scholarly journals Searching for a dusty cometary belt around TRAPPIST-1 with ALMA

2020 ◽  
Vol 492 (4) ◽  
pp. 6067-6073 ◽  
Author(s):  
S Marino ◽  
M C Wyatt ◽  
G M Kennedy ◽  
M Kama ◽  
L Matrà ◽  
...  
Keyword(s):  
Liquid Water ◽  
Kuiper Belt ◽  
Dust Emission ◽  
Planetary Systems ◽  
Dynamical Instability ◽  
Solid Mass ◽  
Low Mass Stars ◽  
Upper Limit ◽  
Low Mass ◽  
Collisional Evolution

ABSTRACT Low-mass stars might offer today the best opportunities to detect and characterize planetary systems, especially those harbouring close-in low-mass temperate planets. Among those stars, TRAPPIST-1 is exceptional since it has seven Earth-sized planets, of which three could sustain liquid water on their surfaces. Here we present new and deep ALMA observations of TRAPPIST-1 to look for an exo-Kuiper belt which can provide clues about the formation and architecture of this system. Our observations at 0.88 mm did not detect dust emission, but can place an upper limit of 23 µJy if the belt is smaller than 4 au, and 0.15 mJy if resolved and 100 au in radius. These limits correspond to low dust masses of ∼10−5 to 10−2 M⊕, which are expected after 8 Gyr of collisional evolution unless the system was born with a >20 M⊕ belt of 100 km-sized planetesimals beyond 40 au or suffered a dynamical instability. This 20 M⊕ mass upper limit is comparable to the combined mass in TRAPPIST-1 planets, thus it is possible that most of the available solid mass in this system was used to form the known planets. A similar analysis of the ALMA data on Proxima Cen leads us to conclude that a belt born with a mass ≳1 M⊕ in 100 km-sized planetesimals could explain its putative outer belt at 30 au. We recommend that future characterizations of debris discs around low-mass stars should focus on nearby and young systems if possible.

scholarly journals Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. IV. Updated Properties for 86 Cool Dwarfs Observed during Campaigns 1–17

2019 ◽  
Vol 158 (2) ◽  
pp. 87 ◽  
Author(s):  
Courtney D. Dressing ◽  
Kevin Hardegree-Ullman ◽  
Joshua E. Schlieder ◽  
Elisabeth R. Newton ◽  
Andrew Vanderburg ◽  
...  
Keyword(s):  
Planetary Systems ◽  
Low Mass Stars ◽  
Low Mass ◽  
Cool Dwarfs

scholarly journals Modification of the Core Overshoot Treatment

2002 ◽  
Vol 207 ◽  
pp. 736-738
Author(s):  
Jong-Hak Woo ◽  
Pierre Demaque ◽  
Sukyoung Yi
Keyword(s):  
Conventional Method ◽  
Integral Constraint ◽  
Core Radius ◽  
Low Mass Stars ◽  
The Core ◽  
Upper Limit ◽  
Low Mass

Following Roxburgh's integral constraint, we implemented an upper limit of overshoot in the conventional method of α parameterization in order to remove an overly large overshoot effect for low-mass stars. The erroneously large effect of overshoot due to the failure of α parameterization can be effectively corrected by limiting the amount of overshoot to 15 % of the core radius.

scholarly journals Diverse outcomes of planet formation and composition around low-mass stars and brown dwarfs

2019 ◽  
Author(s):  
Y Miguel ◽  
A Cridland ◽  
C W Ormel ◽  
J J Fortney ◽  
S Ida
Keyword(s):  
Planet Formation ◽  
Planetary Systems ◽  
Brown Dwarfs ◽  
Population Synthesis ◽  
Optimal Conditions ◽  
Low Mass Stars ◽  
Water Fraction ◽  
Low Mass ◽  
M Stars ◽  
Mass Form

Abstract The detection of Earth-size exoplanets around low-mass stars –in stars such as Proxima Centauri and TRAPPIST-1– provide an exceptional chance to improve our understanding of the formation of planets around M stars and brown dwarfs. We explore the formation of such planets with a population synthesis code based on a planetesimal-driven model previously used to study the formation of the Jovian satellites. Because the discs have low mass and the stars are cool, the formation is an inefficient process that happens at short periods, generating compact planetary systems. Planets can be trapped in resonances and we follow the evolution of the planets after the gas has dissipated and they undergo orbit crossings and possible mergers. We find that formation of planets above Mars mass and in the planetesimal accretion scenario, is only possible around stars with masses M⋆ ≥ 0.07Msun and discs of Mdisc ≥ 10−2 Msun. We find that planets above Earth-mass form around stars with masses larger than 0.15 Msun, while planets larger than 5 M⊕ do not form in our model, even not under the most optimal conditions (massive disc), showing that planets such as GJ 3512b form with another, more efficient mechanism. Our results show that the majority of planets form with a significant water fraction; that most of our synthetic planetary systems have 1, 2 or 3 planets, but planets with 4,5,6 and 7 planets are also common, confirming that compact planetary systems with many planets should be a relatively common outcome of planet formation around small stars.

scholarly journals Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. III. A High Mass and Low Envelope Fraction for the Warm Neptune K2-55b

2018 ◽  
Vol 156 (2) ◽  
pp. 70 ◽  
Author(s):  
Courtney D. Dressing ◽  
Evan Sinukoff ◽  
Benjamin J. Fulton ◽  
Eric D. Lopez ◽  
Charles A. Beichman ◽  
...  
Keyword(s):  
Planetary Systems ◽  
High Mass ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals EFFECTS OF CHAOTIC “CLEARING” IN PLANETARY SYSTEMS

2019 ◽  
Vol 47 (1) ◽  
pp. 132-134
Author(s):  
I.I. Shevchenko
Keyword(s):  
Binary Star ◽  
Kuiper Belt ◽  
Planetary Systems ◽  
Cometary Nuclei ◽  
Body Contact ◽  
Mean Motion Resonances ◽  
First Order ◽  
Contact Binary ◽  
Low Mass ◽  
Orbital Resonances

The main types of chaotic clearing effects in planetary systems are considered. The clearing consists in the formation of orbital zones free from low-mass bodies (planetesimals, asteroids, particles, fragments), due to the dynamical chaotization in the presence of perturbations. The effects include: (1) the coorbital clearing – the formation of a ring-like clearance in the planetesimal disk due to the accumulation and overlap of «particle–planet» orbital (mean-motion) resonances of the first order in the radial neighborhood of a planetary orbit (Wisdom, 1980; Demidova, Shevchenko, 2016); (2) the circumbinary clearing – the formation of a whole circular clearance in the planetesimal disk around a binary star due to the overlap of «particle–binary» integer orbital resonances accumulating to the separatrix corresponding to the parabolic motion (Shevchenko, 2015); (3) the circumnuclear clearing – the formation of a whole circular clearance in the cloud of particles and fragments around a rotating irregularly-shaped body (contact binary, such as cometary nuclei, many objects in the Kuiper belt, and asteroids) due to the overlap of «particle – contact binary» integer orbital resonances, accumulating to the separatrix corresponding to the parabolic motion (Lages et al., 2017, 2018). Particular attention is paid to the latter case, as identified just recently. The research was supported by the RAS Presidium Program «Nonlinear dynamics: fundamental problems and applications».

scholarly journals The New Generation Planetary Population Synthesis (NGPPS). IV. Planetary systems around low-mass stars

2021 ◽  
Author(s):  
R. Burn ◽  
M. Schlecker ◽  
C. Mordasini ◽  
A. Emsenhuber ◽  
Y. Alibert ◽  
...  
Keyword(s):  
Planetary Systems ◽  
Population Synthesis ◽  
Low Mass Stars ◽  
Low Mass ◽  
New Generation

An upper limit on the density of low-mass stars in the Galactic halo

Nature ◽  
1994 ◽  
Vol 371 (6497) ◽  
pp. 493-495 ◽  
Author(s):  
E. M. Hu ◽  
J.-S. Huang ◽  
G. Gilmore ◽  
L. L. Cowie
Keyword(s):  
Galactic Halo ◽  
Low Mass Stars ◽  
Upper Limit ◽  
Low Mass

scholarly journals Characterizing K2 Candidate Planetary Systems Orbiting Low-mass Stars. I. Classifying Low-mass Host Stars Observed during Campaigns 1–7

2017 ◽  
Vol 836 (2) ◽  
pp. 167 ◽  
Author(s):  
Courtney D. Dressing ◽  
Elisabeth R. Newton ◽  
Joshua E. Schlieder ◽  
David Charbonneau ◽  
Heather A. Knutson ◽  
...  
Keyword(s):  
Planetary Systems ◽  
Low Mass Stars ◽  
Low Mass ◽  
Host Stars

scholarly journals PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS

2014 ◽  
Vol 216 (1) ◽  
pp. 7 ◽  
Author(s):  
Brendan P. Bowler ◽  
Michael C. Liu ◽  
Evgenya L. Shkolnik ◽  
Motohide Tamura
Keyword(s):  
Planetary Systems ◽  
Low Mass Stars ◽  
Low Mass ◽  
M Dwarf

scholarly journals Pebbles versus planetesimals: the case of Trappist-1

2019 ◽  
Vol 631 ◽  
pp. A7 ◽  
Author(s):  
G. A. L. Coleman ◽  
A. Leleu ◽  
Y. Alibert ◽  
W. Benz
Keyword(s):  
Water Content ◽  
Initial Conditions ◽  
Planetary Systems ◽  
Central Star ◽  
Low Mass Stars ◽  
Formation Pathway ◽  
Wide Range ◽  
Mass Size ◽  
Low Mass ◽  
Inner Region

We present a study into the formation of planetary systems around low mass stars similar to Trappist-1, through the accretion of either planetesimals or pebbles. The aim is to determine if the currently observed systems around low mass stars could favour one scenario over the other. To determine these differences, we ran numerous N-body simulations, coupled to a thermally evolving viscous 1D disc model, and including prescriptions for planet migration, photoevaporation, and pebble and planetesimal dynamics. We mainly examine the differences between the pebble and planetesimal accretion scenarios, but we also look at the influences of disc mass, size of planetesimals, and the percentage of solids locked up within pebbles. When comparing the resulting planetary systems to Trappist-1, we find that a wide range of initial conditions for both the pebble and planetesimal accretion scenarios can form planetary systems similar to Trappist-1, in terms of planet mass, periods, and resonant configurations. Typically these planets formed exterior to the water iceline and migrated in resonant convoys into the inner region close to the central star. When comparing the planetary systems formed through pebble accretion to those formed through planetesimal accretion, we find a large number of similarities, including average planet masses, eccentricities, inclinations, and period ratios. One major difference between the two scenarios was that of the water content of the planets. When including the effects of ablation and full recycling of the planets’ envelope with the disc, the planets formed through pebble accretion were extremely dry, whilst those formed through planetesimal accretion were extremely wet. If the water content is not fully recycled and instead falls to the planets’ core, or if ablation of the water is neglected, then the planets formed through pebble accretion are extremely wet, similar to those formed through planetesimal accretion. Should the water content of the Trappist-1 planets be determined accurately, this could point to a preferred formation pathway for planetary systems, or to specific physics that may be at play.

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