O'Connell effect target list

Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 03/27/2021 - 23:52

     A couple of suggestions (or three) and a query about this very useful list.  Firstly, the note seems to appear only on the AAVSO Web site front page:  what happens to it when it drops off the 'news'?  Second/third:  could items like this have a name attached, and a date, so one knows who to contact, and eventually know how stale the list has become?  Thanks.

     The query regards the observing desiderata.  I know very little about eclipsing systems.  From the comments in the text, it would seem that mere times-of-max/min will not help with solving the problem.  These stars have been observed for a very long time with no solution, and the text here doesn't say what's wanted.  Thus it would be helpful to be a little prescriptive about what's needed.  Would having complete lightcurves with a maximal wavelength baseline across the visible be useful?  I could do Sloan u, V, and Sloan z, for instance.  Or some narrowband filters?  Or would you ultimately need spectra at high-enough cadence and resolution to resolve various diagnostic features like H&K + H-alpha emission, and absorption-line radial velocities, and/or spectra in the near-IR to look at accretion diagnostics (i.e. a big project beyond most of our capabilities) ?  Perhaps all that's required are some recent literature citations that summarize the problem and outline some directions for further work.

\Brian

Affiliation
American Association of Variable Star Observers (AAVSO)
Same

I was thinking along the same lines as Brian.  

A VASTLY shorter target list ( stars selected based on maximal interest, suitable comps, magnitudes selected to match typical observer's capabilities, etc ), the type of observations and necessary precision and cadence, short term (months) or long term (decades) observing, what feedback will be offered about progress, and who is the sponsor / contact ?  

Gary Billings

Affiliation
Vereniging Voor Sterrenkunde, Werkgroep Veranderlijke Sterren (Belgium) (VVS)
Not reachable from ROAD

Unfortunately none of the list is reachable from my Southern remote location in Chile.

Josch

Affiliation
American Association of Variable Star Observers (AAVSO)
O'Connell effect target list

Thanks to a tip from John Greaves, a useful link on this topic can be found...in the JAAVSO:

https://ui.adsabs.harvard.edu/abs/2019JAVSO..47..194K/abstract

...which includes BVRI photometry of two systems.  A recent AAS meeting abstract by the same author appears as:

https://ui.adsabs.harvard.edu/abs/2021AAS...23741807K/abstract

...again for northern Kepler field binaries (notice the similar wording of the meeting abstract compared to the anonymous target-list post).  The full-up paper suggests getting 'many' filter photometry goes only so far in explaining the systems, and perhaps my partly whimsical suggestion of u,V,z photometry (i.e. maximal wavelength coverage across the visible) wasn't far-fetched.  But the full paper makes it look like a lot of spectroscopy would be required as well, and perhaps having all that would only deepen the puzzle.  Unfiltered photometry a la TESS only gets you periods, which is something, but more detailed observing is required.

\Brian

Affiliation
American Association of Variable Star Observers (AAVSO)
My Introduction

Hello everyone, my name is Matthew Knote. I created this list of targets and provided it to the AAVSO following discussion after I presented at the most recent AAVSO meeting. These targets are systems I'm characterizing as part of my dissertation. It seemed that there were several people interested in continuing observations after that talk. I tailored the list to be as useful as possible for observers, but I'd like to know what I can do to make it better.

Gary Billings made several suggestions in his post, one of which was a shorter target list. I certainly have an opinion on which systems I think are interesting. It would be good to get an idea of the capabilities of those who are interested, however. A downside of the list is that most systems are faint (only one brighter than mag 10), and many exciting systems are rather dim. What sort of magnitudes can your equipment reach comfortably? What sort of filters are available? Do you do spectroscopy or photometry?

I'm looking for any type of data people can give. Single-filter photometry lets us know if and how these systems change with time (we know many do, some drastically). Multi-filter photometry gives us temperature information. Spectroscopy gets us a spectral type and/or radial velocity data, both of which would be VERY useful. I was able to get complete, 4-color light curves of 7 systems in this list using 1-meter class telescopes, but I never got any spectroscopy.

The most useful observations would be phase-complete photometric light curves in at least 2 - preferably 3 - bands (BVR or RVI would probably be best). That allows for modeling using programs like PHOEBE. Radial velocities from spectra are probably even more useful, but I know that'll be hard for these systems.

My hope is that my dissertation and the papers that come out of it renew interest in this effect. There hasn't been an analysis of the O'Connell effect at the scale I'm doing since the mid-'80s, though. I'm also giving a lot more targets than that one did. I'm new at organizing an effort like this, though, so I don't know the best way to give feedback. Any suggestions are welcome.

If there are any questions or comments you'd prefer to share in an email, my email is mknote2015@my.fit.edu. I'm cutting off my discussion here so I don't accidentally write 20 pages of my dissertation in a forum post. Still, I'm willing to expand on any point you want, either here or in email. I am writing my dissertation, though, so I may not be able to respond right away.

Finally, for anyone interested, you can check out my presentation at the last AAVSO meeting here. There's also some more discussion at the eclipsing binary breakout session a few days after, which can be found here. I don't think there's anything in either that's critical. Still, it gives some background on this sample, my research, and some interesting systems.

-Matthew Knote

Affiliation
American Association of Variable Star Observers (AAVSO)
Perfect!

This is excellent, Matthew.   Thank you.   It gives a lot of info about what you are looking for (and contact info for more followup! ).  I think this project is not ideal for me at this time:  I'm doing single colour photometry, which is necessarily untransformed, so detecting small changes over a long period of time, and exact matching to other people's data is problematic, but I could see it influencing my future direction.  

AAVSO has a number of observers with larger telescopes than mine, who are doing multi-colour transformed photometry, and some might very well want to take this up.

Might I suggest you also "cross post" the post you just made, with a small introduction so people know what you are referring to, to a more general AAVSO forum (perhaps referring back here?), as a "long term photometric monitoring project", or some such.  Some prolific photometrists might not be monitoring the EB forum, because many of us EB observers just monitor period changes via times of minima.

Regards,    Gary Billings

Affiliation
American Association of Variable Star Observers (AAVSO)
Take the project to the AAVSOnet

Have you considered taking this target list to the AAVSOnet? Easy enough to put in a proposal:  https://www.aavso.org/aavsonet

George