ASTRO: SN2017J in M82

Sometime, probably after January 11 and before January 19, the light of
a type 1A supernova in the starburst galaxy M82 hit the earth. It
wasn't "discovered" until the night of January 21 in England. A group
of students got an unexpected introduction to what to do when an event
such as this is first seen. You can read about it at
http://www.ucl.ac.uk/maps-faculty/ma...ation/maps1405. I've
seen images taken as early as January 19 that show it but those taking
the images didn't realize what they had or didn't look at the data until
days later. Earlier images likely exist. These are referred to as
pre-discovery images. I first heard of it on the 22nd but it was
cloudy. It sort of cleared Wednesday night, the 23rd of January (all
times and dates are UT not local time). I had rather poor seeing but
took what data I could prior to moon rise. The temperature here was
running down around -35°C when I started and dropped 3 more degrees
while I was taking the data which meant my image scale changed adding to
my processing steps. Due to other issues I couldn't get it processed
until Friday morning so I'm a bit late to this party. My red data was
taken when the moon was brightening the sky though not yet risen. This
prevented me from capturing the H alpha streamers caused by the
starburst activity in the galaxy.

Starburst activity creates many short lived massive stars that go
supernova after only a few million years of life. Such supernovas are
called type II supernovae. So you'd expect such a massive star's death
to be the cause of the supernova. But, just to be contrary I suppose,
this is a type 1a which is caused by the sudden distruction of one or
maybe 2 white dwarf stars. White dwarf stars are much less massive
stars and live at least a billion years or longer. So the star or stars
that caused this supernova predate the starburst activity in M82. Such
supernova are thought to be standard candles so if you know the apparent
brightness as well as how much dust and gas between us and the supernova
dims the light the distance to the supernova can be calculated. Thus
this supernova might help better determine the distance to M82 which is
currently put at about 12 million light-years. The problem is the light
of a fresh type 1a supernova should be blue. This one is somewhat red.
Not because the supernova is red but because it went off deep inside
the dusty M82's disk. Dust reddens starlight same as it reddens our
sunsets and sunrises. This will make estimating the loss to dust and
gas rather difficult. I'm sure all sorts of methods of adjusting for
this will be tested by this event.

M82 is also Arp 337 so I've added another supernova to my collection of
Arp galaxies. A surprising number of them in my collection were caught
with supernovas including M51 and M101 and about a half dozen others.
I've lost count so need to go back and look that count up. Seems
peculiar galaxies that made his list are above average in the number of
their supernovas by my rather unscientific survey.

I've made an annotated image showing the surrounding galaxies, galaxy
clusters and quasars. I found this field particularly difficult to work
with. Many of the quasars listed in NED as well as some galaxies had
vague coordinates. Often there was nothing close to the right magnitude
within the error circle or even well beyond the error circle. Rather
than guess I didn't include these vague positioned objects. Even when I
could identify the object it was sometimes listed as both a quasar and a
galaxy yet of typical galaxy distance and sometimes showing a slight
disk rather than the point source of a quasar. I listed these as both Q
and G often with a question mark. NED usually preferred the quasar
designation even when a small disk is seen. While NED listed about
twice as many galaxy clusters as I show I only listed those with a Big
Cluster Galaxy listed in NED such that I could pin down its location.
Some used photographic redshift, designated with a p after the light
travel time figure, for the cluster but spectroscopic redshift for the
BCG. The latter is likely more accurate though in these cases they were
in rather close agreement. Many time I find a wide difference but not
with these.

The supernova is expected to continue to brighten for a week or maybe
longer. Due to the extensive light of the galaxy around it I was unable
to get a good magnitude estimate. There are tricks for adjusting for
this but I didn't take the time for them. Most estimates put it at
about magnitude 11 or a bit brighter. It might reach 8th magnitude by
some predictions. Time will tell if those predictions come true.

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

Rick
--
Prefix is correct. Domain is arvig dot net

Rick,

so you managed to get the SN. Somehow I expected it to be brighter.
And you got a very good image of M82 that way. Certainly the best image of
M82 with the SN I have seen so far.

Stefan


"Rick Johnson" schrieb im Newsbeitrag
...

Sometime, probably after January 11 and before January 19, the light of
a type 1A supernova in the starburst galaxy M82 hit the earth. It
wasn't "discovered" until the night of January 21 in England. A group
of students got an unexpected introduction to what to do when an event
such as this is first seen. You can read about it at
http://www.ucl.ac.uk/maps-faculty/ma...ation/maps1405. I've
seen images taken as early as January 19 that show it but those taking
the images didn't realize what they had or didn't look at the data until
days later. Earlier images likely exist. These are referred to as
pre-discovery images. I first heard of it on the 22nd but it was
cloudy. It sort of cleared Wednesday night, the 23rd of January (all
times and dates are UT not local time). I had rather poor seeing but
took what data I could prior to moon rise. The temperature here was
running down around -35°C when I started and dropped 3 more degrees
while I was taking the data which meant my image scale changed adding to
my processing steps. Due to other issues I couldn't get it processed
until Friday morning so I'm a bit late to this party. My red data was
taken when the moon was brightening the sky though not yet risen. This
prevented me from capturing the H alpha streamers caused by the
starburst activity in the galaxy.

Starburst activity creates many short lived massive stars that go
supernova after only a few million years of life. Such supernovas are
called type II supernovae. So you'd expect such a massive star's death
to be the cause of the supernova. But, just to be contrary I suppose,
this is a type 1a which is caused by the sudden distruction of one or
maybe 2 white dwarf stars. White dwarf stars are much less massive
stars and live at least a billion years or longer. So the star or stars
that caused this supernova predate the starburst activity in M82. Such
supernova are thought to be standard candles so if you know the apparent
brightness as well as how much dust and gas between us and the supernova
dims the light the distance to the supernova can be calculated. Thus
this supernova might help better determine the distance to M82 which is
currently put at about 12 million light-years. The problem is the light
of a fresh type 1a supernova should be blue. This one is somewhat red.
Not because the supernova is red but because it went off deep inside
the dusty M82's disk. Dust reddens starlight same as it reddens our
sunsets and sunrises. This will make estimating the loss to dust and
gas rather difficult. I'm sure all sorts of methods of adjusting for
this will be tested by this event.

M82 is also Arp 337 so I've added another supernova to my collection of
Arp galaxies. A surprising number of them in my collection were caught
with supernovas including M51 and M101 and about a half dozen others.
I've lost count so need to go back and look that count up. Seems
peculiar galaxies that made his list are above average in the number of
their supernovas by my rather unscientific survey.

I've made an annotated image showing the surrounding galaxies, galaxy
clusters and quasars. I found this field particularly difficult to work
with. Many of the quasars listed in NED as well as some galaxies had
vague coordinates. Often there was nothing close to the right magnitude
within the error circle or even well beyond the error circle. Rather
than guess I didn't include these vague positioned objects. Even when I
could identify the object it was sometimes listed as both a quasar and a
galaxy yet of typical galaxy distance and sometimes showing a slight
disk rather than the point source of a quasar. I listed these as both Q
and G often with a question mark. NED usually preferred the quasar
designation even when a small disk is seen. While NED listed about
twice as many galaxy clusters as I show I only listed those with a Big
Cluster Galaxy listed in NED such that I could pin down its location.
Some used photographic redshift, designated with a p after the light
travel time figure, for the cluster but spectroscopic redshift for the
BCG. The latter is likely more accurate though in these cases they were
in rather close agreement. Many time I find a wide difference but not
with these.

The supernova is expected to continue to brighten for a week or maybe
longer. Due to the extensive light of the galaxy around it I was unable
to get a good magnitude estimate. There are tricks for adjusting for
this but I didn't take the time for them. Most estimates put it at
about magnitude 11 or a bit brighter. It might reach 8th magnitude by
some predictions. Time will tell if those predictions come true.

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

Rick
--
Prefix is correct. Domain is arvig dot net

When the image is stretched to bring out the faint detail few levels are
left for the bright levels. This gives a false impression of the SN
brightness. I've attached a linear stretch of the luminance channel
such that the SN just reaches the maximum level allowed by JPG's 8 bit
format. This more correctly shows the relative brightness of the galaxy
and SN.

Rick

On 1/26/2014 4:21 PM, Stefan Lilge wrote:
Rick,

so you managed to get the SN. Somehow I expected it to be brighter.
And you got a very good image of M82 that way. Certainly the best image
of M82 with the SN I have seen so far.

Stefan