For my OOTD, I present a composite of 18 SDSS pictures into a montage I have named
'Markarian Peas'. For GZ forum aficianados, both terms will be familiar, although not
necessarily in the same title.
Firstly the Markarian bit. The First Byurakan Survey was made during the sixties at the
Byurakan Observatory in Armenia. From this, Benyamin Markarian extracted 1500
galaxies which were unusually bright in the ultraviolet. These galaxies are unusual in that
they appear very blue, with many of them being dominated by a bright nucleus. In short,
Markarian galaxies are vigorously active places, but no one is quite sure why, or in what
critical ways they differ from our own quiescent Milky Way.There are more than 200
Seyferts, dozens of QSOs, few hundreds of starburst and HII galaxies, BL Lac objects,
radio, IR and X-ray sources among them. The active star formation in Markarian galaxies
also makes them prime objects for infrared studies because the copious dust in these
regions emits strongly in the infrared.
This link takes you to the GZ topic:
http://www.galaxyzooforum.org/index.php?topic=10047.0So, these are well-known astronomical objects...What then are 'Peas'?
'Peas' are an unofficial title for objects that have a very high presence of OIII, or doubly-
ionised Oxygen. OIII has had two of its electrons stripped away because of massive energetic
activity taking place. The term was coined by Hanny here:
http://www.galaxyzooforum.org/index.php?topic=3638.0 and was at first, maybe still, humourously applied to objects that appeared green. These objects have
since become a subject though for serious study and hopefully a paper might appear which sheds
light on these green OIII objects. This is explained in greater detail here:
http://www.galaxyzooforum.org/index.php?topic=270633.0More generally, all sorts of colours of Peas were found, the main criteria being that they should
have a massive 'spike' in the part of the spectrum where OIII is found. So, using this criteria
I made a list of Markarian objects that are available in SDSS; several hundred it turned out
and for view as an attached text. From that I extracted Peas- objects that had the OIII spike.
Then, I combined the ones I felt most beautiful in to the composite above. I hope you like it!
A text containing who posted what is attached.
