Gas Giants

Strong Correlation Between Inner Super-Earths And Outer Gas Giant

By Keith Cowing
Status Report
March 15, 2024
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Strong Correlation Between Inner Super-Earths And Outer Gas Giant
Left: Average completeness map for the super-Earth RV sample with detected gas giants overplotted in teal. Right: Average completeness map for the super-Earth transit sample with detected gas giants overplotted in teal. Color scale represents detection probability. On average, the RV sample has higher completeness to distant gas giants typically driven by much longer time baselines and more data points. Accounting for differences in individual system sensitivity as well as these broad trends between transit and RV samples is key to calculating frequencies of gas giants in our sample of super-Earth systems. — astro-ph.EP

The connection between outer gas giants and inner super-Earths reflects their formation and evolutionary histories. Past work exploring this link has suggested a tentative positive correlation between these two populations, but these studies have been limited by small sample sizes and in some cases sample biases.

Here we take a new look at this connection with a sample of 184 super-Earth systems with publicly available radial velocity data and fully resolved outer gas giants. We calculate the frequency of outer gas giants (GG) in super-Earth (SE) systems, dividing our sample into metal-rich ([Fe/H] > 0) and metal-poor ([Fe/H]≤0) hosts.

We find P(GG|SE, [Fe/H]>0) = 28.0+4.9−4.6% and P(GG|SE, [Fe/H]≤0) = 4.5+2.6−1.9%. Comparing these conditional occurrence rates to field giant occurrence rates from Wittenmyer et al. 2020, we show that there is a distinct positive correlation between inner super-Earths and outer gas giants for metal-rich host stars at the 2.5σ level, but this correlation disappears for metal-poor systems.

We further find that, around metal-rich stars, the GG/SE correlation enhances for systems with giants that are more distant (beyond 3 AU) and/or more eccentric (e>0.2), while gas giant multiplicity does not appear to affect the level of correlation. Such trends again disappear around metal-poor stars with the exception of systems of multiple giants in which we observe an anti-correlation.

Our findings highlight the critical role metallicity (disk solid budget) plays in shaping the overall planetary architecture.

Marta L. Bryan, Eve J. Lee

Comments: submitted to ApJL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2403.08873 [astro-ph.EP] (or arXiv:2403.08873v1 [astro-ph.EP] for this version)
Submission history
From: Marta Bryan
[v1] Wed, 13 Mar 2024 18:00:12 UTC (1,087 KB)

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