ER UMa stars: IX Dra update

[Stewart John Bean]

Moving on from V1159 Ori ( see earlier topic) I am working on the superoutburst of IX Dra. I am most grateful to R Sargent for observations on 2459906 that fills an observational gap. However, I am stuck with three unobserved super outbursts. TESS, BAA, and AAVSO databases do not cover superoutbursts at the following approximate ( +- 5 days) times:

2460260, 2460630 and 2460750
Does anyone have observations around this time?

I have done battle with ASAS-SN and Lasair and lost. I may well be approaching these two systems incorrectly.

Can anyone help?

Stewart

[Jeremy Shears]

So that’s around 2023 Nov 11, 2024 Nov 15 and 2025 Mar 15. I will check tomorrow.
It was in outburst last night.

[Mr Ian David Sharp]

Hi all,

I got an average of 15.54 CV mag last night (17 exposures). See attached.

Cheers
Ian.

Attachments:

1. 

   20251108_IX-DRA_IRB_PixelSkies-C11-Moravian_IDS_plot_lines_check.png
   

[Stewart John Bean]

Hi ,
I have been looking into IX Dra and its status as a “period bouncer” reported by Olech, A. et al 2004.
Their Fig 12 places IX Dra as a period bouncer. It turns out that decision is based upon an accurate understanding of the difference between P(sh) and P(orb). Determining P(orb) has not been easy. Thorstensen has recently (2020) determined P(orb) accurately and to check I looked at the TESS results for IX Dra. TESS date from the normal outburst sections of the light curve agrres with Thorstensen. So IX Dra can be moved to the upper branch of the curve in the attached figure and join its ER Uma cousins.

Stewart

Attachments:

1. 

   Olech-A-2004-Figure-12.png
   

[Stewart John Bean]

IX Dra is not a period bouncer but sits with ER Uma and V1159 Ori on the upper branch of the evolutionary curve.
I have started a short note for the next VSSC describing the topic.

As an aside, the position of DI Uma on the graph is curious as the absence of RZ Lmi (its twin) on the graph. DI Uma seems to have a solid orbital period and yet its “twin” RZ Lmi has not revealed its orbital period “as it is usually in outburst”. I am wondering if the orbital period for DI Uma is wrong. I think only time resolved Doppler spectroscopy has a chance as the TESS coverage is poor and noisy.

DI Uma is not well observed and is also close to a standard star. Because it is very active (half the time in superoutburst) only very regular observations actually show the light curve clearly.

Stewart

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