Tuesday, 24 March 2015

NGC3372 - Eta Carina nebula: central clusters

Eta Carina Nebula - Central Region Stars. This grainy shot, made at Mt Banks decades ago, captures the major star groups in the brightest part of the Nebula - a region often over-exposed. The Collinder Clusters are numbered Cr, Trumpler clusters Tr. Labelled are two extraordinary stars - Eta Car. and HD 93129A (and B) in cluster Tr 14. The latter cluster may be only half a million years old! Cluster Tr 16 is not labelled but contains the stars that surround Eta including Cr 234.

HD 93129A is often cited as the brightest, most massive star known - on an HR diagram it's always located extreme top left. This is an early type O star - something we wouldnt want for a near neighbour. Close by at the edge of Tr14 is a wide pair of O-type stars that ,in the eyepiece, are seen as a superb triple system - this is HD 93161(arrow)

The photo shows the appearance of this region as seen in an 8" or 10" 'scope from an urban setting. The dark "Keyhole" nebula looms faintly north (right) of star Eta Car. Overall an astounding part of the sky - Enjoy!

Thursday, 19 February 2015

Emission bands in Eta Carinae

Oops! Emission band of Halpha and Hbeta were visible on 2015 Feb 22nd.  The earlier negative is likely due to seeing and patchy cirrus on the 19th.

Disregard: (STOP PRESS!  2015 Feb 19 showed no emission bands in the spectrum of Eta Car. They were last logged by writer 2014 Dec 28: when strongly visible. A confirming log will be made as soon as. More on this event soon.
See this blog entry 2014 Jun 22. Emission points no longer present it seems.)

Thursday, 15 January 2015

AR12192 - Synoptically speaking:

Here AR12192 and its precursor groups are plotted on a flat projection - showing just a piece of the Sun centred on long. 250deg around 10 to 15degS latitude. AR12108 formed at the site three rotations before - and surviving spots of that group made two further rotations (groups 2127 and 2151). Then came AR12172. It became part of a long "train-wreck" of at least three groups that at one stage covered 40deg of longitude. Around Sep. 29 new violet flux emerged at -14,248, as the whole assembly moved behind the Sun's western limb.
   It now seems the patches of V polarity at -11,236 and -14,244 merged, as like polarites may, into the enormous structure known as AR12192! Dotted in Fig4b is the footprint of the huge group when first seen at the east limb - showing the fit with earlier 12172. Fascinating!