XX Oph and V5569 Sgr photometry needed now

American Association of Variable Star Observers (AAVSO)
Thu, 04/13/2023 - 18:50


AAVSO Alert Notice 819 announces a campaign beginning immediately on the eclipsing variables XX Oph and V5569 Sgr. Please see the notice for details and observing instructions.

There are threads for this campaign under the following forums:

- Campaigns and Observing Reports: https://www.aavso.org/xx-oph-v5569-sgr-campaign
 - Eclipsing Binaries: https://www.aavso.org/xx-oph-v5569-sgr-campaign-01

Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomer and by HQ. Join in the discussion or ask questions there!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ

American Association of Variable Star Observers (AAVSO)
XX Opt and As 325 (V5569 Sgr)

Dear observers,

On Sunday night, 17 April 2023 UT, Gemini Staff scientists obtained high-resolution optical spectra of these two stars in the red and blue settings. The S/N in the continua are ~100 and these are the highest resolution spectral ever obtained for these two "Iron Stars".

Your multi-color observations will also them to be placed in a proper scientific context - knowing what the brightness of the variable red supergiant component  is in each system and the state of the colliding winds.


Stay tuned for more updates as the spectra get reduced.

Thank you for your observations.

Cheers, Steve 

American Association of Variable Star Observers (AAVSO)
XX Opt and AS 325 (V5569) Sgr

Dear all,

I see your observations in the light curve. How wonderful. I'd suggest taking multi-color data for these stars for another few days and that will give us a good baseline of what was happening in each star.

The spectra will be reduced in a week or so, and I'll share what in found in them with you all.

Thanks again, Steve


American Association of Variable Star Observers (AAVSO)
XX Oph and AS 325

AAVSO observers, thanks so much for the color photometry. the high resolution spectra are being reduced and should be available in a week or so. The observations you made during this campaign will really help nail down the state ion these two exciting variable stars and help with the detailed interpretation of the spectra.

Stay tuned for further updates.

Thanks, Steve

American Association of Variable Star Observers (AAVSO)
XX Opt and AS 325 (V5569) Sgr

Dear observers, the Gemini GHOST spectrograph has just released the first reduced data on XX Opt. See here: https://www.gemini.edu/news/instrument-announcements/first-pipeline-reduced-ghost-observations-available-data


Your observations will be extremely helpful in the interpretation of this data as well as the forth coming AS 325 spectral observations. 

I plan to work on these observations over the summer.

Thanks again for your help.



American Association of Variable Star Observers (AAVSO)
XX Oph

Dear all, I wanted to share a few snippets of the GHOST spectroscopic observations for XX Opt obtained as a part of this campaign. AS325 was observed as well. The spectra are amazingly complex, high S/N, and really great quality - Far better than the previous medium resolution studies. If you'd like to read up on these two fantastic stars, see Cool et al., 2005 PASP, 117, 462 or Howell et al. PASP, 2009, 121,16. The former benefitted greatly from AAVSO observations. 

I attach here a four-panel sample of the spectra to give you an idea of their complexity. I may be spending the rest of my life fully analyzing the data on these two stars ;-).  The top row shows the hydrogen alpha emission line profile. It is broad and shows absorption dips on its blue wing. These dips are due to absorption by cool gas far from the binary star, likely eminent winds from the system. The full extent of the emission for H-alpha is +/- 2800 km/sec. The bottom row shows the crazy line region near the Hydrogen Beta emission line with its very broad profile as well. The emissions here are mainly due to Fe II, Cr II, Ti II and He I. Finally, the bottom right show the Sodium D line and a broad, complete He I absorption with a velocity offset of -232 km/sec. WOW!! 

The AS 325 spectral are similar and I have a lot of work to do to understand the breadth of such data. The valuable AAVSO photometric observations will be a detailed part of this work as they place into context where in their orbits the stellar components are at the time of these observations. Important for interpretation and to see if the previous developed model still work.  

Thank You all.

Spectra in next reply.