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.

November-December 2013 (#3)

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Contents

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Gaia space observatory launched into space by Ivan Adamin

The five-year-long space trip of the telescope named Gaia started from Kourou in French Guiana on Thursday, December 19, 2013 at 9:12 UTC, where it was taken off on top of a Russian-built Soyuz-Fregat launch vehicle. The Gaia spacecraft is a successor to the Hipparcos satellite that was launched by Arianespace in 1989. The main purpose of the satellite telescope is to build the most detailed 3D map of the Milky Way galaxy. Read more >>

Epsilon Aurigae: a rare stellar eclipse by Ivan Adamin

Epsilon Aurigae is the fifth brightest star in the northern constellation Auriga. It is the eclipsing binary star with the longest known orbital period, showing a single eclipse every 27.1 years. Eclipse duration is extremely long: it takes nearly 2 years for the companion to pass the star for an external observer's line of sight. For the last two centuries the nature of the eclipsing object was not reliably explained, until its long-awaited eclipse in 2009-2011. Read more >>

O-C diagrams basics by Ivan Adamin

Most variable stars change its brightness over a cycle. O-C diagrams compare the actual timing of an event (e.g. the mid-point of an eclipse or a pulsation cycle peak ) to the moment we expect this event is occurred in a case of constant periodicity. These period variations are usually delicate. By building Observed-minus-Calculated (O-C) diagrams one can measure very subtle changes in the period happening with the star. Read more >>

Eclipsing binary systems with eccentric orbits by Ivan Adamin

Eccentric eclipsing binaries are a subgroup of detached binary stars that have provided new and important information for the study of internal stellar structure. Eccentric systems display the phenomenon of Apsidal motion. In particular, apsidal motions in this type of binary systems has proven to be highly rewarding during the past decades, allowing to get valuable astrophysics parameters of the binary system. Read more >>

The nearby eclipsing stellar system δ Velorum by Ivan Adamin

Delta Velorum (δ Vel) is the second brightest star δ(mv = 1.96) in the southern constellation Vela, near the border with Carina. The system is known due to its multiplicity and includes at least three identified components. Delta Velorum is among our closest stellar neighbors. Read more >>

V1369 Cen : a naked-eye nova erupts in Centaurus! by Ivan Adamin

On Monday, December 02, amateur astronomer John Seach from Chatsworth islands of New South Wales (Australia) reported the discovery of a new star (5.5m) in the constellation Centaurus, not far from Beta Centauri. A nova is a massive nuclear explosion on a dying star. These stars - white dwarfs - are the final evolutionary stage of Sun-like stars. This Nova is the second naked-eye nova burst in a couple of months! And it's even brighter than Nova Delphini 2013. Read more >>

Wolf-Rayet stars: extremely hot, luminous and massive by Ivan Adamin

Wolf-Rayet stars are named after Charles Wolf (1827 - 1918) and George Rayet (1839 - 1906), French astronomers who discovered these unusual stars at the Paris Observatory in 1867, using the 40-cm Foucault telescope. 150 years later, we know of only 580 in the Milky Way galaxy, and a few hundred in the surrounding galaxies, so they are rare. Wolf-Rayet are evolved, massive, extremely hot (up to ~50,000 K) and very luminous stars, 10^5 to 10^6 times brighter that of the Sun. Read more >>

NSVS 5907410 = MISAO V1119: a Mira variable confirmed by Siarhey Hadon

Details of a Mira variable in the constellation of Cygnus are presented. The variability of the NSVS 5907410 source was detected in January of 2012 by Ivan Adamin, based on photometric data from the Northern Sky Variability Survey, as a part of data mining project, the VS-COMPAS. Lately, by the time the star's data was finally analyzed in 2013, the object was identified as the Mis V1119 classified as possible semi-regular. Thus, a revision with actual data was submitted. Read more >>

Four new BY Draconis variables found in the NSVS data
Ivan Adamin, Alexandr Ditkovsky, Andrey Prokopovich, Valery Tsehmeystrenko

As a part of VS-COMPAS data-mining program, in the paper four new rotating BY Draconis variables are presented. The research result on these objects is submitted to the VSX catalog for the first time by the VS-COMPAS team members. Photometric data from publicly available surveys (primarily, from the NSVS and CRTS) was used as a source for light curves. Read more >>

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