View Full Version here: : V745 Sco - Request for spectra
Merlin66
07-02-2014, 07:45 AM
Steve Shore has sent me this email:
PLEASE, if possible (and urge others to go for
this too) try to get V745 Sco. This is a symbiotic-like recurrent nova
that was last in outburst in 1989 and observed in the UV at that time.
It is about 45 degrees from the Sun, so a hard case, but any spectra
will be really (!!) important, even low resolution. This will have
very broad lines at first and those will last for only, at most, about
a week or two so it's very important that spectra be obtained ASAOP.
The announcement arrived a few hours ago.
THANKS VERY MUCH!!!
steve
Andrew Pearce
08-02-2014, 12:06 PM
Hi All
V745 Sco is fading fast. This morning (Feb 7.8UT) it was down to mag 10.1 visually.
Regards
Andrew
Ah, intrepid southern amateur spectroscopists ...
Just when we thought it was safe to capture our nova spectra before midnight :-)
Rob_K
08-02-2014, 05:37 PM
Agree, what's with all this early morning rubbish? :P Way beyond my set-up but didn't stop me trying for a spectrum this morning - with nil result.
Well-placed for the south for the next few days, before the Moon moves back. Hope you guys can get something! :thumbsup:
Cheers -
malclocke
08-02-2014, 06:02 PM
Unfortunately while I'm still getting to grips with my set up this is going to be a bit beyond my abilities. Hopefully someone else gets a crack.
Here's a quick and dirty one - just one 3 min sub. I'm collecting 12 and will stack - SNR should improve.
This is clearly an He type, not the Fe types with V1369 Cen and Nova Del.
Very pronounced H alpha. Much more prominent than e.g. V1369 Cen at this early stage. I'm guessing that as this recurrent nova last erupted in 1989, there's a fair bit of hydrogen floating about from previous ejecta.
Here is a spectrum of V745 Sco 10x180s with the Star Analyser 100 in the convergent beam of a 254mm SCT with focal reducer f/6.3, captured with an Atik 383 L+.
I've identified the lines with best guesses based on the literature that I've found. Spectra from the first phase of the 1989 outburst are almost identical - these can be found in Williams et al. 1991 (http://xa.yimg.com/kq/groups/10138021/1909143958/name/EVOLUTION+SPECTRE+NOVAE.pdf). The nova clearly has a strong He emission profile. Some interesting nebular lines developed quite quickly in 1989 - it will be interesting to see if they reappear.
The Ha line is very broad - but includes HeII 6678 at this resolution.
Note that the "emission" feature at around 8350 is the zero-order image of a faint background star.
Cheers
Jonathan
Merlin66
09-02-2014, 03:08 PM
Jon,
Congratulations!
Well done.
I haven't see any other spectra yet.
Do you have a fit file available?
Rob_K
09-02-2014, 04:16 PM
Nice work Jon! This might be of interest if you haven't seen it before:
https://www.eso.org/sci/publications/messenger/archive/no.58-dec89/messenger-no58-34-35.pdf
Cheers -
Thanks Rob and Ken. Interesting article. Ken, I've sent you a .fit file.
Cheers
Jonathan
Here's last night's spectrum. Increase in Ha as you'd expect.
I think I was wrong. The odd "emission" band around 8400 was there again even though I had the camera at a different angle. I suspect it's not a background star after all. Going back to the old 1989 spectra in the Williams article in my first post, after a few days the deep red/infrared features of the nova's red giant companion (M8III) began to emerge. I suspect we're seeing that. If so, it's quite amazing.
Merlin66
10-02-2014, 05:25 PM
Guys,
Just received the attached file from Steve Shore.
Any additional data we can collect will be really, really appreciated!!
Thanks for posting, Ken. I love Steve's commentaries, even though I fully understand about one stentence in three :-)
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