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Re: SN 2020jfo in M61

PostPosted: Sun May 31, 2020 1:39 pm
by Frederic Pastor
Hi all,

I wanted to make a spectrum of SN2020jfo, 3 weeks after its discovery. Here is below my contribution cumulating 4200 sec (only):

SN2020jfo publication ARAS.jpg
Sn2020jfo
SN2020jfo publication ARAS.jpg (83.91 KiB) Viewed 375 times


Despite noise, it fits in GELATO with the SN2008fz, type IIn:

gelatoplot (2).png
gelato
gelatoplot (2).png (66.02 KiB) Viewed 375 times


Recorded at Mag 14.8 the night of 28th of May, according contributors in Rochester site:

http://www.rochesterastronomy.org/sn2020/sn2020jfo.html

Cheers,

Fred

Re: SN 2020jfo in M61

PostPosted: Sun May 31, 2020 3:15 pm
by Robin Leadbeater
Peter Velez wrote:There are a couple of spurious spikes though the emission at around 6600 is genuine.


Hi Peter, They wont be from the supernovae though they could be galactic perhaps. I suggest first checking that they are not sky lines than have not been subtracted cleanly by the sky background subtraction though. The line at ~5600 in particular has that characteristic shape for this sort of problem.

The velocity of ejecta can be estimated from the absorption component of the H balmer p cygni lines (either relative the the unshifted emission component or relative to the local rest wavelength.) Note the value depends on the line measured as we see to different depths depending on the line observed and I understand the apparent slowing with time observed is mainly due to us seeing deeper into the increasingly transparent ejecta rather than an actual slowing)

Cheers
Robin

Re: SN 2020jfo in M61

PostPosted: Sun May 31, 2020 5:18 pm
by Robin Leadbeater
Robin Leadbeater wrote:
The velocity of ejecta can be estimated from the absorption component of the H balmer p cygni lines


for type II eg

viewtopic.php?f=38&t=2533#p14070

For type Ia the Si II 6355A absorption line shift from rest can be used eg
viewtopic.php?f=38&t=2308&start=30#p12679

Filippenko's paper is a good overview of supernova spectra
https://ned.ipac.caltech.edu/level5/Mar ... rames.html
but in general the lines are so blended and shifted in supernova spectra that separating and identifying the lines by eye is difficult and these days it is generally it is done by fitting to models

Cheers
Robin