Eta Carinae low-res spectrum, 25 Dec 2013

[Rob_K]

Shot this one last night after doing V1369 Cen. Never shot it before, very interesting. Should do it regularly...

Cheers -

[Jon]

Fascinating. I don't begin to understand what's going on with Eta Carinae. I wouldn't even know what category of object it is.

Was it easy enough distinguishing the spectrum of the star from the emissions from the surrounding nebula?

I got my first Wolf-Rayet star the other night, setting up for V1369 Cen. There's a whole world of spectroscopy waiting to be explored ...

[Rob_K]

Thanks Jon. Yes it easy easy separating the spectra - while no doubt there is slight contamination, the exposure is what does it. You need a lot longer on the nebula. And we're only dealing with low-res spectra! ;)

Eta Car is hot supergiant, an LBV (luminous blue variable) in a binary system. The system is surrounded by a thick red nebula and enclosed in the Homonculus Nebula so there's a lot going on! There are identifiable, regular spectral cycles - haven't gone right into it but there's plenty to be done in monitoring it spectroscopically! :thumbsup:

Cheers -

[malclocke]

Nice one Rob. I've been meaning to get eta car for a while, didn't realise it would be quite so striking. Obvious similarities to a nova spectrum, and I guess we're looking at a very similar mechanism.

Eta car is a binary system with very high eccentricity, and it reaches periastron next year. I'm hoping to take part in the pro-am campaign for that event, should be interesting.

Have you tried gamma velorum?

[Merlin66]

Eta Car should be on all spectroscopists observing list!
Needs regular attention ;)

They say there are two types of object in the Universe - Eta Car and the others......

[Jon]

:lol:

The next eclipse in the 5.5 year cycle is due next year, from what I've read. Anyone know when, exactly?

[Merlin66]

Jon,
drop me an email for details of the Eta Car 2014 campaign...I think it starts around July. Need to check the docs.

[malclocke]

Jon,

Details of the 2014 Eta Car campaign are here:

http://etacar2014.wikidot.com/

The PDF linked on that page gives a good overview.

Bernard Heathcote is the coordinator for the amateur campaign, see here for details http://spectro-aras.com/forum/viewtopic.php?f=2&t=645

[Chochawker]

Are low-res (i.e. SA100) spectra of any use for this study?

[Glenpiper]

The pro-am 'Eta Car 2014 Periastron Campaign' requires spectra with a resolution (R) in the 5,000 to 20,000 range and S/N 200 or higher, preferably 400. As the SA100, and similar, only have a resolution (R) around 150 their spectra unfortunately cannot be used.

If anyone is interested in joining the campaign I can email them the full campaign document.

Bernard Heathcote
(Coordinator for amateur campaign contributors)

[Glenpiper]

The attached plot of some of my recent eta Car spectra is intended to show why a reasonably high resolution (R>5000) and S/N (>200) is needed. The HeII 4686 line is of major campaign interest and while it is low between periastrons (now) it will grow and vary as the main and primary eta Car component stars reach their close approach between June and September. The activity of the HeI 4712A line, due to wind-wind shock instabilities, is also of interest as it has not been previously monitored a high resolution.

Bernard

[Rob_K]

Thanks Bernard, very good explanation and demonstration of why the pro-am collaboration requires hi-res data. Good luck with the campaign!

On a side note, Eta Carinae is worth monitoring spectrally at any resolution on an on-going basis. Low-res spectra still contain qualitative data that can be used, for instance, to provide alerts of changes. I've been really slack since I did the spectrum in the OP (mostly work, partly weather, partly other projects) but intend to carry it forward. Honest! :D

Cheers -

[Glenpiper]

Rob,

I fully agree that it is worthwhile keeping a 'low res' eye on eta Car as often as possible ... you may even be the lucky one to catch it when it finally blows ;)

The simple grating spectrometer, such as the SA-100/200, is very well suited for confirming faint SN and novae activity and an excellent way to start spectroscopy ... if I had my way it would be a compulsory first step ... and should be part of every amateur's toolkit.

I just noticed that I previously referred to the main and primary eta Car component stars. What I obviously meant was main and secondary, or primary and secondary, components.

Cheers,
Bernard

[Chochawker]

Thanks Bernard.

[Rob_K]

Can't believe it's six months since my last EC spectrum! I could try to blame the weather (miserable for months) but despite the best of intentions I reckon it comes down to hopeless organisation... :rolleyes:

Anyway, here's a low-res optical spectrum from tonight. There are subtle differences to the December one and I can see why hi-res spectroscopy would be so useful.

Cheers -

[algwat]

Gidday Rob,
that's really cool, I brought a star analyser but have not used it as yet, several months of clouds.

One of my little brain cells wonders, what would ETA Carina look like in an image based on the weighted colour intensity of the spectrum. Not just time dependant RGB. ??8)

[Rob_K]

That's a brainbanger Al, maybe it might look like the little pink-orange dot on the LHS of the spear of the spectrum at bottom? If the spectrum is the dot broken up into its component colours, then the dot must be the component colours combined. But that's RGB too... :P

Anyway here's an interesting link I found with lots of info on the pro-am collaboration and about the periastron passage coming up in late July:
http://etacar2014.wdfiles.com/local--files/start/etacar2014.pdf
Worth a good read! :thumbsup:

Cheers -

[algwat]

Hmmm....

"If the spectrum is the dot broken up into its component colours, then the dot must be the component colours combined. But that's RGB too... "

you might be right....:question:

[Glenpiper]

Alan,

Given that the Halpha 6763 emission is far larger than any other line (x60 continuum) any image weighted to the visual range spectral response would be red. My attached calibrated visual range spectra shows the prominence of Ha.

Rob, all,

The 2014 periastron campaign is now in full swing, at least from the professional observatories and satellites. Unfortunately I am still the only amateur contributor (when weather allows) so if anyone is willing and able to provide medium resolution (R>4000) high SNR (>200) spectra please contact me. The HeII 4686 emission line, which is of major interest, is now showing the expected high energy wind collision (between primary and secondary stars) that occurs close to periastron.

Cheers,
Bernard

[Glenpiper]

Sorry for the typo ... Halpha wavelength (A) should read 6563.

[algwat]

Thanks for the feed back , Bernard.
Appreciate the chart data.

Yes, I was thinking of the larger nebulousness also.
So, Red it is then .... 8)

kind regards, Alan.

[Jon]

Hi Bernard - just waiting on the arrival of my Spectra L200, otherwise I'm in ...

[Glenpiper]

Jon,

Glad to hear you have a slit spectrometer (L200) on order. I hope you also ordered the 1800 grating as you will need that to reach the required eta Car campaign resolution of R~5,000.

One thing delaying the new shipments is that Ken needs to fully check out the final JTW production product and that is not made easy by the recent very cloudy nights we have been having in Melbourne.

Cheers,

[Jon]

Yep, got the 1800 coming. Do you know if Ken actually has the final JTW product in his hands?

Clouds up in Canberra too, for weeks.

[Glenpiper]

Good ... about the 1800 grid.
Good question ... about Ken having the JTW L200. The last time I asked him, at least 2-3 weeks ago, he said it was in transit so I would be surprised if he doesn't have it by now.

[Terry B]

I'm also waiting on the parts for my L200. The LISA isn't useful for this campaign.

[Glenpiper]

Jon, Terry,

I see that Ken has just posted (on Aatronomical_spectroscopy group) that

"All the initial testing of the latest JTW build of the Spectra-L200 has been successfully completed. Mark will be confirming shipping dates....."

I hope you both get your relevant L200 orders soon, as eta Car is fast approaching periastron and the spectra is evolving nicely. I'm in virtually daily email contact with the various pros involved with ground and satellite data (mainly X-ray) and am happy to pass on the interesting stuff. As this data is not for general publication at this stage I will need Jon's email (I have Terry's), so please contact me at: spectrasouth at bigpond dot com.

As my contributions to this campaign have recently dropped off, due to lousy weather followed by my visibility of eta Car being increasingly restricted by trees, your contributions will be greatly appreciated.

Cheers,

[Rob_K]

Finally getting some clear sky and I obtained another low-res spectrum of Eta Carinae tonight. I haven't done anything other than create the bar yet but I thought I'd post this image which has the spectrum of 27 June 2014 at top and 22 July 2014 at bottom.

These are at full camera resolution, from L image size (5184 x 3456 px), stacks of 15 & 13 subs resp and all 9-sec exposures using SA100 grating & Canon 650D camera with 200mm lens. You may need to expand to full size when the image opens.

The problems in accurate calibration & getting other quantitative data of course include lens aberrations, no flats, etc etc etc. :rolleyes:

Cheers -

[traveller]

Thanks Rob, would you mind add some comments or pointers to the image to help me interpret the lines?
Bo

[Rob_K]

Hi Bo - I've done the full graphic, attached. It has the visible hydrogen emission lines marked, hope that helps. :thumbsup:

The other ones were posted just to give an idea of the detail (real & otherwise!) at full camera resolution. A lot of fine detail is lost in creating the 'pretty' graphic attached.

Cheers -

[Rob_K]

Here's the full-resolution with three Eta Car spectra and some stronger emission lines marked. Not sure if identification is 100% correct (should HeI be HeII?). I used a pretty old paper, Identifications in the Spectra of Eta Carinae and RR Telescopii, here:
http://mnras.oxfordjournals.org/content/113/2/211.full.pdf+html

The calibration is probably OK to about +/- 0.5nm (+/- 5Å).

Rainy/cloudy here again after a very welcome short break. Hoping to follow Eta Car closely through periastron passage if the weather allows - trust things will work out well for those undertaking the valuable hi-res spectroscopy! :thumbsup:

Cheers -

[Rob_K]

Got another low-res spectrum of Eta Carinae tonight, a real battle against cloud banks both drifting through and making-&-breaking. Spectrum from 22 July (top) included, both presented as bars at full camera resolution. 'Spears' included at bottom. Canon 650D & 200mm lens, SA100 grating, 20 x 9 sec (28th), 13 x 9 sec (22nd), ISO 6400, F/5.6, L image size. Scale is 0.22nm/pixel, or 2.2Å/pixel.

Forecast for the next week doesn't look very promising... :mad2:

Cheers -

[Terry B]

I've also been taking spectra of eta car with my newly recommissioned L200 spectrograph.
An interesting star.

Terry

[Rob_K]

Good stuff Terry, hope you keep posting them! :thumbsup: Rain's continuing here but might be a break over the next few days.

As a matter of interest I prepared a comparison graphic between your spectrum and mine of a few days before, hope you don't mind. Pleased to see that the SA100 is picking up all the major features of the high-res spectrum. What mine lacks of course is accurate calibration due to lens aberrations, the dispersion of yours (yours had to be severely 'concertinaed' to fit mine) and precise information on relative intensity due to vignetting (no flats!) & probably a non-linear camera response (??). But that's the difference between hi & low-res spectroscopy! ;) :lol:

Keep up the good work!

Cheers -

[Jon]

Rain? Bloody well snowing here. Plus I have no spectroscope. I guess I'll have to wait another 5.5 years ...

[Rob_K]

Eek! The hills all around the town I live in are dusted with snow, hope that's as close as it gets! :)

About the 5.5 years, it's not guaranteed Jon. It would be dreadful if you missed out on periastron altogether because EC went supernova. That would be damned inconvenient... ;) :lol:

Cheers -

[Rob_K]

My low-res spectrum of Eta Car from tonight, following a couple of unusable spectra from previous two nights. Bar at original size is here (click to enlarge if necessary, 3193 px wide):
http://i727.photobucket.com/albums/ww271/Rob_Kau/ECspectrum28Julyamp04Aug2014comptex t.jpg~original

Cheers -

[Rob_K]

News on Eta Car:
http://www.astronomerstelegram.org/?read=6368

HST/STIS/CCD spectra from U.T. July 13 and July 30:
http://etacar.umn.edu/download/Eta2014/SpecJul13-Jul30.jpg

AAVSO light curve (V), 2013-14:
http://etacar.umn.edu/download/Eta2014/UV-Vis2013-14lightcurves.png

UV light curve, 1998-2014:
http://etacar.umn.edu/download/Eta2014/UVlightcurve.png

Cheers -