Mysterious case of nu Octantis

Our results for this weird radial velocity system. Presented at Extreme Solar Systems 3 in Hawaii.

Transcript

1. Center for Exoplanets and Habitable Worlds ν Octantis: a conjectured circumprimary retrograde planet in a spectroscopic binary system Benjamin Nelson (PSU è NU) David Ramm1, Mike Endl2, Fraser Gunn1, John Hearnshaw1, Pam Kilmartin1, Christoph Bergmann1, Erik Brogt1 Extreme Solar Systems 3 1. University of Canterbury December 3, 2015 2. UT Austin
2. A spectroscopic binary... $8 $8 GD\V GD\V 0䎭 0䎭 0- Credit: Ramm+09 Extreme Solar Systems 3 December 3, 2015
3. $8 $8 GD\V GD\V 0䎭 0䎭 0- ...with a strong periodicity in residuals Extreme Solar Systems 3 December 3, 2015 Credit: Ramm+09 ? ? ?
4. Circumprimary retrograde orbits can be stable... Extreme Solar Systems 3 December 3, 2015 Credit: OGRE (github.com/dtamayo/OGRE) Initial conditions from Goździewski+ 2013 Originally proposed Eberle & Cuntz 2010 With parameter uncertainties Quarles+ 2012 Full n-body+stability fits Goździewski+ 2013
5. Extreme Solar Systems 3 December 3, 2015 140 145 150 155 160 165 170 175 180 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.4 relative inclination ip [deg] semi-major axis ap [au] Credit: Goździewski+ 2013 ...especially if nearly coplanar
6. Extreme Solar Systems 3 December 3, 2015 New radial velocities Ÿ CCF (old detector) w CCF (new detector) ✕ Iodine No. of observations: 222 è 1437 Baseline (years): 5 è 12.5
7. Extreme Solar Systems 3 December 3, 2015 1. Starspots or pulsations Testing 3 theories for the 400 day periodicity
8. Extreme Solar Systems 3 December 3, 2015 1. Starspots or pulsations 2. Orbital precession in a hierarchical triple (Morais & Correia 2012) Testing 3 theories for the 400 day periodicity ˙ ! ⇡ 0.86 deg/yr
9. Extreme Solar Systems 3 December 3, 2015 1. Starspots or pulsations 2. Orbital precession in a hierarchical triple (Morais & Correia 2012) 3. Retrograde planet scenario Testing 3 theories for the 400 day periodicity ˙ ! ⇡ 0.86 deg/yr
10. Extreme Solar Systems 3 December 3, 2015 1. starspots or pulsations Credit: Ramm 2015 RV amp~50m/s ΔT~200K
11. Extreme Solar Systems 3 December 3, 2015 1. starspots or pulsations Credit: Ramm 2015 Low temperature variability RV amp~50m/s ΔT~200K
12. Extreme Solar Systems 3 December 3, 2015 1. starspots or pulsations Low photometric variability Credit: Ramm 2015 HIPPARCOS Converted from temperatures Low temperature variability RV amp~50m/s ΔT~200K
13. Extreme Solar Systems 3 December 3, 2015 2. orbital precession Prediction: -0.86 deg/year
14. Extreme Solar Systems 3 December 3, 2015 2. orbital precession Prediction: -0.86 deg/year ω=74.6° ω=75.0° 1. ω measured from sub-datasets
15. Extreme Solar Systems 3 December 3, 2015 2. orbital precession Prediction: -0.86 deg/year ω=74.6° ω=75.0° 1. ω measured from sub-datasets 2. Fitting precessing Keplerian
16. Extreme Solar Systems 3 December 3, 2015 3. retrograde planet scenario
17. Extreme Solar Systems 3 December 3, 2015 3. retrograde planet scenario + = ... with 3D orbital model! (Nelson+ 2014a) RV Using N-body Differential evolution MCMC
18. Extreme Solar Systems 3 December 3, 2015 Old data do not constrain orbital properties precisely
19. Extreme Solar Systems 3 December 3, 2015 New data favor retrograde and moderately inclined orbits...
20. Extreme Solar Systems 3 December 3, 2015 New data favor retrograde and moderately inclined orbits... 152.5±0.7°
21. Extreme Solar Systems 3 December 3, 2015 140 145 150 155 160 165 170 175 180 1 1.05 1.1 1.15 1.2 1.25 1.3 1.35 1.4 relative inclination ip [deg] semi-major axis ap [au] ...but none of the models are stable Credit: Goździewski+ 2013
22. Extreme Solar Systems 3 December 3, 2015 Locally stable solutions near posterior mode
23. Extreme Solar Systems 3 December 3, 2015 Discussion and Looking Forward Spots/pulsations/hierarchical triple are unlikely scenarios. Observations constrain an inclined retrograde configuration, but posterior samples aren’t dynamically stable.
24. Extreme Solar Systems 3 December 3, 2015 Discussion and Looking Forward Spots/pulsations/hierarchical triple are unlikely scenarios. Observations constrain an inclined retrograde configuration, but posterior samples aren’t dynamically stable. If real, the planet would be an extraordinary discovery and a challenge to planet formation. - Still requires some extraordinary evidence
25. Extreme Solar Systems 3 December 3, 2015 Discussion and Looking Forward Spots/pulsations/hierarchical triple are unlikely scenarios. Observations constrain an inclined retrograde configuration, but posterior samples aren’t dynamically stable. If real, the planet would be an extraordinary discovery and a challenge to planet formation. - Still requires some extraordinary evidence - Hints of other retrograde binary planets? (HR 2877, Trifonov+: P117.03)
26. Extreme Solar Systems 3 December 3, 2015 Discussion and Looking Forward Spots/pulsations/hierarchical triple are unlikely scenarios. Observations constrain an inclined retrograde configuration, but posterior samples aren’t dynamically stable. If real, the planet would be an extraordinary discovery and a challenge to planet formation. - Still requires some extraordinary evidence - Hints of other retrograde binary planets? (HR 2877, Trifonov+: P117.03) Future work - Independent RV observations (w/ e.g. CHIRON, HARPS-S) - 9/2016: maximum binary separation (0.12”) (w/ e.g. GPI, SPHERE, MagAO) - ν Oct explained via some exotic scenario? (e.g. MARVELS-1: Wright+ 2013)
27. Extreme Solar Systems 3 December 3, 2015 Discussion and Looking Forward Spots/pulsations/hierarchical triple are unlikely scenarios. Observations constrain an inclined retrograde configuration, but posterior samples aren’t dynamically stable. If real, the planet would be an extraordinary discovery and a challenge to planet formation. - Still requires some extraordinary evidence - Hints of other retrograde binary planets? (HR 2877, Trifonov+: P117.03) Future work - Independent RV observations (w/ e.g. CHIRON, HARPS-S) - 9/2016: maximum binary separation (0.12”) (w/ e.g. GPI, SPHERE, MagAO) - ν Oct explained via some exotic scenario? (e.g. MARVELS-1: Wright+ 2013) ? ? Credit: OGRE (github.com/dtamayo/OGRE)
28. Extreme Solar Systems 3 December 3, 2015 Credit: Goździewski+ 2013 MENGO dynamical map
29. Extreme Solar Systems 3 December 3, 2015 90 120 150 180 210 240 270 150 160 170 180 190 200 210 ∆ϖ=(ωp +Ωp )-(ωbin +Ωbin ) [deg] Ωp -Ωbin [deg] Credit: Goździewski+ 2013 Stability prefers apsidal alignment
30. Extreme Solar Systems 3 December 3, 2015 No variability in Ca II H & K Credit: Ramm 2015