|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
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 |
#2
|
|||
|
|||
ASTRO: SN2017J in M82
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 |
#3
|
|||
|
|||
ASTRO: SN2017J in M82
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 |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
[sci.astro,sci.astro.seti] Contents (Astronomy Frequently Asked Questions) (0/9) | [email protected] | SETI | 0 | August 15th 07 09:36 PM |
[sci.astro,sci.astro.seti] Contents (Astronomy Frequently Asked Questions) (0/9) | [email protected] | SETI | 0 | May 3rd 07 01:08 AM |
[sci.astro,sci.astro.seti] Contents (Astronomy Frequently Asked Questions) (0/9) | [email protected] | Astronomy Misc | 0 | April 12th 07 01:05 AM |
[sci.astro,sci.astro.seti] Contents (Astronomy Frequently Asked Questions) (0/9) | [email protected] | Astronomy Misc | 0 | May 3rd 06 12:33 PM |
[sci.astro,sci.astro.seti] Contents (Astronomy Frequently Asked Questions) (0/9) | [email protected] | SETI | 0 | October 6th 05 02:34 AM |