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 ...
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!
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.
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)
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.
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)
Quote:
Originally Posted by 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
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!
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.
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...
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.
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)
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)
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...
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-...etacar2014.pdf
Worth a good read!
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.
