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Variable Star Index
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A Variable Star Index (VSX) Milestone
 
December 22, 2011 the Variable Star Index (VSX), the most complete up to date resource for variable star information on Earth, reached a milestone as we passed the 200,000 mark for variable stars included in the database. The brainchild of Christopher Watson, and donated to the AAVSO, the VSX catalogue has been growing steadily over the past few years, with hundreds of new entries, submitted one at a time, and data from surveys being uploaded en masse.
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RE: Variable Stars
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Title: Variable Stars
Authors: G. Handler, K. R. Pollard, M. S. Cunha, K. Olah, K. Kolenberg, C. S. Jeffery, M. Catelan, L. Eyer, T. R. Bedding, S. O. Kepler, D. Mkrtichian, E. Griffin, N. N. Samus

This is the triennial report of IAU Commission 27, mostly presenting a review of recent advances in the field.

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Variable star
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A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth. Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11 year solar cycle, equivalent to a change of one thousandth of a magnitude.
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Cataclysmic Variable Stars (CV's)  Example  Stars

AMAM Herculis stars (Type AM) | AM Her | 

NNovae (Type N) | V2491 Cyg (2008) | V1722 Aql (2009) | GK Per |

SNSupernovae (Type SN) | SN 2006x | SN 2008ax |

UGDwarf Novae (Type UG)  

UGSSSS Cygni stars (Type UGSS) | SS Cyg | U Gem | CY Lyr | RU Peg | 

UGSUSU Ursae Majoris stars (Type UGSU) | SU UMa | FO And | 

 ER UMa subtype | RZ LMi  |  ER UMa  | 

UGWZWZ Sge stars (UGWZ) | WZ Sge |

UGZZ Camelopardalis stars (Type UGZ) | RX And | TT Ari | SY Cnc | CN Ori |

ZANDZ Andromedae stars (Type ZAND) | Z And | CI Cyg |
     

 
 Other/Mixed Types  

 UX - novalike variable (UX UMa subtype) | UX UMa | 

 VY - novalike variable (VY Scl subtype) | KR Aur | 

 Interacting binary white dwarfs (Type IBWD) | AM CVn | 
* Other Stars, FG Sge (Sagitta)(Type) | FG Sge | 

 



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RE: Variable Stars
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Predicted Dates of Maxima and Minima of Long Period Variables for 2010

Month-by-Month Jan10Feb10Mar10Apr10May10Jun10Jul10Aug10Sep10Oct10Nov10Dec10Jan11Feb11

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A New Class of Variable Stars Revealed

Modern astronomy sometimes makes discoveries by looking in new places, the distant universe for example, using telescopes and instruments that extend the previous limits of detection. But sometimes new discoveries can come from applying modern technologies to the task of more carefully examining conventional data. The Harvard College Observatory maintains a collection of more than 500,000 glass photographic plates of the sky taken over a century - from between about 1880 and 1980. They constitute the only continuous record of the whole sky in existence for this period, with every point on the sky having been observed between 500 and 1000 times. The Digital Access to a Sky Century at Harvard (DASCH) is a project now underway to digitise all of these plates and search for changes. In one of the first results of this ongoing program, a new class of variable stars has been discovered.
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Title: Three New Variable Stars in Indus
Authors: Alex Golovin, Kirill Sokolovsky, Natalia Virnina, Javier Lopez Santiago

We report the discovery of three new variable stars in Indus: USNO-B1.0 0311-0760061, USNO-B1.0 0309-0771315, and USNO-B1.0 0315-0775167. Light curves of 3712 stars in a 87' x 58' field centred on the asynchronous polar CD Ind were obtained using a remotely controlled 150 mm telescope of Tzec Maun Observatory (Pingelly, Western Australia). The VaST software based on SExtractor package was used for semi-automatic search for variable stars. We suggest the following classification for the newly discovered variable stars: USNO-B1.0 0311-0760061 - RR Lyr-type, USNO-B1.0 0309-0771315 - W UMa-type, and USNO-B1.0 0315-0775167 - W UMa-type.

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Stars that change brightness are to be studied by a member of Highlands Astronomical Society using its new observatory at Culloden Battlefield.
Known as variable stars, there are more than 30,000 that have been catalogued, according to a US association dedicated to observing them.

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The ancient Greek philosopher Aristotle declared the heavens were perfect and unchanging, and his view went unchallenged for nearly 2,000 years. But keen-eyed renaissance astronomers like Tycho Brahe discovered stars that varied in brightness. The science of variable stars was born.

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Title: The Exciting Star of the Berkeley 59/Cepheus OB4 Complex and Other Chance Variable Star Discoveries
Authors: Daniel J. Majaess, David G. Turner, David J. Lane, Kathleen E. Moncrieff

A study is presented regarding the nature of several variable stars sampled during a campaign of photometric monitoring from the Abbey Ridge Observatory: 3 eclipsing binaries, 2 semiregulars, a luminous Be star, and a star of uncertain classification. For one of the eclipsing systems, BD+66 1673, spectroscopic observations reveal it to be an O5 V((f))n star and the probable ionising star of the Berkeley 59/Cep OB4 complex. An analysis of spectroscopic observations and BV photometry for Berkeley 59 members in conjunction with published observations imply a cluster age of ~2 Myr, a distance of d = 883±43 pc, and a reddening of E(B-V) =1.38±0.02. Two of the eclipsing systems are Algol-type, but one appears to be a cataclysmic variable associated with an X-ray source. ALS 10588, a B3 IVn star associated with the Cepheid SV Vul, is of uncertain classification, although consideration is given to it being a slowly pulsating B star. The environmental context of the variables is examined using spectroscopic parallax, 2MASS photometry, and proper motion data, the latter to evaluate the membership of the variable B2 Iabe star HDE 229059 in Berkeley 87, an open cluster that could offer a unique opportunity to constrain empirically the evolutionary lineage of young massive stars. Also presented are our null results for observations of a sample of northern stars listed as Cepheid candidates in the Catalogue of Newly Suspected Variables.

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