I apologize if this is not the proper forum for this. I was unable to find a forum I thought was the right place for this question.
I do not want to make any assumptions about what I found because I do not have a lot of information, however, it looks like there were either observations placed under the wrong star or someone discovered unusual activity and did not realize it.
Most of the observations for DO Cep appear to be consistent with its brighter companion star NSV 14168. I found this while looking into NSV 14168 as a star I am interested in observing.
NSV 14168: https://www.aavso.org/vsx/index.php?view=detail.top&oid=52792
DO Cep: https://www.aavso.org/vsx/index.php?view=detail.top&oid=8489
Observations for DO Cep: https://www.aavso.org/apps/webobs/results/?star=DO+Cep&num_results=200&obs_types=all&page=1
If anyone coulld help sort this out it would be greatly appreciated.
Hi John,
Thanks for bringing this to our attention at HQ - we'll look into the situation with the data for DO Cep and NSV 14168.
Good observing,
Elizabeth Waagen
Hi John,
the two objects are only 1.4" apart (NSV 14168's J2000.0 position was off in VSX, I have corrected it) and the observations in the AID are thus for the blend of the two objects (V= 9.6).
So in order to be strictly correct, the observations are neither for one or the other and, since the two might be UV-type stars, it doesn't make sense to observe them. We can not know for sure which of the stars is flaring if we happen to catch a flare.
I think moving the observations to the brightest entry (the NSV star) would be better but no solution is perfect.
I encourage observers not to follow this pair (also due to its large proper motion, their positions will be different than those shown in VSP).
Cheers,
Sebastian
Thank you all.
Yes Sebastian, that makes sense moving the observations to the brightest entry, but of course, is not perfect. Some of the magnitude observations appear to be on the lowest end of the dimmer star. Maybe an AUID should be created for the brighter star, NSV 14168. And/or if it is possible, maybe the previous observations should be linked to both stars in VSX instead of just DO Cep.
The observations from 65 years ago have comment codes I am not familiar with like "Q" and "T" and there are a number of obervations with 0.0 entered as the magnitude which seems to be supposed to indicate that there was no flare activity based on the Notes column.
These two objects large proper motion is connected to what interests me about them, that they are in close physical proximity to us.
I finally had a look at the literature for this, best known as Kruger 60, a famous nearby star-system. I may be misreading things, but it seems the certain variable (DO Cep) is the fainter component of the orbiting binary, and the NSV designation applies to the brighter star. As Sebastian noted, the NSV name had no proper motion assigned to it in the GCVS, so it was getting 'left behind' in the cataloguing.
Apart from flares, it is not obvous that rotational variation is known. This would typically be only a few percent amplitude; rotation periods inferred from spectroscopy shown in VizieR range from 0.4 to 7 days. Given the likely errors in rotation (vsini) determined from even high-dispersion spectra, this means it is basically unknown. ASAS-SN shows no period, but it could be that their analysis is messed up by the large proper motion --- the star is fading monotonically in their lightcurve series. Presumably TESS will cover the region at some point, so perhaps we'll have a definitive number. The star is available much of the year, so I will see about adding it to the queue in my observing.
\Brian
The wikipedia page says without citation that "it is an irregular flare that typically doubles in brightness and then returns to normal over an 8-minute period." https://en.wikipedia.org/wiki/Kruger_60
Thank you for including the inferred range of possible rotational periods. I am not very competant with VizieR unfortunately, so I am not able to get information like that.
Following on this thread from June, I have obtained a starter lightcurve for the pair using both the Lowell 0.7-m and 1.1-m telescopes + V filter. The system is hardly variable, with full amplitude of only 0.02 mag and period about 12 days. The provisional phased lightcurve is here:
ftp://ftp.lowell.edu/pub/bas/vardat/Kruger_60-temp.PNG
The rms scatter on the simple sine fit is .005 mag. I will continue this until the phase coverage is more secure.
\Brian