T CrB & R CrB Spectra

[James Foster]

Here is my recently Isis processed spectra of R CrB (plotted in BaSS 1.96):

There is definite activity in the near UV -end in the Ca+K and Ca+H lines, while the rest of the balmer series (Ha, Hb, Hy, H-delta) looks weak. For a Yellow-Orange supergiant,
this star has interesting Na Fe, and Ti lines; much more rarefied/cooler solar wind than the sun for these complex metal to form. The O2 at 6869A is very prominent.
This was shot at an air mass of Z(sec)= 1.05

Here is my recently Isis processed spectra of T CrB (plotted in BaSS 1.96):

A much cooler and dimmer star than R CrB. It has numerous HeI and HeII emission lines and very pronounced Ha emission at 7x the intensity of the continuum average.
Note, the typical see-saw patter of Carbon emissions increasing from shorter to longer wavelengths. This will definitely be a target for my LISA with the IR extension kit!
This was shot close to the air mass of R CrB. Both spectra were instrument response calibrated on the same nearby A3V star SAO84281.

James

[Olivier GARDE]

Hi James,

Very nice spectra with a good instrumental response even in the blue part of your spectrum.

Don't forget to send T Crb spectrum to ARAS data base...

Olivier GARDE

[Peter Somogyi]

Hi James,

Very nice results!
Indeed, in order to see the details close to continuum if it's a single shot, there is a feature in ISIS named "double plot" - so that we can see both Balmer and closed to continuum scaled graph.
To go even further, in ISIS you can use the "FWHM" tool to measure "EW" for some of the main emissions - that's more or less independent from our resolution and setup -, so that you can follow any sudden change by any emission (compared to other's EW) compared to a previous and notify us. (e.g. HeII 4686 / H-beta, or O III 5007 changes)
I personally also prefer showing a difference graph including a previous observation (matching by resolution, or decrease its R-power via convolution to see a direct match).
It also takes time to show up in database, so that it's welcome to get us notified on this forum the soonest if there's any unexpected change.

Cheers,
Peter

[James Foster]

Here is a comparison between spectra of T CrB taken 24Mar17 to one taken last night on 24Apr17:


I manually scaled the y-axis of the 2nd (blue) 24Apr17 continuum of T CrB to match the 24Mart17 data.

I'm not sure if there is much change. On the 24Mar17 version, I used a 19-micron slit, while on
the 24Apr17 version I used a 23-micron slit. I also used a different reference star for my IR correction.
I'm using only stars in the Miles catalog as IR references from now on.

For the 24Apr17 data, the H-Alpha looks "depressed" relative to the Hy & H-del, while the He1 look weaker.
I'll do a comparison of R CrB next.

James

[James Foster]

Here is a newer spectra of R CrB, taken on 24Apr16, IR corrected against Miles star HD118244 (F4V):

As usual, processed in Isis and plotted in BaSS V1.96; All spectra lines outside of the hydrogen balmer series are tentative.

James