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doubt about a new variable star

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doubt about a new variable star

Hallo to all , we are new to this forum. We are two friends who like to observe and to search new variable stars . After some submissions of new variable stars , now we have some doubts about this last discovery . The first problem is about the period : we have found two periods , the first one is 0.81 d and seems to be compatible with a asymmetrical EA type variable star , while the second one is 1.63 d but in this case it seems to be  maybe a EA type with one of the two to be an intrinsic variable . 

The second doubt is about the fact that the star is overlayed to a faint galaxy , as you can see in the image in attach . We know the deblending routine when the star is contaminated by a companion , but what in this  case ? 

We will appreciate any help from this forum.

Thanks to all.

Andrea Ferrero and Roberto Bonamico _ P-VASSAR project .

mishnik's picture
You need more data from the

You need more data from the main directories or the coordinates of the object.


Further data related to the star

Catalog data:

2MASS J= 13.079, K= 12.378, J-K= 0.701

GALEX-DR5 NUV= 21.085

AllWISE W1= 12.172, W2= 12.138, W3= 11.291, W4= 8.277, W1-W2= 0.034, W3-W4= 3.014

APASS-DR9 B= 16.314, V= 15.321, B-V= 0.993

Andrea Ferrero and Roberto Bonamico _ P-VASSAR project .

mishnik's picture
I think that if there is

I think that if there is ultraviolet, it means that the system is interacting. Starting from the phase curve, the period 1.6d is more real for this system. Check for X-rays. I would classify this system as EA / RS.


Thank you for your answer.

Thank you for your answer.

Some idea for the galaxy deblend?

Clear skies

Andrea e Roberto P-VASSAR Peoject

mishnik's picture
Debling is needed. But it can

Debling is needed. But it can affect the magnitude and limits.


BGW's picture

I see arguments in favour of both the 0.8 and 1.6 days periods.

1.6 day:  the two eclipses seem to have different depths, which supports one being primary, and the other secondary.  But then the "wave" in the out-of-eclipse (OOE) brightness seems to be unusual.  It has two cycles per period of the orbit.  This is compatible with ellipsoidal variations, except the eclipses should occur at minima of the wave, but they don't.  (But would such a LC be possible with sub/super-synchronous rotation of the ellipsoidal star?)  Alternatively, the OOE wave could be RS CVn - type variations.  But then it is remarkable that the LC requires two signficant antipodean spots. Possible, but I don't know how likely it is.  If the OOE wave is due to intrinsic variability, then it is remarkable that there are two pulsations per orbital cycle, with the period of pulsations being 0.8 days.

0.8 day:  The OOE wave is compatible with RS CVn variations with one large dominant spot, but this doesn't honour the different eclipse depths.  And of course, it is compatible with 0.8 day pulsations.  The data does look a bit "smeared" when phased at 0.8 days

I would conduct further observations/research:

1) get B-V or other colour data to see if this supports or can distinguish the RS CVn or pulsational models

2) confirm the differing eclipse depths with repeated observations

3) monitor the out-of-eclipse variations and see if they change with time.  Is it consistent with spots changing with time?  Or pulsations not exactly in sync with the eclipses.

4) as Mishevskiy Nikolay said, look for X-ray data.  And a spectrum if possible.

5) look for lightcurves of candidate similar systems:  RS CVns with two maxima per cycle, or a pulsator with 0.8 day period synced with a period 1/2 the period of a binary orbit, or ellipsoidal variation with eclipse displaced from the minimum.

Gary Billings



This star cannot be exhibiting either ellipsoidal or reflection. However, there is one rather unusual (possibly crazy) possibility: Doppler boosting. This is a relativistic effect where the light is boosted as the star is coming towards you and dimmed as the star goes away from you. The signal in the light curve would have max/min and 0.25/0.75 and go through "zero" at 0.0 and 0.5, which is almost exactly what your light curve does in the phased on 0.8 d. All that being said, while it fits the observations this explanation is still highly unlikely. Generally boosting is a very small effect, much less than a millimag. The only time it is on the milli-mag level way is if the stars are moving really fast (several hundreds  of km/s). This is really only likely if these stars are fairly massive. 

Anyway, while i don't think answer is likely it is a fun rabbit hole to at least try and see if it makes sense.


Bert Pablo
Staff Astronomer, AAVSO

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