ASTRO: SN 2012aw in M95

M95 in Leo is a rather common target for small telescopes. I found two
different estimates for the distance to M95. Most sources say 38
million light-years but others say 32.6 ± 1.4 million light-years.
Wikipedia gives BOTH distances in the same article without realizing the
discrepancy. By redshift alone it is 50 million light-years distant but
that has a very wide error bar that easily includes either shorter
distance. I'll get back to M95 but first the supernova.

SN 2012aw is a type IIP supernova. The "P" stands for Plateau. The
light curve has a plateau near maximum brightness. It fades only very
slowly for a while before starting a "normal" brightness decline. This
was fortunate for me as I was clouded out for weeks before getting clear
skies in the early evening letting me get this image on April 17 UT. It
was still at magnitude 13.0 by my rather crude measurement. Maximum was
only slightly brighter so it was still in the plateau period when I took
the image. Probably still is but the clouds returned so I can't verify
this. A type II supernova is also called a core collapse super nova.
The massive star has converted hydrogen to helium then helium to carbon
and oxygen. These are fused into other heavier elements such as neon,
sodium, magnesium aluminum silicon sulfur and other elements. These in
turn are fused to even heaver elements such as nickel which decays to
iron. Iron can' fuse so the core suddenly can't create the heat needed
to support itself against gravity and collapses into degenerate matter
but when that is above a limit, about 1.4 times the mass of the sun,
even that can't stand the gravitational pressure and total collapse
occurs. After this things get really complicated. You can read about
it at: http://en.wikipedia.org/wiki/Type_II...#Core_collapse

While a search of old high resolution images of the galaxy tried to find
the star that exploded prior to the event, I've not seen anyone
reporting it has been found. So the idea it was a red giant, while
likely the case, carries some risk of being wrong. Still most are so
the odds favor it.

M95 is a rather odd galaxy at its core. Instead of a steadily
brightening core there's a broken ring of star formation about 10
seconds of arc from the core. The core region appears darker due to
obscuring by a heavy dust layer. I tried to process the core to bring
out this ring. Two dark bands of dust funnel dust and gas into this
core region fueling the massive star formation going on there. The
eastern dust lane breaks into two equal parts feeding each end of the
largest star forming arc. The single lane coming in from the other side
seems to fuel the smaller arc. The supernova however is far removed
from all this activity.

Not much of interest in the annotated image. Just two quasars and one
appears to be more a galaxy than a quasar. My image shows some size to
it so I'm seeing a galaxy rather than a dominant quasar at its heart.
It is only 2.7 billion light-year distant. To its northeast is a true
quasar at 9.7 billion light-years. Between the two and below a bright
orange star and must above a white star is a tight group of 7 galaxies.
This is SDSSCGB 10567 a listed galaxy group of 7 members but no
redshift data is available for it unfortunately so I didn't mark it. It
is quite obvious in the image however.

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME

Rick

--
Prefix is correct. Domain is arvig dot net