CoRoT-9 system update

Bonomo et al. "A deeper view of the CoRoT-9 planetary system. A small non-zero eccentricity for CoRoT-9b likely generated by planet-planet scattering"
https://arxiv.org/abs/1703.06477

The significance of the orbital eccentricity is now 3.6σ, the scenario they suggest is ejection of a ~50 Earth mass planet. There is no evidence for additional planets in the system.

There is also mention of a forthcoming paper about the search for rings and moons around the planet from the Spitzer observations.

Quote :

Both Spitzer observations were secured with the Channel 2 at 4.5µm of the IRAC camera (Fazio et al. 2004). These infrared observations and their reduction are described in Lecavelier des Étangs et al. (2017, submitted) who present a search for signatures of rings and satellites around CoRoT-9b.

(Emphasis mine)

"...the 2010 Spitzer transit light curve shows two residual systematic effects (Lecavelier des
Etangs et al. 2017): first, it presents a “bump” near the middle of the transit, which is unlikely to be due to the crossing of a large starspot by the planet given that the host star is very quiet (no activity features are seen in the CoRoT light curve); secondly, the transit is significantly deeper than that observed in 2011 by ∼ 13% (see Fig. 1 and Sect. 4.1). This larger depth cannot be attributed to unocculted starspots because it would imply a spot filling factor of ∼ 40%3 that is again unrealistic for the CoRoT-9 low activity level..."

Do you think we have a signature of an exomoon ?

Led_Zep wrote:

Do you think we have a signature of an exomoon ?

They describe it as a systematic effect, so it doesn't sound like it. We will have to wait for the Lecavelier des Étangs et al. paper to find out more.

Lecavelier des Etangs et al. "Search for rings and satellites around the exoplanet CoRoT-9b using Spitzer photometry"
https://arxiv.org/abs/1705.01836

No detection. Moons larger than 2.5 Earth radii are excluded at 3σ, though given this would be a very large moon they do note that this is "not very constraining". For rings filling the Roche limit, rocky rings are excluded if they are more than 13° from edge-on, while ice rings (or material with a similar density) are excluded for angles more than 3° from edge on.

I think icy rings would be impossible anyway.