A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models

Stefánsson, Guðmundur; Mahadevan, Suvrath; Miguel, Yamila; Robertson, Paul; Delamer, Megan; Kanodia, Shubham; Cañas, Caleb I.; Winn, Joshua N.; Ninan, Joe P.; Terrien, Ryan C.; Holcomb, Rae; Ford, Eric B.; Zawadzki, Brianna; Bowler, Brendan P.; Bender, Chad F.; Cochran, William D.; Diddams, Scott; Endl, Michael; Fredrick, Connor; Halverson, Samuel; Hearty, Fred; Hill, Gary J.; Lin, Andrea S. J.; Metcalf, Andrew J.; Monson, Andrew; Ramsey, Lawrence; Roy, Arpita; Schwab, Christian; Wright, Jason T.; Zeimann, Gregory

doi:10.1126/science.abo0233

Cited by 8 publications

(2 citation statements)

References 83 publications

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“…However, we emphasize that such measurements should be done under the same definition of CJs (100 M ⊕ M p 13.6 M J , 1 a 5 au); otherwise, they cannot be directly compared with the results in this work. Ground-based blind RV surveys, notably in the nearinfrared band, definitely provide a pathway to constrain the η CJ around M dwarfs (e.g., Morales et al 2019;Stefansson et al 2023). Microlensing (Mao & Paczynski 1991;Gould & Loeb 1992) and direct imaging (Montet et al 2014;Zhang et al 2021) have also shown their capability in discovering cold giants around M stars, though the detection rates of these two techniques are relatively low.…”

Section: Future Prospectsmentioning

confidence: 99%

Relative Occurrence Rate between Hot and Cold Jupiters as an Indicator to Probe Planet Migration

Gan,

Guo,

Liu

et al. 2024

ApJ

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We propose a second-order statistic parameter ε, the relative occurrence rate between hot Jupiters (HJs) and cold Jupiters (CJs) (ε = η HJ/η CJ), to probe the migration of gas giants. Since the planet occurrence rate is the combined outcome of the formation and migration processes, a joint analysis of HJ and CJ frequency may shed light on the dynamical evolution of giant planet systems. We first investigate the behavior of ε as the stellar mass changes observationally. Based on the occurrence rate measurements of HJs (η HJ) from the Transiting Exoplanet Survey Satellite survey and CJs (η CJ) from the California Legacy Survey, we find a tentative trend (97% confidence) that ε drops when the stellar mass rises from 0.8 to 1.4 M ⊙, which can be explained by different giant planet growth and disk migration timescales around different stars. We carry out planetesimal and pebble accretion simulations, both of which can reproduce the results of η HJ, η CJ, and ε. Our findings indicate that the classical core accretion + disk migration model can explain the observed decreasing trend of ε. We propose two ways to increase the significance of the trend and verify the anticorrelation. Future works are required to better constrain ε, especially for M dwarfs and for more massive stars.

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Section: Future Prospectsmentioning

confidence: 99%

Relative Occurrence Rate between Hot and Cold Jupiters as an Indicator to Probe Planet Migration

Gan,

Guo,

Liu

et al. 2024

ApJ

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“…The existence of a few giant planets around mid-to late (later than M3) M stars has challenged the core accretion planet formation theory (e.g., Morales et al 2019;Stefánsson et al 2023). Planet population synthesis simulations often fail to form any giant planet around these very low mass stars, in both the planetesimal accretion case (e.g., Miguel et al 2020) and the pebble accretion case (e.g., Liu et al 2019;Burn et al 2021;Mulders et al 2021;Schlecker et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Small and Large Dust Cavities in Disks around Mid-M Stars in Taurus

Shi 施,

Long 龙,

Herczeg 沈

et al. 2024

ApJ

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High angular resolution imaging by Atacama Large Millimeter/submillimeter Array (ALMA) has revealed the near universality and diversity of substructures in protoplanetary disks. However, disks around M-type pre-main-sequence stars are still poorly sampled, despite the prevalence of M dwarfs in the Galaxy. Here we present high-resolution (∼50 mas, 8 au) ALMA Band 6 observations of six disks around mid-M stars in Taurus. We detect dust continuum emission in all six disks, 12CO in five disks, and 13CO line in two disks. The size ratios between gas and dust disks range from 1.6 to 5.1. The ratio of about 5 for 2M0436 and 2M0450 indicates efficient dust radial drift. Four disks show rings and cavities, and two disks are smooth. The cavity sizes occupy a wide range: 60 au for 2M0412, and ∼10 au for 2M0434, 2M0436, and 2M0508. Detailed visibility modeling indicates that small cavities of 1.7 and 5.7 au may hide in the two smooth disks 2M0450 and CIDA 12. We perform radiative transfer fitting of the infrared spectral energy distributions to constrain the cavity sizes, finding that micron-sized dust grains may have smaller cavities than millimeter grains. Planet–disk interactions are the preferred explanation to produce the large 60 au cavity, while other physics could be responsible for the three ∼10 au cavities under current observations and theories. Currently, disks around mid- to late M stars in Taurus show a higher detection frequency of cavities than earlier-type stars, although a more complete sample is needed to evaluate any dependence of substructure on stellar mass.

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A hot-Jupiter progenitor on a super-eccentric retrograde orbit

Gupta,

Millholland,

et al. 2024

Nature

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Giant exoplanets orbiting close to their host stars are unlikely to have formed in their present configurations1. These ‘hot Jupiter’ planets are instead thought to have migrated inward from beyond the ice line and several viable migration channels have been proposed, including eccentricity excitation through angular-momentum exchange with a third body followed by tidally driven orbital circularization2,3. The discovery of the extremely eccentric (e = 0.93) giant exoplanet HD 80606 b (ref. 4) provided observational evidence that hot Jupiters may have formed through this high-eccentricity tidal-migration pathway5. However, no similar hot-Jupiter progenitors have been found and simulations predict that one factor affecting the efficacy of this mechanism is exoplanet mass, as low-mass planets are more likely to be tidally disrupted during periastron passage6–8. Here we present spectroscopic and photometric observations of TIC 241249530 b, a high-mass, transiting warm Jupiter with an extreme orbital eccentricity of e = 0.94. The orbit of TIC 241249530 b is consistent with a history of eccentricity oscillations and a future tidal circularization trajectory. Our analysis of the mass and eccentricity distributions of the transiting-warm-Jupiter population further reveals a correlation between high mass and high eccentricity.

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A Neptune-mass exoplanet in close orbit around a very low-mass star challenges formation models

Cited by 8 publications

References 83 publications

Relative Occurrence Rate between Hot and Cold Jupiters as an Indicator to Probe Planet Migration

Relative Occurrence Rate between Hot and Cold Jupiters as an Indicator to Probe Planet Migration

Small and Large Dust Cavities in Disks around Mid-M Stars in Taurus

A hot-Jupiter progenitor on a super-eccentric retrograde orbit

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