V745 Sco - Request for spectra

[Merlin66 (Ken)]

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]

Hi All

V745 Sco is fading fast. This morning (Feb 7.8UT) it was down to mag 10.1 visually.

Regards
Andrew

[Jon (Jonathan)]

Ah, intrepid southern amateur spectroscopists ...

Just when we thought it was safe to capture our nova spectra before midnight :-)

[Rob_K]

Originally Posted by Jon

Just when we thought it was safe to capture our nova spectra before midnight :-)

Agree, what's with all this early morning rubbish? 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!

Cheers -

[malclocke (Malc)]

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.

[Jon (Jonathan)]

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.

[Jon (Jonathan)]

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. 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 (Ken)]

Jon,
Congratulations!
Well done.
I haven't see any other spectra yet.
Do you have a fit file available?

[Rob_K]

Nice work Jon! This might be of interest if you haven't seen it before:
https://www.eso.org/sci/publications...no58-34-35.pdf

Cheers -

[Jon (Jonathan)]

Thanks Rob and Ken. Interesting article. Ken, I've sent you a .fit file.

Cheers

Jonathan

[Jon (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 (Ken)]

Guys,
Just received the attached file from Steve Shore.
Any additional data we can collect will be really, really appreciated!!

[Jon (Jonathan)]

Thanks for posting, Ken. I love Steve's commentaries, even though I fully understand about one stentence in three :-)