about variable stars science. It's made by amateurs and for amateurs. Here simplified contemporary data about different aspects of variable stars research is published. The bulletin is scheduled for six issues per year.

March-April 2014 (#5)

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Contents

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KOI-3278: A self-lensing binary star system by Ivan Adamin

More than 40% of stars are in pairs that orbit around each other, called binary star systems. KOI-3278 is a pair of stars consisting of a white dwarf and a main sequence G-star with an orbital period of 88.18 days. This system produces the first ever case of periodic microlensing signal, based on data collected by NASA's Kepler planet-hunting space observatory. Previously theorized, around forty years ago, this phenomenon has never actually been observed directly until now. Read more >>

Outburst of the recurrent nova V745 Scorpii by Ivan Adamin

An outburst of the recurrent nova V745 Sco (Nova Sco 1937) has been reported by Rod Stubbings from Australia. Observations made on 2014 February 6.694 UT revealed the star at visual magnitude 9.0. This is only the third recorded outburst of this nova, the others occurred in 1937 and 1989. Read more >>

RS Puppis: the light echoes calibrate standard candles for
accurate distance measurements by Ivan Adamin

Cepheids allow astronomers to measure vast distances across space. RS Puppis is an unusual cepheid embedded into an interstellar dust cloud illuminated by the variable light, enabling a phenomenon known as a light echo to be observed in details. Sparks (1994) showed that the polarization of a light echo can be used to measure its distance geometrically. This approach was used to determine the distance to RS Puppis with great accuracy, and hence calibrate the cosmic distance scale, based on the period-luminosity relation of classical Cepheid variables. Read more >>

SS Lacertae: The non-eclipsing eclipsing binary by Ivan Adamin

Among the brighter members of the open cluster NGC 7209, SS Lacertae has gained considerable attention during the past decades due to its extraordinary behavior, not typical of eclipsing systems: the complete cessation of eclipses in the middle of the twentieth century. SS Lac belongs to a small class of triple systems in which changes due to dynamical effects can be seen over a single human lifetime. Read more >>

BL Boötis stars - anomalous Cepheids by Ivan Adamin

BL Boö is the prototype of a subclass of pulsating variable stars called the Anomalous Cepheids. These stars are similar to classical Cepheid variables, but they do not follow the same relationship between their period and luminosity. Read more >>

Revised elements of seven known red variable stars from the article
«59 New Red Variable Stars»: NSVS 16324859 and NSVS 16329544 are confirmed to be Mira variables by Siarhey Hadon, Ivan Adamin

Abstract: A careful review of the article «59 New Red Variable Stars» - published in PZP ("Peremennye Zvezdy", Prilozhenie, vol. 14, N 4 (2014)) - revealed that elements and variability types could be refined for several red variable stars. We were able to classify NSVS 16324859 and NSVS 16329544 as Mira variables; furthermore, the identification of NSVS 16329544, which was obviously misidentified in the original article, could be improved. Magnitude ranges are now given in V. Most stars' data required a deblending procedure to eliminate light contamination from neighboring stars and get an improved magnitude range. Read more >>

A revision of NSV 13538 = NSVS 17231162 by Alexandr Ditkovsky

Abstract: A revision of the variable star NSV 13538 is presented. Light curve elements were improved by using a modern data from photometric surveys available online. The following photometric elements of the minimum of the Long Secondary Period were found: Min = HJD 2454611 + 324 * E. Read more >>

NSVS 11075037 = Dauban V53:
updated elements of a Mira variable in Hercules by Siarhey Hadon

Abstract: Refined elements of a Mira variable in the constellation of Hercules are presented in the paper. The variability of the NSVS 11075037 source was detected in December of 2012 by I. Sergey, based on photometric data from the NSVS. Lately, the object was identified as Dauban V53, with no period and classification specified. Thus, a revision with up-to-date data was submitted. Read more >>

Updated photometric elements of three variables in Lynx: GSC 03405-00823, GSC 03408-02627 and TYC 3408-00557-1 by Siarhey Hadon

Abstract: Refined elements of a Mira variable in the constellation of Hercules are presented in the paper. The variability of NSVS 11075037 was detected in December of 2012 by I. Sergey, based on photometric data from the Northern Sky Variability Survey, as a part of the VS-COMPAS data mining project. Lately, by the time the star's data was finally analyzed in 2013, the object was identified as the Dauban V53 in the VSX catalog, with no period and classification specified. Thus, a revision with up-to-date data was submitted. Read more >>

The Crab Nebula (M1, NGC 1952)
Minsk, Belarus (Spring 2014)
Image courtesy of Andrei Ioda (2014)

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or please simply drop an email to [ivan dot adamin at gmail dot com]