In the framework of a project to update VSX with the latest information from the GCVS and adding information that was missing in thousands of records, I am giving special attention to eclipsing binaries (as announced in the EB webinar last month).
The goal is to add elements to the largest possible number of eclipsing binaries to leave a clean sample of objects that really need observations to find their periods.
I have a large number of unpublished EAs with long periods found years ago mostly querying the NSVS database (yes, 20 years have passed and a lot of these stars are still undiscovered). Now that we have ASAS-SN data available for the Northern hemisphere, I am solving them and adding them to VSX.
Most are very long period objects and that's why they hadn't been found before or they have eccentric orbits, which makes it harder to find their periods.
From this list, there are two stars that stand out:
GSC 04481-00358: A system in Cepheus ranging from V= 9.99 to 10.34 with total eclipses and eclipse depth strongly depending on wavelength. The period is 90.5288 d. but unfortunately I solved it today and the eclipse ended this afternoon :(
Take a look at these plots.
GSC 04433-00065: A very eccentric eclipsing binary (the secondary eclipse occurs at phase 0.19) in Draco. The range is V= 11.74 - 12.30 and the period is 26.35150 d.
Plot.
Other systems solved so far:
GSC 04573-01597 UMi 69.7111 d. 12.42 - 13.0 V Plot
GSC 04213-00425 Dra 47.7081 d. 12.53 - 13.1 V Plot
NSVS 2844818 Dra 38.4864 d. 10.79 - 11.30 V (already known, wrong period) Plot
GSC 04347-01486 Cam 19.67038 d. 11.27 - 11.67 V Plot
More objects will be published the upcoming days.
Check the "Changes since last log in" option in VSX and you will be able to track them.
Cheers,
Sebastian
Hi Sebastian
Great stuff. Are all the ones that appear in the "Changes since last log in" option solved? Or do they need more data? If they are solved, how do we find the EA's that need more data so that they can be solved? Also, is there a reason why AAVSO data is not used to solve?
Ray
Hello Ray,
The changes since last log in option shows you everything that was updated in or added to VSX since your last VSX activity. There might be solved or unsolved objects although most of the additions will be objects with known information.
The purpose of this is to add as much information as possible so we can be able to identify objects who **really** need observations and not objects that have data elsewhere that have not been checked.
ASAS-SN information on known variables will have to be checked yet anyway because we haven't added their information.
To search for variable stars without periods, you have to do a VSX search (clicking on the "More" button twice to get extended search options). You can select type EA% and set the period range to 0 - 0 and you will get the list. This is valid for all types. You can also search by groups.
Regarding why AAVSO data were not used for these ones, it is because they are mostly new discoveries, they weren't known before. Systems without periods haven't been observed by AAVSO observers often. Most won't have data. It would be good to change that so they can be used in the future.
We will be adding GCVS periods for several objects this week so it would be better to wait a few days before doing a candidate search.
Cheers,
Sebastian
VSX has been updated with the latest GCVS version so now a search for eclipsing binaries with no periods can be made without the need to check the GCVS.
A quick look at the ASAS-SN database (following the VSX external link) should be made though because we haven't added their data yet.
Cheers,
Sebastian