Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Supernova Imposter?

  • Please log in to reply
23 replies to this topic

#1 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 14 February 2018 - 09:18 PM

Two nights ago I shot an image of NGC 3432 / ARP 206. In comparing it with other images I noted a "star" in the "ejectate" (As described by Arp) that was not present on numerous other similarly deep or even deeper images over many years, including a NASA VLA image. It was present in the unprocessed stacks of each LRGB channel, included a luminance stack that had drifted nearly off the chip after guide star loss. With supernova thoughts , I posted a followup in my original thread which I promptly deleted after reviewing Rick Js image from 2008 here on CN which clearly shows this "star". The most recent image of it is from Dan Crowson which shows barely a trace of it. And numerous other images between these time frames, show it not at all (mostly) or perhaps a trace. I found this very curious. So I started reading about rare supernova imposters which are stellar explosions that do not destroy their progenitor stars and are subject to subsequent repeated eruptions.The most notable of these is SN2006JC in UGC 4904 which blew to bits as a SN two years after an amateur discovered an initial outburst which was mistakenly thought to be a SN, but the star faded but survived. Luminous blue variable (LBVs) are examples of these unstable stars. Eta Carina, which has erupted at least three times is another example of a supernova imposter.

 

Full image is here:

http://www.pbase.com...005054/original

 

This is a crop of my image showing the star in question:

NGC3432LRGBSNI.jpg

 

This is the NASA VLA data from 1997

NGC3432Nasa.jpg

 

These are a few images at least as deep as mine that show at most traces or no evidence of the star while other stars and small galaxies are not variable:

 

https://www.cloudyni...573005-arp-206/

 

https://www.astrobin.com/full/82878/C/

 

http://www.pbase.com/image/143306089

 

http://www.faintgalaxy.com/ngc3432.htm

 

And Rick Js image from 2008 which clearly shows it:

https://www.cloudyni...p-206-ngc-3432/

 

Perhaps its just related to depth of image and processing variability and this is just a silly post. Its just curious that all of the other stars / faint galaxies, etc seemed to be consistent without similar variability from image to image. Any thoughts or comments would be much appreciated.

 

Derek


Edited by schmeah, 14 February 2018 - 09:38 PM.

  • bill w, nmoushon, t_image and 2 others like this

#2 Rick J

Rick J

    Cosmos

  • *****
  • Posts: 8352
  • Joined: 01 Mar 2008
  • Loc: Mantrap Lake, MN

Posted 14 February 2018 - 09:46 PM

My 2008 image is in dire need of reprocessing.  That is before I did any research on objects I took.  I hadn't noticed the star wasn't on other images. 

 

I had a grad student write me about a different galaxy in which I had caught such a star.  He mentioned that some turn out to just be previously unknown variable stars.  Have you checked to see if that might be the case here?  I've not had time to look into that.

 

Rick



#3 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 14 February 2018 - 09:59 PM

Hi Rick. Its statistically more likely to be a foreground variable star. But if it blows itself to smithereens I'm going to go buy a lottery ticket :) I'll have to look into this further, though don't really know where to start.

 

Derek



#4 starblue

starblue

    Mariner 2

  • -----
  • Posts: 256
  • Joined: 01 Apr 2015
  • Loc: Austin, TX, USA

Posted 15 February 2018 - 01:09 AM

The star is visible in this photo on Astrobin from a year ago. Doubt it's a supernova after such a long time.

 



#5 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 15 February 2018 - 06:48 AM

The star is visible in this photo on Astrobin from a year ago. Doubt it's a supernova after such a long time.

Thanks starblue. I hadn't seen that one. But again, I'm not suggesting its a supernova, in which case once it had faded after blowing, it would be gone for good. I'm questioning whether this could be a star with variable brightness, erupting but surviving with some regular or random periodicity, because it is there sometimes, and so clearly not there on other images similar in depth.

 

Derek



#6 bill w

bill w

    Voyager 1

  • *****
  • Posts: 11259
  • Joined: 26 Mar 2005
  • Loc: southern california

Posted 15 February 2018 - 12:07 PM

nice discovery

have you run it thru aladin?



#7 starblue

starblue

    Mariner 2

  • -----
  • Posts: 256
  • Joined: 01 Apr 2015
  • Loc: Austin, TX, USA

Posted 15 February 2018 - 03:10 PM

Maybe here's your answer? <link>


  • bill w and A10-c like this

#8 Rick J

Rick J

    Cosmos

  • *****
  • Posts: 8352
  • Joined: 01 Mar 2008
  • Loc: Mantrap Lake, MN

Posted 15 February 2018 - 06:44 PM

Interesting.  My image was taken on March 12, 2008 from 4:20 through 06:32 UT.  One image Starblue found was taken October 25 the same year.  So it is bright for some time, over 7 months at least.  Or did it fade then brighten that quickly?  Interesting object. 

 

I did a quick reprocess of my 2008 image.  For some reason 3 luminance images were take then there was a gap of 30 minutes for 3 color frames before the fourth was taken.  Why I did that is long lost.  Image scale is 0.8" per pixel.

 

Rick

NGC3432ARP206L4X10RGB1X10X3R3-SN2000chCROP125.JPG


Edited by Rick J, 16 February 2018 - 04:08 PM.


#9 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 15 February 2018 - 07:08 PM

Maybe here's your answer? <link>

Holy smokes! I can't believe this. Very cool, and yet very embarrassing. I guess a proper google search would have turned this up before I actually got all excited about it. I hope no one thinks that this was a surreptitious attempt to gain a little notoriety. This truly was an honest endeavor. And it does actually encourage me that we can find very cool things by carefully inspecting our images ... even if 8 years too late ...

 

Thanks starblue for doing the investigation that I should have done before posting.

 

Derek


Edited by schmeah, 15 February 2018 - 07:58 PM.


#10 NorthField

NorthField

    Viking 1

  • *****
  • Posts: 680
  • Joined: 01 Jun 2017
  • Loc: SW Missouri

Posted 15 February 2018 - 07:28 PM

( scary smart is starblue I think )

Excellent find Derek!!.. embarrassed? Ha!!

You captured/noticed/reported something that obviously has had $$$$$$$ equipment trying to figure out/catalog **** it is for a long little while..
  • schmeah likes this

#11 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 15 February 2018 - 07:55 PM

Interesting.  My image was taken on March 12, 2008 from 4:20 through 06:32 UT.  One image Starblue found was taken October 25 the same year.  So it is bright for some time, over 7 months at least.  Or did it fade then brighten that quickly?  Interesting object. 

 

I did a quick reprocess of my 2008 image.  For some reason 3 luminance images were take then there was a gap of 30 minutes for 3 color frames before the fourth was taken.  Why I did that is long lost.  Image scale is 0.8" per pixel.attachicon.gif NGC3432ARP206L4X10RGB1X10X3R2CROP125.JPG

 

Rick

The article that starblue linked suggests a periodicity of about 200 days, at least during the short period presented in the initial images. This would be consistent with with the three most recent images pointed out in this thread. It is nearly invisible in Dan Crowsons image from April 2017, fairly luminous in Richard Bratt's image from November, and perhaps fading a bit in my image 3 months later. Neat stuff. I wonder how likely it is that this will blow as a SN similar to SN2006SJ which exhibited this same flaring two years before. Perhaps we should keep our scopes trained on this one and capture a SN "real time" :)

 

Derek 

 

Derek  



#12 starblue

starblue

    Mariner 2

  • -----
  • Posts: 256
  • Joined: 01 Apr 2015
  • Loc: Austin, TX, USA

Posted 16 February 2018 - 02:07 AM

Personally, I find it remarkable that an individual star (ignoring supernovae) can be photographed by an amateur in a galaxy that's as far away as 45 Mly (give or take: SS6 says 37 Mly).

 

If LBV's are that bright and every galaxy has at least one (the MW has < 20 of them, M31 5, and M81 3, according to Wikipedia), does that imply that every galaxy (let's simplify and assume just major spirals and ellipticals, not irregulars or dwarfs) out to that distance has at least one LBV that can be imaged by an amateur? That is, in a photograph of a galaxy < 45 Mly away, there is at least one star in the image that belongs to that galaxy and is not a field star in the MW.

 


  • schmeah likes this

#13 WadeH237

WadeH237

    Gemini

  • *****
  • Posts: 3243
  • Joined: 24 Feb 2007
  • Loc: Snohomish, WA

Posted 16 February 2018 - 11:13 AM

Very cool, and yet very embarrassing. I guess a proper google search would have turned this up before I actually got all excited about it.

Nonsense!

 

I'm inspired when people discover things like this in their own data.  And presenting it the way you did, I got to go along for the ride by following the thread.  This is an object that I might not have otherwise been interested in, and I learned something about a class of stars that I wasn't aware of.



#14 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 16 February 2018 - 12:54 PM

 

Very cool, and yet very embarrassing. I guess a proper google search would have turned this up before I actually got all excited about it.

Nonsense!

 

I'm inspired when people discover things like this in their own data.  And presenting it the way you did, I got to go along for the ride by following the thread.  This is an object that I might not have otherwise been interested in, and I learned something about a class of stars that I wasn't aware of.

 

Thanks Wade. I learned quite a bit about these LBV stars, SN imposters, variables etc in my initial frenzied search. It just kills me that I didn't include "NGC 3432" when googling any of the above terms. Had I, I would have eventually come across this discovery article from 2004, in which they describe a short term evolution of what had been known as SN2000CH, named after its initially recognized "supernova" outburst. The article is fascinating and suggests to me that there is still much to be learned with ongoing observation of this object:

 

https://www.jstor.or...1086/382997.pdf

 

Derek



#15 robin_astro

robin_astro

    Viking 1

  • -----
  • Posts: 511
  • Joined: 18 Dec 2005

Posted 16 February 2018 - 02:09 PM

Yes it is a well known supernova impostor (originally called 2000ch)  which has been cropping up from time to time since May 2000 and the latest outburst was picked up by Itagaki on 5th Feb this year.

Here is David Bishop's page on it (from his bright supernova website, the goto place for all supernova news)

http://www.supernova...0/sn2000ch.html

 

Cheers

Robin



#16 robin_astro

robin_astro

    Viking 1

  • -----
  • Posts: 511
  • Joined: 18 Dec 2005

Posted 16 February 2018 - 03:54 PM

Here's the reference (in Astronomical Telegram  #1534) of the outburst in 2008

https://ui.adsabs.ha...CBET.1534....1N

 

Cheers

Robin



#17 rigel123

rigel123

    Hubble

  • *****
  • Posts: 15380
  • Joined: 29 Jun 2009
  • Loc: SW Ohio

Posted 16 February 2018 - 08:27 PM

Pretty cool that you "re-discovered" it, great observation!



#18 Rick J

Rick J

    Cosmos

  • *****
  • Posts: 8352
  • Joined: 01 Mar 2008
  • Loc: Mantrap Lake, MN

Posted 17 February 2018 - 12:22 AM

Here's the reference (in Astronomical Telegram  #1534) of the outburst in 2008

https://ui.adsabs.ha...CBET.1534....1N

 

Cheers

Robin

Yes, that's the October outburst but it also blew in March of that year that no one seems to have caught but me, totally by accident.  The article Starblue cites gives it about a 200 day period which fits it blowing in March when I caught it.  It likely blew many times between 2000 and 2008 but apparently wasn't caught or if caught not recognized.  I missed it until  Derek realized it was in my old image.  Many others likely did as well.

 

At one time someone proposed a place to store all images, pro and amateur, so it could be mined to find things unknown at the time they were taken.  I suppose with the huge volume of data today it wouldn't be practical.  Ownership issues abound as well.  It's now well followed it appears but wasn't for many years.

 

Rick



#19 Eric Benson

Eric Benson

    Sputnik

  • -----
  • Posts: 45
  • Joined: 02 Sep 2009

Posted 17 February 2018 - 10:14 AM

Hello Derek,

Well that is quite something to have noticed, and even better that you chased it down and with some help was able to identify such a rare object, at least in amateur circles. Congrats.

 

When you first posted in the other thread I thought the object was familiar, and indeed I had data from 2006 when I was just starting out in astrophotography. It was the 3rd object I had acquired data for with my at the time brand new C11+G11 rig setup/taken down each night in my Ottawa backyard, although I was still using the fancy (at the time!) 'family' Canon 350D DSLR. (I'm the www.faintgalaxy.com website in your list of links)

 

Things have evolved since and I present better data, even though the object only peaks at altitude 23 deg from my new digs down under. I squeaked in 1.5hrs of luminance on my CDK20 remotely operated in Arkaroola in the Northern Flinders Ranges of South Australia. The LBV is obvious at the moment.

 

Some acquisition data:

Telescope: Planewave CDK20 Aperture 0.5m, EFL 3420 mm

Mount: Planewave A200HR

Camera: FLI Proline 16803

Exposure: 3 x 1800 sec with luminance filter

Calibration: Bias and dark correction only, background flattened by software. (I don't have my flats downloaded yet!)

The image has been cropped and resized to 50% (1.1 "/pixel), north up, east to the left.

I estimate it's visual magnitude to be 17.7 using the 16.16m star UCAC4 star 40" to the east.

 

Cheers,

EB

 

Arp206-crop-rsz-Lum.jpg


  • schmeah and happylimpet like this

#20 Rick J

Rick J

    Cosmos

  • *****
  • Posts: 8352
  • Joined: 01 Mar 2008
  • Loc: Mantrap Lake, MN

Posted 17 February 2018 - 03:16 PM

I suggest you send this to David Bishop's page for this LBV where he is tracking it.  He had a huge gap from 2000 to 2013.  I filled in March 12, 2008.  This would add another when it was in eruption.  The exact date would be helpful if known.

 

Rick



#21 schmeah

schmeah

    Aurora

  • *****
  • topic starter
  • Posts: 4621
  • Joined: 26 Jul 2005
  • Loc: Morristown, NJ

Posted 17 February 2018 - 09:59 PM

Hello Derek,

Well that is quite something to have noticed, and even better that you chased it down and with some help was able to identify such a rare object, at least in amateur circles. Congrats.

 

When you first posted in the other thread I thought the object was familiar, and indeed I had data from 2006 when I was just starting out in astrophotography. It was the 3rd object I had acquired data for with my at the time brand new C11+G11 rig setup/taken down each night in my Ottawa backyard, although I was still using the fancy (at the time!) 'family' Canon 350D DSLR. (I'm the www.faintgalaxy.com website in your list of links)

 

Things have evolved since and I present better data, even though the object only peaks at altitude 23 deg from my new digs down under. I squeaked in 1.5hrs of luminance on my CDK20 remotely operated in Arkaroola in the Northern Flinders Ranges of South Australia. The LBV is obvious at the moment.

 

Some acquisition data:

Telescope: Planewave CDK20 Aperture 0.5m, EFL 3420 mm

Mount: Planewave A200HR

Camera: FLI Proline 16803

Exposure: 3 x 1800 sec with luminance filter

Calibration: Bias and dark correction only, background flattened by software. (I don't have my flats downloaded yet!)

The image has been cropped and resized to 50% (1.1 "/pixel), north up, east to the left.

I estimate it's visual magnitude to be 17.7 using the 16.16m star UCAC4 star 40" to the east.

 

Cheers,

EB

 

 

Thanks Eric. Sorry to have linked your image without having notified you. Your newly posted image is recent? The magnitude seems very similar to mine. This target has really peaked my curiosity. I suspect I will be taking a quick shot at it now and again for some time to come.

 

Derek



#22 happylimpet

happylimpet

    Mercury-Atlas

  • *****
  • Posts: 2807
  • Joined: 29 Sep 2013
  • Loc: Southampton, UK

Posted 19 February 2018 - 09:59 AM


This is the NASA VLA data from 1997

attachicon.gif NGC3432Nasa.jpg

Note that only the contours are VLA data (Its a radio telescope) and the B/W image in the background is from  a different optical telescope.


  • schmeah likes this

#23 Eric Benson

Eric Benson

    Sputnik

  • -----
  • Posts: 45
  • Joined: 02 Sep 2009

Posted 25 February 2018 - 10:31 AM

Thanks Eric. Sorry to have linked your image without having notified you. Your newly posted image is recent? The magnitude seems very similar to mine. This target has really peaked my curiosity. I suspect I will be taking a quick shot at it now and again for some time to come.

 

Derek

 

Hi Derek,

Hey no worries, all the image details are my webpage, and this kind of thing is exactly what the web is for.

 

The lum data I posted in the thread above was captured in the early morning hours of Feb 17th. I programmed ACP to acquire colour frames the next night and they completed on the 20th. I'm now finally getting back to this data, and with proper flats, I have completed an LRGB image that shows the LBV as a surprisingly green object (the appearance reminds me of the green peas discovered in the galactic zoo project). Too bad the L data is of sub par quality, but the color data came out pretty good considering the object altitude from latitude 30deg south!

 

The LRGB is 3 x 1800s for each channel, so 6 hrs all up. I've providing two 800x800 crops, one at 1.1"/pix, the other a wider field at 2.2"/pix. The processing was very minimal, just a non-linear stretch and some noise reduction on the background, no color saturation enhancement!

 

Thanks again for bringing our attention to this object, it has been fun following this one up.

EB

 

Data from Arkaroola Remote Observatory, South Australia, Feb 17, 18, 20th, 2018.

Arp206_crop_rsz_LRGB.jpg

 

and the wider field:

Arp206_crop_qsz_LRGB.jpg



#24 Eric Benson

Eric Benson

    Sputnik

  • -----
  • Posts: 45
  • Joined: 02 Sep 2009

Posted 25 February 2018 - 10:43 AM

I suggest you send this to David Bishop's page for this LBV where he is tracking it.  He had a huge gap from 2000 to 2013.  I filled in March 12, 2008.  This would add another when it was in eruption.  The exact date would be helpful if known.

 

Rick

Hi Rick,

Thanks for the hint, I was unaware of that log. I actually recorded photometric V and R filtered images on the 18th of Feb, along with the RGB frames, so that might be useful.

EB




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics