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Special Notice #47: Increased Activity in P Cyg

May 19, 2007

P Cyg (2014+37A) is the prototype of massive stars with high mass outflow; it is characterized by blue-shifted emission lines along with red-shifted absorption lines. Surprisingly, we've never created a Variable Star of the Season article for this neat star - I'll have to make sure that happens soon.

Located at

20:17:47.20 +38:01:58.5 J2000

it is typically around V=4.8 (though its outburst in AD1600 reached 3rd magnitude), and is the nearest of the Luminous Blue Variable (or S Dor) class, currently thought to be the progenitors to some types of supernovae. eta Car is another example.

P Cyg also has a weakly visible surrounding nebulae of about 3arcmin diameter, and an inner nebulae about 20arcsec diameter.

Lamers and de Groot (1992, A&A 257, 153) also indicate that P Cyg has been slowly increasing in mean brightness over the past few centuries, at a rate of about 0.15mag per century. Recently, P Cyg has also been showing increased H-alpha activity, as observed by Ernst Pollman, a German spectroscopist.

Since P Cyg is an ideal target for the AAVSO PEP observers, I would like to ask them to give P Cyg high priority in their monitoring activity over the current season. You can find the PEP chart on the web page, including the suggested comparison and check star. There are no nearby comp stars for CCD observers, but those with wide-field systems could also give this a try. This remains an interesting target for visual observers as well; the increased activity could be a precursor for an outburst.

Arne

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