Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets

AbstractOwing to their small masses and radii, Ultracool Dwarfs (UCDs; late-M, L, and T dwarfs) may be excellent targets for planet searches and may afford astronomers the opportunity to detect terrestrial planets in the habitable zone. The precise measurements necessary to detect extrasolar planets orbiting UCDs represent a major challenge. We describe two efforts to obtain precise measurements of UCDs in the Near Infrared (NIR). The first involves the robotic NIR observatory PAIRITEL and efforts to obtain photometric precision sufficient for the detection of terrestrial planets transiting UCDs. The second effort involves precise radial velocity measurements of UCDs in the NIR and a survey undertaken with the NIRSPEC spectrograph on Keck.

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Formation of Habitable Planets in Inclined Planetary Systems

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313012908 ◽

2012 ◽

Vol 8 (S293) ◽

pp. 238-240

Author(s):

Jianghui Ji ◽

Sheng Jin

Keyword(s):

Late Stage ◽

Planetary Systems ◽

Numerical Results ◽

The Other ◽

Terrestrial Planets ◽

Habitable Zone ◽

Planetary Formation ◽

Habitable Planets ◽

Final Assembly ◽

Inner Region

AbstractWe extensively investigate the terrestrial planetary formation for the inclined planetary systems (considering the OGLE-2006-BLG-109L system as example) in the late stage. In the simulations, we show that the occurrence of terrestrial planets appears to be common in the final assembly stage. Moreover, we find that a lot of runs finally occupy at least one planet in the habitable zone (HZ). On the other hand, the numerical results also indicate that the inner region of the planetesimal disk, ranging from ~ 0.1 to 0.3 AU, plays an important role in building up terrestrial planets. The outcomes suggest that it may exist moderate possibility for the inclined systems to harbor terrestrial planets in the HZ.

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Physical properties of terrestrial planets and water delivery in the habitable zone using N-body simulations with fragmentation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936061 ◽

2019 ◽

Vol 632 ◽

pp. A14 ◽

Cited By ~ 3

Author(s):

A. Dugaro ◽

G. C. de Elía ◽

L. A. Darriba

Keyword(s):

Terrestrial Planets ◽

Habitable Zone ◽

Water Delivery ◽

Class A ◽

Class B ◽

Solar Type ◽

Formation And Evolution ◽

Final Fraction ◽

The Masses ◽

Water Contents

Aims. The goal of this research is to study how the fragmentation of planetary embryos can affect the physical and dynamical properties of terrestrial planets around solar-type stars. Our study focuses on the formation and evolution of planets and water delivery in the habitable zone (HZ). We distinguish class A and class B HZ planets, which have an accretion seed initially located inside and beyond the snow line, respectively. Methods. We developed an N-body integrator that incorporates fragmentation and hit-and-run collisions, which is called D3 N-body code. From this, we performed 46 numerical simulations of planetary accretion in systems that host two gaseous giants similar to Jupiter and Saturn. We compared two sets of 23 N-body simulations, one of which includes a realistic collisional treatment and the other one models all impacts as perfect mergers. Results. The final masses of the HZ planets formed in runs with fragmentation are about 15–20% lower than those obtained without fragmentation. As for the class A HZ planets, those formed in simulations without fragmentation experience very significant increases in mass with respect to their initial values, while the growth of those produced in runs with fragmentation is less relevant. We remark that the fragments play a secondary role in the masses of the class A HZ planets, providing less than 30% of their final values. In runs without fragmentation, the final fraction of water of the class A HZ planets keeps the initial value since they do not accrete water-rich embryos. In runs with fragmentation, the final fraction of water of such planets strongly depends on the model used to distribute the water after each collision. The class B HZ planets do not show significant differences concerning their final water contents in runs with and without fragmentation. From this, we find that the collisional fragmentation is not a barrier to the survival of water worlds in the HZ.

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Obliquity Variability of Terrestrial Planets in the Habitable Zone

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319000061 ◽

2018 ◽

Vol 14 (S345) ◽

pp. 291-292

Author(s):

Yutong Shan ◽

Gongjie Li

Keyword(s):

Solar System ◽

Analytical Techniques ◽

Spin Axis ◽

Current Understanding ◽

Terrestrial Planets ◽

Habitable Zone ◽

Axial Tilt

AbstractObliquity (axial tilt) and its variability could play an important role in the climate and habitability of a planet. We explore the spin-axis dynamics of two specific habitable zone exoplanets, Kepler-62f and Kepler-186f, using numerical and analytical techniques. Based on our current understanding of their orbital architecture, we find that, in contrast with the typical conditions in the Solar System, Kepler-62f and 186f should have low obliquity variations except in fine-tuned conditions. Extra undetected planetary companions and/or the existence of a satellite could either stabilize or destabilize obliquities at a variety of values.

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Water delivery to dry protoplanets by hit-and-run collisions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318008621 ◽

2018 ◽

Vol 14 (S345) ◽

pp. 287-288

Author(s):

Christoph Burger ◽

Thomas I. Maindl ◽

Christoph Schäfer

Keyword(s):

Terrestrial Planets ◽

Habitable Zone ◽

Water Delivery ◽

Smooth Particle Hydrodynamics ◽

Particle Hydrodynamics ◽

Hit And Run

AbstractFinal water inventories of newly formed terrestrial planets are shaped by their collision history. A setting where volatiles are transported from beyond the snowline to habitable-zone planets suggests collisions of very dry with water-rich bodies. By means of smooth particle hydrodynamics (SPH) simulations we study water delivery in scenarios where a dry target is hit by a water-rich projectile, focusing on hit-and-run encounters with two large surviving bodies, which probably comprise about half of all similar-sized collisions (Genda et al. 2017).

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Formation, Frequency and Spacing of Habitable Planets

International Astronomical Union Colloquium ◽

10.1017/s0252921100014809 ◽

1997 ◽

Vol 161 ◽

pp. 289-297

Author(s):

Jack J. Lissauer

Keyword(s):

Planet Formation ◽

Orbital Stability ◽

Young Stars ◽

Giant Planets ◽

Terrestrial Planets ◽

Habitable Zone ◽

Habitable Planets ◽

Habitable Zones ◽

Planetary Orbits ◽

Rocky Planets

AbstractModels of planet formation and of the orbital stability of planetary systems are described and used to discuss estimates of the abundance of habitable planets which may orbit stars within our galaxy. Modern theories of star and planet formation, which are based upon observations of the Solar System and of young stars and their environments, predict that most single stars should have rocky planets in orbit about them. Terrestrial planets are believed to grow via pairwise accretion until the spacing of planetary orbits becomes large enough that the configuration is stable for the age of the system. Giant planets orbiting within or near the habitable zone could either prevent terrestrial planets from forming, destroy such planets or remove them from habitable zones. The implications of the giant planets found in recent radial velocity searches for the abundances of habitable planets are discussed.

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