WR140 aproaching periastron

Show your spectra, your results ...

WR140 aproaching periastron

Postby Robin Leadbeater » Wed Nov 02, 2016 7:04 pm

Periastron of the binary system WR140 is due on 18th December so I took a final control spectrum last night for the Pro-Am campaign. (LHIRES III 1200 l/mm grating).

wr140_20160815_906-20161101_780.png
wr140_20160815_906-20161101_780.png (11 KiB) Viewed 4159 times


Nothing much has changed since August except for a just detectable blue shift in the WR star component countered by a small red shift in the O star features as the stars move in their orbit.

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Sat Nov 12, 2016 12:10 pm

Nothing much happening yet

wr140_ 20161110_756_Leadbeater.png
wr140_ 20161110_756_Leadbeater.png (24.66 KiB) Viewed 4121 times


wr140_ 20161110_756_Leadbeater_detail.png
wr140_ 20161110_756_Leadbeater_detail.png (23.67 KiB) Viewed 4121 times
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Paul Luckas » Fri Nov 18, 2016 1:29 am

Hi Robin,

Forgive my lack of knowledge of the astrophysics of these types of objects, but I wonder if you could elaborate slightly on the means by which we can be sure the slight shift is 'real' and not an instrumental or processing artefact.

Cheers,

Paul
Paul Luckas
 
Posts: 99
Joined: Tue Jun 24, 2014 5:08 pm
Location: Perth, Western Australia

Re: WR140 aproaching periastron

Postby Joan Guarro Flo » Fri Nov 18, 2016 5:13 pm

Hello Paul :

Do not worry, it's very healthy to have doubts. But Robin graphics are very good. As you can see my match.
It would be hopeless were all bad .. ;)

Friendly, Joan.
Attachments
WR140-20161101-1110.png
WR140-20161101-1110.png (7.18 KiB) Viewed 4066 times
Joan Guarro Flo
 
Posts: 345
Joined: Thu Nov 03, 2011 8:50 pm

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Sat Nov 19, 2016 12:00 am

Hi Paul,

Paul Luckas wrote:Hi Robin,

Forgive my lack of knowledge of the astrophysics of these types of objects, but I wonder if you could elaborate slightly on the means by which we can be sure the slight shift is 'real' and not an instrumental or processing artefact.

Cheers,

Paul


The spectrum is very reproduceable in the continuum away from the broad emission lines and the SNR is better than 200 so we can have confidence that variations larger than say ~ 2% are real.

The moving ripples on the top of the flat topped CIII 5696 line we are currently seeing are caused by variations in the stellar wind and occur continuously, even outside periastron. (The central blip is from the companion O star) There was a specific Pro-Am study of these wind variations recently in WR134
http://adsabs.harvard.edu/abs/2016MNRAS.460.3407A

Near periastron of WR140 + O star, the colliding winds from the two stars produce additional emission. You can see an animation of what I measured last periastron here
http://www.threehillsobservatory.co.uk/ ... tra_41.htm
Those observations were part of another Pro-Am campaign published here
http://adsabs.harvard.edu/abs/2011MNRAS.418....2F

The objective this time is to determine how repeatable the effects around periastron are.

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Sat Nov 19, 2016 12:15 am

We can also have confidence in the red and blue shifts of the WR and O star components due to their orbits. The wavelength calibration can be verified to high precision using the narrow interstellar Na D lines. One key result of combining amateur and professional observations last periastron was an improved set of orbital parameters for the system. In fig 1 of the resulting paper
http://mnras.oxfordjournals.org/content ... 2.full.pdf
the quality of the amateur points are generally indistinguishable from the professional ones.

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Paul Luckas » Sat Nov 19, 2016 3:31 am

Thanks Robin, much appreciate your detailed response. I have a few month's worth of CIII data of gam2 Vel taken back in late 2014 / early 2105 in which the orbital shift is very obvious, but have always presumed the error margin to be much higher (and therefore do not always trust the very small shifts I see from night to night).

http://jazzistentialism.com/blog/?p=1489

As you say, S/N is the key, together with signposts such as the interstellar Na, etc. I'll have to start trusting this a little more.

Paul
Paul Luckas
 
Posts: 99
Joined: Tue Jun 24, 2014 5:08 pm
Location: Perth, Western Australia

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Sat Nov 19, 2016 4:07 pm

Hi Paul,

Yes the LHIRES is not the most stable of instruments but if a good wavelength reference can be found eg by superimposing lamp lines during the exposures as here
viewtopic.php?f=10&t=1111&p=5010#p5011
or by using tellurics as here
https://arxiv.org/ftp/arxiv/papers/1206/1206.6754.pdf (fig 5)
I managed to get long term RV precision down to around 1-2km/s using the 2400 grating.

Though when the profile is changing so much, the limiting factor is probably just deciding what the line wavelength actually is !

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Sat Nov 19, 2016 4:19 pm

Great blog by the way :) . I had dipped in occasionally in the past but never fully realised how much useful and interesting stuff you have on there, particularly with your southern perspective. Now bookmarked in my favourites !

Cheers
Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Re: WR140 aproaching periastron

Postby Robin Leadbeater » Mon Nov 21, 2016 12:09 am

I think the first signs of excess emission can be seen on the blue edge of the CIII line tonight

wr140_ 20161110_756_20161112_703_Leadbeater.png
wr140_ 20161110_756_20161112_703_Leadbeater.png (25.8 KiB) Viewed 3991 times


Robin
LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
http://www.threehillsobservatory.co.uk
Robin Leadbeater
 
Posts: 1484
Joined: Mon Sep 26, 2011 4:41 pm

Next

Return to Spectra, results, information on activity ...

Who is online

Users browsing this forum: No registered users and 6 guests

x