Mira in near UV---Outburst?

[James Foster]

I just shot my first LhiresIII (2400 l/mm Grat) spectrum on Mira in the near UV, centered near the CaH/CaK lines and noticed two prominent H-line (zeta/eta) emissions.
Is the DA exchanging matter with the primary or otherwise causing these emissions?


Here's the 2d image, Isis processed from 10 x 120 sec. integrations:


Unusual behavior or typical for this symbiotic?

James

[James Ley]

My understanding is that emission around maximum light is due to shock waves in Mira type variables. The intensities of the Balmer emissions do not follow their typical nebular decrement.
Here's a paper showing H-zeta and H-eta like in your spectrum.
http://adsbit.harvard.edu/cgi-bin/nph-i ... etype=.pdf

[James Foster]

To: James,

RE:"The intensities of the Balmer emissions do not follow their typical nebular decrement. Here's a paper showing H-zeta and H-eta like in your spectrum."

Thanks for the paper. This older (1984) research depicts spectral velocity displacement for metals and H5-9 lines in the near UV-----good read never the less!
I wonder if they knew of the symbiotic characteristics of this system back in 1978-79 when they took the data for this article?

Here is another spectra of this object, shot a little deeper in the UV:

Here is the 2D spectra image after processing with Isis V1.91 (very bloated from atmospheric dispersion):


I'm not sure what that feature at the very far left of the spectra (3713A) is? BeSS V1.90 shows an O2 at that position but I was reluctant to depict that here.

James

[Ernst Pollmann]

James,
the emissions of the higher Balmer lines are not an indicator for an "outburst". The are simply normal visible dependend of the phase of this sort of Mira variables. It is nice to observable, how this lines change their intensities depending on the phase.
If you are interested, I could show you such a observation on photografical films by a colleague of mine taken around the years 1985.

Ernst

[James Foster]

To: Ernst,

It would be interesting to see how the photographic spectra of this star with big scope (1 metere and above) compares with ours taken with much smaller aperture scopes with
LhiresIII and modern CCDs.

James

[Ernst Pollmann]

James,
here are the photographic spectra of my friend and colleague Bernd Hanisch (Germany, Frankfurt/Oder, near polish Border.)
The spectra were taken with a small Newton telescope 120/690 mm combined with a 45° prism in front of the telescope, on "ORWO NP27" (film material of a company in Eastern-Germany) between 1989 to 1991. The size of the prism did cover the total aperture of the telescope.
The spectra series have been take depending on the phase after the maximum in visual brightness.

omicron Ceti.jpg (62.02 KiB) Viewed 9712 times

Ernst

[James Foster]

To: Ernst,

Nice C2 and Ti absorptions! Are the duplicate spectra underneath the 4 dates 2nd order? Looks like the TI absorption strength change before and after maximum.

James

[Francois Teyssier]

A nice piece of history, Ernst!

Note that C2 can't exist in Mira, which a M star, with only TiO bands (VO also in the near IR)
C bands appears in Carbon stars due to the lack of oxygen

Looks like the TI absorption strength change before and after maximum.

Yes, James, the spectral type for Mira varies from M5 to M9 (maximum to minimum luminosity)
Nice project for low resolution

Is the DA exchanging matter with the primary or otherwise causing these emissions?

No, the intereraction of the hot Mira B on Mira A is very weak due to the large scale of the system. High ionisation lines only sen in the UV

The current spectrum is typical for Mira near maximum luminosity, but each pulsation will differ



François

[Ernst Pollmann]

... no James, not the second order.
The used prism was made from a very special (rare) sort of material (in german: Bor-Kron-Glas), which provided spectra of the first order until the near UV-area on the used sort of emulsion.

Ernst

[James Foster]

Shot Omi Ceti again on 06Feb18:

Not much change in the line strengths compared with last spectra. I will probably do only one more at this wavelength as Mira has already crossed the meridian as it
gets dark and is almost too low to begin with shooting near UV.

James