Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Aliases #49

Open
astudillo-defru opened this issue Aug 7, 2018 · 6 comments
Open

Aliases #49

astudillo-defru opened this issue Aug 7, 2018 · 6 comments

Comments

@astudillo-defru
Copy link

Hi,
kima favors a 2 planets model but the posterior distribution of the orbital periods shows that one is the 1-day alias of the other. How can I prevent this?
Thank you!

@eggplantbren
Copy link
Collaborator

Do you know whether the ambiguity is genuine? If it is, there's nothing you can do (but it should favour a one planet model, sometimes with one period and sometimes with the other period). If it is really just an alias (and this is clear given the data), then this shouldn't happen and I can't figure out why it is happening without more information.

@astudillo-defru
Copy link
Author

Thanks for your reply. I am (analytically) sure it is the genuine 1 day alias. In addition, the periodogram of RV residues when subtracting one of the periodicity do not show power excess at the alias periodicity. The posterior distribution of the orbital periods from kima shows both (alias) periodicities at the same time. What additional information do you need?

@j-faria
Copy link
Owner

j-faria commented Aug 8, 2018

I'm also surprised the two planet model is favoured because that means solutions with keplerians at the two periods together fit the data better.
In cases with an alias I would expect two nearly equal peaks in the period posterior but the one planet model being preferred.

There is no 3rd signal in the data?

As a 'solution' (a workaround, really) try restricting the prior to periods above 1 day.

@eggplantbren
Copy link
Collaborator

In addition, the periodogram of RV residues when subtracting one of the periodicity do not show power excess at the alias periodicity.

In this situation, kima should not be inferring both frequencies. Is it possible to provide the data?

@astudillo-defru
Copy link
Author

Thank you for the support, but sorry, for the moment I can not provide the data

@eggplantbren
Copy link
Collaborator

eggplantbren commented Aug 14, 2018 via email

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
None yet
Projects
None yet
Development

No branches or pull requests

3 participants