Most Planets Might Have More than 5 Myr of Time to Form

Pfalzner, Susanne; Dehghani, Shahrzad; Michel, Arnaud

doi:10.3847/2041-8213/ac9839

Cited by 25 publications

(20 citation statements)

References 70 publications

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“…3), because gas is more bound for higher-mass stars. This positive correlation is at odds with observations that find that disc lifetimes are either independent of or anticorrelated with stellar mass (Carpenter et al 2006;Kennedy & Kenyon 2009;Bayo et al 2012;Ribas et al 2015;Pfalzner et al 2022) and should be investigated in the future.…”

Section: Discussioncontrasting

confidence: 68%

“…It is difficult to reconcile the results of our synthetic disc populations with observations. We find that it is particularly hard to obtain discs with characteristic lifetimes of 2 to 3 Myr according to Mamajek (2009) or Fedele et al (2010), and even less lifetimes of 5 to 10 Myr following Pfalzner et al (2022). Here, we assumed that the initial mass is constrained by the dust-mass measurements of Tychoniec et al (2018, M D /M ∼ 10 −3 ) , and dust-to-gas ratios similar to the solar initial abundance, namely f D/G = 1.49 % (Lodders 2003), combined with the predictions of internal and external photoevaporation models.…”

Section: Discussionmentioning

confidence: 75%

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Towards a population synthesis of discs and planets. II. Confronting disc models and observations at the population level

Emsenhuber¹,

Burn²,

Weder³

et al. 2023

Preprint

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Aims. We want to find the distribution of initial conditions that best reproduces disc observations at the population level. Methods. We first ran a parameter study using a 1D model that includes the viscous evolution of a gas disc, dust, and pebbles, coupled with an emission model to compute the millimetre flux observable with ALMA. This was used to train a machine learning surrogate model that can compute the relevant quantity for comparison with observations in seconds. This surrogate model was used to perform parameter studies and synthetic disc populations.Results. Performing a parameter study, we find that internal photoevaporation leads to a lower dependency of disc lifetime on stellar mass than external photoevaporation. This dependence should be investigated in the future. Performing population synthesis, we find that under the combined losses of internal and external photoevaporation, discs are too short lived. Conclusions. To match observational constraints, future models of disc evolution need to include one or a combination of the following processes: infall of material to replenish the discs, shielding of the disc from internal photoevaporation due to magnetically driven disc winds, and extinction of external high-energy radiation. Nevertheless, disc properties in low-external-photoevaporation regions can be reproduced by having more massive and compact discs. Here, the optimum values of the α viscosity parameter lie between 3 × 10 −4 and 10 −3 and with internal photoevaporation being the main mode of disc dispersal.

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Section: Discussioncontrasting

confidence: 68%

Section: Discussionmentioning

confidence: 75%

Towards a population synthesis of discs and planets. II. Confronting disc models and observations at the population level

Emsenhuber¹,

Burn²,

Weder³

et al. 2023

Preprint

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show abstract

“…This would imply a formation timescale of ≈5-15 Myr, which would suggest formation via core accretion, which takes many Myr to operate, over rapid giant planet formation via disk instability. Typical protoplanetary disk lifetimes are 5-10 Myr for Sun-like and lower-mass (<2 M e ) stars (Pfalzner et al 2022). Other possibilities for resolving this discrepancy include a younger age of the system, young L/T transition objects being more luminous than predicted by current evolutionary models, and another planet in the system biasing the dynamical mass measurement.…”

Section: Orbit Fit and Dynamical Massmentioning

confidence: 99%

Astrometric Accelerations as Dynamical Beacons: A Giant Planet Imaged inside the Debris Disk of the Young Star AF Lep

Franson

Bowler

Zhou

et al. 2023

ApJL

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We present the direct-imaging discovery of a giant planet orbiting the young star AF Lep, a 1.2 M ⊙ member of the 24 ± 3 Myr β Pic moving group. AF Lep was observed as part of our ongoing high-contrast imaging program targeting stars with astrometric accelerations between Hipparcos and Gaia that indicate the presence of substellar companions. Keck/NIRC2 observations in L ′ with the vector vortex coronagraph reveal a point source, AF Lep b, at ≈340 mas, which exhibits orbital motion at the 6σ level over the course of 13 months. A joint orbit fit yields precise constraints on the planet’s dynamical mass of 3.2 − 0.6 + 0.7 M Jup, semimajor axis of 8.4 − 1.3 + 1.1 au, and eccentricity of 0.24 − 0.15 + 0.27 . AF Lep hosts a debris disk located at ∼50 au, but it is unlikely to be sculpted by AF Lep b, implying there may be additional planets in the system at wider separations. The stellar inclination (i * = 54 − 9 + 11 ° ) and orbital inclination (i o = 50 − 12 + 9 ° ) are in good agreement, which is consistent with the system having spin–orbit alignment. AF Lep b is the lowest-mass imaged planet with a dynamical mass measurement and highlights the promise of using astrometric accelerations as a tool to find and characterize long-period planets.

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“…The lifetime of disks of the TTSs appears to be strongly correlated with the stellar mass, as disks around more massive stars tend to dissipate more rapidly than those around less massive stars (e.g., Yao et al 2018;Luhman 2022a;Pfalzner et al 2022). Most K-and M-type stars are thought to be surrounded by disks at about 1 Myr (Barenfeld et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…The e-folding timescale of the disks for K-type TTSs is estimated to be 4.7 Myr (Pecaut & Mamajek 2016), while for M-type stars the disk should last much longer (Silverberg et al 2020), and the disk fraction is even still as high as about 9% at 20 Myr. Pfalzner et al (2022) suggested that low-mass stars have a median disk lifetime of 5-10 Myr. However, we should be aware that all the timescales mentioned above are for disks, not just for full disks.…”

Section: Introductionmentioning

confidence: 99%

Discovery of Two Different Full Disk Evolutionary Patterns of M-type T Tauri Stars with LAMOST DR8

Haerken 哈斯铁,

Li 李,

Li 李

et al. 2023

ApJ

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The full disk, full of gas and dust, determines the upper limit of planet masses, and its lifetime is critical for planet formation, especially for giant planets. In this work, we studied the evolutionary timescales of the full disks of T Tauri stars (TTSs) and their relations to accretion. Combined with Gaia EDR3, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer data, 1077 disk-bearing TTS candidates were found in LAMOST DR8, and stellar parameters were obtained. Among them, 783 are newly classified by spectra as classical T Tauri stars (CTTSs; 169) or weak-lined T Tauri stars (WTTSs). Based on EW and FWHM of Hα, 157 TTSs in accretion were identified, with ∼82% also having full disks. For TTSs with M < 0.35M ☉, about 80% seem to already lose their full disks at ∼0.1 Myr, which may explain their lower mass, while the remaining 20% with full disks evolve at similar rates of non-full disks within 5 Myr, allowing enough time and material to form giant planets. The fraction of accreting TTSs to disk-bearing TTSs is stable at ∼10% and can last ∼5–10 Myr, suggesting that full disks and accretion evolve with similar rates as non-full disks. For TTSs with M > 0.35 M ☉, almost all full disks can survive more than 0.1 Myr, most for 1 Myr and some even for 20 Myr. For TTSs with M > 0.35 M ☉, almost all full disks can survive more than 0.1 Myr, most for 1 Myr, and some even for 20 Myr, which implies planets are more likely to be formed in their disks than those of M < 0.35 M ☉, and thus M dwarfs with M > 0.35 M ☉ can have more planets. The fraction of full-disk TTSs to disk-bearing TTSs decreases with age following the relation f ∝ t −0.35, and similar relations existed in the fraction of accreting TTSs and the fraction of full-disk CTTSs, suggesting faster full disks and accretion evolution than non-full disks. For full-disk stars, the ratio of accretion of lower-mass stars is systematically lower than that of higher-mass stars, confirming the dependence of accretion on stellar mass, which may be reflective of an observational bias in the detection of accretion levels, with the lower-mass stars crossing below the detection threshold earlier than higher-mass stars.

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Most Planets Might Have More than 5 Myr of Time to Form

Cited by 25 publications

References 70 publications

Towards a population synthesis of discs and planets. II. Confronting disc models and observations at the population level

Towards a population synthesis of discs and planets. II. Confronting disc models and observations at the population level

Astrometric Accelerations as Dynamical Beacons: A Giant Planet Imaged inside the Debris Disk of the Young Star AF Lep

Discovery of Two Different Full Disk Evolutionary Patterns of M-type T Tauri Stars with LAMOST DR8

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