potentially bright supernova in NGC4636

potentially bright supernova in NGC4636

Postby Robin Leadbeater » Sun Jan 12, 2020 11:44 pm

https://wis-tns.weizmann.ac.il/object/2020ue

Discovered today at mag 15 by Koichi Itagaki and confirmed as a type Ia, this could reach brighter than mag 12 depending on the extinction in the host galaxy so potentially bright enough for medium resolution spectra in the coming days

Cheers
Robin
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Thu Jan 16, 2020 11:51 am

I have had a request for spectra of SN 2020ue from Prof Subo Dong on behalf of the ASAS-SN team. He writes

"We've just analyzed the latest 2020ue images, and it is at about 14
mag and rising. It'd be very useful to take high-cadence spectra for
this object. We plan to take spectroscopic polarimetry observations
too."

Theoretically the brightness could increase to mag 12 (SN 1939A also a type Ia in the same galaxy reached 11.9)

Cheers
Robin
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Sat Jan 18, 2020 12:11 pm

Currently 12.8 as measured by Itagaki
https://www.flickr.com/photos/snimages/49401526653/
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Sun Jan 19, 2020 11:03 pm

Currently mag 12.6 and still rising, heading to be the brightest for 5 years.

Here is a high SNR spectrum from last night using the ALPY600.

sn2020ue_20200119_100_Leadbeater.png
sn2020ue_20200119_100_Leadbeater.png (24.13 KiB) Viewed 3334 times


which gives and excellent detailed match in SNID to several type Ia supernovae still a few days from maximum eg

sn2020ue_SNID_fit.png
sn2020ue_SNID_fit.png (36.46 KiB) Viewed 3334 times


Cheers
Robin
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Re: potentially bright supernova in NGC4636

Postby etienne bertrand » Tue Jan 21, 2020 3:51 pm

Bravo Robin, exellent spectr !
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Re: potentially bright supernova in NGC4636

Postby James Foster » Tue Jan 21, 2020 9:07 pm

To: Robin,

Thanks for the heads-up on this SN! I barely had time to slap the Alpy600 on my scope after finishing a run with the LhiresIII on Be stars.
Seeing was also questionable (as well as my focus), but I was able to get 8 images before the sky got too bright to shoot any more.
Previous to shooting this object in NGC 4636, I took a quick shot of Denebola (A3V) for my image response curve and got this spectrum of SN2020ue:
Image
Very interesting spectrum and as previously mentioned, its probably before brightest light. I need to set my C-11/Photometry scope on this
object over the next 2 weeks to get BVRI calibrated magnitudes of this bright SN. As usual, (except for the telluric OII) all identified spectral
lines are (very) speculative!

James
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Wed Jan 22, 2020 8:34 pm

Hi James,

James Foster wrote: all identified spectral
lines are (very) speculative!


Nice spectrum. Are you adding it to the BAA database?.

Don't forget to identify lines you have to take into account the redshift of the galaxy and for absorption lines the blue shift due to the velocity of the explosion so the lines are very broad and can end up a long way from their rest wavelength. To get you started, the deep absorption "line" at ~6100A is Si II (rest wavelength 6355A) and is the result of the thermonuclear explosion and the main identifying feature of type Ia supernovae. You can use this to roughly calculate the current explosion velocity which reduces with time as we see deeper into the ejected material. (There is a good thread on here somewhere which follows the evolution of a type Ia in detail.)

The spectrum taken using Seimei 3.8m - KOOLS in TNS which was used to classify it is corrupted by some very high values so does not display properly there but attached is a corrected version to compare with the current spectra. The changes since then are quite dramatic, though the Si II line is still clear, just less blueshifted now

Cheers
Robin
Attachments
tns_2020ue_2458861.36_other_other_crop.zip
(16.97 KiB) Downloaded 146 times
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Wed Jan 22, 2020 8:57 pm

Robin Leadbeater wrote: (There is a good thread on here somewhere which follows the evolution of a type Ia in detail.)



I did not have to look too far, it was SN 2019ein a few topics down :)
viewtopic.php?f=38&t=2308
Not sure why the brighter SN 2020ue has not generated as much interest. The inconvenient early morning observing hour I suppose.

There is a nice graphic by Stephane Blondin (who co-wrote the SNID supernova identifcation software) here showing the typical evolution of a type Ia with time
https://people.lam.fr/blondin.stephane/ ... g_anim.gif

Cheers
Robin
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Re: potentially bright supernova in NGC4636

Postby James Foster » Fri Jan 24, 2020 12:09 am

Here is my most recent data on SN2020ue shot with Alpy600(22Jan20) & LISA-IR(23Jan20), stiched in BeSS Project and plotted in PlotSpectra:
Image
Despite imaging almost 10x420sec2x2 binned shots with the LISA-IR, there doesn't seem much IR energy coming from this SN.
I cropped lower than 9200A because it was so noisy after that point.

James
Last edited by James Foster on Fri Jan 24, 2020 12:48 am, edited 1 time in total.
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Re: potentially bright supernova in NGC4636

Postby Robin Leadbeater » Fri Jan 24, 2020 12:38 am

Hi James

Note the correct designation is SN 2020ue not SN2020ue (mind the gap ! I sometimes forget too) I had already registered SN 2020ue as a new object in the BAA database so I have added SN2020ue as an alias so either designation will now call up all the spectra

BAASDB_SN_2002ue.png
BAASDB_SN_2002ue.png (32.51 KiB) Viewed 3116 times


Cheers
Robin
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