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53 Aquarii

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#1 PJ Anway

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Posted 11 September 2013 - 04:32 PM

Last weekend while at the GLSG star-party, I was observing double stars in Aquarius with my 110/616 refractor. When viewing 53 Aqr, I noticed it seemed tighter than the 1.5" that my target list listed. I checked the WDS and it too states 1.5" separation. Does anyone know if this is the correct?
Thanks for any help.

#2 fred1871


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Posted 11 September 2013 - 08:16 PM

53 Aqr is SHJ 345 - and it's been gradually closing ever since the days of South and John Herschel. The most recent WDS figure is 1.4" in 2011; someone has optimistically calculated an orbit, despite the limited arc traversed, which gives a current separation of ~1.27". Both numbers suggest you're right to think it's closer than 1.5" these days.

It's been closing more rapidly in recent years - Hipparcos measured 2.2" in 1991, so it was nice'n'easy then. Given the rate of change, increasing, it could become quite difficult a few decades from now. And the period is likely very long, so it may stay tight for a quite long time through periastron and beyond, before again becoming of easy separation.

#3 7331Peg


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Posted 11 September 2013 - 11:01 PM

The WDS Ephemerides shows this for 53 Aqr:

2011: 1.297"
2012: 1.284"
2013: 1.276"
2014: 1.272"
2015: 1.273"

Here's a link to the data: WDS Sixth Orbit Catalog - Ephemerides.

Scroll down to 22266-1645,which is about 90% of the way down the page.

Those are the same figures shown on the Stelledoppie page, which shows the plotted orbit as a grade 4, so I suppose you could call the figures semi-reliable.

I agree with Fred -- not a lot of data, so it does seem a bit on the optimistic side. I noticed that the Ephemerides plot for 2012 doesn't match the actual 1.5" measurement listed in the WDS for that year. Something doesn't quite add up between those two figures, but given that the pair has been closing, it's certainly less than 1.5".

Edit: I just realized Pi Aquilae is at 1.4" right now and is also similar in magnitude (6.34 and 6.75 vs. 6.29 and 6.39 for the AB pair of 53 Aqr). Should be interesting to compare the two to see if it's possible to detect any difference in separation.

John :refractor:

#4 PJ Anway

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Posted 12 September 2013 - 08:09 PM

Thanks for the confirmation and information. Though a bit difficult to locate by star-hopping, I enjoyed the view - split at 175X in my 4.3", a nice equal pair.

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