The raw string from the Washington Double Star (WDS) database:
13100+1732STF1728AB 1827 2011 656 190 12 0.6 0.6 4.85 5.53 F5V F6V -430+138 -430+138 +18 2697 NOD 130959.55+173144.8
Extracted:
| full WDS identifier | 13100+1732STF1728 | |
| components | AB | |
| number of observations | 656 | |
| observations | first | last |
| date | 1827 | 2011 |
| PA | 190 | 12 |
| Sep. | 0.6 | 0.6 |
SkyTools 3 Pro (ST3P) says:
Object Information--
Diadem; STF1728; Definitive Orbit: P=25.8 yr, a=0.67"; (2014.1)
PA 192°
Sep 0.21"
Interactive Atlas--
PA 192.3
Sep 0.2
The RASC 2014 Observer's Handbook (OH) says:
| α Com AB | 2014 | 2015 |
| PA | 12 | 12 |
| Sep. | 0.29 | 0.04 |
With an orbital period of 26 years.
Conclusion:
The OH numbers closely match the WDS. A note in the OH says that B star will reach periastron in the spring of 2015. SkyTools shows the orbit to be edge-on. If this is correct then it means that every 13 years, the PA flips. So then it is just a question of when. When exactly will the B component pass the A star. The thing that is peculiar is that SkyTools shows the B star is currently south of the A.
§
See the follow-up post.
4 comments:
is it possible that the exact dates of periastron can be known? eg. by counting forward from previous PA and comparing?? do u have an idea when in spring '15 it will occur? u said but rt now AB are separate... i guess that is to be expected since it's winter, or shd they not need to have so far to travel?? thx
I just checked SkyTools 3 Pro.
PA 13° Sep 0.05" (2015.0): not splittable currently (not splittable at best).
Also, SkyTools says the orbit is "definitive." So that means it can be computed with some confidence.
I posted a new note, with orbital diagram, here:
http://blog.lumpydarkness.com/2015/01/checked-diadem.html
http://blog.lumpydarkness.com/2015/01/checked-diadem.html
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