As part of the collaboration that we (AAVSO Exoplanet Section) have with our counterparts at the BAA, we discovered from TESS data a long period (202 day) eclipsing binary that appears to be in an eccentric orbit given the time differences of the primary and secondary eclipses. However, we have seen that some of the primary eclipses have a “brightening” during the primary eclipse ( see attached). What typically would cause such a brightening?
Dennis Conti
Perhaps this is also a Heartbeat star?
Jiashuo Zhang
I agree with Jiashuo. Can you show a phase plot?
This is the Heartbeat (HB) definition from VSX:
Heartbeat stars. A type of eccentric binary stars (e >0.2) whose light curves resemble a cardiogram. They are ellipsoidal variables that undergo extreme dynamic tidal forces. As the two stars pass through periastron, brightness variations occur as a consequence of tidal deformation and mutual irradiation. There may also be tidally induced pulsations present. The morphology of the photometric periastron variation (heartbeat) depends strongly on the eccentricity, inclination and argument of periastron. The amplitude of variations is very small, usually below 0.01 mag. but it may exceed 0.3 mag. in extreme cases.
69 out of 275 HB stars in VSX also show eclipses.
Cheers,
Sebastian
You say “some of the primary eclipses” have this effect. Can you show more examples of eclipses that do and those that don’t? You have to be very careful about systematics with TESS data and ensure that you’re not seeing an instrumental issue.
We were discussing this in private with Dennis, I forgot to follow the discussion here, apologies!
I checked TESS data and indeed they were all artifacts. I have removed them and there is no additional variability, so it is not a heartbeat system, even when the orbit is indeed very eccentric. The eclipse duration is very different between Min I and II.
I have added the object to VSX.
Cheers,
Sebastian
