77 replies to this topic

[robin_astro]

It is quite close to NGC 5461 - lots of papers about it. Probably images as well.
From my previous non HA images (and many on astrobin) the whole area is quite reddish.
 

Yes there are many such sources but they would need to be concentrated within a few arcsec of the location of  the supernova to contaminate the spectrum. Any constant or smoothly varying background emission is taken care of by  the sky subtraction step in the spectrum processing.

 

Cheers

Robin

[yuzameh]

I've looked at the cross section of the spectrum at the H alpha location.

 

SN2023ixf_HII_region.png

 

That particular HII region right next to the spectrum (actually ~7 arcsec from it) does appear to be separated from the supernova in the spectrum. but the problem is we don't know what is directly underneath/on top at the location of  the supernova image.  A high resolution (at an arcsec or two) H alpha image pre explosion might tell us. Does anyone know where I might find one ?

Yep, several places, all of varying unfriendliness.  MAST portal at mast.stsci.edu .  There's an HLA survey around somewhere (forget where it is) where I was able to find the progenitor image mentioned in an ATEL, and of course there's ALADIN, it's not in the main 'optical' section it's in either OTHER or OUTREACH.

 

MAST portal might suit you best though.  Select HLA and in other things in the left hadn sidebar select F656N, in other words Halpha narrow band.  You'll get a fits file.

 

Coincidence :- most of the data available for these things are public, but they are colour coded if PI and/or proposed observations.  SN 2023ixf is actually listed separately along with NGC 4561.  Interestingly there are currently 76 proposals (probably not that many teams, but accumulations of multiple filters for a few teams, and probably more than one of the cameras).

 

I've obtained one of these F656N fits files, stuck it in Aladin as a local file, messed with the pixel historgram for illustration (it was quite dark at default) and exported it to jpeg and imported it into a graphic editor to check.  For some reason the colour palette was messed up with black having gone to lime green, so I greyscaled it and it went back to okay, then I pixel histogrammed again just to bring out objects.  I also had to GIF it because the exported JPG was far too big for CN's 500kb limit.

 

This is because something I'd noticed before could be made more evident.  There are one or two ring nebulae around here, shock fronts around stars, although some seem empty.  The the biggest one is just off the left edge.  Whether stellar wind shockfronts in the ambient local ISM around trapeziumesque O star clumps, Wolf Rayet Nebulae or even in some cases past SN explosions I know not.  Latter seems a bit unlikely.  Formers possible, middle one is one I like but for no firm reason based on data, and gut feeling isn't part of the scientific method.  Wolf Rayet stars are mentioned in places as one potential progenitor of SN IIn but I'm still of the viewpoint that the latter is a grabbag taxonomy for SN II that either have a bit more CSM in the line of sight than usual or a coincident density of ISM in the line of sight, which should be no great shock if they are more likely to lie near dense HII complexes, themselves often radiated out hollows in Giant Molecular Clouds

 

Crosshairs mark the TSN supernova position to five decimals and North is up, largest area of overexposure is NGC 5461, the object that's an island of overexposure above and just to the right of the SN position I'm pretty sure is the small pimple that could be seen on some amateur full maxima images.  Again, this is HST Halpha only, I haven't looked up the passband width of F656N.

 

[robin_astro]

Any constant or smoothly varying background emission is taken care of by  the sky subtraction step in the spectrum processing.

 

There is no sign of this in the spectrum background though. Just the strong sources like the one caught in the spectrograph slit just 7 arcsec away are a potential problem

[robin_astro]

 

 

Crosshairs mark the TSN supernova position to five decimals and North is up, largest area of overexposure is NGC 5461, the object that's an island of overexposure above and just to the right of the SN position I'm pretty sure is the small pimple that could be seen on some amateur full maxima images.  Again, this is HST Halpha only, I haven't looked up the passband width of F656N.

 

 

Thanks, that very useful and actually quite promising. There is a region approximately 5 arcsec or so surrounding  the SN devoid of any strong H alpha sources. I think what I am seeing close to the SN in the spectrum image is probably the edge of  that region about 10 arcsec just west of north (my slit runs approximately north south within a few degrees, I will do a plate solve on my guider image to plot the exact location.) 

[robin_astro]

 

 

 I'm still of the viewpoint that the latter is a grabbag taxonomy for SN II that either have a bit more CSM in the line of sight than usual or a coincident density of ISM in the line of sight, which should be no great shock if they are more likely to lie near dense HII complexes, themselves often radiated out hollows in Giant Molecular Clouds

 

 

Any CSM/ISM would have to be pretty local to the event though to show up as  shock emission in the spectrum in a few tens of days at say 10000km/s  Even any light echoes would only be a few light days away so far 

[yuzameh]

Any CSM/ISM would have to be pretty local to the event though to show up as  shock emission in the spectrum in a few tens of days at say 10000km/s  Even any light echoes would only be a few light days away so far

yep, I was meaning in the context of the ones that can be seen elsewhere to the SN.  They've been building up over very long periods of time and maintained for as long and I'd to mess with the histogram quite a bit to make them anything more than subtle.  Probably should have tried to say it better (often the case).  They've swept up very little over a long time, and that's even if it is ISM and not them puffing out their own atmsopheres.  And of course we don't know if they are behind or in front or whatever of the SN.

 

There doesn't appear to be any hint of any blips I've seen in papers showing bunches of SN for some SN IIn candidates due to hitting CSM or whatever.

 

NB Just fyi.  On the new astro-ph offerings today at arxiv.org a paper from Japanese professinal authors exists in which they apparently present some conclusions about certain parameters and their velocities from fhwm and stuff.  I personally only read their abstract as it plainly stated they were using R ~ 1000 and for my limited understanding that's a pretty low R for any hard conclusions to be derived, so I didn't bother with the full preprint.  They reckon 'a high luminosity SN II with a N/He rich CSM' (paraprhase) and through a few new SN names in as look-alikes.  The abstract finishes with "These observational facts support that SN 2023ixf is well consistent with a high-luminosity SN II with the dense nitrogen/helium-rich CSM".  For R ~ 1000 that's all pushing the data a bit for me but I've no real idea on spectra, just that I'm happy with big R.  Nevertheless you may find it of interest.  Meanwhile an ATEL today said the Japanese neutrino detector (I think it's a cerenkov radiation one using water) data was searched up to two days prior of maximum with null results.  That's neither muon nor electron (anti)neutrinos then.  Still just that bit too far for even current technology.  And I think LIGO was turned back on after a long upgrade just two days after the explosion.

 

https://www.astronom...org/?read=16070

 

edit: https://arxiv.org/abs/2306.00263

Edited by yuzameh, 02 June 2023 - 01:13 PM.

[robin_astro]

The current low resolution spectrum continues to show a cooling continuum with relatively weak features. The higher Balmer lines are showing a growing blue shifted absorption at around 8000km/s but H alpha is just a very broad shallow emission with a hint of structure seen at higher resolution.

https://britastro.or...s&legend_pos=ne

 

SNID gives a reasonable match to  type IIL SN 1980K 7 days past maximum

https://britastro.or...hp?obs_id=13821

 

Compare this for example with recent type IIP supernovae

SN 2022fuc

https://britastro.or...hp?obs_id=11817

https://britastro.or...hp?obs_id=11817

and SN 2022ejw

https://britastro.or...hp?obs_id=11706

https://britastro.or...hp?obs_id=11706

 

 

Cheers

Robin

[seryddwr]

The current low resolution spectrum continues to show a cooling continuum with relatively weak features. The higher Balmer lines are showing a growing blue shifted absorption at around 8000km/s but H alpha is just a very broad shallow emission with a hint of structure seen at higher resolution.

https://britastro.or...s&legend_pos=ne

 

SNID gives a reasonable match to  type IIL SN 1980K 7 days past maximum

https://britastro.or...hp?obs_id=13821

 

Compare this for example with recent type IIP supernovae

SN 2022fuc

https://britastro.or...hp?obs_id=11817

https://britastro.or...hp?obs_id=11817

and SN 2022ejw

https://britastro.or...hp?obs_id=11706

https://britastro.or...hp?obs_id=11706

 

 

Cheers

Robin

Some of our partners at the Large Binocular Telescope have taken a lot of high resolution spectra, but I don't have access to it. It takes a while for this stuff to be published.

[robin_astro]

An update on the evolution of the spectrum.

 

 

 

It  is now showing increasing features more typical of type II supernovae (Broad P Cygni Balmer lines)  Here is an example match in SNID to SN1980K 9 days past maximum  

 

 

Cheers

Robin

 

 

[yuzameh]

Some of our partners at the Large Binocular Telescope have taken a lot of high resolution spectra, but I don't have access to it. It takes a while for this stuff to be published.

you'll find multiepoch stuff here

 

https://arxiv.org/pdf/2306.04721

 

https://arxiv.org/pdf/2306.04722 may also be of interest.

[yuzameh]

Some of our partners at the Large Binocular Telescope have taken a lot of high resolution spectra, but I don't have access to it. It takes a while for this stuff to be published.

They, today, have now put the preprint containing some of these high resolution spectra on astroph.

 

https://arxiv.org/abs/2306.07964

 

"We present a series of high-resolution echelle spectra of SN~2023ixf in M101, obtained nightly during the first week or so after discovery using PEPSI on the LBT."

 

1st line of abstract.

[robin_astro]

The second part of my animation of the spectrum, showing the emerging broad P Cygni line profiles over the past couple of weeks

 

https://britastro.or...767104d96087a30

 

Cheers

Robin

[mwr]

About the discoverer of SN2023ixf in Science journal:

 

"Amateur astronomer Koichi Itagaki is one of the most prolific supernova hunters of all time." 

https://www.science....upernova-hunter

[mborland]

I've been monitoring the supernova since May 26, taking ten 180 second R/G/B images every clear night. With the monsoon having arrived, I probably won't get any more data, so I thought I'd process and share what I have. I used a 9.25" Edge HD at f/7 and a ZWO ASI2600MM.

 

I used python for most of the processing, in particular the DAOStarFinder routine in photoutils. That allowed performing aperture photometry on many stars automatically. I selected the brightest 5 stars for further processing, after cropping a square image around the galaxy. The brightest star was the supernova. I used the other four stars to normalize the supernova flux.

 

The first image is just the flux vs time without any additional normalization. The second image has each channel normalized to a maximum of 1, just to make it easier to compare the different colors.

 

 

 

The first data point seems a bit off, but the others show a fairly smooth trend that is a bit different for each color.

 

--Michael

 

[robin_astro]

Part three of a series of animations showing the development of the spectrum of SN 2023ixf

https://britastro.or...f9ec183a85f2b58

 

Cheers

Robin

[mwr]

Part three of a series of animations showing the development of the spectrum of SN 2023ixf

 

Great animation! Scientifically illustrative as well as aesthetically pleasing. Is it possible to merge the three parts?

[yuzameh]

Part three of a series of animations showing the development of the spectrum of SN 2023ixf

https://britastro.or...f9ec183a85f2b58

 

Cheers

Robin

so Halpha's back with a vengeance?  Surmise it's hitting interstellar rather than circumstellar stuff.  Maybes stuff in shock waves surrounding its natal OB Association / Star Forming Region.

[AstroCub]

Are we allowed to post pictures in this thread? I captured the supernova before and after but not sure if it's cool to post it here?

 

Siouxsie 

[robin_astro]

so Halpha's back with a vengeance?  Surmise it's hitting interstellar rather than circumstellar stuff.  Maybes stuff in shock waves surrounding its natal OB Association / Star Forming Region.

This is formed within the ejecta. (A broad line with a P Cygni component velocity around 6000 km/s currently.)  Typical of all type II at this stage eg SN 2004dj I observed bottom of the page here

http://www.threehill...o/spectra_6.htm

 

Cheers

Robin

[robin_astro]

Great animation! Scientifically illustrative as well as aesthetically pleasing. Is it possible to merge the three parts?

Yes I will probably do that eventually, (The time runs at different speeds in each stage as the evolution slows)  The next stage will be the transition to the nebular phase with some high ionisation forbidden lines appearing but that will be a few months off yet.

 

Cheers

Robin

[Degen1103]

What is the reason of fast falling of SN brightness? Recombination?

[robin_astro]

What is the reason of fast falling of SN brightness? Recombination?

That is an interesting acceleration of the brightness decline over the past ~10 days. This drop is normally seen around this time in type IIP at the end of the recombination phase but in this case it has followed a gradual fall rather than a plateau. This paper discusses another supernova (2013by) with a similar "hybrid" light curve

https://arxiv.org/abs/1501.06491v2

 

Cheers

Robin

[Rigel7]

Here's a nice article about determining the geometric shape of the explosion by analyzing the polarization of the spectrum.

https://news.berkele...0230828-6895045

Tldr: It's a peanut.

Edited by Rigel7, 05 September 2023 - 04:06 AM.

[yuzameh]

There were a couple more pre-prints on astroph the other night, submissions for Wednesday I think.  Some very similar things given results for, with different numbers in the results when it comes to assumed mass loss rate pre-outburst if I remember rightly.

[robin_astro]

Part 4 of my series of animations covering the evolution of the spectrum

https://britastro.or...dc6ef43502da26b

This covers the period when the brightness dropped rapidly before resuming its gentle decline so I have included animations both scaled to 1 at 5500A as per the other animations and in absolute flux, calibrated using V magnitude values

 

Cheers

Robin